Characteristics on the index date of cases of gastrointestinal bleeding and controls exposed to warfarin.

CI = confidence interval; GI = gastrointestinal; OR = odds ratio; NSAID = non-steroidal anti-inflammatory drug; PPI = proton pump inhibitor.*Adjusted for matching variables, i.e., index date and state.†Ever in the past.‡Either an outpatient diagnosis for GI bleeding during warfarin therapy or a hospital admission for GI bleeding before initiating warfarin therapy, excluding the day prior to and the index date.§Prescription dispensed 0–29 days prior to the index date.