Public Health Nursing Vol. 32 No. 3, pp. 191–200 0737-1209/© 2014 Wiley Periodicals, Inc. doi: 10.1111/phn.12129






Gender Differences in Health-Related Quality of Life of Korean Patients with Chronic Obstructive Lung Disease Jisu Kim, RN, PhD1 and Kisook Kim, RN, PhD2 1

College of Nursing, Chung-Ang University, Seoul, Korea; and 2Department of Nursing, Changwon National University, Changwon, Korea

Correspondence to: Kisook Kim, Assistant Professor, Department of Nursing, Changwon National University, 20 Changwondaehak-ro Uichang-gu Changwon-si, Gyeongsangnam-do 641-773, Korea. E-mail: [email protected]

ABSTRACT Objectives: The aim of this study was to identify the health-related quality of life (HRQOL) of COPD patients over 40 years of age in Korea and to assess the relevance of gender differences. Design and Sample: Original data from KNHANES (Korea National Health and Nutrition Examination Survey) were analyzed using SAS 9.3 software. The sample comprised 556 male and 195 female COPD patients. Measures: Selected demographic variables, HRQOL [EuroQol 5-Dimension], physical and psychological characteristics, and health-related characteristics were examined. Results: The results showed that the HRQOL of COPD patients was better for females than for males, and that the HRQOL among males differed with the education, economic activity, economic level, blood pressure, suicidal ideation, and physical activity, while among females it differed with age, living status, education, economic activity, economic level, blood pressure, stress recognition, suicidal ideation, alcohol use, and physical activity. Further analysis verified that for males, the education, suicidal ideation, and physical activity were factors that affected HRQOL (R2 = 0.139, p < .001), while for females these factors were the education, obesity, and suicidal ideation (R2 = 0.340, p < .001). Conclusion: Effective-health promoting interventions for COPD patients require the development of individualized programs that take into account gender-related factors that can enhance HRQOL. Key words: chronic obstructive, early intervention, gender, health promotion, pulmonary disease, quality of life.

Background Chronic obstructive pulmonary disease (COPD) is a chronic disease whose prevalence and death rate are increasing; it is expected that by 2020, COPD will rank third among the causes of death in the world (Global Chronic Obstructive Lung Disease, 2009; Rabe et al., 2007). In South Korea, the prevalence of COPD in 2011 was 12.5% for people aged 40 years and older (Korea Centers for Disease Control and Prevention [KCDC], 2012); the death rate due to chronic lower airway disease, in which COPD was included, ranked seventh among the total causes of death (Statistics Korea, 2011). Given that the COPD morbidity rate in middle and old

age is high and that the population is aging, it has become a major cause not only of medical expenses for each patient, but also increased social medical costs. There is considerable need to develop effective interventions for the long-term management of the disease (DiBonaventura et al., 2013; Jung & Lee, 2011). The primary therapeutic aim of several chronic diseases has recently changed from complete recovery to symptom control, and measurement of health-related quality of life (HRQOL) for the individual has a significant meaning in evaluating health status (Park & Yang, 2013; Won, Ham, & Ryu, 2011). HRQOL is measured by assessing each



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individual’s subjective cognition with regard to their health status, which includes quantitative evaluation of emotional and social function. It is also used as an index to demonstrate the health status not only of individual but also the population group, as the basis of health policy (Kalafateli et al., 2013; Kim, 2013; Tsiligianni, Kocks, Tzanakis, Siafakas, & der Molen, 2011). Management of COPD based on clinical evidence requires a focus on early diagnosis, risk factors, symptom alleviation, prevention of complications, and enhancement of HRQOL (Anzueto, 2006). Evaluation of HRQOL is continually being highlighted during the management and monitoring of COPD, which has the characteristics of a chronic and incurable illness (Arne et al., 2011; Chin et al., 2008; Ryyn€ anen, Soini, Lindqvist, Kilpel€ainen, & Laitinen, 2013). Advanced studies both in Korea and abroad have verified that the HRQOL of COPD patients is relatively low (Inota, Agh, & Meszaros, 2012; Jung & Lee, 2011; KCDC, 2012; Lee, Lim, Jung, & Park, 2011), and that it is lower than that of chronic patients with rheumatoid arthritis, diabetes, and other diseases (Arne et al., 2009). The only advanced studies related to COPD that have been performed in Korea have been simple prevalence rate investigations (KCDC, 2012) and studies of relevant factors and risk factors (Bang, 2007; Chin et al., 2008; Jung & Lee, 2011; Yoo et al., 2011), while studies on respiratory symptoms, depression, and fragmentary relationships with physical activities was carried out (Jung & Lee, 2011; Kim et al., 2006; Lee et al., 2011). Studies of interactions between several factors that determine HRQOL have been carried out in other nations in a bid to enhance COPD management (DiBonaventura et al., 2013; Tsiligianni et al., 2011), and affecting factors such as age, gender, severity of disease, smoking, social and economic level, mental and psychological variables, and physical activity are currently being considered (Arne et al., 2011; Garrido et al., 2009; Stahl et al., 2005). There appear to be gender differences in the health status among Koreans with respect to marital status, education, income, medical insurance, behavior regarding medical use, number of chronic diseases, perceived health status, social factors, and drinking based on cultural characteristics (Jeon, 2008; Jeon, Choi, & Lee, 2010). A differential approach according to gender is necessary, as the

