Inflammatory markers and bariatric surgery: a meta-analysis

Obesity is a state of chronic low grade inflammation with increased levels of inflammatory markers such as C-reactive protein (CRP), interleukin (IL)-6 and tumor necrosis factor (TNF) alpha. The changes of some of the above markers after bariatric surgery are not consistent across studies. The objective of this study is to confirm the changes in blood levels of CRP, IL-6 and TNF alpha after bariatric surgery. A Pubmed and EMBASE search was performed for studies measuring the above cytokines in blood before and after bariatric surgery. A meta-analysis was performed for the changes in CRP, TNF alpha and IL-6 for the maximum follow-up time in each study as well as for discrete follow-up times. Only observational studies could be retrieved. Bariatric surgery produces about 66 and 27 % reduction in CRP and IL-6 levels, respectively. The change in TNF alpha after bariatric surgery did not approach statistical significance. Bariatric surgery decreases the low grade inflammation associated with obesity as measured by CRP and IL-6 levels. The change of TNF alpha after bariatric surgery should be further investigated with randomized trials.