Based on a review of the available evidence, the task force concluded that there is insufficient evidence to assess the balance of benefits and harms of screening for vitamin D deficiency in asymptomatic adults. This is an "I" recommendation.
"Based on our review, the task force determined there is not enough evidence to recommend for or against screening for vitamin D deficiency in adults without signs or symptoms," task force member Michael Silverstein, M.D., M.P.H., said in a news release. "We need more research to know what level of vitamin D people need to keep them healthy, and what level is too low and can have negative health impacts."
The draft recommendation statement applies only to adults who have no signs or symptoms of vitamin D deficiency or conditions for which treatment with vitamin D is recommended. It does not apply to individuals who are pregnant, live in nursing homes or have health conditions that require vitamin D supplementation. Those who are concerned about their vitamin D levels are advised to consult with their clinician about their individual health needs.
It should also be noted that the recommendation statement focuses on screening, not supplementation. The USPSTF has issued several recommendation statements that address supplementation with vitamin D for other conditions, including prevention of fractures in community-dwelling adults, prevention of cancer and cardiovascular disease and prevention of falls in older adults.
The draft recommendation updates the task force's existing recommendation on the topic, which was published in 2014 and supported by AAFP. The 2014 recommendation statement also stated that the evidence was insufficient to assess the balance of benefits and harms of screening for vitamin D deficiency in asymptomatic adults.
To update the recommendation, the USPSTF commissioned a systematic review of the evidence, building on the literature included in the 2014 evidence review with additional studies published between Jan. 1, 2013, and March 12, 2020.
The review included 46 studies that evaluated various doses, frequency and duration of treatment with vitamin D, both with and without calcium. Ten new randomized, controlled trials published since 2013 were included.
None of the studies in the evidence review evaluated the benefits or harms of screening for vitamin D deficiency. In asymptomatic community-dwelling populations with low vitamin D levels, the evidence suggested that treatment with vitamin D, with or without calcium, had no effect on mortality, fractures, depression, diabetes incidence, cardiovascular disease, cancer or adverse events. Evidence regarding the impact of vitamin D treatment on falls, physical functioning and infection was inconclusive.
In addition to the evidence review, the task force also posted a fact sheet for clinicians and patients on screening for vitamin D deficiency. Among other things, the fact sheet defines vitamin D deficiency, describes the role of vitamin D in calcium absorption and other aspects of health, and explains how screening for vitamin D deficiency is performed.
The evidence review stated that despite no direct evidence of benefits or harms associated with screening for vitamin D deficiency, screening has increased among community-dwelling populations over the past two decades. Directly determining the benefits and harms of screening for vitamin D deficiency, the task force noted, would require randomized, controlled trials.
The task force suggested that rigorously designed and adequately powered placebo-controlled treatment trials in vitamin D-deficient populations be conducted. Such trials would be needed to clarify the impact of vitamin D on outcomes for which the current evidence is inconclusive or insufficient; to determine optimal doses and regimens for benefits; to clarify potential harms resulting from intermittent high-dose regimens; and to differentiate the effects of treatment among patient subgroups such as sex and race/ethnicity.
"We don't know the precise level of vitamin D in the body that leads to poor health outcomes or which test might be a better indicator of vitamin D deficiency," explained task force member John Wong, M.D. "Once we know the level of vitamin D that people need to remain healthy or if there is a better test, more research on whether screening can help prevent negative outcomes such as falls, cancer or heart problems will be helpful."
The USPSTF is accepting comments on the draft recommendation statement and draft evidence review until 11:59 p.m. ET on Oct. 19. All comments received will be considered as the task force prepares its final recommendation.
The AAFP will review the USPSTF's draft recommendation statement and supporting evidence and will provide comments to the task force. The Academy will release its own recommendations on the topic after the task force finalizes its guidance.