Support Care Cancer (2014) 22:689–695 DOI 10.1007/s00520-013-2023-0
ORIGINAL ARTICLE
Stress and physical activity in young adults treated for cancer: the moderating role of social support Jennifer Brunet & Caitlin Love & Raveena Ramphal & Catherine M. Sabiston
Received: 20 June 2013 / Accepted: 18 October 2013 / Published online: 8 November 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Purpose The first objective of the current investigation was to explore the relationships between adolescents and young adults’ (AYA) experiences of stress and social support resources (i.e., perceived social support and support group involvement) following treatment for cancer. The second objective was to examine the relationship between stress and physical activity behavior, and test if social support resources are moderators of this relationship. Methods AYAs (N =64; mean age=28.8 years, standard deviation (SD)=5.5 years; mean time since diagnosis=2.9, SD=3.0 years) completed an online questionnaire. Data were analyzed using correlation and hierarchical multivariate linear regression analyses. Results Stress was negatively related to perceived social support, support group involvement, and physical activity behavior. Support group involvement, but not perceived social support, moderated the association between stress and physical activity behavior. Conclusions Findings suggest establishing support groups, as part of psychosocial rehabilitation services, may help to reduce stress and promote an active lifestyle in AYAs treated for cancer.
J. Brunet (*) School of Human Kinetics, University of Ottawa, 125 University Pr., Montpetit Hall Room 339, Ottawa, ON K1N 6N5, Canada e-mail: [email protected] C. Love Oregon Research Institute, 1776 Millrace Dr, Eugene, OR 97403, USA R. Ramphal Division of Hematology/Oncology, Children’s Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada C. M. Sabiston Faculty of Kinesiology & Physical Education, University of Toronto, 55 Harbord Street, Toronto, ON M5S 2W6, Canada
Keywords Distress . Social support . Physical activity . Cancer . Moderation analysis Adolescence and young adulthood are transitional periods characterized by significant developmental changes [1]. A diagnosis of cancer and subsequent treatments can add to the stress of these transitional periods [2]. In Canada, there are over 6,300 adolescents and young adults (AYA) between 15 and 39 years of age diagnosed with cancer each year [3]. Although current treatment protocols offer AYAs a positive outlook for surviving cancer, they face many social, psychological, physical, and biological complications [4, 5]. These health challenges are likely to foster experiences of stress, with people treated for cancer experiencing stress 1.5 times more than the general population [6]. Stress can adversely impair AYAs’ life-course development, health, and wellbeing. It can increase the risk of longterm and late effects of cancer treatments, fear of recurrence, poor psychological adjustment, and financial struggles [7–9]. Also, it can decrease efforts to make positive changes in preventive health behaviors, such as physical activity and healthy eating [10]. However, not all AYAs experiencing stress have difficulty adapting after cancer. Some AYAs adjust relatively well to the experience of cancer [11, 12]. According to Lazarus and Folkman’s [13] transactional model of stress and coping, the availability of social support can be critical to help AYAs cope with stress and thus can mitigate the negative outcomes associated with stress. As such, AYAs with adequate social support may adjust better as it may help offset the negative impact of stress—a phenomenon known as the “stress-buffering effect” [14]. Social support can be broadly conceptualized as a multidimensional concept that reflects one’s perceptions of informational, emotional, and instrumental support he/she receives from existing support network members, such as family and friends (i.e., perceived social support). From the findings in the literature [15–17], perceived social support appears to
690
have a protective effect on wellbeing and adjustment to cancer. For instance, researchers have shown that the effect of stress on general distress, depression, anxiety, and sleep disturbances is higher in a context of low perceived social support [10, 18–21]. These studies provide support for the stressbuffering effect of perceived social support in middle-aged and older adults with cancer, though much remains to be learned about this hypothesis in AYAs [22, 23]. While the most common reported sources of social support for AYAs are their family and friends [22], obtaining support from one’s existing social circle may be challenging at times. AYAs may sometimes feel that family members or friends do not understand what they are going through or they simply may not want to burden their close ones. Under these circumstances, social support groups may be an alternative source of support for AYAs diagnosed and treated for cancer [24]. Support groups may provide AYAs occasions to have their support needs met by interacting with supportive and understanding mentors and peers. In addition, mentors and peers may help AYAs relieve stress by sharing information and resources, offering suggestions, and helping AYAs realize that they are not alone. They may also encourage AYAs to adopt healthy behaviors that can promote health and wellbeing in the aftermath of cancer [25]. Despite these potential benefits, there has been little focus on whether involvement in support groups moderates the effect of stress [e.g., 26]. This is a compelling research question as it would suggest that resources should be directed at increasing the