Effect of Peer Comparison Feedback and Professional Norms on Vitamin D Testing and Generic Medication Prescribing.

What Was Tested

Researchers studied Vitamin D, K2, Magnesium and Zinc in this randomized controlled trial publication.

Previous interventions have had limited success in discouraging low-value care in medical practice.

Who Took Part

The abstract describes 100 patients taking part.

PubMed indexes the participants as middle-aged adults, both men and women.

Primary endpoints were (1) the number of vitamin D tests per 100 patients and (2) the share of generic medications prescribed.

The researchers estimated average treatment effects using linear regression and assessed effect heterogeneity with a causal forest.

How the Study Was Run

In design terms this was a randomized study.

Random assignment meant chance, not the researchers, decided who got Vitamin D, K2, Magnesium and Zinc and who got the comparison, which limits bias.

The researchers conducted a nationwide randomized controlled trial among primary care physicians (PCPs) in Switzerland (November 2020-December 2021).

The researchers randomly assigned PCPs to one of three intervention groups related to low-value care (vitamin D testing, generic prescribing, or a cost intervention) or a control group.

This article reports results for the vitamin D testing and generic prescribing interventions compared with the common control group.

PCPs in the intervention groups received a personalized information letter combining professional norms and peer comparison feedback about the low-value service (either vitamin D testing or prescribing of nongeneric medications).

What Was Measured

The subject headings attached to it are Vitamin D, Drugs, Generic, Switzerland, Practice Patterns, Physicians', Physicians, Primary Care, Feedback and Drug Prescriptions.

What This Means in Plain Language

The paper is a randomized study of Vitamin D, K2, Magnesium and Zinc in 100 patients.

Its findings take up roughly 7 sentences of the abstract and are left out here on purpose; the source paper is the place to read them.

The publication is from 2026 (NEJM evidence), a journal based in United States.

More context: the Vitamin D, K2, Magnesium and Zinc compound page, all human trials.