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Table 2 Results of 18 randomised controlled trials of vitamin D supplements reporting subgroup analyses for baseline 25-hydroxyvitamin D

From: Assessment of research waste part 2: wrong study populations- an exemplar of baseline vitamin D status of participants in trials of vitamin D supplementation

Study 25OHD threshold (nmol/L) Subgroup Resulta Comparison to primary analysisa
Jackson 2006 [33] 32.2 Neutral Same
Jorde 2008 [55] 40 NR N/Ab
Wejse 2009 [56] 75 Neutral Same
Martineau 2011 [48] 20 Neutral Same
Rastelli 2011 [57] 50 Neutral Samec
Kjaergaard 2012 [58] 25 Neutral Same
Lehouck 2012 [59] 25 Neutral Sameb
Murdoch 2012 [60] 50 Neutral Same
Abou-Raya 2013 [61] 25 Benefit Same
McAlindon 2013 [62] 37.5 Neutral Same
Amrein 2014 [63] 30 Neutral Sameb
Lopez-Torres Hidalgo 2014 [64] 80 Neutral Same
Tran 2014 [65] 50 Neutral Same
Turner 2014 [66] 50 Neutral Same
Baron 2015 [36] 57.9 Neutral Same
Martineau 2015 [67] 50 Benefit Differentd
Miskulin 2015 [68] 37.5 Neutral Same
Sandoughi 2015 [69] 50 Neutral Same
Tukvadze 2015 [70] 25 Neutral Same
  1. a Assessed independently by two authors (MB, AG)
  2. b Benefit for secondary endpoint in subgroup analysis
  3. c Primary endpoint not specified. Benefits in subgroup analyses for some but not all reported endpoints
  4. d Two co-primary endpoints. Benefit in subgroup analysis for one co-primary endpoints. For other co-primary endpoint, subgroup analysis was neutral. In primary analyses, results for both co-primary endpoints were neutral
  5. Studies are listed in Additional file 1: Table S3 and Reference list
  6. Abbreviations: 25OHD 25-hydroxyvitamin D, NR not reported; N/A not applicable