Researchin Nursing& Health, 1991, 14, 155-163
Development and Evaluation of the Osteoporosis Health Belief Scale Katherine K. Kim, Mary L. Horan, Phyllis Gendler, and Minu K. Patel
The Osteoporosis Health Belief Scale was developed to measure health beliefs related to osteoporosis. It is a 35-item self-report questionnaire based on the Health Belief Model which is specifically designed to assess beliefs related to exercise behaviors and calcium intake of elderly subjects. The instrument consists of seven subscales: Seriousness, Susceptibility, Health Motivation, Calcium Benefits, Calcium Barriers, Exercise Benefits, and Exercise Barriers. The instrument was tested on a sample of 150 elderly individuals. The psychometric properties of the scales are discussed along with recommendations for its use in research and practice.
The purpose of this study was to develop and evaluate the Osteoporosis Health Belief Scale which is based on the Health Belief Model. Osteoporosis is a major public health problem affecting as many as 15 to 20 million individuals in the United States (National Institute of Health [NIH], 1984). While both sexes are affected, osteoporosis is more prevalent in women. By age 90, 32% of women and 17% of men will have experienced a hip fracture primarily due to osteoporosis. Many fractures, particularly those of the spine, cause pain, deformity and disability, limiting activities and well-being of the elderly. It is estimated that the cost of osteoporosis in the United States is 10 billion dollars a year (Special Committee on Aging [SCA], 1989). The resulting hip fractures are associated with a 5-20% excess mortality within the first year (Conference Report, 1987). While osteoporosis is indeed costly to society, individual suffering, deformity, and disability profoundly affect the elderly’s emotional well-being and life satisfaction. For many elderly, the reduction of disability is more important than extending life (Persky & Alexander, 1989).
Important risk factors related to osteoporosis
are f d y history, menopause, inadequate calcium intake, and sedentary life style (Aloia, Cohn, Voswani, Yeh, Yuen, & Ellis, 1985; Spencer, 1982). Researchers have determined that the condition can be prevented or delayed in its development by a change in dietary habits and exercise (Heaney et al., 1982; SCA, vol. 2, 1988; Smith, Reddan, & Smith, 1981). The disease is manifested by a decrease in skeletal mass and density. The skeleton consists of two types of bone: trabecular bone which has a open meshwork structure and cortical bone which has a compact structure. Although the pathogenesis of osteoporosis is not completely understood, recent evidence supports two classifications. Type 1 osteoporosis is believed to be precipitated by menopause when there is a relatively brief period of bone loss affecting the trabecular bone. Clinical manifestations include vertebral crush fractures and Colles’ fractures of the wrist (Persky & Alexander, 1989). The major causes of postmenopausal osteoporosis are estrogen and calcium deficiencies (SCA, vol. l . , 1988). Type 2 osteoporosis occurs in both men and women
Katherine K. Kim, PhD, RN, is an associate professor in the Kirkhof School of Nursing, Grand Valley State University, Allendale, Michigan. Mary L. Horan, PhD, RN, is a professor in and the director of that school, and Phyllis Gendler, Ph(C), RNC, is an assistant professor in the same school. Minu K. Patel, MSC, is an assistant professor in the College of Nursing and Research Resources Center, University of Illinois at Chicago. This research was supported by a research and development grant from Grand Valley State University. The authors gratefully acknowledge the contributions of Victoria Champion, DNS, RN, Gordon Alderink, MS, Brian Curry, PhD, Pamela Oosterink, BS, and student assistants. This article was received on April 9, 1990, was revised, and accepted for publication August 10. 1990. Requests for reprints can be addressed to Dr. Katherine K. Kim. Kirkhof School of Nursing, Grand Valley State University, Allendale, MI 49401.
0 1991 John Wiley & Sons, Inc. 0160-6891/91/020155-09 $04.00
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over 75 years old (SCA, vol. 2, 1988) and is thought to be a consequence of age-related changes. Both cortical and trabecular bone are affected resulting in fractures of the hip and wedge deformities of the spine (Persky & Alexander, 1989). Although distinctions are being made for some clinical and research purposes, general health education literature and popular magazines do not distinguish between the two types of osteoporosis and recommend adequate amounts of calcium and exercise as appropriate methods for maintaining bone health. Additionally, although the role of calcium intake in the etiology of osteoporosis is controversial, health professionals consider it prudent to encourage adequate intake of calcium and moderate exercise in order to decrease the risk of osteoporosis (Conference Report, 1987; Consensus Conference, 1984; Cummings, Kelsey , Nevitt, & O’Dowd, 1986; Resnick & Greenspan, 1989; Santora, 1987). Nursing interventions related to osteoporosis prevention have consisted primarily of educational programs aimed at changing dietary and exercise habits. However, knowledge and skills gained from health education do not always translate into subsequent healthful behaviors. Therefore, it is important to consider the influence of other psychological variables in effecting behavior change. Identification of such variables could enhance individualization of health promotion strategies. Hence, the purpose of this study was to develop and test an instrument designed to measure personal attitudes and beliefs related to the potential for developing osteoporosis.
Health Be1ief Model Since its introduction in 1950, the Health Belief Model (HBM) has been used in a variety of studies of health behavior including disease detection and prevention (Janz & Becker, 1984). According to the model, a number of variables are associated with the likelihood of taking action to detect or prevent the occurrence of disease (Becker, 1985; Becker, Maiman, Kmcht, Haefner, & Drachman, 1977). Health behaviors are more likely to occur if an individual believes in personal susceptibility to the condition and, at the same time, perceives that having the condition would have serious consequences. The model also recognizes the impact of health motivation and perceived barriers and benefits to taking the healthful action. More recently, self-efficacy as a construct in explaining health behaviors and its integration in the HBM has been addressed (Rosenstock, Strecher, &
Becker, 1988). However, the present study was initiated prior to availability of relevant publications, therefore, self-efficacy as a concept was not included. The impact of the HBM on participation in disease detection has been studied by a variety of investigators (Becker, Kabeck, Rosenstock, & Ruth, 1975; Brailey, 1986; Champion, 1984, 1985, 1987, 1988; Hallal, 1982; Rutledge, 1987; Trotta, 1980). The results were varied, but suggested that certain HBM variables are useful in predicting specific behaviors. Champion (1984), concerned with the inconsistency in application of the model and the lack of valid and reliable instruments for measuring the constructs, developed and tested an instrument designed specifically for the study of the HBM variables as they relate to self breast examination (SBE). Her findings indicated that the variables of seriousness, benefits, barriers, and health motivation discriminated groups of women according to frequency of breast self-examination (Champion, 1985). A more recent study added knowledge as a variable and revealed that, along with knowledge, barriers and susceptibility were correlated with frequency of SBE (Champion, 1987). Specific investigations regarding the influence of the HBM variables in disease prevention and health maintenance behaviors also support the conceptualization (Becker et al., 1977; Cummings, Becker, Kirscht, & Levine, 1982; Dai & Catanzaro, 1987; Pederson, Walklin & Baskerville, 1984). In a major review of the HBM literature, Janz and Becker (1984) substantiated the importance of HBM concepts in preventive health behaviors. However, the literature testing the HBM variables in health related activities of the elderly is limited. Aho (1979) evaluated the health beliefs of elderly subjects in relation to participation in a flu inoculation program. The investigator found that susceptibility, benefits, barriers, and health motivation predicted those who presented for inoculation. Although the focus of the instrument described here is preventive behavior on the part of elderly subjects and not disease detection among younger subjects as is Champion’s, the self breast examination HBM instrument was used as the basis for development of this tool because of its strong conceptual and psychometric properties. The Champion instrument is comprised of five subscales representing beliefs for each of the five HBM concepts. Reliability and validity for the SBE instrument was initially reported in 1984 and it has continued to be reevaluated in a variety of studies (Champion, 1984, 1985, 1987, 1988). Although
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there have been alternative definitions proposed for some of the concepts, for example, barriers (Melnyk, 1988), the Champion definitions are consistent with those of the original HBM conceptualization. Therefore, the conceptual definitions used for this osteoporosis study were adapted from those of Champion. Susceptibility refers to the perceived risk of developing osteoporosis. Seriousness is the perception of threat from having osteoporosis, including harmful consequences in relation to personal physical health, role and social status, and ability to complete desired tasks. Benejts focuses on the belief in the effectiveness of specific behaviors to prevent the occurrence of the disease. Barriers are the beliefs about the negative components of the behaviors which would be undertaken to prevent the disease. Health Motivation relates to a general tendency for an individual to engage in health behaviors. Unlike the other constructs which relate to beliefs about behaviors, health motivation is concerned directly with behaviors.