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prevalence of COPD among males is more than twice that among females (Jung & Lee, 2011). Nevertheless, very few studies have considered how to enhance the HRQOL of COPD patients while considering possible gender differences. To enhance the HRQOL of all COPD patients, it is first necessary to identify multidimensional factors that affect the quality of life of male and female COPD patients. The aim of this study was thus to establish fundamental data for gender-specific intervention programs that will enable improvements in the HRQOL of COPD patients by assessing both male and female COPD patients older than 40 years using data for the 1st and 2nd years (2010 and 2011) of Period V of the Korea National Health and Nutrition Examination Survey (KNHANES), for which the data and their affecting factors possess representativeness and credibility as national statistical data.

Methods Design and Sample The original data for the 1st and 2nd years (2010 and 2011) of KNHANES Period V, which was carried out by the KCDC, were analyzed. The objective of the KNHANES investigation was to calculate statistics that are representative and credible pertaining to both the whole nation and the metropolitan cities with regard to the citizens’ health status, health-related consciousness, and behavior; the statistical data have been provided to the World Health Organization (WHO) and Organization for Economic Cooperation and Development. A rolling survey sampling method was used so that 3-year samples of KNHANES Period V (2010–2012) data may become independent probability samples representing the entire country, and samples with similar characteristics by year may be selected. Sample enumeration districts were extracted through the first stratification by metropolitan city, and through the second stratification using standards such as gender and population ratio, and 20 final surveying households per enumeration district were extracted via a systematic sampling method among the extracted sample enumeration districts. The subjects were people aged ≥1 year from the extracted households. Pulmonary function testing,

Kim: Gender Differences in HRQOL of Korean COPD Patients which was obtained only for subjects over 40 years of age, was also used as an item in the survey. Among the original data for the 1st and the 2nd years (2010–2011) of KNHANES Period V, the data of 556 males and 195 females who had been diagnosed with COPD after pulmonary function testing were analyzed. COPD diagnosis for the subjects was made when the ratio of forced expiratory volume in 1-second (FEV1) versus forced vital capacity was less than 70% and there was airflow limitation after carrying out the pulmonary function test (Digital Computed Spirometry; SensorMedic, Anaheim, CA, USA). The level of FEV1 relative to the estimated normal value according to the Global Chronic Obstructive Lung Disease (2009) classification was classified into period I (mild, FEV1 ≥ 80%), period II (moderate, 50% ≤ FEV1 < 80%), period III (severe, 30% ≤ FEV1 < 50%), and period IV (very severe, FEV1 < 30%).

Measures HRQOL. EuroQol 5-Dimension (EQ-5D), developed by the EuroQol Group, was used to measure the subjects’ HRQOL. EQ-5D comprises five items: mobility, self-care, usual activity, pain/disability, and anxiety/depression. Each question in EQ-5D has three possible responses to express the current state (1 = nondisruptive; 2 = more or less disruptive; and 3 = completely disruptive), and the total score was calculated with the aid of a quality weight model that was developed to present the weight of quality of life unique to Koreans (KCDC, 2012). The final HRQOL score falls in the range 0–1, with higher scores indicating a better quality of life (KCDC, 2012; Nam, Kwon, Ko, & Paul, 2007). General characteristics of the subjects The following variables were used as individual subject characteristics: age, living with spouse, living area, educational level, current economic activity, and economic level. The subjects were stratified into two groups according to age (40–64 years and ≥65 years), and “living with spouse” was categorized as “Yes” in the case of living together with a spouse and “No” where the subject was single, had no spouse, or was living separately from a spouse due to death or divorce. Educational level was classified as “lower than elementary school graduation,” “lower than high school graduation,” and “higher than university graduation.” Economic activity was


classified as “Yes” when the subject was currently employed and “No” in the case of unemployment or being economically inactive. The economic level of the household was classified according to equivalent income (average monthly household income/ number of family members): the lowest 25% was designated as the 1st quartile, and the subsequent three 25% levels as the 2nd, 3rd, and 4th quartiles.

