What happens when patients suddenly stop their medications? We study the health consequences of drug interruptions caused by large, abrupt, and arbitrary changes in price. Medicare’s prescription drug benefit as-if-randomly assigns 65-year-olds a drug budget as a function of their birth month, beyond which out-of-pocket costs suddenly increase. Those facing smaller budgets consume fewer drugs and die more: mortality increases 0.0164 percentage points per month (13.9%) for each ${\$}$100 per month budget decrease (24.4%). This estimate is robust to a range of falsification checks, and lies in the 97.8th percentile of 544 placebo estimates from similar populations that lack the same idiosyncratic budget policy. Several facts help make sense of this large effect. First, patients stop taking drugs that are both ‘high-value,’ and suspected to cause life-threatening withdrawal syndromes when stopped. Second, using machine learning, we identify patients at the highest risk of drug-preventable adverse events. Contrary to the predictions of standard economic models, high-risk patients (e.g., those most likely to have a heart attack) cut back more than low-risk patients on exactly those drugs that would benefit them the most (e.g., statins). Finally, patients appear unaware of these risks. In a survey of 65-year-olds, only one-third believe that stopping their drugs for up to a month could have any serious consequences. We conclude that, far from curbing waste, cost-sharing is itself highly inefficient, resulting in missed opportunities to buy health at very low cost (${\$}$11,321 per life-year).

中文翻译：

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费用分摊的健康成本

当患者突然停止用药时会发生什么？我们研究价格大幅、突然和任意变化造成的药物中断对健康的影响。医疗保险的处方药福利就像随机地为 65 岁的人分配了一个药物预算，作为他们出生月份的函数，超过这个预算，自付费用就会突然增加。预算较少的人消耗的药物较少，死亡人数较多：每月预算每减少 100 美元（24.4%），死亡率每月增加 0.0164 个百分点（13.9%）。这一估计值对一系列伪造检查来说是稳健的，并且位于缺乏相同特殊预算政策的类似人群的 544 个安慰剂估计值中的 97.8%。有几个事实有助于理解这种巨大的影响。首先，患者停止服用既“高价值”又怀疑在停止时会导致危及生命的戒断综合症的药物。其次，利用机器学习，我们识别出药物可预防不良事件风险最高的患者。与标准经济模型的预测相反，高风险患者（例如，最有可能心脏病发作的患者）比低风险患者减少了更多对他们最有利的药物（例如他汀类药物）的使用。最后，患者似乎没有意识到这些风险。在一项针对 65 岁老年人的调查中，只有三分之一的人认为停药长达一个月可能会产生严重后果。我们的结论是，成本分摊不仅不能抑制浪费，而且效率极低，导致错失以极低成本（每生命年 11,321 美元）购买健康的机会。