Factors driving vitamin D and B12 testing in Dutch primary care from the general practitioners' perspective: a...

Unnecessary vitamin tests are among the most frequently mentioned low-value care practices among Dutch general practitioners (GPs). Understanding drivers for vitamin testing from a GP's perspective is key for developing effective interventions.

This study explored GPs' perspectives on drivers of vitamin D and B12 testing, focusing on potential differences between GPs in practices with high and low testing rates, using the Capability, Opportunity, and Motivation Model of Behaviour (COM-B) behavioural science framework.

Laboratory data from 57 primary care centres (PCCs) in the South of the Netherlands (2016-2019) identified the 15 PCCs with the lowest and highest vitamin testing rates. Thirty GPs, one per PCC, were purposively sampled to ensure variation in testing rate and background. Semi-structured interviews (May-July 2020) covered general perceptions, as well as social, cognitive, and motivational factors. Interviews were analysed by mapping factors driving vitamin testing to the COM-B model.

Several medical and non-medical factors affecting vitamin D and B12 test ordering in general practice were identified, which could be linked to all three COM-B components at the GP (e.g. education), patient (e.g. informational material), and service level (e.g. laboratory forms).

Education, feedback on testing behaviour, evidence-based patient informational material, clear evidence-based guidelines, and modification of laboratory request forms by adding test costs and indications of at-risk groups were identified by participants as promising strategies to reduce unnecessary vitamin testing.