Study	Reason for exclusion
BMS summary	170‐01‐88, 170‐02‐88, and 171‐01‐88: number of participants in each treatment arm not reported Remaining studies: no usable data, only summary statistics reported
Jain 1988	Invalid comparison: ibuprofen 400 mg compared with ibuprofen 200 mg + caffeine 100 mg
Laska 1984	Studies 1 to 17 and 30 excluded due to invalid comparison, for example aspirin compared with aspirin + acetaminophen + caffeine. Studies 18 to 29 make a valid comparison, but fail to report the number of participants in each treatment arm. Four of these are believed to have been reported in full (Laska 1983 Study 1; Laska 1983 Study 2; Laska 1983 Study 3; Laska 1983 Study 4)
Migliardi 1994a	Only the 4 APAP/ASA/CAF studies excluded. Invalid comparison: paracetamol 1000 mg compared with paracetamol 500 mg + aspirin 500 mg + caffeine 130 mg
Mitchell 2008	Invalid comparison: paracetamol 300 mg + caffeine 15 mg + codeine 30 mg compared with paracetamol 325 mg + ibuprofen 400 mg. In addition, no single‐dose outcome data
Schachtel 1991b	Invalid comparison ‐ paracetamol 1000 mg compared with aspirin 1000 mg + caffeine 64 mg

APAP: paracetamol (American); ASA: aspirin (acetylsalicylic acid); CAF: caffeine;