Vitamin D deficiency as adverse drug reaction? A cross-sectional study in Dutch geriatric outpatients

Adverse drug reactions as well as vitamin D deficiency are issues of public health concern in older people. However, relatively little is known about the impact of drug use on vitamin D status. Our primary aim is to explore associations between drug use and vitamin D status in older people. Furthermore, prevalences of drug use and vitamin D deficiency are estimated. In a population of 873 community-dwelling Dutch geriatric outpatients, we explored the cross-sectional relationships of polypharmacy (a parts per thousand yen5 medications concomitantly used), severe polypharmacy (a parts per thousand yen10 medications), and use of twenty-one specific drug groups, with serum 25-hydroxyvitamin D (25(OH)D) by analysis of covariance. Overall prevalence of polypharmacy was 65 %, of severe polypharmacy 22 %. Depending on the cut-off value, prevalence of vitamin D deficiency was 49 % (< 50 nmol/l) or 77 % (< 75 nmol/l). Of the patients using a vitamin D supplement, 17 % (< 50 nmol/l) or 49 % (< 75 nmol/l) were still deficient. In non-users of supplemental vitamin D, after adjustment for age and gender, negative associations were found for severe polypharmacy, metformin, sulphonamides and urea derivatives (SUDs), vitamin K antagonists, cardiac glycosides, loop diuretics, potassium-sparing diuretics, ACE inhibitors, and serotonin reuptake inhibitors; for non-selective monoamine reuptake inhibitors (NSMRIs) the association was positive. The most extreme impacts of drug use on adjusted mean 25(OH)D were -19 nmol/l for SUDs and +18 nmol/l for NSMRIs. Drug use should be considered a risk factor for vitamin D deficiency amongst geriatric outpatients.