Beyond the Body Burden

Objectives and Theoretical Framework This study addresses the social dynamics of associations between chronic inflammation and quality of life in older adults, as well the ability of social factors to cause inflammatory disease. It builds on growing evidence in sociological and clinical literatures that chronic inflammation has negative net effects on quality of life across the life course, as well as negative indirect effects via social mechanisms (Hamer and Chida 2011; Lal 2006; Marnell et al. 2005; Testa and Simonson 1996; Sprangers et al. 2000; Epel et al. 2004; Finch and Crimmins 2004; Willson et al. 2007). Biomarkers are used to capture inflammatory pathology, ensuring that people with rare inflammatory conditions are included and thus avoiding many of the challenges presented by the diagnosis data used in previous research (Mirowsky and Ross 1989; Mirowsky and Ross 2003; Crimmins and Seeman 2001). Using this more inclusive method for studying people with chronic inflammation, elaboration models are created to explore how social factors influence the consequences and causation of chronic inflammation. Methods and Data Sources Data from Wave I of the National Social Life, Health, and Aging Project (NSHAP) are used to examine relationships between levels of the inflammatory biomarker C-reactive protein and two different sets of quality of life outcomes. Because many inflammatory diseases are present at birth, studying older adults can reveal long-term effects from living with chronic inflammation (Geronimus 1992). Quality of life is measured in two ways: self-ratings of satisfaction with life in general (happiness, enjoyment of life, and sadness), and self-ratings of satisfaction with intimate relationships (overall happiness, physical satisfaction, and emotional satisfaction). Three types of social factors are examined: structure variables (age, race, sex, income, education), sociomedical sequelae (disability, pain, diagnosis), and process factors (communication and social support, relationship participation). The unique role of each of these elements of social life is explored via mediation, moderation, and fundamental causation analyses. All analyses use ordinal logistic and ordinary least-squares regression techniques as theoretically and mathematically indicated. Findings reveal how chronic inflammation may entrench and even foster social inequality. Key Findings Bivariate models suggest that total effects of chronic inflammatory biomarker levels on quality of life are significant and negative, indicating that chronic inflammation can decrease satisfaction with life and relationships. However, effect significance varies somewhat depending on the measure used; the effects of chronic inflammation on quality of life may thus be sensitive to slight differences between domains of psychosocial experience. Each additional milligram per liter of C-reactive protein appears to reduce the odds of reporting high levels of quality of life between 7 and 10 percent for the following outcomes: overall happiness, happiness with intimate relationships, physical satisfaction with relationships, and emotional satisfaction with relationships. Including sociomedical, interactional, and sociodemographic variables reveals inconsistency in the effects of different social attributes and processes. Associations between emotional quality of life and chronic inflammation may be partially mediated by sociomedical sequelae and social relationship factors. Associations between relational quality of life and chronic inflammation appear to be partially mediated by social relationships, but not by sociomedical sequelae. In both cases, dynamics related to partner intimacy may play an important mediating role. Social structure factors do not appear to moderate overall associations between chronic inflammation and quality of life. However, these constructs do demonstrate consistent ability to predict both emotional and relational outcomes when incorporated into models containing C-reactive protein as the main predictor. Likewise, both social structure and relationship factors may play a role in causing chronic inflammation. Extant research and theory from both sociological and clinical disciplines support these findings, and recommend multiple strategies for further study. Significance and Future Directions Using biomarker data to measure inflammation status reveals important information about how chronic inflammation may impact psychosocial quality of life. Looking at a variety of quality of life outcomes in tandem suggests that several individual domains of emotional and relational quality of life may be especially vulnerable to detrimental effects from chronic inflammation, and that these negative effects occur through different social pathways. Emphasizing social structure and relationship factors that shape relationships between inflammation and different quality of life outcomes can illuminate specific ways that chronic inflammation may predispose people to psychosocial disadvantage and/or exacerbate existing social inequalities. Relational processes, especially those related to participation in and dynamics of intimate partnerships, may be more important than social structures in shaping the effects of chronic inflammation on quality of life. Likewise, further research is needed to explore how different social factors may fundamentally cause chronic inflammation. Future scholarship on these topics can contribute immensely to understanding of both social inequality and medical risk. Finally, effects of chronic inflammation are likely underestimated due to very small samples of people with extremely high C-reactive protein levels; more data on these individuals are thus needed.