Dor Avi, Lage Maureen J, Tarrants Marcy L, Castelli-Haley Jane
George Washington University, Washington, DC, USA.
Adv Health Econ Health Serv Res. 2010;22:175-93. doi: 10.1108/s0731-2199(2010)0000022011.
The authors focus on understanding the relationship between costs and cost sharing on medication adherence for individuals who initiated a disease-modifying therapy (DMT) for the treatment of multiple sclerosis (MS). DMTs reduce the risk of relapse and are an essential component of MS treatment. Furthermore, the authors compare monthly payment levels for copayments versus coinsurance and estimate the effects on adherence.
Using the MarketScan Commercial Claims and Encounters database evidence from July 1 2005 to March 31 2008, the authors employ a multivariate two-stage least-squares model (2SLS) to examine the impact of copayments or coinsurance on the medication possession ratio (MPR).
Descriptive results show that the mean out-of-pocket (OOP) costs of DMT per month were higher for patients with coinsurance than for patients with copayments. For the cohort of patients with copayment there was little difference in monthly copayments across adherence thresholds. Regression analysis shows that an increase in cost sharing reduces adherence overall, but this effect was small and insignificant in the copayment cohort. In contrast, in the coinsurance cohort increased cost sharing was significantly associated with decreased adherence to DMT medication; with a 10% increase in cost sharing leading to an 8.6% decline in adherence.
Employers increasingly rely on coinsurance, despite evidence that reliance on coinsurance results in lower adherence. Our research findings suggest that coinsurance appears to be a greater obstacle to compliance, confirming predictions found in the theoretical literature.
This research converted counts of injectable treatments into a continuous adherence measure. Previous literature on cost sharing did not examine MS.
作者致力于理解成本及成本分担与开始使用疾病修正疗法（DMT）治疗多发性硬化症（MS）患者药物依从性之间的关系。DMT可降低复发风险，是MS治疗的重要组成部分。此外，作者比较了共付额与 coinsurance 的月度支付水平，并估计其对依从性的影响。
利用2005年7月1日至2008年3月31日的MarketScan商业索赔和就诊数据库证据，作者采用多元两阶段最小二乘法模型（2SLS）来检验共付额或coinsurance对药物持有率（MPR）的影响。
描述性结果表明，coinsurance患者每月DMT的自付费用均值高于共付额患者。对于共付额患者群体，不同依从性阈值下的月度共付额差异不大。回归分析表明，成本分担增加总体上会降低依从性，但在共付额群体中这种影响较小且不显著。相比之下，在coinsurance群体中，成本分担增加与DMT药物依从性降低显著相关；成本分担增加10%会导致依从性下降8.6%。
尽管有证据表明依赖coinsurance会导致依从性降低，但雇主越来越依赖coinsurance。我们的研究结果表明，coinsurance似乎是依从性的更大障碍，证实了理论文献中的预测。
本研究将注射治疗次数转化为连续的依从性指标。以往关于成本分担的文献未研究MS。
