Department of Population and Quantitative Health Sciences, School of Medicine, Case Western Reserve University.
Case Comprehensive Cancer Center, Case Western Reserve University.
Med Care. 2022 Nov 1;60(11):821-830. doi: 10.1097/MLR.0000000000001779. Epub 2022 Sep 13.
The mechanisms underlying improvements in early-stage cancer at diagnosis following Medicaid expansion remain unknown. We hypothesized that Medicaid expansion allowed for low-income adults to enroll in Medicaid before cancer diagnosis, thus increasing the number of stably-enrolled relative to those who enroll in Medicaid only after diagnosis (emergently-enrolled).
Using data from the 2011-2017 Ohio Cancer Incidence Surveillance System and Medicaid enrollment files, we identified individuals diagnosed with incident invasive breast (n=4850), cervical (n=1023), and colorectal (n=3363) cancer. We conducted causal mediation analysis to estimate the direct effect of pre- (vs. post-) expansion on being diagnosed with early-stage (-vs. regional-stage and distant-stage) disease, and indirect (mediation) effect through being in the stably- (vs. emergently-) enrolled group, controlling for individual-level and area-level characteristics.
The percentage of stably-enrolled patients increased from 63.3% to 73.9% post-expansion, while that of the emergently-enrolled decreased from 36.7% to 26.1%. The percentage of patients with early-stage diagnosis remained 1.3-2.9 times higher among the stably-than the emergently-enrolled group, both pre-expansion and post-expansion. Results from the causal mediation analysis showed that there was an indirect effect of Medicaid expansion through being in the stably- (vs. emergently-) enrolled group [risk ratios with 95% confidence interval: 1.018 (1.010-1.027) for breast cancer, 1.115 (1.064-1.167) for cervical cancer, and 1.090 (1.062-1.118) for colorectal cancer.
We provide the first evidence that post-expansion improvements in cancer stage were caused by an increased reliance on Medicaid as a source of stable insurance coverage.
医疗保险扩张后早期癌症诊断改善的机制尚不清楚。我们假设医疗保险扩张使低收入成年人能够在癌症诊断前加入医疗保险，从而使稳定参保的人数相对于仅在诊断后（紧急参保）参保的人数增加。
使用 2011-2017 年俄亥俄州癌症发病率监测系统和医疗保险参保文件中的数据，我们确定了诊断为侵袭性乳腺癌（n=4850）、宫颈癌（n=1023）和结直肠癌（n=3363）的个体。我们进行了因果中介分析，以估计扩张前（vs. 扩张后）对诊断为早期（vs. 区域性和远处阶段）疾病的直接影响，以及通过稳定（vs. 紧急）参保组的间接（中介）效应，同时控制个体水平和地区水平的特征。
扩张后稳定参保患者的比例从 63.3%增加到 73.9%，而紧急参保患者的比例从 36.7%减少到 26.1%。在扩张前和扩张后，稳定参保患者的早期诊断比例始终比紧急参保患者高 1.3-2.9 倍。因果中介分析的结果表明，通过稳定（vs. 紧急）参保组，医疗保险扩张存在间接效应[乳腺癌的风险比及其 95%置信区间为 1.018（1.010-1.027），宫颈癌为 1.115（1.064-1.167），结直肠癌为 1.090（1.062-1.118）]。
我们提供了第一个证据，即扩张后癌症阶段的改善是由于增加了对医疗保险作为稳定保险来源的依赖所致。
