The effect of Medicare eligibility on diagnosis of chronic conditions.

Objectives: The near-universal access to Medicare coverage at age 65 years improves access to care. However, little is known about whether Medicare eligibility promotes the diagnosis of chronic diseases. We examined the effects of Medicare eligibility at age 65 years on the diagnosis of chronic conditions.

Study design: Using data from the 2007-2019 Medical Expenditure Panel Survey, we employed a regression discontinuity design.

Methods: Our sample includes 43,620 individuals aged 59 to 71 years. Our primary outcomes were diagnoses of 19 chronic conditions. Using a regression discontinuity design, we exploited the discontinuity in eligibility for Medicare at age 65 years and compared individuals just before and after age 65 years.

Results: Medicare eligibility at age 65 years led to significant increases in having any coverage or Medicare coverage: 8.8 percentage points (95% CI, 8.4-9.2) and 78.1 percentage points (95% CI, 74.9-81.4), respectively. However, there were no or small changes in the diagnosis of chronic conditions at age 65 years. Specifically, there were no significant changes in the diagnoses of 17 chronic conditions, and the changes were minor in magnitude. Significant changes were observed only in the diagnosis of stroke and cancer, at -0.6 percentage points (95% CI, -1.0 to -0.2) and -1.7 percentage points (95% CI, -2.8 to -0.6), respectively.

Conclusions: Our findings suggest that Medicare coverage did not necessarily lead to increased diagnosis of chronic conditions. Further research is necessary to explore the underlying mechanisms behind this observation.