3.1 Baseline characteristics of the patients in the case and control groups
From 2000 to 2013, 9,565 patients aged ≥65 years and who were newly treated with SSRIs met the inclusion criteria (Supplementary Figure 1). During the follow-up period, 630 patients were hospitalized for the first time due to UGIB, and a matched control group of 1,882 patients without UGIB was identified. The mean age of case patients was 79.3 (standard deviation: 6.0) years; of the total patients in the case group, 43.9% were aged more than 80 years (Table 1). Men accounted for 54% of all patients in the case group. Matching revealed that the control group had similar distributions in terms of age and sex. Compared with patients in the control group, those in the case group were more likely to have diabetes, hypertension, coronary artery disease, liver cirrhosis, chronic obstructive pulmonary disease, renal disease, and cancer. Moreover, patients in the case group were more likely to have been prescribed for antiplatelets, oral anticoagulants, and NSAIDs.