Inflammation and sarcopenia: A systematic review and meta-analysis

Inflammatory cytokines have been shown to prompt muscle wasting, ultimately stimulating protein catabolism and suppressing muscle synthesis. However, the possible association between inflammatory parameters and sarcopenia is poorly understood. We therefore aimed to summarize the current evidence about this topic with a meta-analysis of studies reporting serum inflammatory parameters in patients with sarcopenia vs. people without sarcopenia (controls). An electronic PubMed and Scopus search through to 09/01/2016 and meta-analysis of cross-sectional studies comparing serum levels of inflammatory cytokines between patients with sarcopenia and controls was made, calculating randomeffects standardized mean differences (SMDs) ±95% confidence intervals (CIs) as the effect size. Out of 1370 initial hits, 17 studies with a total of 11249 participants (3072 with sarcopenia and 8177 without) were meta-analyzed. Sarcopenic participants had significantly higher levels of CRP (SMD = 0.51; 95%CI 0.26, 0.77; p < 0.0001; I 2 = 96%)than controls. Conversely, serum IL6 levels were not significantly different (SMD = 0.35; 95%CI: -0.19, 0.89; p = 0.21; I 2 = 97%) in people with sarcopenia versus controls. Sarcopenic people did not have higher levels of TNF- than controls (SMD = 0.28; 95%CI -0.26, 0.83; p = 0.31;I 2 = 97%). In conclusion, sarcopenia seems to be associated with elevated serum CRP levels; future longitudinal studies are needed to clarify this relationship.