Effect of cardiac rehabilitation on inflammation: A systematic review and meta-analysis of controlled clinical trials.

BACKGROUND: This systematic review and meta-analysis aimed to assess the effect of cardiac rehabilitation (CR) on serum C-reactive protein (CRP) as an indicator of the inflammatory state and predictor of recurrent cardiovascular events. METHODS: PubMed, SCOPUS, Cochrane library, and Google Scholar databases were searched up to January 2014 for original articles which investigated the effect of CR on CRP among adult patients with previous cardiovascular events. The random effects model was used to assess the overall effect of CR on the variation in serum CRP levels. RESULTS: In the present systematic review and meta-analysis, 15 studies were included. The analysis showed that CR might significantly reduce high-sensitivity CRP (hs-CRP) levels [Difference in means (DM) = -1.81 mg/l, 95% confidence interval (CI): -2.65, -0.98; P = 0.004). However, the heterogeneity between studies was significant (Cochran's Q test, P < 0.001, I-squared = 84.9%). To find the source of variation, the studies were categorized based on study design (quality) and duration. The negative effect was higher among studies which followed their participants for 3 weeks or less (DM = -2.75 mg/l, 95% CI: -3.86, -1.64; P < 0.001) compared to studies which investigated the effect of CR for 3-8 weeks (DM = -0.89 mg/l, 95% CI: -1.35, -0.44; P < 0.001) and those which lasted more than 8 weeks (DM = -1.71 mg/l, 95% CI: -2.53, -0.89; P < 0.001). There was no evidence of heterogeneity when the categorization was based on the follow-up period. CONCLUSION: Both short- and long-term CR have resulted in improvement in serum hs-CRP levels. CR can be perceived as a beneficial tool to reduce inflammatory markers among patients with previous cardiac events.