METHOD
Sample Subjects, 60 years or older, were recruited from four senior centers and one large senior residential apartment complex. To avoid enrolling subjects who were cognitively impaired, staff members at each site identified individuals who were judged capable of providing accurate answers. Individuals who reported that they had osteoporosis were excluded from the study. Since perception and behavior related to osteoporosis were central, actual pathology was not considered in sample selection. The sample included 150 elderly who ranged in age from 60 to 93 years (M = 74 years), the age at which most lay people recognize a risk for osteoporosis. Subjects had an average of 10.5 years of education ranging from 0 to 19 years. Females comprised 80.7% of the sample, which is consistent with the fact that females experience a higher incidence of osteoporosis.
mensions of the HBM. In most cases, the language of the item was preserved as it appeared in the SBE instrument. For example, susceptibility for the SBE instrument was measured by an item, “I feel that my chances of getting breast cancer in the future are great.” For the osteoporosis questionnaire, “breast cancer,” was replaced with “osteoporosis.” A 5-point Likert scale was used to rate items from strong disagreement (1) to strong agreement (5). A review of the literature and input from nursing faculty and nurses in practice were utilized to establish content validity for the items. Questions were worded at a fifth grade readability level. To assure that the subjects understood the concept as it was used in the study, the questionnaire was introduced with a brief explanation of osteoporosis. Although the osteoporosis instrument is a close adaptation of the Champion model, there is one major difference. Unlike the Champion instrument which deals with a single health behavior, namely self breast examination, the osteoporosis instrument focuses on two very important risk reduction behaviors: calcium intake and physical exercise. While the concepts of susceptibility, seriousness, and health motivation relate to the single threat of developing osteoporosis, the concepts of barriers and benefits logically include attitudes about two types of behaviors: the barriers and benefits related to calcium intake and those related to physical exercise. Therefore the format of the instrument was altered from that of Champion’s to include both categories of behaviors (calcium and exercise) in the conceptual focus of perceived benefits and barriers, (see Fig. 1). To evaluate concurrent validity, calcium and exercise behaviors were assessed along with the 50-item HBM instrument. The self-report Athletic Pursuits Questionnaire (Stillman, Lohman, Slaughter, & Massey, 1986) was adapted in con-
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OHB Exercise Scale
Common Subscales
-
Benefits Calcium
Susceptibility
-
Seriousness
Barriers Calcium
Health Motivation
Instruments Using the SBE instrument (Champion, 1984) as a basis, a total of 50 items were generated. Items were reflective of each of the five theoretical di-
-
Benefits Exercise
-
Barriers Exercise
I
-
OHB Calcium Scale FIGURE 1. The Osteoporosis Health Belief scale.
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sultation with exercise physiologists to measure exercise behaviors. The instrument assesses four aspects of physical activity: the type, frequency, and duration of activity, and level of intensity of the exercise session. The types of activities assessed were aerobic in nature, such as brisk walking or swimming. Subjects were asked to identify the type of exercise and how many times and for how long that activity was done in a typical week. The intensity of the activity was estimated by asking the subject to rate hidher breathing at the end of exercise on a scale from 0 to 3 according to the following responses: (0) normal; (1) a little faster than normal; (2) a lot faster, but talking is possible; and (3) so fast that taUung is not possible. Subjects were dichotomized as high and low exercisers. Subjects who exercised more than twice a week for a duration of 15 min or more with an intensity rated as at least 1 were included in the high category (n = 90); all others were included in the low exercise category (n = 60). Calcium intake was assessed using an instrument to evaluate the amount and frequency with which calcium rich foods were eaten and/or supplements were taken. The instrument was developed specifically for this study. Subjects were asked to indicate how often they ate each calcium rich food in a typical day. To assist in recall and increase accuracy, they were provided with examples of typical serving sizes (e.g., yogurt cartons, water glass, wooden block the size of one ounce of cheese). In addition, subjects were asked the specific names and dosage of any supplements containing calcium taken regularly. The USDA Agricultural Handbook of Nutritive Value of American Foods in Common Units (Adams, 1975) was used to calculate the amount of calcium in the calcium rich foods. Research supports the fact that calcium in foods is absorbed in the same way as calcium from the variety of supplements on the market (Sheikh, Santa Ana, Nicar, Schiller, & Fordtran, 1987). Therefore, the amounts of dietary and supplemental calcium were combined as total calcium intake.
Procedure To evaluate ease of administration and understandability, the instruments were pilot tested with 16 elderly. Data collection took place over a 3month period in a metropolitan area of Western Michigan. After the study was explained and informed consent obtained, the questionnaires were administered by 12 nursing students and 2 of the investigators who had participated in an extensive
training program. The level of inter-rater reliability achieved by the data collectors was computed at 99.8%.
DATA ANALYSES AND RESULTS For the final instrument, 15 items were deleted from the original 50 items, resulting in an instrument comprised of 35 items. Decisions to delete items were made according to the following procedure. First, for each of the theoretical subscales, items that did not correlate highly with the total subscale score were eliminated. In addition to the issue of reliability and validity, concern for the efficiency of the instrument is of particular importance for the elderly population for which the tool was designed. Thus, to minimize redundancy among items and deal with the problem of multicollinearity, pairs of items that were highly correlated were identified and one of the pair was eliminated (Tabachnick & Fidell, 1983). The remaining 35 items were submitted to a factor analysis to evaluate construct validity. A principal component factor technique with iteration was used. The orthogonal rotation of the extracted factors was done by Varimax procedure. Kaiser’s criterion of eigenvalues greater than or equal to 1.O was used in delimiting the number of factors in the solution. The factor analysis resulted in a six-factor solution: Susceptibility, Seriousness, Health Motivation, Barriers, Benefits related to calcium, and Benefits related to exercise. That is, all items related to a specific concept loaded under the respective subscale with the exception of Barriers. For the barriers concept, items for exercise and calcium loaded on the same factor. Consistent with the factor analysis results and the fact that the instrument was intended for use in determining its relationship to calcium intake and exercise as distinct behaviors, the 35 items were separated into two scales: the Osteoporosis Health Belief (OHB) Calcium scale and the Osteoporosis Health Belief (OHB) Exercise scale. Fifteen items (five each) were included in three common subscales: Susceptibility, Seriousness, and Health Motivation. The remaining 20 items were divided equally according to the appropriate subscales: Benefits Calcium, Barriers Calcium, Benefits Exercise, and Bamers Exercise. (See Tables 2 and 4 for the items included in each of the OHB Calcium and Exercise subscales.) This initial step in the analysis resulted in the identification of the two 25 item scales, OHB Calcium and OHB Exercise. While each scale shares three common
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subscales composed of 15 items measuring Susceptibility, Seriousness, and Health Motivation, there are 10 unique items related to Calcium and Exercise. Reliability and validity were evaluated separately for the two scales.
