Association of Medicare's Bundled Payment Reform With Changes in Use of Vitamin D Among Patients Receiving Maintenance Hemodialysis: An Interrupted Time-Series Analysis

Background & Rationale Medicare's 2011 prospective payment system (PPS) was introduced to curb overuse of separately billable injectable drugs. After epoietin, intravenous (IV) vitamin D analogues are the biggest drug cost drivers in hemodialysis (HD) patients, but the association between PPS introduction and vitamin D therapy has been scarcely investigated. Study Design Interrupted time-series analyses. Setting & Participants Adult US HD patients represented in the US Renal Data System between 2008 and 2013. Exposures PPS implementation. Outcomes The cumulative dose of IV vitamin D analogues (paricalcitol equivalents) per patient per calendar quarter in prevalent HD patients. The average starting dose of IV vitamin D analogues and quarterly rates of new vitamin D use (initiations/100 person-months) in incident HD patients within 90 days of beginning HD therapy. Analytical Approach Segmented linear regression models of the immediate change and slope change over time of vitamin D use after PPS implementation. Results Among 359,600 prevalent HD patients, IV vitamin D analogues accounted for 99% of the total use, and this trend was unchanged over time. PPS resulted in an immediate 7% decline in the average dose of IV vitamin D analogues (average baseline dose = 186.5 μg per quarter; immediate change = −13.5 μg [ P P = 0.3]) and in the starting dose of IV vitamin D analogues in incident HD patients (average baseline starting dose = 5.22 μg; immediate change = −0.40 μg [ P P  = 0.03]). The baseline rate of vitamin D therapy initiation among 99,970 incident HD patients was 44.9/100 person-months and decreased over time, even before PPS implementation (pre-PPS β = −0.46/100 person-months [ P P  = 0.2]). PPS implementation was associated with an immediate change in initiation levels (by −4.5/100 person-months; P Limitations Incident HD patients were restricted to those 65 years or older. Conclusion PPS implementation was associated with a 7% reduction in the average dose and starting dose of IV vitamin D analogues and a 10% reduction in the rate of vitamin D therapy initiation.