C-reactive protein, anti inflammatory drugs, and quality of life in diabetes

BACKGROUND: C-reactive protein (CRP) is an important biological marker of inflammation that has been linked to cardiovascular disease. The extent to which the inflammatory processes associated with elevated CRP concentrations impair physical functioning and quality of life, and whether this is modulated by hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) and aspirin, which have been shown to lower CRP concentrations, is unclear. OBJECTIVE: To determine whether an association exists between CRP concentrations and health-related quality of life among patients with diabetes, and to determine whether the association is affected by use of statins and nonsteroidal anti inflammatory drugs (NSAIDs). METHODS: A trained interviewer collected self-reported information regarding demographics, health-related quality of life (SF-12), and medication use, and a nurse collected a blood sample from 86 adult subjects with type 2 diabetes mellitus who were part of a larger population-based survey. The serum was analyzed for CRP using a highly sensitive assay. RESULTS: In simple bivariate analysis, there was a significant inverse relationship between CRP and the physical health component score of health-related quality of life (Spearman correlation coefficient [r] = -0.26; p = 0.025). For subjects on statins (r = -0.44; p = 0.02; n = 27), this relationship persisted, while for patients on NSAIDs or aspirin (r = -0.21; p = 0.17; n = 44), no relationship was observed. Similar findings were observed with self-rated health alone as an outcome variable. However, stepwise linear regression revealed no consistent relationship between CRP and health-related quality of life (i.e., standardized SF-12 physical component score) when demographic variables, disease duration, glucose control, serum creatinine, smoking, and medication use were controlled for. CONCLUSIONS: In multivariate regression modeling, the initial inverse relationship between CRP and health-related quality of life was lost, suggesting that other covariates are responsible for this association. While statins and NSAIDs may impact CRP or health-related quality of life independently, they do not appear to modulate a relationship between these factors.