Real World Evidence and Epidemiology, GlaxoSmithKline, Collegeville, PA
Department of Epidemiology, Gillings School of Public Health, University of North Carolina, Chapel Hill, NC.
Diabetes Care. 2020 Sep;43(9):2121-2127. doi: 10.2337/dc19-1880. Epub 2020 Jul 8.
Using the 2016 Medicare Part D coverage gap as an example, we explored effects of increased out-of-pocket costs on adherence to branded dipeptidyl peptidase 4 inhibitors (DPP-4i) in patients without financial subsidies relative to subsidized patients who do not experience increased spending during the gap. We also explored seasonality of reinitiation, because discontinuers may be more likely to reinitiate in January when benefits reset.
We identified DPP-4i or sulfonylurea initiators, aged ≥66 years, from a 20% sample of 2015-2016 Medicare claims. Difference-in-differences Poisson regression was used to compare adherence before and after entering the coverage gap between nonsubsidized and subsidized patients. Among discontinuers, monthly hazard ratios (HRs) for reinitiation relative to January 2016 were derived with Cox models. As a second control, we repeated analyses using sulfonylureas, generic low-cost alternatives.
In 2016, 8,096 subsidized and 6,173 nonsubsidized DPP-4i initiators entered the coverage gap. For nonsubsidized patients, copayment in the coverage gap was 45% ($227 per DPP-4i prescription), and adherence decreased from 68.4% to 49.0% after gap entry. Accounting for adherence differences in subsidized patients, nonsubsidized patients demonstrated reduced adherence to DPP-4i (difference-in-difference: -16.9%; 95% CI -18.7%, -15.1%) but not sulfonylureas (-1.6%; 95% CI -3.4%, 0.2%). Reinitiation was lowest in the months before January (HR 0.4-0.5) among nonsubsidized DPP-4i patients, demonstrating a strong seasonal pattern.
Increased out-of-pocket costs negatively affect adherence and reinitiation of branded antihyperglycemic drugs among patients without financial subsidies. Despite closure of the coverage gap, affordability remains a concern given increasing list prices for many drugs on Medicare and the growing use of deductibles and coinsurance by commercial health plans.
以 2016 年医疗保险部分 D 覆盖缺口为例，我们探讨了对于没有经济补贴的患者而言，自付费用增加对品牌二肽基肽酶 4 抑制剂（DPP-4i）依从性的影响，这些患者与未在缺口期间增加支出的有补贴患者相比。我们还探讨了重新开始的季节性，因为中断治疗的患者可能更有可能在福利重置的 1 月重新开始治疗。
我们从 2015-2016 年医疗保险索赔的 20%样本中确定了年龄≥66 岁的 DPP-4i 或磺酰脲类药物的初始使用者。采用差异-差异泊松回归比较无补贴和有补贴患者在进入覆盖缺口前后的依从性。对于停药患者，通过 Cox 模型得出相对于 2016 年 1 月重新开始的每月危险比（HR）。作为第二个对照，我们使用磺酰脲类药物，即低成本的通用替代品，重复了分析。
2016 年，有 8096 名有补贴和 6173 名无补贴的 DPP-4i 初始使用者进入了覆盖缺口。对于无补贴患者，覆盖缺口内的自付费用为 45%（每份 DPP-4i 处方 227 美元），并且在缺口进入后，依从性从 68.4%下降到 49.0%。考虑到有补贴患者的依从性差异，无补贴患者的 DPP-4i 依从性下降（差异差异：-16.9%；95%CI-18.7%，-15.1%），但磺酰脲类药物没有下降（-1.6%；95%CI-3.4%，0.2%）。在无补贴的 DPP-4i 患者中，在 1 月之前的几个月中重新开始的比例最低（HR0.4-0.5），表明存在很强的季节性模式。
自付费用增加对没有经济补贴的患者的品牌抗高血糖药物的依从性和重新开始使用产生负面影响。尽管覆盖缺口已经关闭，但考虑到医疗保险中许多药物的标价不断上涨，以及商业健康计划越来越多地使用免赔额和自付额，药物的可负担性仍然是一个问题。