OHB Calcium Scale Internal consistency of each of the calcium subscales was evaluated to establish reliability. As shown in Table 1, Cronbach alpha reliability coefficients ranged from .61 (Health Motivation) to .80 (Susceptibility). Construct validity of the OHB Calcium scale was determined by factor analysis. As expected, five mutually exclusive factors were extracted, reflective of the five subscales. Factor loadings ranged from .40 to .80 (Table 2). The five factors accounted for 49.4% of the total variance. The percentages of variance explained by Susceptibility, Barriers, Benefits, Seriousness and Health Motivation were 14.4, 12.4, 9.1, 7.7, and 5.8, respectively. To evaluate concurrent validity, subjects were grouped according to calcium intake scores. One group consisted of subjects with calcium intake greater than or equal to 50% of the RDA (Food and Nutrition Board, 1989) and the second group with intake less than 50% RDA. Two of the five variables, Barriers-Calcium and Health Motivation, discriminated between high and low calcium intake groups (see Table 3). A discriminant function analysis revealed that 72% of the subjects were correctly classified by Barriers Calcium and Health Motivation. Of the 22 subjects with low calcium intake, 17 (77.3%) were accurately classified and 91 of the 128 (71.1%) in the high calcium intake group were correctly identified.
OHB Exercise Scale Internal consistency of each exercise subscale was evaluated to establish reliability. Cronbach alpha
coefficients ranged from .61 for Health Motivation to .80 for Susceptibility (Table 1). As for the OHB Calcium scale, construct validity for the OHB Exercise scale was evaluated by factor analysis. Five factors were extracted, with loadings ranging from .45 to .80 (Table 4). The five factors accounted for 49.3% of the total variance. The percentages of variance accounted for by Susceptibility, Benefits Exercise, Barriers Exercise, Seriousness, and Health Motivation were 15.9, 12.1, 9.2, 6.4, and 5.7, respectively. All items on a factor were related to a single theoretical dimension, indicating mutual exclusivity of the subscales. Discriminant function analysis was used to evaluate concurrent validity of the OHB Exercise scale. To determine the ability of the HBM variables to dlfferentiate the level of exercise, subjects were grouped as high or low exercisers according to the Athletic Pursuits Questionnaire scores. Two of the five variables were discriminators of a person’s exercise group status. The order and discriminating power of the five variables are presented in Table 3. Health Motivation was the strongest discriminator followed by Barriers Exercise. The two variables correctly classified low versus high exercisers in 62% of the cases. Of the 60 low exercisers, 37 (61.7%) were accurately classified and of 90 high exercisers, 56 (62.2%) were correctly identified.
DISCUSSION The instrument described here consists of seven subscales; three of which are common to both the OHB Calcium and Exercise scales, two that relate only to OHB calcium and two that relate only to OHB exercise. The OHB Calcium and Exercise scales may be administered alone, that is, five subscales each; or together, in which case, the entire instrument would consist of the seven sub-
Table 1. Internal Consistency for the OHB Subscales (N = 150) Cronbach Alpha Subscale Susceptibility Seriousness Health motivation Benefits Barriers
No. of Items
Calcium
Exercise
5 5 5 5 5
.80 .65 .61 .68
.80 .65 .61 .74 .72
.73
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Table 2. Factor Scores for the OHB Calcium Subscales (N = 150) Item
Loading
Factor 1 --Susceptibility You feel your chances of getting osteoporosis in the future are good There is a good possibility that you will get osteoporosis Your physical health makes it more likely that you will get osteoporosis Your chances of getting osteoporosis are great Your family history makes it more likely that you will get osteoporosis
.80 .80 .74 .67 .64
Factor 2-Barriers-Calcium Eating calcium rich foods requires changing your dietary habits which is difficult You are afraid you would not be able to always eat calcium rich foods Calcium rich foods do not agree with you Calcium rich foods are too expensive You dislike calcium rich foods
.75 .74 .67 .55 .45
Factor 3- Benefits-Calcium You would not be so anxious about osteoporosis if you ate calcium rich foods Eating calcium rich foods reduces risks of broken bones Eating calcium rich foods helps to build bones Eating calcium rich foods prevents future problems from osteoporosis Eating calcium rich foods prevents future pain
.74 .70 .63 .60 .40
Factor 4 -Seriousness If you had osteoporosis, your whole life would change The thought of osteoporosis scares you Your feelings about yourself would change if you got osteoporosis Having osteoporosis would make daily activities more difficult Osteoporosis would endanger your marriage (or a significant relationship) Factor 5-Health You frequently do things to improve your health You eat a well-balanced diet You search for new information related to your health You exercise regularly-at least three times a week Maintaining good health is extremely important to you
scales. The total instrument can be administered in 20 min. The results of psychometric analysis demonstrated similarities to those of the Champion instrument (Champion, 1984, 1985, 1987). One area of dissimilarity involves the results of discriminant function analysis. In a recent study, Champion (1987) reported that 54% of persons were correctly classified into three SBE groups by barriers, knowledge, and susceptibility. In this study, the percentages of subjects correctly classified into high and low calcium intake and exercise groups were 72% and 62% respectively. It should be noted that Champion included a Knowledge construct in addition to 5 HBM constructs in her
.75 .65 .61 .55 .48
Motivation
.69 .64 .59 .57 .57
study. In contrast to a disease specific health behavior such as self breast examination, calcium rich diet and exercise behavior may be motivated by the desire to prevent any number of diseases (e.g., cardiac disease). Therefore, the relationships of these behaviors to osteoporosis beliefs may be less discriminating. In this study the internal reliability coefficients ranged from .61 to .80. Although these are acceptable coefficients, it should be pointed out that the reliability coefficient is a function of the number of items in the scale. The Spearman Brown Prophecy Formula would predict correlation coefficients ranging from .76 to .89 if the subscales were composed of 10 items rather than 5 as in
OSTEOPOROSIS HEALTH BELIEF SCALE / KIM ET AL.
