Vitamin D insufficiency predicts mortality among older men, but not women: A nationwide retrospective cohort from Thailand

Abstract

Aim Previous studies on the association between low vitamin D level and increased mortality mainly came from high‐income countries. The primary objective of the present study was to examine the effect of sex on the association between 25‐hydroxyvitamin D2 and D3 and mortality among community‐dwelling older people in Thailand. Methods A cohort of individuals aged ≥60 years from the Thai 4th National Health Examination Survey carried out in 2008 were followed and linked to a vital registry in 2015. Data regarding comorbid diseases, physical activity and serum vitamin D were obtained at the baseline assessment. Factors associated with all‐cause mortality were determined using Cox proportional hazards models. Results A total of 1268 participants with a median age of 74.0 years (interquartile range 67.0–81.0) were included. The prevalence of vitamin D insufficiency was 24.5% and 43.9% in men and women, respectively. Vitamin D insufficiency was significantly associated with all‐cause mortality only among men (adjusted HR 1.77, 95% CI 1.25–2.51), but not women. Analysis of 25‐hydroxyvitamin D3 divided into tertiles also showed an association with an adjusted HR of 1.83 (95% CI 1.23–2.72) for the lowest tertile in men. Diabetes was an effect modifier for low serum vitamin D and male sex, with HR 3.34 (95% CI 1.76–6.33, P < 0.001) in diabetic men with vitamin D insufficiency. Conclusions Low serum vitamin D is an independent risk factor for increased mortality in community‐dwelling Thai older men. Further randomized controlled study to investigate the benefit of vitamin D3 supplementation in older persons, particularly men, is warranted. Geriatr Gerontol Int 2018; 18: 1585–1590.