Document Type

Thesis or dissertation

Date of this Version



Mark Pauly


This paper examines health insurance crowd-out in the context of the 2001 Medicare expansion for amyotrophic lateral sclerosis (ALS) patients. It first identifies the number of patients with ALS in the US over 1998-2004, and then estimates the extent of crowd-out among patients under 65 years of age before and after the policy. Last, it examines correlations between Medicare enrollment and hospital length-of-stay. The key finding is a statistically significant increase in the probability of Medicare enrollment status for ALS patients under 65 years after the policy change, while overall ALS patient demographics and inpatient admissions stayed relatively constant. Comparisons with counterfactual predictions demonstrate similar correlations. Together, these results imply a large crowd-out rate of approximately 64.5 percent, though it is difficult to identify which private insurance types new Medicare coverage replaced. Preliminary analysis also suggests expansion may have helped improve outcomes for ALS patients under 65 years old.


insurance, Medicare, crowd-out, rare disease, patient care, health systems, als, policy



Date Posted: 24 May 2023


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