To investigate the association of vitamin D status with all-cause mortality in a Norwegian population and the potential influences of existing chronic diseases on the association.
A population-based prospective cohort study.
Nord-Trøndelag County, Norway.
A random sample (n=6613) of adults aged 20 years or older in a cohort.
Serum 25-hydroxyvitamin D (25(OH)D) levels were measured in blood samples collected at baseline (n=6377). Mortality was ascertained from the Norwegian National Registry. Cox regression models were applied to estimate the HRs with 95% CIs for all-cause mortality in association with serum 25(OH)D levels after adjustment for a wide spectrum of confounding factors as well as chronic diseases at baseline.
The median follow-up time was 18.5 years, during which 1539 subjects died. The HRs for all-cause mortality associated with the first quartile level of 25(OH)D (