Impact of Social Support on Patients with Chronic Obstructive Pulmonary Disease

Abstract

Background: Chronic obstructive pulmonary disease (COPD) is a common inflammatory disease and is a major cause of morbidity worldwide. Social support has been found to be associated with better self-care behaviors and systemic inflammation in adults as well as in clinical populations. However, little is known about these relationships in patients with COPD. This dissertation is composed of two papers. The purpose of the first paper is to determine the association between social support and self-care behaviors in patients with COPD. The second paper is to examine the association between social support and systemic inflammation in patients with COPD. Methods: The first paper was a longitudinal study using two-years of follow-up data from the CASCADE (COPD Activity: Serotonin Transporter, Cytokines, and Depression) cohort (n=282). Self-care behaviors included the following: 1) Physical activity (PA) was measured with a validated accelerometer (Stepwatch) over a 7-day period at baseline, year 1, and year 2; 2) Four yes/no questions on smoking status, participation in pulmonary rehabilitation, and receipt of influenza and/or pneumonia vaccinations; 3) Inhaler/nebulizer medication adherence was based on four questions: carelessness, forgetting, stopping medication when feeling better, and using less of the medication than prescribed when feeling better. Structural social support was measured by self-reported questions on living alone or with others, being partnered, the number of close friends/relatives, and presence of an unpaid caregiver. Functional, or perceived, social support was measured with the Medical Outcomes Social Support Survey (MOSSS). Mixed-effects and logistic regression models were used for the analysis. The second paper was a cross-sectional study using baseline data collected from the CASCADE study. Structural social support was measured by asking whether patients lived alone or with others. Functional social support was measured using the MOSSS total score. Inflammatory biomarkers were measured by tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and C-reactive protein (CRP). Logistic regression models were used for the analysis. Results: In 282 participants with moderate to very severe COPD, 80% were men with a mean age of 68 ± 9. In the first paper, participants who lived with others accrued 903 more steps per day than those who lived alone (β=903, 95% CI: 373, 1433, p=0.001). Higher MOSSS total score (p=0.03) and tangible support (p=0.004) was associated with lower odds of smoking. The odds of participation in pulmonary rehabilitation was more than 11 times higher if a patient had a spouse or partner as caregiver compared to not having a caregiver (p<0.01). Perceived social support was associated with marginally higher odds of pneumonia vaccination (p<0.05). There was no significant association between social support and influenza vaccination or adherence with an inhaler or nebulizer medication. In the second paper, in Model 1 (unadjusted), Model 2 (adjusted for age, gender, income, body mass index [BMI], and forced expiratory volume in 1 second percent predicted [FEV1% predicted]), and Model 3 (contains all adjustments from Model 2 with addition of physical activity, current smoking status, depression, and anxiety), neither structural (living with others) nor functional social support were associated with TNF-α, IL-6, or CRP levels. However, physical activity was inversely associated with CRP level (p<0.001). Conclusions: We found that the type and level of social support had differing effects on core self-care behaviors in patients with COPD. Living with others had a stronger impact on physical activity than functional social support and was associated with a clinically meaningful increase of over +900 steps per day compared to living alone. Having a caregiver was associated with more than a tenfold increase in pulmonary rehabilitation participation compared to having no caregiver. Only functional social support had a small beneficial impact on smoking behavior and pneumococcal vaccinations of unclear clinical significance. Neither structural nor functional support were associated with getting an influenza vaccination or adherence to inhaler or nebulizer medications. Finally, there were no association between social support and systemic inflammation. Future studies should measure how other social support dimensions, such as ambivalent relationships, impacts self-care behaviors and inflammatory markers in patients with COPD.