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Table 1 Characteristics of included articles (n = 303) and RCTs described in these articles (n = 319)*

From: Dealing with heterogeneity of treatment effects: is the literature up to the challenge?

Characteristic Articles Represented # RCTs Included
Journal of publication   
   Annals 30 (10) 30 (9)
   BMJ 43 (14) 47 (15)
   JAMA 45 (15) 50 (16)
   Lancet 97 (32) 101 (32)
   NEJM 88 (29) 91 (29)
Year of publication   
   1994 86 (28) 91 (29)
   1999 102 (34) 106 (33)
   2004 115 (38) 122 (38)
Medical condition under study   
   Cardiovascular 69 (23) 74 (23)
   Infectious Disease 62 (20) 70 (22)
   Cancer 41 (14) 42 (13)
   Psychiatry/Neurology 25 (8) 25 (8)
   Other 106 (35) 108 (34)
First author's study region   
   North America 115 (38) 121 (38)
   Other 188 (62) 198 (62)
Study design   
   Parallel - 304 (95)
   Crossover - 15 (5)
Analysis reported   
   HTE analysis - 92 (29)
   Subgroup without statistical comparison - 88 (28)
   None - 139 (44)
Sample size   262 (101 – 708)
  - [6–41,000]
  1. Abbreviations: RCTs, randomized controlled trials; BMJ, British Medical Journal; JAMA, Journal of the American Medical Association; NEJM, New England Journal of Medicine; HTE, heterogeneity of treatment effects.
  2. *Discrete data are expressed as No. (%); continuous values are presented as median (inter-quartile range) [range].