Physical and psychological characteristics The physical and psychological characteristics of the patients that were considered were experience of cough and sputum as typical symptoms of COPD (experienced for >3 months/year), severity of COPD, obesity, anemia, high blood pressure, diabetes, stress recognition, depression, and suicidal ideation. Obesity was defined as a body mass index above 25.0 kg/m2 (Korean Endocrine Society & Korean Society for the Study of Obesity, 2010), and anemia as a blood hemoglobin level of 90 mmHg (National Heart, Lung, & Blood Institute, 2004), or medication with blood pressure-lowering agents. The presence of diabetes was confirmed in cases with a fasting glucose of >126 mg/dL, according to the guidelines of the Korean Diabetes Association (2007), or on physical examination or medication with hypoglycemic agents or with insulin injections. Stress was recognized as “Yes” when the subjects’ answered “feel so much,” “feel much,” and “more likely to feel a bit,” and as “No” when they responded “scarcely feel.” Depression was determined as being present or not with answers of “Yes” or “No,” respectively, in response to questions such as “Have you felt so sad or desperate as to disrupt your daily life for more than 2 weeks in succession during the past year?” Suicidal ideation was also dichotomized as “Yes” or “No” in response to questions such as “Did you ever think that you want to die during the past year?” Health-related characteristics The following variables were assessed as healthrelated characteristics: current smoking status, number of smoking times per day for a smoker, plan to quit smoking during the past month, passive smoking, Alcohol Use Disorders Identification Test (AUDIT), and amount of physical activity. Smoking status was categorized as “current smoker” in the


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case of “smoking” and “past smoker” in the case of “ever smoked, but not smoking now,” and “nonsmoker” in the case of “no smoking” in response to the question “Do you smoke now?” Planning to quit smoking was classified as “Yes” where the response was that “I will quit within the next 6 months” or “I plan to quit, although not in the next 6 months,” and “No” for the response “I will never quit” to the question of “Do you plan to quit smoking within 6 months from now?” Domestic passive smoking was classified as “Not” in the case of 0 hr and “Being” in the case of 1 hr in answer to the question “How many hours do you smell cigarette smoke from others in the house?” AUDIT was stratified according to WHO standards (Babor, Higgins-Biddle, Saunders, & Monteiro, 2001) into the following categories: medium level of alcohol problems, 8–15 points; high level of alcohol problems, 16–19 points; and alcohol dependence, >20 points. The level of physical activity was classified according to the score conversion method presented by the IPAQ Research Committee (2005). The amount of physical activity was calculated based on the metabolic equivalent score and classified into three phases: inactivity, minimal activity, and health-enhancing physical activity.

Analytic strategy Complex sample analysis was carried out to reflect the sample design and weighted values using SAS 9.3 (SAS Institute, Cary, NC, USA). Continuous variables (general characteristics of the subjects) are presented as mean (SE) values, while categorical variables are presented as percentage (SE) values and relative to gender. The t test and F-test were used for comparison of general characteristics among groups with regard to EQ-5D; the Scheffe test was used as a post hoc test. Factors affecting EQ-5D for the final subjects revealed that age was the largest affecting factor for quality of life; multiple regression analysis was thus carried out for variables with p < .10 among individual characteristics, physical/mental health status, and characteristics related with health activity.

Results EQ-5D level according to gender EQ-5D scores according to subfactor and gender are listed in Table 1. The EQ-5D scores were higher

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TABLE 1. Level of EQ-5D by Gender M (SE) or % (SE)

EQ-5D Mobility Self-care Usual activities Pain/ discomfort Anxiety/ depression

Male (n = 556)

Female (n = 195)



0.86 (0.02) 20.5 (2.2) 5.3 (1.2) 14.2 (1.9)

0.93 (0.01) 43.7 (5.0) 9.8 (3.0) 25.3 (4.7)

Gender differences in health-related quality of life of Korean patients with chronic obstructive lung disease.

The aim of this study was to identify the health-related quality of life (HRQOL) of COPD patients over 40 years of age in Korea and to assess the rele...
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