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Table 1 Characteristics of the studies included in the systematic reviews

From: Vitamin D and subsequent all-age and premature mortality: a systematic review

Study Year Country Design Population Sample size Average age (years)a Response rate% Overall representativeness of populationb Average follow-up duration (years)a
Bates [28] 2011 UK Prospective cohort Men and women aged ≥65y 1,054 Males 75.8 Females 77.3 36 Fair 13.5
Ford [29] 2011 USA Prospective cohort Men and women aged over 20 across USA 7,531 Mean 45–46 (by ascending 25OHD concentration) 80 (2001/2 sample), 76 (2003/4 sample) Excellent Median 3.8
Ginde [30] 2009 USA Prospective cohort Men and women aged over 65 across USA 3,408 Mean 72–76 (by ascending 25OHD category) 60.1 Good Median 7.3
Hutchinson [31] 2010 Norway Prospective cohort Men and women over age of 25 living in city of Tromso Smokers – 2,410 Non-smokers – 4,751 Smokers – mean 57–58 (by ascending 25OHD quartile). 78 Good Mean Smokers – 11.4 Non-smokers 11.8
Non-smokers mean 59–61 (by ascending 25OHD quartile)
Jia [32] 2007 UK Prospective cohort Men and women over age of 75 living in city of Aberdeen 398 Median 80 Men 25 Women 17 Fair Median 5.95
Johansson [33] 2011 Sweden Prospective cohort Men aged 70–81 years living in cities of Gothenburg, Malmo and Uppsala 3,014 Mean 75 45 Fair 6
Melamed [34] 2008 USA Prospective cohort Men and women aged over 20 across USA 13,331 Mean 41.0-46.7 (by 25OHD quartile) 67.7 Excellent Median 8.7
Michaelsson [35] 2010 Sweden Prospective cohort Men born during 1920–4 living in city of Uppsala 1,194 Mean 71 73 Good Median 12.7
Semba [36] 2010 Italy Prospective cohort Men and women over 65 living in Tuscany 1,155 Median 71–78 (by ascending 25OHD quartile) 90.3 Good 6.5
Virtanen [37] 2011 Finland Prospective cohort Middle aged men and women in Eastern Finland 1,136 Mean 61–62 (by ascending 25OHD tertile) Men – 85.6 Women – 78.4 Good 9.1
Visser [38] 2006 Netherlands Prospective cohort Men and women aged over 65 living in city of Amsterdam 1,260 No average given, all over 65, recalculated as mean 70.2-78.5 by category 81.7 Good 6
  1. a – mean or median specified where reported in original study.
  2. b - based on recruitment method and response rate.