1. The U.S. Preventive Services Task Force (USPSTF) concluded that current evidence was insufficient to assess the balance of benefits and harms of screening for vitamin D deficiency in asymptomatic adults.
2. Variation in the accuracy of vitamin D assays and the definition of vitamin D deficiency represented important limitations in assessing vitamin D screening practices.
Evidence Rating Level: 2 (Good)
Study Rundown: The U.S. Preventive Services Task Force (USPSTF) has previously evaluated the role of vitamin D supplementation for various population subgroups, however no assessment had been conducted on the general practice of screening for vitamin D deficiency. Currently, no professional organization recommends population-wide screening, and a lack of agreement on an internationally recognized threshold for defining vitamin D deficiency has made estimating the prevalence of deficiency difficult. Studies evaluating current practices have shown that both outpatient visits for vitamin D deficiency-related concerns and the testing of vitamin D levels have increased. While a review of the literature revealed factors that may affect the risk of vitamin D deficiency, including obesity, ethnicity, and sun exposure, there was not enough evidence to support screening. There exists inconsistent evidence on the association between low vitamin D levels and negative health outcomes such as fractures, cancer, and cardiovascular disease, and treatment with oral vitamin D carries a risk for rare but potential complications including hypercalcemia, hyperphosphatemia, and suppressed parathyroid function. After reviewing current literature, the USPSTF found that there is insufficient evidence to determine whether the benefits of screening and early treatment outweigh potential harms. Furthermore, while there are various methods available for measuring vitamin D serum levels, the sensitivities and specificities are unclear.
Click to read the recommendation statement, published today in the Annals of Internal Medicine
Click to read the systematic review editorial, published today in the Annals of Internal Medicine
Relevant Reading: Vitamin D and Calcium to Prevent Fracture: Preventive Medication
In-Depth [systematic review]: The USPSTF commissioned a review of the evidence on screening for vitamin D deficiency. The population considered included community-dwelling, non-pregnant adults >18 years of age without known vitamin D deficiency or health conditions associated with vitamin D deficiency. The USPSTF reviewed 17 studies that evaluated the effects of treatment of vitamin D deficiency on health outcomes, 17 studies that assessed the effectiveness of oral vitamin D treatment, and 24 studies that reported adverse effects of vitamin D treatment. The primary limitation of this review was the lack of studies that directly assessed the effectiveness of screening for vitamin D deficiency, though another major issue was the variability in definitions of vitamin D deficiency. Furthermore, there was a dearth of studies using an international reference standard for the measurement of vitamin D serum levels. Overall, more and better evidence is needed to properly assess the risks and benefits of vitamin D screening.
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