Characteristics of the included studies.

Abbreviations: US, United States;UK, United Kingdom; BMT, Bone Marrow Transplant; ESRD, End Stage Renal Disease; GPRD – general practice research database; IBD, Inflammatory Bowel Disease; CD, Clostridium Difficile; CDAD, Clostridium difficile associated diarrhea; LOS, Length of Stay; LTCF, Long Term Care Facility; Gen, General.; Pop, Population; d, day/days; mo, month/months; yr, year/year; wk, week/week; Pts, Patients; Pt, Patient; Med, Medical; CT, Cardio-thoracic; NL, Netherland; CA, Canada; IL, Israel; Abd, Abdominal; (P), prospective; (R), Retrospective.*, Mostly hospital.