availability and accessibility of support groups to AYAs to help them cope with the negative effects of a cancer diagnosis and its treatments. Therefore, the first objective of the current investigation was to explore the associations between AYAs’ experiences of stress and two types of social support resources (i.e., perceived social support and support group involvement). In addition, participation in physical activity is important for the self-management of stress. There is a growing body of research showing that physical activity can reduce stress in cancer survivors [27, 28]. It can also aid in the management of side effects, improve general health and wellbeing, help prevent secondary malignancies and comorbidities, and protect against all-cause and cancer death [27–30]. Despite this evidence, more than 50 % of young people treated for cancer are inactive [31]. Thus, there is a critical need to better understand factors related to AYAs’ physical activity behavior following treatment for cancer. These data may help in the development and evaluation of interventions aimed at increasing physical activity levels in this typically inactive population and thereby improve AYAs’ health and wellbeing post-treatment. One factor that may impede participation in physical activity in AYAs treated for cancer is stress. Stress has commonly been studied as an outcome of physical activity behavior, whereby physical activity has been shown to reduce feelings of stress [27, 28]. However, the unique concerns of AYAs and
Support Care Cancer (2014) 22:689–695
their experiences of stress may compromise their ability or willingness to engage in physical activity in the first place. As AYAs’ levels of stress increase, it may be difficult for them to maintain a physically demanding program while managing the disruptions in daily routines and the side effects (e.g., pain and fatigue) resulting from their cancer treatments. As such, research is needed to examine if stress is directly related to lower levels of physical activity in this population. It is also possible that stress does not always affect participation in physical activity. On the basis of the stress-buffering effect hypothesis [14], social support resources may moderate the relationship between stress and physical activity behavior. In this respect, social support resources may help differentiate groups of AYAs who will engage in physical activity, and likely reap the multitude of benefits associated with physical activity, from those who will avoid it. Thus, the second objective of the current study was to examine the relationship between stress and physical activity behavior, and test social support resources as moderators of this relationship.
Methods Participants Eligibility criteria for participants were (1) diagnosed with cancer, (2) currently between 15 and 39 years of age, and (3) completed cancer treatment. Sixty-four AYAs meeting these criteria provided consent and were included in the analysis for this study. As shown in Table 1, participants had a mean age of 28.8 years, and most described themselves as Caucasian, female, not currently married, having an undergraduate degree or higher degree from a university, and employed either full time or part time. Furthermore, the sample consisted of AYAs with mixed cancer diagnoses, who had a mean of 2.9 years post-diagnosis and who had been treated with different treatment protocols. Procedures Following institutional ethics approval and permission from respective administrators, participants were recruited through advertisements posted on four young adult cancer websites and four social media pages (i.e., Facebook). The text advertisements included a brief introduction to the study, the research teams’ contact information, and a link to a consent form and secure online questionnaire. The goal was that AYAs with cancer visiting these websites would view the advertisement, learn about the study, and click on the link to the study website. A web-based online data collection was selected for this study in light of the advantages outlined by Ahern [32] when doing research with special populations such as AYAs with cancer. Prior to gaining access to the questionnaire,
Support Care Cancer (2014) 22:689–695
691
Table 1 Participants’ demographic and medical characteristics presented as means (standard deviations) for continuous variables and frequencies (percentage) for dichotomous/categorical variables
Age in years Female White Married University degree Employed part time/full time Cancer site Carcinoma Lymphoma Leukemia Sarcoma Central nervous system Skin Unknownb
Range
Means (SD)
20–39
28.8 (5.5) 43 (72.9) 56 (94.9) 25 (43.1) 37 (57.8) 39 (60.9) 26 (54.2) 13 (27.1) 6 (12.5) 3 (6.3) 3 (6.3) 2 (4.2) 6 (12.5)
Stage 0 I II III IV Type of treatment Chemotherapy Radiation Lymph node dissection Hormonal therapy Otherc Years since diagnosis Years since treatment completion
Frequenciesa (%)
4 (8.3) 14 (29.2) 15 (31.2) 14 (29.2) 1 (2.1) 41 (64.1) 35 (54.7) 19 (29.7) 12 (18.8) 35 (54.7) 0–9 0–7
2.9 (3.0) 2.9 (1.6)
a
Numbers may not equal 64 due to missing data
b
Lacked necessary information regarding classification
c
Other treatments included surgery and various cancer-related medications
participants were prompted to provide informed consent provided that they meet the eligibility criteria listed in the consent form. Data collection occurred over a 6-month period (i.e., September to February). Measures Personal characteristics A brief questionnaire was used to collect data on demographic variables (i.e., age, sex, marital status, ethnicity, and education) and cancer-specific variables (i.e., type and stage of cancer, age at diagnosis, and types of treatment).
