Background: It is unclear if screening for vitamin D deficiency can improve the health of asymptomatic individuals with this deficiency.
Purpose: The U.S. Preventive Services Task Force will use this report to develop a recommendation statement on screening for vitamin D deficiency in asymptomatic adults not known to have this deficiency.
Data Sources: We searched the Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews (through August 2014) and MEDLINE® (1946 to August 2014), and manually reviewed reference lists from applicable review articles.
Study Selection: We included systematic reviews; randomized, controlled trials (RCTs); and case-control studies nested within an RCT to examine the benefits of vitamin D treatment (with or without calcium) compared with placebo, calcium alone, or no treatment. We included systematic reviews, RCTs, and cohort or case-control studies to evaluate harms. Included study populations were asymptomatic (i.e., not selected for signs or symptoms of vitamin D deficiency or medical conditions that increase risk for deficiency) adults (age ≥18 years) from the United States, Canada, and Europe with reported serum 25-hydroxyvitamin D [25(OH)D] concentrations of 30 ng/mL or less.
Data Extraction: No study examined the effect of vitamin D screening on health outcomes. In treatment studies, mortality was decreased in participants randomized to vitamin D treatment (with or without calcium) (11 studies; pooled risk ratio [RR], 0.83 [95% confidence interval (CI), 0.70 to 0.99]). This risk reduction, however, was limited to studies of older institutionalized persons (3 trials; pooled RR, 0.72 [95% CI, 0.56 to 0.94]). Vitamin D treatment was associated with possible decreased risk for falling, including risk for at least one fall (5 studies; RR, 0.84 [95% CI, 0.69 to 1.02]) and number of falls per person (5 studies; incidence rate ratio, 0.66 [95% CI, 0.50 to 0.88]). These findings were not influenced by institutionalized status. Vitamin D treatment (with or without calcium) was not associated with decreased fracture risk (5 studies; pooled RR, 0.98 [95% CI, 0.82 to 1.16]). Neither vitamin D dosage nor baseline level of 25(OH)D in the population influenced risk estimates. Data were limited (≤2 studies) for cancer risk, type 2 diabetes risk, psychosocial functioning, disability, and physical functioning. No trials on the effect of vitamin D treatment on risk for cardiovascular or immune disease met inclusion criteria. Vitamin D treatment (with or without calcium) was not associated with increased risk for harms.
Limitations: There was no direct evidence on the effect of screening for vitamin D on health outcomes. Evidence on the effects of vitamin D treatment on health outcomes was limited. Most studies that reported harms were not designed to assess harms and lacked rigorous reporting. No study examined effects according to subgroups defined by race, age, and sex. Few studies were conducted in nonwhite, nonfemale populations. There was variability in types of assays used to measure 25(OH)D, baseline 25(OH)D levels of the study population, dosages used, calcium cosupplementation, and duration of followup.
Conclusions: Treatment with vitamin D, with or without calcium, may be associated with decreased risk for mortality and falls in older or institutionalized adults. Vitamin D treatment did not reduce fracture risk. More research is needed to determine vitamin D treatment's effects in younger noninstitutionalized adults and to clarify the subpopulations that are most likely to benefit from treatment.