Task Force finds insufficient evidence to recommend for or against routine vitamin D screening

The U.S. Preventive Services Task Force found insufficient evidence to assess the benefits and harms of screening for vitamin D deficiency in asymptomatic, community-dwelling, nonpregnant adults.

Researchers found no direct evidence on the effects of screening for vitamin D deficiency compared to no screening. They did find evidence that treating vitamin D deficiency in non-institutionalized patients might decrease risk of falls, but it was not associated with decreased risk of fractures or mortality in this population.

The recommendation statement and systematic evidence review were published online Nov. 25 by Annals of Internal Medicine.

The recommendation focused on screening, defined as testing asymptomatic adults for vitamin D deficiency and treating those who are found to have a deficiency, which is different from other Task Force recommendations on supplementation for patients at increased risk for outcomes such as falls, regardless of whether they have a deficiency.

The systematic evidence review reported that no study examined the effects of vitamin D screening versus no screening on clinical outcomes. Vitamin D treatment was associated with decreased mortality compared to placebo or no treatment (11 studies; risk ratio [RR], 0.83; 95% CI, 0.70 to 0.99). The benefits were no longer seen after excluding trials of institutionalized people (8 studies; RR, 0.93; 95% CI, 0.73 to 1.18). Vitamin D treatment was associated with possible decrease in risk for having at least 1 fall (5 studies; RR, 0.84; 95% CI, 0.69 to 1.02) and falls per person (5 studies; incidence rate ratio, 0.66; 95% CI, 0.50 to 0.88) but not fractures (5 studies; RR, 0.98; 95% CI, 0.82 to 1.16). Vitamin D treatment was not associated with a statistically significant increased risk for serious adverse events (RR, 1.17; 95% CI, 0.74 to 1.84).

The recommendation statement noted that reported estimates of the prevalence of vitamin D deficiency vary widely depending on a study's period, cut point, population, design, and testing method. Estimates range from as low as 19% using a statistical modeling approach to as high as 77% based on National Health and Nutrition Examination Survey data from 2001 to 2004, which used a cut point of less than 75 nmol/L (<30 ng/mL). The recommendation statement's use of the phrase “vitamin D deficiency” reflected evidence from study populations generally representing total serum vitamin D levels of 75 nmol/L (30 ng/mL) or less or subpopulations of studies with levels less than 50 nmol/L (<20 ng/mL). Testing rates for vitamin D levels seem to be increasing, despite the uncertainty about the definition of deficiency and benefits of screening, the recommendation noted.

Although there is not enough evidence to support screening for vitamin D deficiency, some evidence suggests factors that may increase risk for vitamin D deficiency. Persons with low vitamin D intake, decreased vitamin D absorption, and little or no sun exposure (for example, due to the winter season, high latitude, or physical sun avoidance) may be at increased risk for vitamin D deficiency. Treatment with increased sun exposure (specifically ultraviolet B radiation) may increase risk for skin cancer, so increased sun exposure is generally not recommended as treatment of vitamin D deficiency.