Vitamin D and subsequent all-age and premature mortality: a systematic review
1 NHS Greater Glasgow and Clyde, G12 0XH, Scotland
2 NHS Health Scotland, Glasgow G2 2AF, Scotland
3 Glasgow Centre for Population Health, Glasgow G2 4DL, Scotland
4 Institute of Health and Wellbeing, University of Glasgow, Glasgow G12 8QQ, Scotland
BMC Public Health 2013, 13:679 doi:10.1186/1471-2458-13-679Published: 24 July 2013
All-cause mortality in the population < 65 years is 30% higher in Glasgow than in equally deprived Liverpool and Manchester. We investigated a hypothesis that low vitamin D in this population may be associated with premature mortality via a systematic review and meta-analysis.
Medline, EMBASE, Web of Science, the Cochrane Library and grey literature sources were searched until February 2012 for relevant studies. Summary statistics were combined in an age-stratified meta-analysis.
Nine studies were included in the meta-analysis, representing 24,297 participants, 5,324 of whom died during follow-up. The pooled hazard ratio for low compared to high vitamin D demonstrated a significant inverse association (HR 1.19, 95% CI 1.12-1.27) between vitamin D levels and all-cause mortality after adjustment for available confounders. In an age-stratified meta-analysis, the hazard ratio for older participants was 1.25 (95% CI 1.14-1.36) and for younger participants 1.12 (95% CI 1.01-1.24).
Low vitamin D status is inversely associated with all-cause mortality but the risk is higher amongst older individuals and the relationship is prone to residual confounding. Further studies investigating the association between vitamin D deficiency and all-cause mortality in younger adults with adjustment for all important confounders (or using randomised trials of supplementation) are required to clarify this relationship.