Stress The ten-item Perceived Stress Scale [PSS-10; 33] was used to assess participants’ stress levels. The PSS-10 assesses the extent to which situations in one’s life are appraised as stressful on a five-point Likert scale (0=never to 4=very often). Positively stated items were reverse coded, and a mean score was calculated, where higher scores indicated higher perceived stress levels. The items from the PSS-10 were internally consistent (α =0.85) in this study. The psychometric properties of the PSS-10 have been established previously. Specifically, Cronbach’s α ’s>0.70, intraclass correlation coefficients> 0.70, and medium to large correlation coefficients between the PSS-10 and theoretically related constructs (e.g., depression, anxiety, and mental health) were reported in a recent review [34]. Perceived social support The Social Provisions Scale [SPS; 35] was used to assess the degree to which participants’ social relationships provided various dimensions of social support (i.e., attachment, social integration, reassurance of worth, reliable alliance, guidance, and opportunity for nurturance). Responses were recorded on a four-point Likert scale (1=strongly disagree to 4=strongly agree). A mean score was calculated for overall perceived social support, where higher scores represented greater perceived social support. The Cronbach’s α coefficient for the SPS items was 0.65 in this study. In addition, SPS scores have demonstrated adequate reliability (α =0.92), as well as convergent and divergent validity in previous work [35]. Specifically, scores on the SPS had moderate and positive correlations with other measures of support (e.g., satisfaction with support, number of supportive persons, number of helping behaviors, and attitudes toward support) and negative or weak/non-significant correlations with measures conceptually distinct [e.g., social desirability, depression, introversion–extraversion, neuroticism, and number of stressful events; 35]. Social support group involvement Similar to previous research on coping and stress in people with cancer [e.g., 36], participants indicated if they had been involved in a support group designed for people with cancer. This question was coded as 0=no and 1=yes. Physical activity A modified version of the Leisure Time Exercise Questionnaire [LTEQ; 37] was used to assess physical activity behavior. Participants were asked to indicate the number of times they engaged in light, moderate, and vigorous physical activity during a 7-day period, as well as the average duration of these activities. Scores were converted into weekly minutes of physical activity by multiplying the weekly frequencies and durations of light, moderate, and vigorous activities, respectively. Scores for all three intensities were summed to create an overall physical activity score. Researchers have shown that LTEQ scores are reliable (i.e.,
692
test–retest) and valid as evidenced by moderate positive correlations with other self-report questionnaires and direct measures of physical activity [38, 39]. Data analysis Descriptive statistics (e.g., means, standard deviations (SDs), skewness, kurtosis, and Cronbach’s alpha) were computed for stress, social support, and physical activity variables. Pearson and point–biserial correlations were conducted to investigate the relationship among stress, social support, and physical activity variables. Hierarchical multivariate linear regression analyses were conducted to examine the association between stress and physical activity and determine if perceptions of social support and/or involvement in a social support group moderated this relationship. For these analyses, interaction terms were created for (1) mean-centered stress and meancentered perceived social support, and (2) mean-centered stress and support group involvement by multiplying the respective variables. In order to minimize the number of interaction terms assessed in any one analysis given the small sample size, two separate models were conducted with perceived social support (Model A) and support group involvement (Model B). Entry was specified a priori where stress was included in the first step, the social support variable was entered in the second step, and the product term between stress and the social support variable was included in the final step to test for moderation. A moderator effect was supported if the interaction term was significant. Where the interaction term was significant, a simple slope analysis was performed to examine if the regression slopes that correspond to the association between stress and physical activity when the level of social support was low (i.e., >1 SD below the mean for perceived social support and “no” for support group involvement) and high (i.e., >1 SD above the mean for perceived social support and “yes” for support group involvement) significantly differed from each other. In addition, a graphical representation using the regression coefficients obtained in the simple slope analysis was used to plot the significant interaction term to aid in the interpretation of the moderating effect [40]. Specifically, the graph would show how the association between stress and physical activity is dependent on the value of the social support variable.
