Medicaid Expansion and Mechanical Ventilation in Asthma, Chronic Obstructive Pulmonary Disease, and Heart Failure.

The Affordable Care Act's Medicaid expansion has led to increased access to chronic disease care among newly insured adults. Despite this, its effects on clinical outcomes, particularly for patients with asthma, chronic obstructive pulmonary disease, and heart failure, are uncertain. To assess whether Medicaid expansion was associated with changes in mechanical ventilation rates among hospitalized patients with heart failure, asthma, and chronic obstructive pulmonary disease. Difference-in-differences analysis comparing discharge data from four states that expanded Medicaid in 2014 (Arizona, Iowa, New Jersey, and Washington) and three comparison states that did not (North Carolina, Nebraska, and Wisconsin) was performed. Models were adjusted for patient and hospital factors. Mechanical ventilation rates at baseline were 7.2% in nonexpansion states and 8.8% in expansion states. Medicaid expansion was associated with a decline in mechanical ventilation rates at -0.2% per quarter (95% confidence interval [CI], -0.3% to 0.0%;  = 0.010). We did not observe a change in the rate of ICU admission (-0.4% per quarter; 95% CI, -0.8% to 0.1%;  = 0.10) or in-hospital mortality (0.1% per quarter; 95% CI, 0.0% to 0.1%;  = 0.30). In a negative control among adults aged 65 years or older, changes in mechanical ventilation rates were similar, though the CIs crossed zero (-0.1%; 95% CI, -0.2% to 0.0%;  = 0.08). Medicaid expansion may have been associated with a decline in mechanical ventilation rates among uninsured and Medicaid-covered patients admitted with heart failure, chronic obstructive pulmonary disease, and asthma.