Background
Methods
Data source
Study selection
Data extraction
Analysis
Results
Characteristics | Total (N = 81) | Year 2002 (N = 29) | Year 2012 (N = 52) |
---|---|---|---|
Journal characteristics | |||
Journal Impact Factor, median (IQR) | 4.2 (2.3–6.1) | 4.4 (2.9–5.6) | 3.9 (2.0–6.6) |
General medical journal | 15 (19%) | 5 (17%) | 10 (19%) |
Core clinical journals | 19 (23%) | 9 (31%) | 10 (19%) |
Author characteristics | |||
Affiliated with industry | 5 (6%) | 3 (10%) | 2 (4%) |
Affiliated with biostatistics or epidemiology department | 35 (43%) | 16 (55%) | 19 (37%) |
Ten or more of studies | 73 (90%) | 26 (90%) | 47 (90%) |
Drug intervention | 38 (47%) | 15 (52%) | 23 (44%) |
Type of outcome in meta-regression analysis | |||
Binary | 39 (48%) | 13 (45%) | 26 (50%) |
Continuous | 48 (59%) | 18 (62%) | 30 (58%) |
Clinical field | |||
Psychiatry & Psychology | 13 (16%) | 5 (17%) | 8 (15%) |
Cardiology | 10 (12%) | 3 (10%) | 7 (13%) |
Oncology | 8 (10%) | 1 (3%) | 7 (13%) |
Infectious disease | 7 (9%) | 2 (7%) | 5 (10%) |
Endocrinology & Metabolism | 7 (9%) | 3 (10%) | 4 (8%) |
Surgery | 6 (7%) | 0 (0%) | 6 (12%) |
General internal medicine | 5 (6%) | 3 (10%) | 2 (4%) |
Paediatrics | 4 (5%) | 2 (7%) | 2 (4%) |
Nutrition & dietetics | 4 (5%) | 0 (0%) | 4 (8%) |
Rheumatology | 4 (5%) | 3 (10%) | 1 (2%) |
Miscellaneous | 13 (16%) | 7 (24%) | 6 (12%) |
Main outcome
Pitfall | Total (N = 81) | Year 2002 (N = 29) | Year 2012 (N = 52) |
---|---|---|---|
Ecological fallacy | 53 (65%, 55 to 75%) | 20 (69%, 51 to 83%) | 33 (63%, 50 to 75%) |
Overfitting | 14 (17%, 11 to 27%) | 6 (21%, 10 to 38%) | 8 (15%, 8 to 28%) |
Meta-regression on risk of the analysed outcome | 5 (6%, 3 to 14%) | 2 (7%, 2 to 22%) | 3 (6%, 2 to 16%) |
Any potential meta-regression pitfall | 57 (70%, 60 to 79%) | 21 (72%, 54 to 85%) | 36 (69%, 56 to 80%) |
Characteristics associated with pitfalls
Any potential meta-regression pitfall | Yes (n = 57) | No (n = 24) | Odds Ratio (95% CI) |
---|---|---|---|
Published in 2012 | 36 (63%) | 16 (67%) | 0.87 (0.33 to 2.34) |
Journal characteristics | |||
Core clinical journals | 12 (21%) | 7 (29%) | 0.64 (0.22 to 1.85) |
General medical journals | 11 (19%) | 4 (17%) | 1.13 (0.34 to 3.77) |
Impact factor higher than median | 29 (51%) | 11 (46%) | 1.22 (0.47 to 3.11) |
Author characteristics | |||
Affiliated with industry | 5 (9%) | 0 (0%) | 5.13 (0.27 to 96.57) |
Affiliated with biostatistics or epidemiology department | 23 (40%) | 12 (50%) | 0.68 (0.27 to 1.75) |
Ten or more of studies | 53 (93%) | 20 (83%) | 2.61 (0.64 to 10.61) |
Drug intervention | 28 (49%) | 10 (42%) | 1.33 (0.52 to 3.44) |
Binary outcome variable | 25 (44%) | 14 (58%) | 0.57 (0.22 to 1.47) |