Prevalence of vitamin D deficiency in an inpatient population in the Swiss Canton of Basel-Country.

Aims: Vitamin D deficiency remains very common in the general population. Adding to the importance of this issue is the discovery that vitamin D plays a role in many other tissues apart from the bone, including muscle, brain, prostate, breast and colon. In this study, we investigated the prevalence of vitamin D deficiency in a large group of patients hospitalised in the cantonal hospital Basel-Country, and analysed the dependence of serum vitamin D concentrations on gender, time of the year and age.

Methods: We retrospectively analysed anonymised data received from the central laboratory of the cantonal hospital Basel-Country. The pool of data contains values obtained between 2013 and 2017 from 8861 patients aged between 18 and 102 years. If sequential measurements were available from a patient, only the first was used for the analyses. Vitamin D deficiency was defined as a serum concentration of <50 nmol/l and severe deficiency as <25 nmol/l. Vitamin D values between 50 and 75 nmol/l are considered a grey zone. Optimal values are >75 nmol/l.

Results: Mean ± standard deviation serum vitamin D concentration was 52.5 ± 30.5 nmol/l, with women having a higher mean of 55.5 ± 31.5 nmol/l as compared with 48.1 ± 28.6 nmol/l in men (p <10-5). Of the 8861 first measurements taken within the observation period, 4527 (51%) were vitamin D deficient with levels <50 nmol/l, including 1860 (21.0%) with levels <25 nmol/l. There was only a weak positive association of average vitamin D levels with age (p = 0.06). Women reached peak concentrations of 56.9 ± 35.4 nmol/l in the age group 90–102 years, whereas men reached peaks of 50.3 ± 31.9 nmol/l in 50–59-year-olds. Mean autumn and spring concentrations differed less (51.6 ± 29.6 vs 52.7 ± 30.7 nmol/l, respectively, p = 0.38) than mean summer and winter concentrations (57.1 ± 29.5 vs 48.0 ± 31.2 nmol/l, respectively, p <10-5).

Conclusions: Vitamin D deficiency was a common finding in our cohort, affecting all age groups and occurring in over half (51%) of the values measured. As current guidelines recommend vitamin D concentrations >75 nmol/l, only 22.1% of measured values indicated adequate vitamin D levels. This issue should be addressed in order to improve quality of life and reduce medical costs.    .