this study. Recognizing the importance of efficiency as a criterion for designing an instrument for the elderly, the number of items was purposely kept at a minimum. Sample size is a concern when performing factor analysis. Gorsuch (1983) suggested a sample of a minimum ratio of 5 subjects per variable (item), but not less than 100 subjects for any factor analysis. In this study, a ratio of subjects to the number of items was four to one with a total sample size of 150 which is more than the 100 minimum suggested by Gorsuch. Despite the sample size limitation, the results of the psychometric analysis of the OHB Scale provide sufficient support for the purpose of instrument development. Questionable levels of reliability and validity of the criterion measures of calcium intake and exercise behaviors may explain the limitations in the findings from the discriminant function analyses. In this study, a frequency method was used to measure calcium intake. Perhaps another method, such as a 24-hour intake record with multiple measurements per subject, would yield more accurate estimates of calcium intake (Witschi, 1990). Likewise, the exercise criterion requires measurement refinement. Recent advances in evaluating exercise behavior are based on levels of oxygen consumption (Block, Smith, Black, & Genant, 1987; Taylor et al., 1978). An instrument such as the Leisure Time Physical Activity Ques-
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tionnaire, which is based on levels of oxygen consumption (Taylor et al., 1978), would provide a more accurate reflection of exercise behavior. Assessment of exercise and calcium behaviors was based on self-report. Accuracy of information gained through self-report may be problematic, particularly for research on elderly subjects. However, direct observation of the behaviors under study is not practical. The results of this study demonstrate the importance of health motivation in influencing health related behaviors. This finding is consistent with that of Champion (1986). As Champion (1984) suggested, if the HBM is found to be theoretically sound and if reliable instruments are available, it can be used to structure individualized health promotion nursing strategies. In this study, Barriers and Health Motivation were found to be important constructs in explaining both calcium intake and exercise behaviors. This information is useful to clinicians working with the elderly who are at risk for the development of osteoporosis. For example, rather than focusing mainly on behaviors, assessment of perceived barriers could suggest an intervention designed to decrease specific deterrents. Development of the OHB Scale is in the initial stages. The authors encourage further use and revision of the instrument. Consideration should be given to the inclusion of self-efficacy as an
Table 3. Discriminant Function Analyses of Health Belief Model Variables by Low and High Levels of Calcium Intake and Exercise (N = 150)
Variable
Standardized Discriminant Coefficient
Wilks Lambda
F
,917 .887 ,878 ,877 ,876
13.40' 4.98' 1.42 0.32 0.03
,907 ,876 ,864 ,855
15.20' 5.23' 1.96 1.63 0.17
Calcium Intake Barriers-calcium Health motivation Benefits-calcium Seriousness Susceptibility
,736 - ,460 - ,267 -.144 ,038
Health motivation Barriers-exercise Susceptibility Benefits-exercise Seriousness
- ,717
Exercise
,644 - ,284 ,314 - ,095
.854
Note. Group centroids for low calcium intake group (less than 50% of the RDA) and high calcium intake group (greater than or equal to 50% of the RDA) were .90and -.15,respectively Group centroids for low exercise group and high exercise group were .50 and - . 3 4 , respectively.
' p < .01.
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Table 4. Factor Scores for the OHB Exerclse Subscales (N = 150) ~
Loading
Item Factor 1-Susceptibility You feel your chance of getting osteoporosis in the future are good There is a good possibility that you will get osteoporosis Your physical health makes it more likely that you will get osteoporosis Your chances of getting osteoporosis are great Your family history makes it more likely that you will get osteoporosis
.79 .78 .73 .70 .61
Factor 2-Benefits-Exercise Exercising regularly reduces risks of broken bones You would not be so anxious about osteoporosis if you exercised regularly Exercising regularly prevents future pain Exercising regularly helps to build bones Exercising regularly prevents future problems from osteoporosis
.80 .70 .70 .68 .50
Factor 3-Barriers-Exercise Exercising regularly interferes with your daily activities Exercising regularly can be time consuming Exercising regularly can be painful Exercising regularly would require starting a new habit which is difficult You are not strong enough to exercise regularly
.74 .73 .61 .56 .54
Factor 4-Seriousness If you had osteoporosis, your whole life would change Your feelings about yourself would change if you got osteoporosis The thought of osteoeorosis scares you Osteoporosis would endanger your marriage (or a significant relationship) Having osteoporosis would make daily activities more difficult Factor 5-Health You frequently do things to improve your health You eat a well-balanced diet You search for new information related to your health You exercise regularly-at least three times a week Maintaining good health is extremely important to you
additional dimension. As discussed earlier, the application of the Health Belief Model to the elderly has been limited. Therefore, previous findings from similar populations are not available for comparison. These findings contribute to the initial effort of HBM research with the elderly.
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.71 .67 .66 .63 .45
Motivation .76 .66 .59 .49 .49
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Journal of the American Medical Association, 257, 3115-3117. Brailey, L.J. (1986). Effects of health teaching in the workplace on women’s knowledge, beliefs, and practices regarding breast self-examination. Research in Nursing &Health, 9, 223-231. Champion, V.L. (1 984). lnstrument development for health belief model constructs. Advances in Nursing Science, 6(3), 73-85. Champion, V.L. (1985). Use of the health belief model in determining frequency of breast selfexamination. Research in Nursing & Health, 8 , 373 - 379. Champion, V.L. (1987). The relationship of breast self-examination to health belief model variables. Research in Nursing &Health, 10, 375-382. Champion, V.L. (1988). Attitudinal variables related to intention, frequency and proficiency of breast self-examination in women 35 and over. Research in Nursing & Health, I!, 283-291. Conference Report. (1987). Consensus development conference: Prophylaxis and treatment of osteoporosis. BritishMedical Journal, 295,914-915. Consensus Conference. (1984). Osteoporosis. Journal of the American Medical Association, 252, 799-802. Cummings, K.M., Becker, M.H., Kirscht, J.P., & Levin, N.W. (1982). Psychosocial factors affecting adherence to medical regimens in a group of hemodialysis patients. Medical Care, 20, 567-580. Cummings, S . R . , Kelsey , J .L., Nevitt, M.C., & O’Dowd, K.J. (1986). Epidemiology of osteoporosis and osteoporotic fractures. Epidemiologic Reviews, 7, 178-208. Dai, Y.T., & Catanzaro, M. (1987). Health beliefs and compliance with a skin care regimen. Rehabilitation Nursing, 1 2 , 13- 16. Food and Nutrition Board (1989). Recommended Dietary Allowances, (10th ed.). Washington, DC: National Academy of Science. Gorsuch, R.L. (1983). Factor analysis (2nd ed.). Hillsdale, NJ: Lawrence Erlbaum. Hallal, J.C. (1982). The relationship of health beliefs, health locus of control, and self concept to the practice of breast self-examination in adult women. Nursing Research, 31, 137- 142. Heaney, R.P., Gallagher, J.C., Johnston, C.C., Neer, R., Parfitt, A.M., Chir, B . , & Whedon, G.D. (1982). Calcium nutrition and bone health in the elderly. American Journal of Clinical Nutrition, 36, 986- 1013. Janz, N.K., & Becker, M.H. (1984). The health belief model: A decade later. Health Education Quarterly, I I , 1-47. Melnyk, K.A.M. (1988). Barriers: Acriticalreview of recent literature. Nursing Research, 37, 196201. National Institute of Health. (1984). Osteoporosis. Consensus Development Conference Statement, 5(3). (DHHS Publication No. 421 - 132:4652).
