Statin use and the risk of Clostridium difficile infection: a systematic review with meta-analysis Raseen Tariq,1,2 Dhruvika Mukhija,3 Arjun Gupta,4 Siddharth Singh,5 Darrell S Pardi,1 Sahil Khanna1 1Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, 2Department of Internal Medicine, Rochester General Hospital, Rochester, NY, 3Department of Internal Medicine, Cleveland Clinic, Cleveland, OH, 4Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, 5Division of Gastroenterology and Hepatology, University of California San Diego, La Jolla, CA, USA Purpose: Statins have pleiotropic effects beyond cholesterol lowering by immune modulation. The association of statins with primary Clostridium difficile infection (CDI) is unclear as studies have reported conflicting findings. We performed a systematic review and meta-analysis to evaluate the association between statin use and CDI.Patients and methods: We searched MEDLINE, Embase, and Web of Science from January 1978 to December 2016 for studies assessing the association between statin use and CDI. The Newcastle–Ottawa Scale was used to assess the methodologic quality of included studies. Weighted summary estimates were calculated using generalized inverse variance with random-effects model.Results: Eight studies (6 case–control and 2 cohort) were included in the meta-analysis, which comprised 156,722 patients exposed to statins and 356,185 controls, with 34,849 total cases of CDI available in 7 studies. The rate of CDI in patients with statin use was 4.3%, compared with 7.8% in patients without statin use. An overall meta-analysis of 8 studies using the random-effects model demonstrated that statins may be associated with a decreased risk of CDI (maximally adjusted odds ratio [OR], 0.80; 95% CI, 0.66–0.97;