Results Means, SD, score ranges, skewness, kurtosis, and correlation coefficients for study variables are reported in Table 2. Initial inspection of the data showed that the stress, social support, and physical activity variables were normally distributed based on skewness and kurtosis values. Participants reported moderate levels of stress and high levels of perceived social
Support Care Cancer (2014) 22:689–695
support relative to the scale range. Half of participants were involved in a support group. Also, participants reported an average of 241.66 min of total physical activity per week. Based on the correlation coefficients, stress was significantly and negatively related to perceived social support, support group involvement, and physical activity behavior. Perceived social support was significantly and positively related to physical activity behavior. In regard to the main effects observed in the hierarchical regression analyses (see Table 3), stress was inversely related to physical activity behavior in the first step in both models. Perceived social support (Model A; ΔR 2 =0.03) and support group involvement (Model B; ΔR 2 =0.02) were positively, albeit not statistically significantly, related to physical activity behavior in step 2. In regard to the interaction effects modeled in step 3 of the models, the “stress×perceived social support” product term was not statistically significant in Model A (ΔR 2 =0.02). However, the “stress×support group involvement” product term in Model B was statistically significant (ΔR 2 =0.07). As shown in Fig. 1 and based on the simple slope analysis, the negative association between stress and physical activity was statistically significant for participants who were not involved in a social support group (β =−0.48, p
ORIGINAL ARTICLE
Stress and physical activity in young adults treated for cancer: the moderating role of social support Jennifer Brunet & Caitlin Love & Raveena Ramphal & Catherine M. Sabiston
Received: 20 June 2013 / Accepted: 18 October 2013 / Published online: 8 November 2013 # Springer-Verlag Berlin Heidelberg 2013
Abstract Purpose The first objective of the current investigation was to explore the relationships between adolescents and young adults’ (AYA) experiences of stress and social support resources (i.e., perceived social support and support group involvement) following treatment for cancer. The second objective was to examine the relationship between stress and physical activity behavior, and test if social support resources are moderators of this relationship. Methods AYAs (N =64; mean age=28.8 years, standard deviation (SD)=5.5 years; mean time since diagnosis=2.9, SD=3.0 years) completed an online questionnaire. Data were analyzed using correlation and hierarchical multivariate linear regression analyses. Results Stress was negatively related to perceived social support, support group involvement, and physical activity behavior. Support group involvement, but not perceived social support, moderated the association between stress and physical activity behavior. Conclusions Findings suggest establishing support groups, as part of psychosocial rehabilitation services, may help to reduce stress and promote an active lifestyle in AYAs treated for cancer.
