Vitamin D testing: Impact of changes to testing guidelines on detection of patients at risk of vitamin D deficiency.

BACKGROUND

Changes were made to the Australian guidelines for vitamin D testing in November 2014 which restricted the patients who could be tested and reimbursed under the Medical Benefits Schedule. A retrospective study was conducted to assess the impact of the changes.

METHODS

Data from 588,021 cases tested for vitamin D over the period of 2014 to 2017 were obtained and the results in 149,808 cases tested before the change in guidelines were compared to 438,213 cases tested afterwards.

RESULTS

The results showed an initial fall in requests took place after the introduction of changes, but request numbers had returned to pre-change levels by November 2016. Furthermore, following the intervention, there was a significant reduction in the number of cases of vitamin D deficiency (<50 nmol/L) detected after November 2014 ( < 0.001) with odds ratio (OR) calculations showing the strongest effect for the sub-cohort of 0-20 nmol/L (OR = 1.77). For patient vitamin D levels >71 nmol/L, the pattern of detection inverted with more cases of sufficiency being detected after the intervention than before (OR from 0.84 to 0.48, <0.001).

CONCLUSIONS

The failure to show a sustained reduction in vitamin D testing is a common finding with demand management strategies to limit test requesting. More significant is the failure of the intervention to improve the detection of vitamin D deficiency. These failures highlight the need for better tools to manage test requesting including the use of audit and outcomes measurement to guide future interventions.