Crowe FL, et al. - Through an open cohort design using the Health Improvement Network primary care database between 2005 and 2015 of 6,416,709 people aged 18 years and older, the researchers sought to examine trends in the testing incidences for vitamin D deficiency and the prevalence suggestive of deficiency (<30 nmol/L) of patients with circulating concentrations of 25-hydroxyvitamin D (25(OH)D). Association between vitamin D deficiency and being male, younger, more economically deprived and ethnic minority patients were concluded. One-third of UK adults who had a vitamin D test performed in primary care were found with vitamin D deficiency. Among adults in the UK, a significant increase in testing for vitamin D deficiency over the past decade was noted.