Appropriate Testing and Management of Vitamin D Levels in General Internal Medicine Inpatients

Abstract Background Vitamin D level testing in hospitalized patients is common but inconsistently guided by evidence, risking unnecessary healthcare costs, over-treatment, or missed diagnoses. This study evaluated adherence to the Health Service Executive (HSE) Laboratory criteria for vitamin D testing1, assessed therapeutic responses to results, and identified predictors of vitamin D levels in general internal medicine (GIM) inpatients. Methods A retrospective review evaluated 408 GIM inpatients that were categorised into four groups based on HSE-defined testing appropriateness: 1) testing indicated and ordered, 2) indicated but not ordered, 3) not indicated but ordered, 4) not indicated and not ordered. Testing appropriateness was assessed against HSE Laboratory criteria1, and predictors of testing practices and vitamin D levels were analysed using logistic regression models in R statistical software (v4.1.2), adjusted for age, gender, ethnicity and hospital length of stay. Results Of 408 patients, 35% (n=143) deviated from guidelines: 22.3% (n=91) did not receive a test despite an indication, while 12.3% (n=50) underwent testing without indication. Patients undergoing unindicated testing were older and had longer hospital stays. Older age (OR 1.08 per year, 95% CI 1.04-1.13; p<0.001) was associated with testing after controlling for indication. Of 77 tested patients, 62.3% (n=48) had sufficient levels (>50 nmol/L), 16.9% (n=13) insufficient (30-49 nmol/L) and 20.8% (n=16) deficient (<30 nmol/L). Supplementation was omitted in 32/48 (66.7%) of patients with adequate levels who required maintenance therapy. Conclusion Deviations from HSE Laboratory criteria were frequently observed, with older patients over-tested and high-risk populations undertested. Integrating electronic decision-support tools into electronic patient records, education and standardised protocols are essential to aligning practices with HSE guidelines and improving patient outcomes. Pre-admission supplementation may mitigate deficiency, suggesting a role for proactive outpatient interventions. Reference 1. Health Service Executive (2024). Indications for Measurement of Vitamin D Levels [PDF]. Available at: https://www.hse.ie/eng/about/who/cspd/lsr/resources/indications-for-measurement-of-vitamin-d-levels.pdf [Accessed 10th Oct 2024]