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Table 3 Characteristics of included randomized controlled trials (RCTs) in metformin (MET) for polycystic ovary syndrome (PCOS)

From: A retrospective survey of quality of reporting on randomized controlled trials of metformin for polycystic ovary syndrome

Features of included RCTs Number of studies (n = 39) %
Year of publication   
   1996 to 2001 7 17.9
   2002 to 2007 12 30.8
   2008 to February 2013 20 51.3
Revised CONSORT 2001   
   Before 7 17.9
   After 32 82.1
Regions in which RCTs were conducted   
   North America 6 15.4
   Europe 16 41.0
   Others 17 43.6
Sources of trial funding   
   Yes 19 48.7
   No 20 51.3
Collaboration of different countries   
   Yes 8 20.5
   No 31 79.5
Choice of comparator interventions   
   Placebo 16 41.0
   Sole intervention 11 28.2
   MET plus other therapies 3 7.7
   Some of above combinations 9 23.1
Journals with most frequently published   
   The Journal of Clinical Endocrinology & Metabolism 9 23.1
   Fertility and Sterility 7 17.9
   Human Reproduction 6 15.4
   The New England Journal of Medicine 3 7.7
   Eleven other journalsa 14 35.9
Impact factors of included journalb   
   0.00 to 2.99 10 25.6
   3.00 to 5.99 24 61.5
   6.00- 4 10.3
  1. Abbreviations: CONSORT, Consolidated Standards of Reporting Trials; MET, metformin; PCOS, polycystic ovary syndrome; RCT, randomized controlled trial.
  2. aEach journal published fewer than three RCTs.
  3. bOne journal (Acta Med Indones) did not have an impact factor.