Ya-li Lv, Fei-fei Han, Yang-jie Jia, Zi-rui Wan, Li-li Gong, He Liu, Li-hong Liu

Human cytomegalovirus (HCMV) infection has been associated with inflammatory bowel disease (IBD). Numerous studies have been conducted to analyze the association between HCMV infection and risk of IBD and steroid-resistant IBD, but no clear consensus had been reached. The aim of this study was to confirm this relationship precisely by doing a systematic review and meta-analysis. We identified relevant studies through a search of PubMed and Embase. Studies were eligible for inclusion if they 1) evaluated the association between HCMV infection and IBD disease; 2) evaluated the association between HCMV infection and steroid-resistant IBD disease; 3) were case-control studies or nested case-control studies; 4) provided the numbers (or percentage) of positivity for HCMV infection in cases and controls, respectively. Data were extracted and analyzed independently by two investigators. A total of 18 studies including 1,168 patients and 951 health groups was identified, and HCMV infection was distinctly confirmed as a risk factor for the occurrence and development of IBD. When involving 17 studies including 1,306 IBD patients, a total of 52.9% of patients in the cytomegalovirus (CMV)-positive groups were observed to have steroid resistance, compared with 30.2% of patients in the CMV-negative groups. There was a significant difference in the risk of steroid resistance between people exposed to HCMV infection and those not exposed HCMV infection in IBD patients. This meta-analysis suggested that HCMV infection is associated with an increased risk for IBD and steroid-resistant IBD.