Financial strain modifies the association between inflammation and cardiovascular disease risk: The English longitudinal study of ageing: European Congress of Epidemiology “Crises, epidemiological transitions and the role of epidemiologists”

Introduction Atherosclerosis and cardiovascular disease (CVD) have an inflammatory origin. Moreover, chronic psychosocial stress is associated both with inflammation and CVD. Fibrinogen, a coagulation factor and CVD risk factor, is also a positive acute-phase reactant protein, its concentration increasing with presence of inflammation. Elevated inflammation measured on a single occasion can reflect either systemic inflammation and be the consequence of chronic psychosocial stress or the acute response to a recent stressful event or infection in an otherwise healthy, non-psychosocially stressed individual. Therefore, the prognostic value for future CVD risk of a single inflammation test may depend on the presence of chronic psychosocial stress. We tested this hypothesis in middle-aged to older adults aged 52 and above participating in a nationally representative cohort study. Methods A total of 4541 men and women, free of CVD and aged 52 to 92 at baseline (2004–2005), participants in the English Longitudinal Study of Ageing, provided serum levels of fibrinogen during the nurse visit at baseline, alongside with clinical measurements and other blood biomarkers. Psychosocial factors were collected during the computer assisted personal interview and included financial strain, depression, social isolation, loneliness and social support. The outcome of interest was CVD mortality as ascertained up to February 2013. Cox proportional hazards regression models using age as the underlying time variable were fitted to estimate the relationship (hazard ratios [HR] and 95% confidence intervals) between fibrinogen and CVD death. Interactions terms between fibrinogen and each psychosocial factor were tested. Models were stratified by sex and adjusted for age, smoking, body mass index, physical activity, cholesterol, triglycerides and diabetes. Restricted cubic splines were used to assess the shape of the associations and test nonlinearity by using the likelihood ratio test, comparing nested models with a linear or linear and cubic spline terms. Results In this sample with a baseline median age of 63 years (interquartile range 57–71), there were 130 CVD deaths after a median follow-up of 8.1 y. The association between fibrinogen and hazard of CVD mortality was linear and positive: HR for the increase in 1g/L of fibrinogen=1.56; 95% CI: 1.26, 1.94, P