Treatment of Vitamin D Deficiency Within a Large Integrated Health Care Delivery System

BACKGROUND: In the past decade, increasing attention has focused on identification and treatment of vitamin D deficiency although repletion outcomes of pharmacologic vitamin D therapy have not been examined at a population level. OBJECTIVES: To investigate population trends and outcomes of pharmacologic treatment of vitamin D deficiency. METHODS: We conducted a retrospective cohort study using data from an integrated health system with approximately 3.2 million members. Automated laboratory and pharmacy databases were used to identify patients aged 18 years or older with hypovitaminosis D (defined as a 25-hydroxy-vitamin D [25(OH)D] serum level less than 20 nanograms [ng] per mL) who newly initiated pharmacologic ergocalciferol (50,000 international units [IU] per week) during 2007-2010 and did not have a prescription for ergocalciferol in the prior 12 months. Patients were required to be continuously enrolled for 12 months before and 6 months after ergocalciferol initiation. Age, gender, race/ethnicity, body mass index, and 25(OH)D levels were obtained from health plan electronic medical records and administrative, laboratory, and pharmacy databases. Outcome and predictors of repletion among the subset who received 12 weekly doses of 50,000 IU ergocalciferol (total dose 600,000 IU) were examined using multivariable logistic regression. RESULTS: There were 72,093 vitamin D-deficient patients who newly initiated pharmacologic ergocalciferol. During the study period, the use of ergocalciferol increased nearly 8-fold from 161 per 100,000 adult members in 2007 to 1,241 per 100,000 adult members in 2010. One-fifth (n = 14,727) had severe vitamin D deficiency (25[OH]D level less than 10 ng per mL). Among 23,322 patients receiving 50,000 IU ergocalciferol for 12 weeks in whom subsequent 25(OH)D levels were measured between 90 and 365 days after the index ergocalciferol prescription date, 74.0% achieved 25(OH)D of at least 20 ng per mL, and 35.8% achieved 25(OH)D of at least 30 ng per mL. Increasing age (adjusted odds ratio [OR] 1.02, 95% CI 1.02-1.02) and higher baseline 25(OH)D level (OR 1.11, 95% CI 1.10-1.12) were associated with greater odds of successful repletion. Asian race (OR 0.80, 95% CI 0.73-0.88), Hispanic ethnicity (OR 0.71, 95% CI 0.65-0.77), and increasing overweight/obesity (OR 0.78, 95% CI 0.72-0.85 for body mass index [BMI], 25.0-29.9 kg/m2; OR 0.66, 95% CI 0.60-0.71 for BMI 30.0-39.9 kg/m2; OR 0.53, 95% CI 0.48-0.60 for BMI ≥ 40 kg/m2) were associated with lower odds of repletion compared with BMI 18.5-24.9 kg/m2. CONCLUSIONS: There is increasing recognition and treatment of vitamin D deficiency within the health care setting. Patients of younger age, Asian and Hispanic race/ethnicity, and those who are obese or with more severe vitamin D deficiency may be at greater risk for incomplete repletion using standard regimens and may require additional treatment to achieve optimal levels.