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

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

Study	25OHD threshold (nmol/L)	Subgroup Result^a	Comparison to primary analysis^a
Jackson 2006 [33]	32.2	Neutral	Same
Jorde 2008 [55]	40	NR	N/A^b
Wejse 2009 [56]	75	Neutral	Same
Martineau 2011 [48]	20	Neutral	Same
Rastelli 2011 [57]	50	Neutral	Same^c
Kjaergaard 2012 [58]	25	Neutral	Same
Lehouck 2012 [59]	25	Neutral	Same^b
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	Same^b
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	Different^d
Miskulin 2015 [68]	37.5	Neutral	Same
Sandoughi 2015 [69]	50	Neutral	Same
Tukvadze 2015 [70]	25	Neutral	Same

^a Assessed independently by two authors (MB, AG)
^b Benefit for secondary endpoint in subgroup analysis
^c Primary endpoint not specified. Benefits in subgroup analyses for some but not all reported endpoints
^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
Studies are listed in Additional file 1: Table S3 and Reference list
Abbreviations: 25OHD 25-hydroxyvitamin D, NR not reported; N/A not applicable

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