Eur J Epidemiol 2008 6;23(2):95-103. Epub 2007 Nov 6.
Preventive Medicine, Department of Public Health Sciences, Karolinska Institutet, Karolinska Hospital, Norrbacka 6th floor, 17176 Stockholm, Sweden.
Objective: To assess the relationship between economical stress, as an indicator of SES, and inflammation in women patients with coronary heart disease (CHD).
Design: a cross-sectional study.
Setting And Participants: Two hundred and thirteen women patients recruited from two hospitals in Stockholm, Sweden; mean age 63+/-8, range 35-75 years, hospitalised for acute myocardial infarction, coronary angioplasty or bypass surgery between 1996 and 2000, examined in a stable phase, 1 year and 5 months (+/-2.5 months) after the index event.
Main Outcome Measures: Economical stress, and other SES indicators were assessed by questionnaires. Levels of high-sensitivity C-reactive protein (CRP) were measured by nephelometry and the concentrations of interleukin-6 (Il-6) and interleukin-1 receptor antagonist (Il-1ra) were determined by enzyme-linked immunoassay.
Results: After controlling for the potential confounders, i.e. treatment, menstruational, marital and education status in addition to age, patients having economical stress showed higher levels of hsCRP (2.79 vs. 1.83 mg/l, p=0.04), Il-6 (3.12 vs. 2.38 mg/l, p=0.015) and Il-1ra (599 vs. 456 mg/l, p=0.02). The association persisted after controlling for other measures of economical status, like personal and household income. According to our mediational analyses, lifestyle variables, especially BMI, could partly explain the observed association.
Conclusion: High economical stress was associated with higher Il-6, CRP and Il-1ra levels in women with stable CHD. The direction of causality cannot be inferred from such a cross-sectional study however, our results raise the possibility that increased inflammatory activity is a mediator for the effect of economical stress on adverse outcomes after a coronary event.