Vitamin D retesting by general practitioners: a factor and cost analysis.

Area of Science:

• Clinical Medicine
• Endocrinology
• Public Health

Background:

• Vitamin D testing is increasing in primary care, raising healthcare system workloads.
• There is limited data on vitamin D retesting patterns and associated costs in Ireland.

Purpose of the Study:

• To investigate factors associated with vitamin D retesting by Irish General Practitioners (GPs).
• To examine the costs resulting from vitamin D retesting practices.

Main Methods:

• Retrospective analysis of 36,458 GP-requested 25-hydroxyvitamin D (25(OH)D) tests over 5 years (2014-2018) in Dublin.
• Comparison of patients with single tests versus those retested, categorizing samples to track changes in vitamin D status.

Main Results:

• Nearly 25% of patients were retested, with female gender, age (60-69), Co. Kildare location, and initial deficiency/insufficiency being positive predictors.
• Vitamin D status improved upon retesting; deficiency halved after the first retest and dropped further with subsequent retests.
• Significant costs arose from inappropriate testing, including 12.2% retested within 3 months, 29% with ≥2 retests annually, and 57% of retests in initially replete individuals (€61,976 annually).

Conclusions:

• Vitamin D retesting frequency varies by patient demographics and location.
• A substantial proportion of retests were performed too early or in individuals with adequate vitamin D levels, incurring unnecessary costs.
• Clear guidelines for GPs on minimum retesting intervals and improved laboratory ordering systems are necessary to optimize vitamin D testing practices.