J. Brunet (*) School of Human Kinetics, University of Ottawa, 125 University Pr., Montpetit Hall Room 339, Ottawa, ON K1N 6N5, Canada e-mail: [email protected] C. Love Oregon Research Institute, 1776 Millrace Dr, Eugene, OR 97403, USA R. Ramphal Division of Hematology/Oncology, Children’s Hospital of Eastern Ontario, 401 Smyth Road, Ottawa, ON K1H 8L1, Canada C. M. Sabiston Faculty of Kinesiology & Physical Education, University of Toronto, 55 Harbord Street, Toronto, ON M5S 2W6, Canada
Keywords Distress . Social support . Physical activity . Cancer . Moderation analysis Adolescence and young adulthood are transitional periods characterized by significant developmental changes [1]. A diagnosis of cancer and subsequent treatments can add to the stress of these transitional periods [2]. In Canada, there are over 6,300 adolescents and young adults (AYA) between 15 and 39 years of age diagnosed with cancer each year [3]. Although current treatment protocols offer AYAs a positive outlook for surviving cancer, they face many social, psychological, physical, and biological complications [4, 5]. These health challenges are likely to foster experiences of stress, with people treated for cancer experiencing stress 1.5 times more than the general population [6]. Stress can adversely impair AYAs’ life-course development, health, and wellbeing. It can increase the risk of longterm and late effects of cancer treatments, fear of recurrence, poor psychological adjustment, and financial struggles [7–9]. Also, it can decrease efforts to make positive changes in preventive health behaviors, such as physical activity and healthy eating [10]. However, not all AYAs experiencing stress have difficulty adapting after cancer. Some AYAs adjust relatively well to the experience of cancer [11, 12]. According to Lazarus and Folkman’s [13] transactional model of stress and coping, the availability of social support can be critical to help AYAs cope with stress and thus can mitigate the negative outcomes associated with stress. As such, AYAs with adequate social support may adjust better as it may help offset the negative impact of stress—a phenomenon known as the “stress-buffering effect” [14]. Social support can be broadly conceptualized as a multidimensional concept that reflects one’s perceptions of informational, emotional, and instrumental support he/she receives from existing support network members, such as family and friends (i.e., perceived social support). From the findings in the literature [15–17], perceived social support appears to
690
have a protective effect on wellbeing and adjustment to cancer. For instance, researchers have shown that the effect of stress on general distress, depression, anxiety, and sleep disturbances is higher in a context of low perceived social support [10, 18–21]. These studies provide support for the stressbuffering effect of perceived social support in middle-aged and older adults with cancer, though much remains to be learned about this hypothesis in AYAs [22, 23]. While the most common reported sources of social support for AYAs are their family and friends [22], obtaining support from one’s existing social circle may be challenging at times. AYAs may sometimes feel that family members or friends do not understand what they are going through or they simply may not want to burden their close ones. Under these circumstances, social support groups may be an alternative source of support for AYAs diagnosed and treated for cancer [24]. Support groups may provide AYAs occasions to have their support needs met by interacting with supportive and understanding mentors and peers. In addition, mentors and peers may help AYAs relieve stress by sharing information and resources, offering suggestions, and helping AYAs realize that they are not alone. They may also encourage AYAs to adopt healthy behaviors that can promote health and wellbeing in the aftermath of cancer [25]. Despite these potential benefits, there has been little focus on whether involvement in support groups moderates the effect of stress [e.g., 26]. This is a compelling research question as it would suggest that resources should be directed at increasing the availability and accessibility of support groups to AYAs to help them cope with the negative effects of a cancer diagnosis and its treatments. Therefore, the first objective of the current investigation was to explore the associations between AYAs’ experiences of stress and two types of social support resources (i.e., perceived social support and support group involvement). In addition, participation in physical activity is important for the self-management of stress. There is a growing body of research showing that physical activity can reduce stress in cancer survivors [27, 28]. It can also aid in the management of side effects, improve general health and wellbeing, help prevent secondary malignancies and comorbidities, and protect against all-cause and cancer death [27–30]. Despite this evidence, more than 50 % of young people treated for cancer are inactive [31]. Thus, there is a critical need to better understand factors related to AYAs’ physical activity behavior following treatment for cancer. These data may help in the development and evaluation of interventions aimed at increasing physical activity levels in this typically inactive population and thereby improve AYAs’ health and wellbeing post-treatment. One factor that may impede participation in physical activity in AYAs treated for cancer is stress. Stress has commonly been studied as an outcome of physical activity behavior, whereby physical activity has been shown to reduce feelings of stress [27, 28]. However, the unique concerns of AYAs and
Support Care Cancer (2014) 22:689–695
their experiences of stress may compromise their ability or willingness to engage in physical activity in the first place. As AYAs’ levels of stress increase, it may be difficult for them to maintain a physically demanding program while managing the disruptions in daily routines and the side effects (e.g., pain and fatigue) resulting from their cancer treatments. As such, research is needed to examine if stress is directly related to lower levels of physical activity in this population. It is also possible that stress does not always affect participation in physical activity. On the basis of the stress-buffering effect hypothesis [14], social support resources may moderate the relationship between stress and physical activity behavior. In this respect, social support resources may help differentiate groups of AYAs who will engage in physical activity, and likely reap the multitude of benefits associated with physical activity, from those who will avoid it. Thus, the second objective of the current study was to examine the relationship between stress and physical activity behavior, and test social support resources as moderators of this relationship.
