This article is more than 5 years old. Information may no longer be current.
USPSTF finds insufficient evidence for universal vitamin D screening
Click Here to Manage Email Alerts
The balance of benefits and harms of screening asymptomatic adults for vitamin D deficiency cannot be assessed based on existing evidence, according to a US Preventive Services Task Force recommendation and systematic review released together in the Annals of Internal Medicine.
“It not a recommendation that says people should not screen,” Albert L. Siu, MD, MSHP, Vice-Chairperson, USPSTF, of Mount Sinai School of Medicine, New York, told Endocrine Today. “It says the evidence is insufficient to recommend for or against this practice.”
Albert L. Siu
Through a systematic review, researchers for the USPSTF found no direct evidence for effects on clinical outcomes with vitamin D screening vs. no screening.
Some evidence in the review suggested treatment of asymptomatic vitamin D deficiency has no benefit in terms of cancer, type 2 diabetes or decreasing the risk of fracture in adults who were not otherwise at high risk for fractures, Siu explained.
Many other health outcomes did not have enough evidence in terms of the effect of treatment of vitamin D deficiency in people who might be found deficient on screening, Siu added.
Some evidence suggested that treating vitamin D deficiency in individuals outside of institutional settings could reduce the risks for falls but would not reduce the risks for fracture or mortality.
Siu said the task force has issued a number of related recommendations on vitamin D, mainly on supplementation. “The only area where the task force found sufficient evidence for vitamin D supplementation was in older adults who would be at risk of falling, where we recommended vitamin D supplementation among other things.”
Taken together, the recommendations show vitamin D requires further investigation, Siu said.
“The importance of the recommendation is highlighting the need for additional research,” Siu said. “Vitamin D is an important nutrient in terms of bones and a variety of areas. We recognize there is a great deal of interest in this. We believe, however, based upon our review of the evidence, there was not sufficient evidence in terms of net effect of vitamin D screening on human health.”
Under investigation
Erin S. LeBlanc, MD, MPH, of the Center for Health Research, Kaiser Permanente, Portland, Oregon, and colleagues selected randomized trials of screening for, and treatment of, vitamin D deficiency and case–control studies within the Women’s Health Initiative.
Erin S. LeBlanc
“Almost every week you can look and find studies about the association between vitamin D and a health outcome,” LeBlanc told Endocrine Today. “Our systematic evidence review adds to this information because we looked at randomized controlled trials, and found the best evidence, to determine whether treatment of vitamin D deficiency resulted in improved health outcomes.”
LeBlanc noted that association studies can offer important information on areas that need to be evaluated further, but they cannot conclude whether treating the deficiency improves outcomes.
Through a search of Ovid MEDLINE (through the third week of August 2014), Cochrane Central Register of Controlled Trials and Cochrane Database of Systematic Reviews, the investigators found no studies evaluating clinical outcomes after screening people, finding vitamin D deficiency and treating it. “It’s not been done because it’s very difficult to do,” LeBlanc said.
Instead, the researchers had to take a two-step approach, LeBlanc explained. “If we could prove that treating people with vitamin D deficiency would make them healthier, then even without screening studies, the question would be does that translate to screening people to look for the deficiency because we know treating it will make people healthier.”
The investigators divided duties; one abstracted data, a second reviewed data for accuracy and the two remaining independently assessed study quality using predefined criteria.
Vitamin D treatment was associated with decreased mortality vs. placebo or no treatment (11 studies; RR=0.83; 95% CI, 0.70-0.99), but benefits did not remain after trials of individuals in institutions were excluded (8 studies; RR=0.93; 95% CI, 0.73-1.18).
Vitamin D treatment was also associated with possible decreased risk for having at least 1 fall (5 studies; RR=0.84; 95% CI, 0.69-1.02) and falls per person (5 studies; incidence rate ratio=0.66; CI, 0.50-0.88) but not fractures (5 studies; RR=0.98; 95% CI, 0.82-1.16).
Vitamin D treatment was not associated with a statistically significant increased risk for serious adverse events (RR=1.17; 95% CI, 0.74-1.84).
Under consideration
Defining vitamin D deficiency was an issue that both gave the task force pause in making a recommendation on screening and complicated the evidence review.
“There is some continuing controversy in the literature in terms of what level do we define as vitamin D deficient, whether that cutoff is 20 ng/mL or 30 ng/mL,” Siu said.
LeBlanc explained “while experts generally agree that levels lower than 20 ng/ml are not good for bones, disagreement exists about whether optimal 25(OH)D levels are higher than 20 ng/mL.”
Siu noted further concern among the task force members that no consensus exists in terms of screening for vitamin D and is further compounded by variability in laboratory results.
LeBlanc concurred, noting “the results can vary quite a bit depending on the assay used or the laboratory where the assay was done, and there isn’t an international standard to determine which assay is best.”
Receiving slightly different results in two different labs could result in patients being misclassified as being vitamin D deficient or not, Siu explained.
Although the researchers showed what evidence was there, LeBlanc said the review points out more information is needed and more work needs to be done.
“Studies have been done in certain populations, but not all populations have been studied, and for some of the outcomes there really was not a lot of data,” LeBlanc said.
The USPSTF recommendation is consistent with that of the Endocrine Society, with screening for vitamin D recommended only in individuals at risk for deficiency based on having “no evidence that it’s beneficial to screen in general, healthy adults,” Siu said.
Task force recommendations often come with calls for additional research that are highlighted in annual reports to Congress, Siu said, which are reviewed by the NIH and other granting agencies when planning their own program announcements.
“A trial of vitamin D screening in a diverse population would be the ideal way to evaluate benefits and harms of screening,” LeBlanc said. “Future studies of treatment should examine results according to the baseline vitamin D level to see if those who are deficient have different benefits and harms than those who are not deficient.” — by Allegra Tiver
Albert L. Siu, MD, MSHP, can be reached at the Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, NY, 10029-6574; email: albert.siu@mssm.edu.
Erin S. LeBlanc, MD, MPH, can be reached at the Center for Health Research, Kaiser Permanente, 3800 North Interstate Avenue, Portland, OR, 97227; email: erin.s.leblanc@kpchr.org.
For More Information:
LeBlanc ES. Ann Intern Med. 2014;doi:10.7326/M14-1659.
LeFevre ML. Ann Intern Med. 2014;doi:10.7326/M14-2450.
Disclosures: The review was funded by the Agency for Healthcare Research and Quality. The task force was supported by a grant from the agency.