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Table 1 Characteristics of included studies with meta-regression analysis

From: Most published meta-regression analyses based on aggregate data suffer from methodological pitfalls: a meta-epidemiological study

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%)
  1. There were no important differences in baseline characteristics between the two assessed years