Low serum vitamin D, airway obstruction independently predict mortality
Airway obstruction and low serum 25-hydroxyvitamin-D (s-25[OH]D) are independent predictors of mortality in adults, suggest the results of a 33-year follow-up study.
Multivariable analysis adjusted for age, sex, smoking, education, body mass index, leisure physical activity, asthma and serum C-reactive protein revealed the independent association of obstruction and low s-25(OH)D with mortality.
On the other hand, a statistically significant interaction was found between mortality and low s-25(OH)D among patients without (adjusted mortality hazard ratios [HR] for s-25(OH)D in tertiles, 1.00 [lowest]; 0.96, 95 percent CI, 0.87–1.05; 0.89, 0.81–0.98) and with obstruction (adjusted HR, 1.00; 0.96, 0.71–1.31; 0.57, 0.40–0.80).
An earlier study involving 13,331 adults from the Third National Health and Nutrition Examination Survey also found that the lowest quartile of 25(OH)D level was independently associated with all-cause mortality in the general population. [Arch Intern Med 2008;168:1629-1637]
“In conclusion, obstruction and low s-25(OH)D predict mortality independently of each other,” the authors said. “Our findings suggest that low vitamin D status might be particularly detrimental among [patients] with obstruction.”
This study investigated a joint effect of airway obstruction and vitamin D status on mortality by analysing data of 6,676 Finnish adults participating between 1978 and 1980 in a national health examination survey, undergoing spirometry and having all necessary data collected.
Participants were followed up in national registers through record linkage until 31 December 2011. Those with airway obstruction were categorized using the lower limit of normal and the measured s-25(OH)D into tertiles.