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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.