University of Maryland, Baltimore, 220 Arch St, Rm 12-328, Baltimore, MD 21201. E-mail:
Am J Manag Care. 2017 Aug 1;23(8):e265-e274.
To evaluate the effects of formulary restrictions on utilization and costs of oral hypoglycemic agents (OHAs), statins, and renin-angiotensin system (RAS) antagonists among low-income subsidy (LIS) recipients in Medicare Part D plans.
We analyzed a 5% sample of 2012 Medicare data from the Chronic Conditions Data Warehouse together with a customized dataset capturing beneficiaries' histories of plan assignment.
We constructed 3 nonexclusive study cohorts comprising of users of OHAs, statins, and RAS antagonists. Eligible study subjects were LIS recipients randomized to benchmark plans. Formulary restrictions of interest were noncoverage, prior authorization, and step therapy. Study outcomes included generic dispensing rate (GDR), mean cost per prescription fill, and medication adherence based on proportion of days covered (PDC). Random intercept regression models were performed to estimate the effects of formulary restrictions on the study outcomes by drug class.
After covariate adjustment, beneficiaries who were subject to formulary restrictions on brand name pioglitazone and single-source brand name dipeptidyl peptidase-4 inhibitors (saxagliptin, sitagliptin, and sitagliptin-metformin) had a GDR 3 percentage points higher and a cost per prescription fill $10.8 less, but similar PDC compared with those who faced no restrictions. Restricting access to brand name atorvastatin and single-source brand name statins (rosuvastatin and ezetimibe-simvastatin) was associated with a GDR 14.9 percentage points higher and a cost per prescription fill $29.6 less, but with no impact on PDC. Restricting use of single-source brand name RAS antagonists (olmesartan, valsartan, and valsartan-hydrochlorothiazide) was associated with a GDR 15.0 percentage points higher, a cost per prescription fill $27.2 less, and a PDC 1.3 percentage points lower.
Placing formulary restrictions on brand name drugs shifts utilization toward generic drugs, lowers the overall cost per prescription fill, and has minimal impact on overall adherence for OHAs, statins, and RAS antagonists among LIS recipients.
评估医疗保险处方药计划中低收入补贴（LIS）受助人的处方限制对口服降糖药（OHA）、他汀类药物和肾素-血管紧张素系统（RAS）拮抗剂的利用和成本的影响。
我们分析了 2012 年医疗保险数据仓库中慢性疾病数据的 5%样本，以及一个捕获受益人的计划分配历史的定制数据集。
我们构建了由 OHA、他汀类药物和 RAS 拮抗剂使用者组成的 3 个非排他性研究队列。合格的研究对象是被随机分配到基准计划的 LIS 受助人。感兴趣的处方限制是非覆盖、事先授权和阶梯治疗。研究结果包括通用配药率（GDR）、每处方填充的平均成本和基于覆盖天数比例（PDC）的药物依从性。使用随机截距回归模型按药物类别估计处方限制对研究结果的影响。
在调整了协变量后，与没有限制的受助人相比，面临品牌吡格列酮和单源品牌二肽基肽酶-4 抑制剂（沙格列汀、西他列汀和西他列汀-二甲双胍）处方限制的受助人的 GDR 高 3 个百分点，每处方填充的成本低 10.8 美元，但 PDC 相似。限制使用品牌阿托伐他汀和单源品牌他汀类药物（瑞舒伐他汀和依折麦布-辛伐他汀）与 GDR 高 14.9 个百分点、每处方填充的成本低 29.6 美元相关，但对 PDC 没有影响。限制使用单源品牌 RAS 拮抗剂（奥美沙坦、缬沙坦和缬沙坦-氢氯噻嗪）与 GDR 高 15.0 个百分点、每处方填充的成本低 27.2 美元和 PDC 低 1.3 个百分点相关。
对品牌药物实施处方限制会促使药物利用转向通用药物，降低每处方填充的总成本，对 LIS 受助人的 OHA、他汀类药物和 RAS 拮抗剂的总体依从性影响最小。
