Hip fracture risk in relation to vitamin D supplementation and serum 25-hydroxyvitamin D levels: a systematic review and meta-analysis of randomised controlled trials and observational studies

Table 3 Characteristics of cohort studies

Study First author (country) year	n	Follow up time	Study population Mean age years	Hip Fractures	Findings
Study of Osteoporotic Fractures	9704	Up to 5.9 years	Postmenopausal women	332	< 47.5 nmol/L vs. ≥47.5 nmol/L 25(OH)D
Cummings [51] (USA) 1998			73 years (using randomly selected cases and controls)		RR Hip fracture 1.2 (0.7, 1.9)
WHI-OS	39793	Up to 9.3 years	Postmenopausal women	400	Each 25 nmol/L decrease in 25(OH)D R Hip fracture 1.33 (1.06, 1.68)
Cauley [52] (USA) 2008		(median 7.1 years)	71 years		≤47.5 nmol/L vs. ≥70.7 nmol/L OR Hip fracture 1.71 (1.05, 2.79)
NHANES III	1917	Mean 6.7 y	≥65 y Caucasian adults	156	≥62.5 nmol/L vs. <62.5 nmol/L 25(OH)D
Looker [53] (USA) 2008			73 years		RR Hip fracture 0.64 (0.46, 0.89)

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