Abstract
Objectives
Vitamin D testing by Primary Care doctors is increasing, placing greater workloads on healthcare systems. There is little data though on vitamin D retesting in Ireland. This study aims to investigate the factors associated with vitamin D retesting by Irish General Practitioners (GPs) and examine the resulting costs.
Methods
This is a retrospective analysis over 5 years (2014–2018) of GP requested 25-hydroxyvitamin D (25(OH)D) results in 36,458 patients at a major city hospital in Dublin, Ireland. Those with one test were compared with individuals who were retested and samples categorised to determine changes in status between tests.
Results
Nearly one in four patients (n=8,305) were retested. Positive predictors of retesting were female (p<0.001), age (60–69 years, p<0.001), location (Co. Kildare, p<0.001) and initial deficiency (<30 nmol/L, p<0.001) or insufficiency (30–49.9 nmol/L, p<0.001). Vitamin D status improved on retesting, with deficiency halving on first retest (9 vs. 18%, p<0.001) and dropping to 6% on further retests. About 12.2% of retests were done within 3 months and 29% had ≥2 retests within 1 year. 57% of retests were in those initially vitamin D replete (>50 nmol/L). The annual cost of inappropriate testing was €61,976.
Conclusions
One in four patients were retested and this varied by age, gender and patient location. Over 10% of retests were inappropriately early (<3 months), a third too frequent and over half were in replete individuals incurring significant costs. Clear guidance for GPs on minimum retesting intervals is needed, as well as laboratory ordering systems to limit requests using pre-defined criteria.
Funding source: Mercers’ Institute
Funding source: Glanbia PLC
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Research funding: This research is partially funded by Mercers’ Institute and Glanbia PLC. Glanbia has no role in study design, data collection and analysis, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.
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Author contributions: Conceptualization, EL, JBW and KMcC; Data curation, MH and VC; Formal analysis, HS, EL, KMcC, MH and VC; Funding acquisition, EL, JBW and KMcC; Investigation, HS; Methodology, HS; Project administration, HS; Supervision, KMcC; Writing – original draft, HS; Writing – review & editing, HS, EL, MH, JBW, VC and KMcC. All authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Competing interests: Authors state no conflict of interest.
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Informed consent: Not Applicable.
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Ethical approval: St James’s Hospital/Tallaght University Hospital (SJH/TUH) joint ethics committee granted ethical approval for this study (Ref: 5475) which was conducted according to the guidelines laid down in the Declaration of Helsinki 1964.
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Supplementary Material
The online version of this article offers supplementary material (https://doi.org/10.1515/cclm-2021-0607).
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