Prescriptions for vitamin D to U.K. children have risen dramatically over the years, and medical records suggest inappropriate use, according to a study published online December 3 in BMJ Open. The results feed into international debates about overuse and the high costs of supplementation and testing.
In the study of records of 2 million children ages newborn to 17, the annual rate of prescriptions for vitamin D in the primary care setting increased 26-fold between 2008 and 2016, from 10.8 per 100,000 person years to 276.8 per 100,000 person years, wrote Mandy Wan, a pharmacist researcher and doctoral student at King's College London, and colleagues. The trend was most pronounced in children between the ages of 12 and 17 -- particularly girls -- but it was also seen across other age groups, the researchers reported.
An increase in and of itself is not surprising, as there had been educational initiatives about treating and preventing vitamin D deficiency; however, the researchers found evidence of inappropriate use. U.K. national guidelines advise the prescription of therapeutic doses of vitamin D for children who are deficient -- that is, with a level of 25-hydroxyvitamin D, or 25-OH D, below 25 nmol/L. Although prescribing for deficiency should be guided by testing, there was a trend for prescribing regardless of baseline levels, and there were no test results prior to prescribing in more than 30% of cases annually since 2009.
"Prescribing at pharmacological doses for children with deficient status increased from 3.8% to 79.4%, but the rise was also observed in children for whom guidelines recommended prevention doses (0% to 53%)," the authors wrote.
Prescriptions exceeding the recommended doses and/or at doses for prevention may not be the best use of limited health resources, and yet they accounted for at least 32.3% of the cases analyzed, the researchers noted. Using a conservative estimate based on the direct cost of prescriptions per year and not including related costs such as consultations, dispensing, and testing, Wan et al estimated potential cost savings to the U.K. health system of 500,000 pounds ($655,000) annually.
A growing health concern worldwide
Wan and colleagues acknowledged that there is evidence supporting the use of supplementation to prevent conditions such as rickets and osteomalacia. Yet while low levels of vitamin D have been associated with many other conditions based on epidemiological studies, randomized trials have failed to show a benefit for supplementation and "meta-analyses are inconclusive and widely debated," they noted.
"Against this backdrop of ongoing debate, vitamin D deficiency is widely prevalent in all age groups and seen as a growing public health concern worldwide," the authors wrote. "The [U.S.], Canada, Australia, France and the [U.K.] have all reported a significant increase in laboratory vitamin D testing, with as much as a 90-fold increase over a 10-year period."
The study, which was funded by a grant from the U.K. National Institute for Health Research, was conducted to quantify prescribing practices in primary care, evaluate appropriateness and adherence to practice guidelines, and assess costs. National and international guidelines differ in their definitions of deficiency and advice on prescribing, which makes it harder to get a grip on what is appropriate.
In the study, fewer than one-third of children who were prescribed supplements had symptoms of vitamin D deficiency. Wan and colleagues noted that "aberrant prescribing practice incurs a huge, potentially avoidable, expense to our healthcare system."
