Micro‐inflammation in functional dyspepsia: A systematic review and meta‐analysis

Background and Purpose Functional dyspepsia (FD) is a gastrointestinal disorder of unknown etiology. Although micro‐inflammation appears to be important in the pathogenesis, studies evaluating immune activation in FD have been inconsistent. A systematic review of literature and meta‐analysis was performed to compare immunologic cell counts and cytokine levels in the mucosa and peripheral blood of individuals with FD and healthy controls. PubMed, Embase, and the Cochrane library were searched. Data on immunologic cell counts and cytokines levels among individuals with FD and control groups were extracted and compared by calculating standard mean differences (SMD). Thirty‐seven studies met the inclusion criteria. Mast cell (SMD = 0.94, 95%CI 0.26‐1.62, P = .007) and eosinophil counts (SMD = 0.36, 95%CI 0.06‐0.68, P = .03) in the stomach were increased, among individuals with FD compared to controls. Similarly, mast cell (SMD = 0.66, 95%CI 0.20‐1.13, P = 0.005) and eosinophil (SMD = 0.95, 95%CI 0.66‐1.24; P