Over a year ago I wrote about the explosion in vitamin D testing for Medicare patients between 2000 and 2010.A new study has found that at least in primary care practices in central New York State, the primary driver of increased vitamin D testing comes from patients, not practice guidelines.
In this qualitative study, the researchers conducted five focus group discussions about emerging practice around vitamin D supplementation. The focus groups included 42 participants from primary care practices, primarily physicians. In these groups, the participants from primary care practices were asked to discuss topics, including their concerns and policies on vitamin D and vitamin D testing.
The researchers report that providers “are establishing practice patterns concerning the diagnosis and management” of vitamin D status, but that there are currently a wide mix of patterns “and the sources of information used to establish these patterns remain unclear.”
“The minimum level of acceptable vitamin D generally centered around 20 ng/mL or above; however, several individuals mentioned optimal ranges of 40 to 60 ng/mL, 50 to 70 ng/mL, or any number up to 100 ng/mL.”
Some reported that they had “lost a lot of fear” about vitamin D toxicity and didn’t specify what a toxic level would be. Most said levels above 100 ng/mL were too high, although some set the toxic level as above 50 ng/mL.
In terms of dose, the researchers found that the providers who were more concerned about toxicity limited dosage recommendations to 800 to 2,000 IUs per day. Other providers suggested a variety of dosages, with higher dosages for those with low baseline vitamin D levels. Many providers suggested different dosages for remediation and for maintenance. The remediation dose “could be as high as 50,000 IUs per week.” The maintenance doses ranged from 2,000 to 12,000 IUs per day. (Note that 12,000 IUs per day is 84,000 IUs a week, more than 50% higher than a remediation dose of 50,000 IUs a week.)
When asked where they obtained information about vitamin D, most participants referred to discussions with their colleagues. They also mentioned medical guidelines, such as the Cochrane Library and the U.S. Preventative Services Task Force. However, the researchers note “that these resources were often listed within hypothetical contexts and did not necessarily reflect actions taken in obtaining information on vitamin D.”
Four of the five focus groups occurred after release of the Institute of Medicine’s Dietary Reference Intakes for Calcium and Vitamin D in early 2011, but none of the participants mentioned this as a source of information.
The researchers reported, “it appears that the members of the focus groups were not actively seeking information regarding vitamin D guidelines and practices, despite knowing the appropriate resources to obtain this information.”
The researchers also identified four themes about vitamin D practices from their focus groups:
The researchers summarized their findings by saying,
“The overall impression of the formation of emerging practice concerning vitamin D is that it was often initiated by patient demand, but was then constructed and reinforced by incidental reading; brief, purposeful research; influence by physician champions; informal conversations with colleagues; results of consultations by specialists; and more patient demand. There was only a rare example of physicians actively attempting to “break out” of this swirl of constructed knowledge and find an answer for themselves based on evidence or high-quality guidelines. Instead, they largely relied on the social transmission and construction of this new knowledge, through interactions with patients, colleagues, and the media.
Finally, they suggest,
“To promote the use of the best knowledge about vitamin D screening and management, clear, authoritative guidelines are only a first step. Promoting active and intentional communities of practice through which primary care clinicians can interpret, refine, and contextualize this guideline information might improve the dissemination of this knowledge into clinical practice.”