Methods Participants Eligibility criteria for participants were (1) diagnosed with cancer, (2) currently between 15 and 39 years of age, and (3) completed cancer treatment. Sixty-four AYAs meeting these criteria provided consent and were included in the analysis for this study. As shown in Table 1, participants had a mean age of 28.8 years, and most described themselves as Caucasian, female, not currently married, having an undergraduate degree or higher degree from a university, and employed either full time or part time. Furthermore, the sample consisted of AYAs with mixed cancer diagnoses, who had a mean of 2.9 years post-diagnosis and who had been treated with different treatment protocols. Procedures Following institutional ethics approval and permission from respective administrators, participants were recruited through advertisements posted on four young adult cancer websites and four social media pages (i.e., Facebook). The text advertisements included a brief introduction to the study, the research teams’ contact information, and a link to a consent form and secure online questionnaire. The goal was that AYAs with cancer visiting these websites would view the advertisement, learn about the study, and click on the link to the study website. A web-based online data collection was selected for this study in light of the advantages outlined by Ahern [32] when doing research with special populations such as AYAs with cancer. Prior to gaining access to the questionnaire,
Support Care Cancer (2014) 22:689–695
691
Table 1 Participants’ demographic and medical characteristics presented as means (standard deviations) for continuous variables and frequencies (percentage) for dichotomous/categorical variables
Age in years Female White Married University degree Employed part time/full time Cancer site Carcinoma Lymphoma Leukemia Sarcoma Central nervous system Skin Unknownb
Range
Means (SD)
20–39
28.8 (5.5) 43 (72.9) 56 (94.9) 25 (43.1) 37 (57.8) 39 (60.9) 26 (54.2) 13 (27.1) 6 (12.5) 3 (6.3) 3 (6.3) 2 (4.2) 6 (12.5)
Stage 0 I II III IV Type of treatment Chemotherapy Radiation Lymph node dissection Hormonal therapy Otherc Years since diagnosis Years since treatment completion
Frequenciesa (%)
4 (8.3) 14 (29.2) 15 (31.2) 14 (29.2) 1 (2.1) 41 (64.1) 35 (54.7) 19 (29.7) 12 (18.8) 35 (54.7) 0–9 0–7
2.9 (3.0) 2.9 (1.6)
a
Numbers may not equal 64 due to missing data
b
Lacked necessary information regarding classification
c
Other treatments included surgery and various cancer-related medications
participants were prompted to provide informed consent provided that they meet the eligibility criteria listed in the consent form. Data collection occurred over a 6-month period (i.e., September to February). Measures Personal characteristics A brief questionnaire was used to collect data on demographic variables (i.e., age, sex, marital status, ethnicity, and education) and cancer-specific variables (i.e., type and stage of cancer, age at diagnosis, and types of treatment).