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Washington, DC: U.S. Government Printing Office. Pederson, L.L., Walklin, J.W., & Baskerville, J.C. (1984). The role of health beliefs in compliance with physician advice to quit smoking. Social Science and Medicine, 19, 573-580. Persky, N.W., & Alexander, N. (1989). Issues of aging in preventive medicine and the example of osteoporosis. Primary C a r e , 16, 231-243. Resnick, N.M., & Greenspan, S.L. (1989), “Senile” osteoporosis reconsidered. Journal of the American Medical Association, 261, 1025- 1029. Rosenstock, I.M., Strecher, V.J., & Becker, M.H. (1988). Social learning theory and the health belief model. Health Education Quarterly, 1 5 , 175183. Rutledge, D. (1987). Factors related to women’s practice of breast self-examination. Nursing Research, 36, 117-121. Santora, A.C. (1987). Role of nutrition and exercise in osteoporosis. The American Journal of Medicine, 82(Suppl. l B ) , 73-79. Sheikh, M.S., Santa Ana, C.A., Nicar, M.J., Schiller, L.R., & Fordtran, J.S. (1987). Gastrointestinal absorption of calcium from milk and calcium salts. The New England Journal of Medicine, 317, 532-536. Smith, E.L., Reddan, W., & Smith, P.E. (1981). Physical activity and calcium modalities for bone mineral increase in aged women. Medicine and Science in Sports and Exercise, 13, 60-64. Special Committee on Aging, United States Senate. (1989). Developments in aging: 1988, Volume 1 . (Report No. 101-4) Washington, DC: U.S. Government Printing Office. Special Committee on Aging, United States Senate. (1989). Developments in aging: 1988, Volume 2-Appendixes. (Report No. 101-4) Washington, DC: U . S . Government Printing Office. Spencer, H. (1982). Osteoporosis: Goals of therapy. Hospital Practice, 17(3), 131-151. Stillman, R.J., Lohman, T.G., Slaughter, M.H., & Massey, B.H. (1986). Physical activity and bone mineral content in women aged 30 to 85 years. Medicine and Science in Sports and Exercise, 1 8 , 576-580. Tabachnick, B.G., & Fidell, L.S. (1983). Using multivariate statistics. New York: Harper & Row. Taylor, H.L., Jacobs, D.R., Schucker, B., Knudsen, J . , Leon, A.S., & Debucker, G . (1978). A questionnaire for the assessment of leisure time physical activities. Journal of Chronic Disease, 3 1 , 741 -755. Trotta, P. (1980). Breast self-examination factors influencing compliance. Oncology Nursing Forum, 7, 13-17. Witschi, J.C. (1990). Short-term dietary recall and recording methods. In W. Willett (Ed.), Nutritional epidemiology (pp. 52-68). New York: Oxford University Press.
Development and Evaluation of the Osteoporosis Health Belief Scale Katherine K. Kim, Mary L. Horan, Phyllis Gendler, and Minu K. Patel
The Osteoporosis Health Belief Scale was developed to measure health beliefs related to osteoporosis. It is a 35-item self-report questionnaire based on the Health Belief Model which is specifically designed to assess beliefs related to exercise behaviors and calcium intake of elderly subjects. The instrument consists of seven subscales: Seriousness, Susceptibility, Health Motivation, Calcium Benefits, Calcium Barriers, Exercise Benefits, and Exercise Barriers. The instrument was tested on a sample of 150 elderly individuals. The psychometric properties of the scales are discussed along with recommendations for its use in research and practice.
The purpose of this study was to develop and evaluate the Osteoporosis Health Belief Scale which is based on the Health Belief Model. Osteoporosis is a major public health problem affecting as many as 15 to 20 million individuals in the United States (National Institute of Health [NIH], 1984). While both sexes are affected, osteoporosis is more prevalent in women. By age 90, 32% of women and 17% of men will have experienced a hip fracture primarily due to osteoporosis. Many fractures, particularly those of the spine, cause pain, deformity and disability, limiting activities and well-being of the elderly. It is estimated that the cost of osteoporosis in the United States is 10 billion dollars a year (Special Committee on Aging [SCA], 1989). The resulting hip fractures are associated with a 5-20% excess mortality within the first year (Conference Report, 1987). While osteoporosis is indeed costly to society, individual suffering, deformity, and disability profoundly affect the elderly’s emotional well-being and life satisfaction. For many elderly, the reduction of disability is more important than extending life (Persky & Alexander, 1989).
Important risk factors related to osteoporosis
are f d y history, menopause, inadequate calcium intake, and sedentary life style (Aloia, Cohn, Voswani, Yeh, Yuen, & Ellis, 1985; Spencer, 1982). Researchers have determined that the condition can be prevented or delayed in its development by a change in dietary habits and exercise (Heaney et al., 1982; SCA, vol. 2, 1988; Smith, Reddan, & Smith, 1981). The disease is manifested by a decrease in skeletal mass and density. The skeleton consists of two types of bone: trabecular bone which has a open meshwork structure and cortical bone which has a compact structure. Although the pathogenesis of osteoporosis is not completely understood, recent evidence supports two classifications. Type 1 osteoporosis is believed to be precipitated by menopause when there is a relatively brief period of bone loss affecting the trabecular bone. Clinical manifestations include vertebral crush fractures and Colles’ fractures of the wrist (Persky & Alexander, 1989). The major causes of postmenopausal osteoporosis are estrogen and calcium deficiencies (SCA, vol. l . , 1988). Type 2 osteoporosis occurs in both men and women
Katherine K. Kim, PhD, RN, is an associate professor in the Kirkhof School of Nursing, Grand Valley State University, Allendale, Michigan. Mary L. Horan, PhD, RN, is a professor in and the director of that school, and Phyllis Gendler, Ph(C), RNC, is an assistant professor in the same school. Minu K. Patel, MSC, is an assistant professor in the College of Nursing and Research Resources Center, University of Illinois at Chicago. This research was supported by a research and development grant from Grand Valley State University. The authors gratefully acknowledge the contributions of Victoria Champion, DNS, RN, Gordon Alderink, MS, Brian Curry, PhD, Pamela Oosterink, BS, and student assistants. This article was received on April 9, 1990, was revised, and accepted for publication August 10. 1990. Requests for reprints can be addressed to Dr. Katherine K. Kim. Kirkhof School of Nursing, Grand Valley State University, Allendale, MI 49401.
0 1991 John Wiley & Sons, Inc. 0160-6891/91/020155-09 $04.00
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over 75 years old (SCA, vol. 2, 1988) and is thought to be a consequence of age-related changes. Both cortical and trabecular bone are affected resulting in fractures of the hip and wedge deformities of the spine (Persky & Alexander, 1989). Although distinctions are being made for some clinical and research purposes, general health education literature and popular magazines do not distinguish between the two types of osteoporosis and recommend adequate amounts of calcium and exercise as appropriate methods for maintaining bone health. Additionally, although the role of calcium intake in the etiology of osteoporosis is controversial, health professionals consider it prudent to encourage adequate intake of calcium and moderate exercise in order to decrease the risk of osteoporosis (Conference Report, 1987; Consensus Conference, 1984; Cummings, Kelsey , Nevitt, & O’Dowd, 1986; Resnick & Greenspan, 1989; Santora, 1987). Nursing interventions related to osteoporosis prevention have consisted primarily of educational programs aimed at changing dietary and exercise habits. However, knowledge and skills gained from health education do not always translate into subsequent healthful behaviors. Therefore, it is important to consider the influence of other psychological variables in effecting behavior change. Identification of such variables could enhance individualization of health promotion strategies. Hence, the purpose of this study was to develop and test an instrument designed to measure personal attitudes and beliefs related to the potential for developing osteoporosis.
