Did changes to recommended testing criteria affect the rate of vitamin D testing among Australian women

We examine whether new government criteria designed to reduce overuse of vitamin D testing changed testing rates in Australian women. Although testing initially declined, the reduction was not sustained. Women who had more doctor visits and who had been tested previously were more likely to have vitamin D testing.

Vitamin D testing increased substantially in the 2000s in many countries, particularly in women. Because of concerns about potential over-testing, in 2014, the Australian criteria for subsidised testing were restricted to those at high risk of vitamin D deficiency. We aimed to describe vitamin D testing trends in Australian women (1996 to 2019) and investigate sociodemographic and health factors associated with testing under the new criteria.

We used joinpoint regression to assess changes in national testing trends in Australian women (aged 15+ years) using universal health insurance system data. Additionally, we investigated the factors associated with vitamin D testing through Poisson regression with robust error variance using survey and linked insurance system data from participants born 1946-51 in the Australian Longitudinal Study on Women's Health (ALSWH).

Between 1996 and 2013, vitamin D testing rates increased in all age groups. Rates declined between 2013 and 2016, but increased again between 2016 and 2019. In the ALSWH cohort, a higher likelihood of testing under the new criteria was associated with 12 or more doctor visits per year compared to two or fewer visits per year (relative risk (RR) 1.85; 95% CI 1.61-2.12), and women who had two or more vitamin D tests between 2012 and 2014 compared to no test (RR 1.55; 95% CI 1.48-1.62).

The introduction of new criteria has not led to sustained declines in testing. High testing rates and repeated testing suggest that over-testing for vitamin D deficiency in Australian women is still occurring.