Table 1

Characteristics of included meta-analyses

Cochrane meta-analyses
Non-Cochrane meta-analyses
Year of publication, N (%)
 201604 (3)
 201722 (21)31 (22)
 201885 (79)108 (76)
Number of Included RCTs, mean±SD21.4±24.419.6±46.4
Registered in PROSPERO or published protocol, N (%)107 (100)25 (17)*
Impact factor, mean±SD6.8±03.6±5.4
 ≤30106 (74%)
 3.1–6.7027 (19%)
 6.8107 (100%)0
 >6.8010 (7.0%)
Meta-analysis funding sources, N (%)
 Not reported4 (4)†39 (27)
 Industry03 (2)
 Non-industry93 (87)55 (38)
 No funding10 (9)46 (32)
Meta-analysis author financial ties to industry (including employment), N (%)‡
 Not reported1 (1)11 (8)
 No authors with reported financial ties70 (65)117 (81)
 ≥1 author with reported financial ties36 (34)15 (10)
 Proportion of authors with financial ties, mean±SD§11%±17%4%±15%
Journal category, N (%)
 Cochrane review107 (100)0
 Specialty medicine0100 (70)
 General medicine (non-Cochrane)¶033 (23)
 Multidisciplinary**010 (7)
  • *One meta-analysis reported that they registered in PROSPERO but did not provide a registration number and one could not be found. We contacted the authors, and they did not provide us with further information; thus, this was coded as not registered.

  • †Only three included meta-analyses reported author–industry employment, and these were grouped with author–industry financial ties for this table.

  • ‡Cochrane reviews typically have a ‘Sources of Support’ section with funding information. These reviews did not include that section.

  • §Proportion of authors with financial ties or employment of those that reported.

  • ¶Of the 33 included general medicine journals, 28 were published in the journal ‘Medicine’.

  • **Of the 10 journals classified as multidisciplinary, nine were published in the journal ‘PLOS One’.

  • ††Classifications for specialty medicine journals (note that some journals had more than one classification): anaesthesiology: n=3; biochemistry and molecular biology: n=1; biotechnology and applied microbiology: n=2; cardiac and cardiovascular systems: n=7; cell biology: n=1; chemistry, medicinal: n=4; chemistry, multidisciplinary: n=2; clinical neurology: n=6; critical care medicine: n=2; dermatology: n=3; emergency medicine: n=2; endocrinology and metabolism: n=2; gastroenterology and hepatology: n=6; genetics and heredity: n=1; haematology: n=2; immunology: n=6; infectious diseases: n=3; integrative and complementary medicine: n=1; medicine, research and experimental: n=3; microbiology: n=2; neurosciences: n=3; no classification: n=2; obstetrics and gynaecology: n=4; oncology: n=11; ophthalmology: n=3; orthopaedics: n=6; parasitology: n=1; peripheral vascular disease: n=5; pharmacology and pharmacy: n=13; physiology: n=1; psychiatry: n=4; psychology: n=1; reproductive biology: n=1; respiratory system: n=6; rheumatology: n=3; sport sciences: n=1; surgery: n=11; toxicology: n=2; tropical medicine: n=1; urology and nephrology: n=1.