Health Be1ief Model Since its introduction in 1950, the Health Belief Model (HBM) has been used in a variety of studies of health behavior including disease detection and prevention (Janz & Becker, 1984). According to the model, a number of variables are associated with the likelihood of taking action to detect or prevent the occurrence of disease (Becker, 1985; Becker, Maiman, Kmcht, Haefner, & Drachman, 1977). Health behaviors are more likely to occur if an individual believes in personal susceptibility to the condition and, at the same time, perceives that having the condition would have serious consequences. The model also recognizes the impact of health motivation and perceived barriers and benefits to taking the healthful action. More recently, self-efficacy as a construct in explaining health behaviors and its integration in the HBM has been addressed (Rosenstock, Strecher, &
Becker, 1988). However, the present study was initiated prior to availability of relevant publications, therefore, self-efficacy as a concept was not included. The impact of the HBM on participation in disease detection has been studied by a variety of investigators (Becker, Kabeck, Rosenstock, & Ruth, 1975; Brailey, 1986; Champion, 1984, 1985, 1987, 1988; Hallal, 1982; Rutledge, 1987; Trotta, 1980). The results were varied, but suggested that certain HBM variables are useful in predicting specific behaviors. Champion (1984), concerned with the inconsistency in application of the model and the lack of valid and reliable instruments for measuring the constructs, developed and tested an instrument designed specifically for the study of the HBM variables as they relate to self breast examination (SBE). Her findings indicated that the variables of seriousness, benefits, barriers, and health motivation discriminated groups of women according to frequency of breast self-examination (Champion, 1985). A more recent study added knowledge as a variable and revealed that, along with knowledge, barriers and susceptibility were correlated with frequency of SBE (Champion, 1987). Specific investigations regarding the influence of the HBM variables in disease prevention and health maintenance behaviors also support the conceptualization (Becker et al., 1977; Cummings, Becker, Kirscht, & Levine, 1982; Dai & Catanzaro, 1987; Pederson, Walklin & Baskerville, 1984). In a major review of the HBM literature, Janz and Becker (1984) substantiated the importance of HBM concepts in preventive health behaviors. However, the literature testing the HBM variables in health related activities of the elderly is limited. Aho (1979) evaluated the health beliefs of elderly subjects in relation to participation in a flu inoculation program. The investigator found that susceptibility, benefits, barriers, and health motivation predicted those who presented for inoculation. Although the focus of the instrument described here is preventive behavior on the part of elderly subjects and not disease detection among younger subjects as is Champion’s, the self breast examination HBM instrument was used as the basis for development of this tool because of its strong conceptual and psychometric properties. The Champion instrument is comprised of five subscales representing beliefs for each of the five HBM concepts. Reliability and validity for the SBE instrument was initially reported in 1984 and it has continued to be reevaluated in a variety of studies (Champion, 1984, 1985, 1987, 1988). Although
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there have been alternative definitions proposed for some of the concepts, for example, barriers (Melnyk, 1988), the Champion definitions are consistent with those of the original HBM conceptualization. Therefore, the conceptual definitions used for this osteoporosis study were adapted from those of Champion. Susceptibility refers to the perceived risk of developing osteoporosis. Seriousness is the perception of threat from having osteoporosis, including harmful consequences in relation to personal physical health, role and social status, and ability to complete desired tasks. Benejts focuses on the belief in the effectiveness of specific behaviors to prevent the occurrence of the disease. Barriers are the beliefs about the negative components of the behaviors which would be undertaken to prevent the disease. Health Motivation relates to a general tendency for an individual to engage in health behaviors. Unlike the other constructs which relate to beliefs about behaviors, health motivation is concerned directly with behaviors.
METHOD
Sample Subjects, 60 years or older, were recruited from four senior centers and one large senior residential apartment complex. To avoid enrolling subjects who were cognitively impaired, staff members at each site identified individuals who were judged capable of providing accurate answers. Individuals who reported that they had osteoporosis were excluded from the study. Since perception and behavior related to osteoporosis were central, actual pathology was not considered in sample selection. The sample included 150 elderly who ranged in age from 60 to 93 years (M = 74 years), the age at which most lay people recognize a risk for osteoporosis. Subjects had an average of 10.5 years of education ranging from 0 to 19 years. Females comprised 80.7% of the sample, which is consistent with the fact that females experience a higher incidence of osteoporosis.
mensions of the HBM. In most cases, the language of the item was preserved as it appeared in the SBE instrument. For example, susceptibility for the SBE instrument was measured by an item, “I feel that my chances of getting breast cancer in the future are great.” For the osteoporosis questionnaire, “breast cancer,” was replaced with “osteoporosis.” A 5-point Likert scale was used to rate items from strong disagreement (1) to strong agreement (5). A review of the literature and input from nursing faculty and nurses in practice were utilized to establish content validity for the items. Questions were worded at a fifth grade readability level. To assure that the subjects understood the concept as it was used in the study, the questionnaire was introduced with a brief explanation of osteoporosis. Although the osteoporosis instrument is a close adaptation of the Champion model, there is one major difference. Unlike the Champion instrument which deals with a single health behavior, namely self breast examination, the osteoporosis instrument focuses on two very important risk reduction behaviors: calcium intake and physical exercise. While the concepts of susceptibility, seriousness, and health motivation relate to the single threat of developing osteoporosis, the concepts of barriers and benefits logically include attitudes about two types of behaviors: the barriers and benefits related to calcium intake and those related to physical exercise. Therefore the format of the instrument was altered from that of Champion’s to include both categories of behaviors (calcium and exercise) in the conceptual focus of perceived benefits and barriers, (see Fig. 1). To evaluate concurrent validity, calcium and exercise behaviors were assessed along with the 50-item HBM instrument. The self-report Athletic Pursuits Questionnaire (Stillman, Lohman, Slaughter, & Massey, 1986) was adapted in con-
-
OHB Exercise Scale
Common Subscales
-
Benefits Calcium
Susceptibility
-
Seriousness
Barriers Calcium
Health Motivation
Instruments Using the SBE instrument (Champion, 1984) as a basis, a total of 50 items were generated. Items were reflective of each of the five theoretical di-
-
Benefits Exercise
-
Barriers Exercise
I
-
OHB Calcium Scale FIGURE 1. The Osteoporosis Health Belief scale.
