Call to curb inappropriate vitamin D testing by clinicians

Public health

By Mardi Chapman

8 Nov 2023

More than 70% of antenatal patients have an unnecessary vitamin D test adding to healthcare costs and the health system’s carbon footprint without returning any health benefit, research shows.

A Letter to the Editor in the Australian and New Zealand Journal of Obstetrics and Gynaecology [link here], quantified out-of-guidelines 25-hydroxyvitamin D testing at The Royal Women’s Hospital, Melbourne between November 2021 and October 2022.

The electronic medical record (EMR) identified 7,435 patients who had antenatal booking appointments during the study period and 6,451 of those women (86.8%) had 25(OH)D tests ordered.

Only 3.8% of these tests were indicated by obesity and malabsorption while 24.8% were justified by demographic factors such as new migrants, deeply pigmented skin and chronic lack of sun exposure.

“The remaining 5,308 (71.4%) women did not have a clear indication for testing,” the Letter said.

Demographic factors were unlikely to explain the 71% of women who had 25(0H) D testing without a medical indication.

“Our findings suggest there is a significant amount of 25(OH)D testing initiated by both hospital- and community-based clinicians that is outside national and local guidelines.”

“This is significant because studies have shown that antenatal vitamin D supplementation did not improve maternal obstetric outcomes, infant serum 25(OH)D levels beyond 3 months of age or neonatal bone density as measured at two weeks post-birth.”

The investigators, led by Dr Melissa Qiao Wei Ang, concluded there should be a requirement for all clinicians to acknowledge the approved criteria prior to requesting 25(OH)D testing in the EMR.

“Furthermore, maternity units, RANZCOG and the Royal Australian College of General Practitioners should provide educational support to community-based clinicians regarding current indications for 25(OH)D testing including the lack of benefit from supplementation.”

Their findings were consistent with a larger 2019 study in the general population [link here] which found the proportion of 25(OH)D tests being performed without a relevant indication was 76.5%. This was after the 2014 tightening of the MBS criteria for a Medicare rebate on 25(OH)D testing.

As previously reported in the limbic [link here], another Australian study found unnecessary vitamin D testing contributes to healthcare costs and avoidable CO2e emissions.

It said the carbon footprint of unnecessary 25(OH)D testing each year in Australia was equivalent to driving ~160,000–230,000 km in a standard passenger car.

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