Stress The ten-item Perceived Stress Scale [PSS-10; 33] was used to assess participants’ stress levels. The PSS-10 assesses the extent to which situations in one’s life are appraised as stressful on a five-point Likert scale (0=never to 4=very often). Positively stated items were reverse coded, and a mean score was calculated, where higher scores indicated higher perceived stress levels. The items from the PSS-10 were internally consistent (α =0.85) in this study. The psychometric properties of the PSS-10 have been established previously. Specifically, Cronbach’s α ’s>0.70, intraclass correlation coefficients> 0.70, and medium to large correlation coefficients between the PSS-10 and theoretically related constructs (e.g., depression, anxiety, and mental health) were reported in a recent review [34]. Perceived social support The Social Provisions Scale [SPS; 35] was used to assess the degree to which participants’ social relationships provided various dimensions of social support (i.e., attachment, social integration, reassurance of worth, reliable alliance, guidance, and opportunity for nurturance). Responses were recorded on a four-point Likert scale (1=strongly disagree to 4=strongly agree). A mean score was calculated for overall perceived social support, where higher scores represented greater perceived social support. The Cronbach’s α coefficient for the SPS items was 0.65 in this study. In addition, SPS scores have demonstrated adequate reliability (α =0.92), as well as convergent and divergent validity in previous work [35]. Specifically, scores on the SPS had moderate and positive correlations with other measures of support (e.g., satisfaction with support, number of supportive persons, number of helping behaviors, and attitudes toward support) and negative or weak/non-significant correlations with measures conceptually distinct [e.g., social desirability, depression, introversion–extraversion, neuroticism, and number of stressful events; 35]. Social support group involvement Similar to previous research on coping and stress in people with cancer [e.g., 36], participants indicated if they had been involved in a support group designed for people with cancer. This question was coded as 0=no and 1=yes. Physical activity A modified version of the Leisure Time Exercise Questionnaire [LTEQ; 37] was used to assess physical activity behavior. Participants were asked to indicate the number of times they engaged in light, moderate, and vigorous physical activity during a 7-day period, as well as the average duration of these activities. Scores were converted into weekly minutes of physical activity by multiplying the weekly frequencies and durations of light, moderate, and vigorous activities, respectively. Scores for all three intensities were summed to create an overall physical activity score. Researchers have shown that LTEQ scores are reliable (i.e.,
692
test–retest) and valid as evidenced by moderate positive correlations with other self-report questionnaires and direct measures of physical activity [38, 39]. Data analysis Descriptive statistics (e.g., means, standard deviations (SDs), skewness, kurtosis, and Cronbach’s alpha) were computed for stress, social support, and physical activity variables. Pearson and point–biserial correlations were conducted to investigate the relationship among stress, social support, and physical activity variables. Hierarchical multivariate linear regression analyses were conducted to examine the association between stress and physical activity and determine if perceptions of social support and/or involvement in a social support group moderated this relationship. For these analyses, interaction terms were created for (1) mean-centered stress and meancentered perceived social support, and (2) mean-centered stress and support group involvement by multiplying the respective variables. In order to minimize the number of interaction terms assessed in any one analysis given the small sample size, two separate models were conducted with perceived social support (Model A) and support group involvement (Model B). Entry was specified a priori where stress was included in the first step, the social support variable was entered in the second step, and the product term between stress and the social support variable was included in the final step to test for moderation. A moderator effect was supported if the interaction term was significant. Where the interaction term was significant, a simple slope analysis was performed to examine if the regression slopes that correspond to the association between stress and physical activity when the level of social support was low (i.e., >1 SD below the mean for perceived social support and “no” for support group involvement) and high (i.e., >1 SD above the mean for perceived social support and “yes” for support group involvement) significantly differed from each other. In addition, a graphical representation using the regression coefficients obtained in the simple slope analysis was used to plot the significant interaction term to aid in the interpretation of the moderating effect [40]. Specifically, the graph would show how the association between stress and physical activity is dependent on the value of the social support variable.
Results Means, SD, score ranges, skewness, kurtosis, and correlation coefficients for study variables are reported in Table 2. Initial inspection of the data showed that the stress, social support, and physical activity variables were normally distributed based on skewness and kurtosis values. Participants reported moderate levels of stress and high levels of perceived social
Support Care Cancer (2014) 22:689–695
support relative to the scale range. Half of participants were involved in a support group. Also, participants reported an average of 241.66 min of total physical activity per week. Based on the correlation coefficients, stress was significantly and negatively related to perceived social support, support group involvement, and physical activity behavior. Perceived social support was significantly and positively related to physical activity behavior. In regard to the main effects observed in the hierarchical regression analyses (see Table 3), stress was inversely related to physical activity behavior in the first step in both models. Perceived social support (Model A; ΔR 2 =0.03) and support group involvement (Model B; ΔR 2 =0.02) were positively, albeit not statistically significantly, related to physical activity behavior in step 2. In regard to the interaction effects modeled in step 3 of the models, the “stress×perceived social support” product term was not statistically significant in Model A (ΔR 2 =0.02). However, the “stress×support group involvement” product term in Model B was statistically significant (ΔR 2 =0.07). As shown in Fig. 1 and based on the simple slope analysis, the negative association between stress and physical activity was statistically significant for participants who were not involved in a social support group (β =−0.48, p