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sultation with exercise physiologists to measure exercise behaviors. The instrument assesses four aspects of physical activity: the type, frequency, and duration of activity, and level of intensity of the exercise session. The types of activities assessed were aerobic in nature, such as brisk walking or swimming. Subjects were asked to identify the type of exercise and how many times and for how long that activity was done in a typical week. The intensity of the activity was estimated by asking the subject to rate hidher breathing at the end of exercise on a scale from 0 to 3 according to the following responses: (0) normal; (1) a little faster than normal; (2) a lot faster, but talking is possible; and (3) so fast that taUung is not possible. Subjects were dichotomized as high and low exercisers. Subjects who exercised more than twice a week for a duration of 15 min or more with an intensity rated as at least 1 were included in the high category (n = 90); all others were included in the low exercise category (n = 60). Calcium intake was assessed using an instrument to evaluate the amount and frequency with which calcium rich foods were eaten and/or supplements were taken. The instrument was developed specifically for this study. Subjects were asked to indicate how often they ate each calcium rich food in a typical day. To assist in recall and increase accuracy, they were provided with examples of typical serving sizes (e.g., yogurt cartons, water glass, wooden block the size of one ounce of cheese). In addition, subjects were asked the specific names and dosage of any supplements containing calcium taken regularly. The USDA Agricultural Handbook of Nutritive Value of American Foods in Common Units (Adams, 1975) was used to calculate the amount of calcium in the calcium rich foods. Research supports the fact that calcium in foods is absorbed in the same way as calcium from the variety of supplements on the market (Sheikh, Santa Ana, Nicar, Schiller, & Fordtran, 1987). Therefore, the amounts of dietary and supplemental calcium were combined as total calcium intake.
Procedure To evaluate ease of administration and understandability, the instruments were pilot tested with 16 elderly. Data collection took place over a 3month period in a metropolitan area of Western Michigan. After the study was explained and informed consent obtained, the questionnaires were administered by 12 nursing students and 2 of the investigators who had participated in an extensive
training program. The level of inter-rater reliability achieved by the data collectors was computed at 99.8%.
DATA ANALYSES AND RESULTS For the final instrument, 15 items were deleted from the original 50 items, resulting in an instrument comprised of 35 items. Decisions to delete items were made according to the following procedure. First, for each of the theoretical subscales, items that did not correlate highly with the total subscale score were eliminated. In addition to the issue of reliability and validity, concern for the efficiency of the instrument is of particular importance for the elderly population for which the tool was designed. Thus, to minimize redundancy among items and deal with the problem of multicollinearity, pairs of items that were highly correlated were identified and one of the pair was eliminated (Tabachnick & Fidell, 1983). The remaining 35 items were submitted to a factor analysis to evaluate construct validity. A principal component factor technique with iteration was used. The orthogonal rotation of the extracted factors was done by Varimax procedure. Kaiser’s criterion of eigenvalues greater than or equal to 1.O was used in delimiting the number of factors in the solution. The factor analysis resulted in a six-factor solution: Susceptibility, Seriousness, Health Motivation, Barriers, Benefits related to calcium, and Benefits related to exercise. That is, all items related to a specific concept loaded under the respective subscale with the exception of Barriers. For the barriers concept, items for exercise and calcium loaded on the same factor. Consistent with the factor analysis results and the fact that the instrument was intended for use in determining its relationship to calcium intake and exercise as distinct behaviors, the 35 items were separated into two scales: the Osteoporosis Health Belief (OHB) Calcium scale and the Osteoporosis Health Belief (OHB) Exercise scale. Fifteen items (five each) were included in three common subscales: Susceptibility, Seriousness, and Health Motivation. The remaining 20 items were divided equally according to the appropriate subscales: Benefits Calcium, Barriers Calcium, Benefits Exercise, and Bamers Exercise. (See Tables 2 and 4 for the items included in each of the OHB Calcium and Exercise subscales.) This initial step in the analysis resulted in the identification of the two 25 item scales, OHB Calcium and OHB Exercise. While each scale shares three common
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subscales composed of 15 items measuring Susceptibility, Seriousness, and Health Motivation, there are 10 unique items related to Calcium and Exercise. Reliability and validity were evaluated separately for the two scales.
OHB Calcium Scale Internal consistency of each of the calcium subscales was evaluated to establish reliability. As shown in Table 1, Cronbach alpha reliability coefficients ranged from .61 (Health Motivation) to .80 (Susceptibility). Construct validity of the OHB Calcium scale was determined by factor analysis. As expected, five mutually exclusive factors were extracted, reflective of the five subscales. Factor loadings ranged from .40 to .80 (Table 2). The five factors accounted for 49.4% of the total variance. The percentages of variance explained by Susceptibility, Barriers, Benefits, Seriousness and Health Motivation were 14.4, 12.4, 9.1, 7.7, and 5.8, respectively. To evaluate concurrent validity, subjects were grouped according to calcium intake scores. One group consisted of subjects with calcium intake greater than or equal to 50% of the RDA (Food and Nutrition Board, 1989) and the second group with intake less than 50% RDA. Two of the five variables, Barriers-Calcium and Health Motivation, discriminated between high and low calcium intake groups (see Table 3). A discriminant function analysis revealed that 72% of the subjects were correctly classified by Barriers Calcium and Health Motivation. Of the 22 subjects with low calcium intake, 17 (77.3%) were accurately classified and 91 of the 128 (71.1%) in the high calcium intake group were correctly identified.
OHB Exercise Scale Internal consistency of each exercise subscale was evaluated to establish reliability. Cronbach alpha
coefficients ranged from .61 for Health Motivation to .80 for Susceptibility (Table 1). As for the OHB Calcium scale, construct validity for the OHB Exercise scale was evaluated by factor analysis. Five factors were extracted, with loadings ranging from .45 to .80 (Table 4). The five factors accounted for 49.3% of the total variance. The percentages of variance accounted for by Susceptibility, Benefits Exercise, Barriers Exercise, Seriousness, and Health Motivation were 15.9, 12.1, 9.2, 6.4, and 5.7, respectively. All items on a factor were related to a single theoretical dimension, indicating mutual exclusivity of the subscales. Discriminant function analysis was used to evaluate concurrent validity of the OHB Exercise scale. To determine the ability of the HBM variables to dlfferentiate the level of exercise, subjects were grouped as high or low exercisers according to the Athletic Pursuits Questionnaire scores. Two of the five variables were discriminators of a person’s exercise group status. The order and discriminating power of the five variables are presented in Table 3. Health Motivation was the strongest discriminator followed by Barriers Exercise. The two variables correctly classified low versus high exercisers in 62% of the cases. Of the 60 low exercisers, 37 (61.7%) were accurately classified and of 90 high exercisers, 56 (62.2%) were correctly identified.
