5 78 Placebo 3,385.5 67 NSAID/analgesicb 9,731 55 NSAID nonsteroidal anti-inflammatory drug aHigh-dose aspirin: >1,000 mg/day, low-dose aspirin: ≤1,000 mg/day bParacetamol: 3,297 subjects in 5 Captisol chemical structure studies (high-dose: >1,000 mg/day, low-dose: ≤1,000 mg/day); ibuprofen: 3,430 subjects in 13 studies (high-dose: >400 mg/day, AZD4547 low-dose: ≤400 mg/day); naproxen: 211 subjects in 6 studies (high-dose: >500/550 mg/day, low-dose: ≤500/550 mg/day); diclofenac: 479 subjects in 5 studies (high-dose: >25 mg/day, low-dose: ≤25 mg/day); other active

agent: 2,329 subjects in 35 studies A full protocol for the meta-analysis is available from the corresponding author. Bayer HealthCare (Leverkusen, Germany) funded the study, and Bayer employees participated in this website this research. All authors assume responsibility for the integrity of the work. 3 Results 3.1 Studies Overall, 150 publications describing 152 studies and 48,774 patients were selected; 78 of these with 19,829 subjects provided relevant data for at least one safety outcome in comparisons of aspirin with placebo or an active agent (see Table 1 and see Appendix 2 in the Electronic Supplementary Material). Three studies did not describe whether subjects and investigators were blinded to study

treatment, but 69 (88 %) were double-blinded. The most frequently investigated indication was pain—the target condition in 62 studies (79 %). Subjects were aged between 16 and 75 years; about equal numbers of men and women were included. A total of 6,712.5 subjects were allocated aspirin, 3,385.5 placebo, and 9,731 an active comparator. The aspirin treatment was a single dose in 2,694 subjects (43 %). The daily dose was 500–1,000 mg in 2,874 aspirin-treated subjects (46 %) and 1,500–2,000 mg

in 2,920 subjects (47 %). 3.2 Gastrointestinal Risks Five studies comparing aspirin with placebo and five studies comparing aspirin with active comparators MycoClean Mycoplasma Removal Kit reported data on overall gastrointestinal risks, which were recorded in 4.2–18.2 % of subjects (Table 2). Aspirin subjects had higher rates than those allocated placebo (OR 2.12, 95 % confidence interval [CI] 0.95–4.76) and active comparators (OR 1.61 95 % CI 1.43–1.82) [see Table 2 and see Appendix 3 in the Electronic Supplementary Material]. Table 2 Gastrointestinal events in subjects treated with aspirin vs. comparators, all doses Outcome No. of studies No. of events/no. of subjects [%] OR [95 % CI] P valuea Aspirin Comparator Aspirin vs. placebo  Gastrointestinal events 5 23/244 [9.4] 9/213 [4.2] 2.12 [0.95–4.76] 0.55  Minor gastrointestinal events 59 173.3/3,304.5 [5.2] 116/3,170.5 [3.7] 1.46 [1.15–1.86] 0.02   Dyspepsia 22 42.1/1,296 [3.2] 14/1,172 [1.