emulated study of vitamin d correction vs non-correction

Conditions: Vitamin D Deficiency

Summary: * this is a single-site retrospective electronic chart review of cooper health system inpatients and outpatients from 2008 through 2023 aged eighteen years or older. this review is designed as an emulation of a randomized clinical trial with a nonrandomized database. * the primary objectives are to compare healthcare costs and healthcare utilization between subjects who have corrected low vitamin d levels and those without corrected low vitamin d levels.

* the purpose of the study is to characterize healthcare costs and healthcare utilization in subjects with corrected low (\<40 ng/ml) 25-oh vitamin d levels compared to subjects with uncorrected low 25-oh vitamin d levels during a three-year period. * the primary objective of this study is to determine whether ten healthcare costs are lower and ten healthcare utilization parameters occur less frequently in patients with corrected low vitamin d levels compared to patients with uncorrected low vitamin d levels in cooper outpatients and inpatients. the costs are: 1. total billed costs for any reason; 2. total billed costs for hospitalizations; 3. total billed costs for icu admissions; 4. total billed costs for emergency room visits; 5. total billed costs for all other outpatient services; 6. total billed costs for urgent care visits; 7. total billed costs for primary care physician (pcp) services; 8. total billed costs for nurse practitioner (np) services; 9. total billed costs for all other professional services; 10. total billed costs for medical pharmacy services and products. the parameters are: 1. number of hospitalizations for any reason; 2. number of icu admissions for any reason; 3. number of emergency room visits for any reason; 4. all other outpatient services for any reason; 5. number of urgent care visits for any reason; 6. number of primary care physician visits for any reason; 7. number of nurse practitioner visits for any reason; 8. all other professional services for any reason; 9. number of medical pharmacy services for any reason; 10. number of free-standing prescriptions for any reason. * the secondary objective is to determine the effect of sufficient vitamin d levels (≥ 40 ng/ml) in subjects not requiring a prior correction on the ten healthcare costs parameters and the ten healthcare utilization parameters listed in the primary objective above.

Eligibility criteria:
inclusion criteria: * any patient with at least one 25-oh vitamin d test result. patients with one test result will remain in the limited dataset for potential future research. * any patient with a 25-oh vitamin d level(s) always lower than 40 ng/ml (low level) with subsequent level(s) in the 40 ng/ml to 100 ng/ml range. the 40 ng/ml to 100 ng/ml range is maintained for three years. this corrected group is labeled as the treatment group. * any patient with a 25-oh vitamin d level always lower than 40 ng/ml with maintenance of that lower than 40 ng/ml level for 3 years. this uncorrected group is labeled as control group a. * any patient who has an uninterrupted 25-oh vitamin d level greater than or equal 40 ng/ml and less than or equal to 100 ng/ml (sufficient level) for a continuous 3-year period. prior to the 3-year period there were no levels lower than 40ng/ml or higher than 100 ng/ml. this vitamin d3 sufficient group is labeled as control group b. exclusion criteria: * any patient with only one 25-oh vitamin d3 test result or any patient who cannot be included in the treatment group, control group a, or control group b is excluded.

Keywords: vitamin d healthcare cost healthcare utilization hospitalization emergency room visit intensive care unit admission emulated trial target trial real world data combined comorbidity multimorbidity propensity score