DISCUSSION The instrument described here consists of seven subscales; three of which are common to both the OHB Calcium and Exercise scales, two that relate only to OHB calcium and two that relate only to OHB exercise. The OHB Calcium and Exercise scales may be administered alone, that is, five subscales each; or together, in which case, the entire instrument would consist of the seven sub-
Table 1. Internal Consistency for the OHB Subscales (N = 150) Cronbach Alpha Subscale Susceptibility Seriousness Health motivation Benefits Barriers
No. of Items
Calcium
Exercise
5 5 5 5 5
.80 .65 .61 .68
.80 .65 .61 .74 .72
.73
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Table 2. Factor Scores for the OHB Calcium Subscales (N = 150) Item
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Factor 1 --Susceptibility You feel your chances of getting osteoporosis in the future are good There is a good possibility that you will get osteoporosis Your physical health makes it more likely that you will get osteoporosis Your chances of getting osteoporosis are great Your family history makes it more likely that you will get osteoporosis
.80 .80 .74 .67 .64
Factor 2-Barriers-Calcium Eating calcium rich foods requires changing your dietary habits which is difficult You are afraid you would not be able to always eat calcium rich foods Calcium rich foods do not agree with you Calcium rich foods are too expensive You dislike calcium rich foods
.75 .74 .67 .55 .45
Factor 3- Benefits-Calcium You would not be so anxious about osteoporosis if you ate calcium rich foods Eating calcium rich foods reduces risks of broken bones Eating calcium rich foods helps to build bones Eating calcium rich foods prevents future problems from osteoporosis Eating calcium rich foods prevents future pain
.74 .70 .63 .60 .40
Factor 4 -Seriousness If you had osteoporosis, your whole life would change The thought of osteoporosis scares you Your feelings about yourself would change if you got osteoporosis Having osteoporosis would make daily activities more difficult Osteoporosis would endanger your marriage (or a significant relationship) Factor 5-Health You frequently do things to improve your health You eat a well-balanced diet You search for new information related to your health You exercise regularly-at least three times a week Maintaining good health is extremely important to you
scales. The total instrument can be administered in 20 min. The results of psychometric analysis demonstrated similarities to those of the Champion instrument (Champion, 1984, 1985, 1987). One area of dissimilarity involves the results of discriminant function analysis. In a recent study, Champion (1987) reported that 54% of persons were correctly classified into three SBE groups by barriers, knowledge, and susceptibility. In this study, the percentages of subjects correctly classified into high and low calcium intake and exercise groups were 72% and 62% respectively. It should be noted that Champion included a Knowledge construct in addition to 5 HBM constructs in her
.75 .65 .61 .55 .48
Motivation
.69 .64 .59 .57 .57
study. In contrast to a disease specific health behavior such as self breast examination, calcium rich diet and exercise behavior may be motivated by the desire to prevent any number of diseases (e.g., cardiac disease). Therefore, the relationships of these behaviors to osteoporosis beliefs may be less discriminating. In this study the internal reliability coefficients ranged from .61 to .80. Although these are acceptable coefficients, it should be pointed out that the reliability coefficient is a function of the number of items in the scale. The Spearman Brown Prophecy Formula would predict correlation coefficients ranging from .76 to .89 if the subscales were composed of 10 items rather than 5 as in
OSTEOPOROSIS HEALTH BELIEF SCALE / KIM ET AL.
this study. Recognizing the importance of efficiency as a criterion for designing an instrument for the elderly, the number of items was purposely kept at a minimum. Sample size is a concern when performing factor analysis. Gorsuch (1983) suggested a sample of a minimum ratio of 5 subjects per variable (item), but not less than 100 subjects for any factor analysis. In this study, a ratio of subjects to the number of items was four to one with a total sample size of 150 which is more than the 100 minimum suggested by Gorsuch. Despite the sample size limitation, the results of the psychometric analysis of the OHB Scale provide sufficient support for the purpose of instrument development. Questionable levels of reliability and validity of the criterion measures of calcium intake and exercise behaviors may explain the limitations in the findings from the discriminant function analyses. In this study, a frequency method was used to measure calcium intake. Perhaps another method, such as a 24-hour intake record with multiple measurements per subject, would yield more accurate estimates of calcium intake (Witschi, 1990). Likewise, the exercise criterion requires measurement refinement. Recent advances in evaluating exercise behavior are based on levels of oxygen consumption (Block, Smith, Black, & Genant, 1987; Taylor et al., 1978). An instrument such as the Leisure Time Physical Activity Ques-
161
tionnaire, which is based on levels of oxygen consumption (Taylor et al., 1978), would provide a more accurate reflection of exercise behavior. Assessment of exercise and calcium behaviors was based on self-report. Accuracy of information gained through self-report may be problematic, particularly for research on elderly subjects. However, direct observation of the behaviors under study is not practical. The results of this study demonstrate the importance of health motivation in influencing health related behaviors. This finding is consistent with that of Champion (1986). As Champion (1984) suggested, if the HBM is found to be theoretically sound and if reliable instruments are available, it can be used to structure individualized health promotion nursing strategies. In this study, Barriers and Health Motivation were found to be important constructs in explaining both calcium intake and exercise behaviors. This information is useful to clinicians working with the elderly who are at risk for the development of osteoporosis. For example, rather than focusing mainly on behaviors, assessment of perceived barriers could suggest an intervention designed to decrease specific deterrents. Development of the OHB Scale is in the initial stages. The authors encourage further use and revision of the instrument. Consideration should be given to the inclusion of self-efficacy as an
Table 3. Discriminant Function Analyses of Health Belief Model Variables by Low and High Levels of Calcium Intake and Exercise (N = 150)
Variable
Standardized Discriminant Coefficient
Wilks Lambda
F
,917 .887 ,878 ,877 ,876
13.40' 4.98' 1.42 0.32 0.03
,907 ,876 ,864 ,855
15.20' 5.23' 1.96 1.63 0.17
Calcium Intake Barriers-calcium Health motivation Benefits-calcium Seriousness Susceptibility
,736 - ,460 - ,267 -.144 ,038
Health motivation Barriers-exercise Susceptibility Benefits-exercise Seriousness
- ,717
Exercise
,644 - ,284 ,314 - ,095
.854
Note. Group centroids for low calcium intake group (less than 50% of the RDA) and high calcium intake group (greater than or equal to 50% of the RDA) were .90and -.15,respectively Group centroids for low exercise group and high exercise group were .50 and - . 3 4 , respectively.
' p < .01.
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Table 4. Factor Scores for the OHB Exerclse Subscales (N = 150) ~
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Item Factor 1-Susceptibility You feel your chance of getting osteoporosis in the future are good There is a good possibility that you will get osteoporosis Your physical health makes it more likely that you will get osteoporosis Your chances of getting osteoporosis are great Your family history makes it more likely that you will get osteoporosis
.79 .78 .73 .70 .61
Factor 2-Benefits-Exercise Exercising regularly reduces risks of broken bones You would not be so anxious about osteoporosis if you exercised regularly Exercising regularly prevents future pain Exercising regularly helps to build bones Exercising regularly prevents future problems from osteoporosis
.80 .70 .70 .68 .50
Factor 3-Barriers-Exercise Exercising regularly interferes with your daily activities Exercising regularly can be time consuming Exercising regularly can be painful Exercising regularly would require starting a new habit which is difficult You are not strong enough to exercise regularly
.74 .73 .61 .56 .54
Factor 4-Seriousness If you had osteoporosis, your whole life would change Your feelings about yourself would change if you got osteoporosis The thought of osteoeorosis scares you Osteoporosis would endanger your marriage (or a significant relationship) Having osteoporosis would make daily activities more difficult Factor 5-Health You frequently do things to improve your health You eat a well-balanced diet You search for new information related to your health You exercise regularly-at least three times a week Maintaining good health is extremely important to you
additional dimension. As discussed earlier, the application of the Health Belief Model to the elderly has been limited. Therefore, previous findings from similar populations are not available for comparison. These findings contribute to the initial effort of HBM research with the elderly.
REFERENCES Adams, C.F. (1975). Nutritive value of American foods in common units. USDA agriculture handbook, 4 5 6 . Aho, W.R. (1979). Participation of senior citizens in the swine flu inoculation program: An analysis of health belief model variables in preventive
.71 .67 .66 .63 .45
Motivation .76 .66 .59 .49 .49
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