Caldwell Jillian S, Cheng Xingxing S, Bendavid Eran, Chertow Glenn M, Lakdawalla Darius N, Lin Eugene
Division of Nephrology, Stanford University School of Medicine, Palo Alto, California.
Department of Health Policy, Stanford University School of Medicine, Palo Alto, California.
JAMA Health Forum. 2025 Apr 4;6(4):e250452. doi: 10.1001/jamahealthforum.2025.0452.
Calcimimetics are a mainstay of treatment for secondary hyperparathyroidism (sHPT), a ubiquitous condition in end-stage kidney disease (ESKD) associated with fractures, cardiovascular events, and mortality. In 2018, Medicare implemented the Transitional Drug Add-On Payment Adjustment (TDAPA), which shifted calcimimetic coverage from Part D prescription drug plans to Part B. Prior to TDAPA, Medicare beneficiaries with ESKD faced varying out-of-pocket costs for calcimimetics at the point of pharmacy depending on presence and magnitude of low-income subsidies (LISs). TDAPA differentially alleviated barriers to filling these costly medications.
To assess whether calcimimetic prescriptions increased post-TDAPA among patients subject to high out-of-pocket costs prior to the policy change (patients with Part D coverage without LIS and those lacking Part D coverage).
DESIGN, SETTING, AND PARTICIPANTS: In this longitudinal cohort study, a difference-in-differences analysis was performed at the patient-quarter level. The sample included adult Medicare fee-for-service beneficiaries undergoing maintenance dialysis between July 1, 2016, and December 31, 2020, at US outpatient dialysis facilities. The US Renal Data System, a national registry of patients with ESKD, was used to collect patient, facility, and claims data. The data analysis occurred between May 2023 and October 2024.
LIS extent for patients with Part D coverage (fully subsidized, partially subsidized, not subsidized); presence of Medicare Part D coverage; and whether the patient-quarter was before/after TDAPA implementation.
The main outcome was having 1 or more filled calcimimetic prescriptions per quarter of the study period. A linear regression model was estimated, adjusting for demographics, dialysis modality and access, comorbidities, and facility characteristics, with 2-way fixed effects at the patient and quarter level.
A total of 509 765 adult Medicare fee-for-service beneficiaries were included in the analysis. The cohort had a mean (SD) age of 64 (14) years, was 57% male, 4% Asian, 38% Black, 15% Hispanic, 41% non-Hispanic White, and 3% other race and ethnicity. In adjusted difference-in-differences models, TDAPA's estimated effect was an absolute increase of 9.8 percentage points (pp) (95% CI, 9.3-10.2 pp) in calcimimetic prescriptions for patients with Part D but no subsidy and a 2.2 pp (95% CI, 1.8-2.6 pp) increase for patients with partial LIS compared to patients with full LIS.
The results of this longitudinal cohort study showed that after transitioning calcimimetic coverage from Part D to Part B via TDAPA, calcimimetic prescriptions increased in a graded manner, with the largest increases experienced by patients previously subject to the highest out-of-pocket prescription drug costs. Medicare's TDAPA policy has the potential to expand access to medications for patients.
拟钙剂是治疗继发性甲状旁腺功能亢进（sHPT）的主要手段，sHPT是终末期肾病（ESKD）中普遍存在的一种病症，与骨折、心血管事件及死亡率相关。2018年，医疗保险计划实施了过渡性药物附加支付调整（TDAPA），该调整将拟钙剂的保险范围从D部分处方药计划转移至B部分。在TDAPA实施之前，患有ESKD的医疗保险受益人在药房购买拟钙剂时面临的自付费用因低收入补贴（LIS）的有无及补贴幅度而异。TDAPA不同程度地减轻了患者购买这些昂贵药物的障碍。
评估在政策变更前面临高额自付费用的患者（有D部分保险但无LIS的患者以及没有D部分保险的患者）在TDAPA实施后拟钙剂处方量是否增加。
设计、设置与参与者：在这项纵向队列研究中，在患者季度层面进行了双重差分分析。样本包括2016年7月1日至2020年12月31日期间在美国门诊透析设施接受维持性透析的成年医疗保险按服务收费受益人。使用美国肾脏数据系统（一个ESKD患者的全国性登记系统）收集患者、设施及理赔数据。数据分析于2023年5月至2024年10月期间进行。
有D部分保险患者的LIS程度（全额补贴、部分补贴、无补贴）；医疗保险D部分保险的有无；以及患者季度是在TDAPA实施之前还是之后。
主要结局是在研究期间每季度有1张或更多已配药的拟钙剂处方。估计了一个线性回归模型，对人口统计学特征、透析方式与通路、合并症及设施特征进行了调整，并在患者和季度层面采用双向固定效应。
分析共纳入509765名成年医疗保险按服务收费受益人。该队列的平均（标准差）年龄为64（14）岁，男性占57%，亚洲人占4%，黑人占38%，西班牙裔占15%，非西班牙裔白人占41%，其他种族和族裔占3%。在调整后的双重差分模型中，TDAPA的估计效应是，对于有D部分保险但无补贴的患者，拟钙剂处方量绝对增加9.8个百分点（pp）（95%置信区间[CI]，9.3 - 10.2 pp），对于有部分LIS的患者，与有全额LIS的患者相比增加2.2 pp（95% CI，1.8 - 2.6 pp）。
这项纵向队列研究的结果表明，通过TDAPA将拟钙剂保险范围从D部分转移至B部分后，拟钙剂处方量呈分级增加，之前面临最高自付处方药费用的患者增加幅度最大。医疗保险的TDAPA政策有可能扩大患者获得药物的机会。
