Medicaid expansion and chronic obstructive pulmonary disease among low-income adults in the United States.

INTRODUCTION: Chronic obstructive pulmonary disease (COPD) is common but often underdiagnosed in the United States (US). Public health insurance coverage expansion may increase the prevalence of diagnosed COPD due to improved access to care and diagnosis.

OBJECTIVE: We sought to determine the effects of Medicaid expansion on the prevalence of diagnosed COPD among low-income US adults.

METHODS: The 2011-2015 Behavioral Risk Factor Surveillance System survey data were used to identify adults with annual household income <$50 000. The outcome was self-report of being diagnosed with COPD by a health-care provider. Difference-in-difference logistic regression contrasted the influence of period (pre-expansion, 2011-2013, vs post-expansion, 2014-2015) between states participating and opting out of Medicaid expansion.

RESULTS: Data on 521 622 respondents were analysed. The prevalence of diagnosed COPD was 7% in Medicaid expansion states and 8% in non-participating states. In participating states, lack of health insurance among low-income adults decreased from 32% to 21% after Medicaid expansion (P < .001), but the prevalence of diagnosed COPD was unchanged. Multivariable logistic regression confirmed that residents of participating states surveyed after Medicaid expansion were no more likely to report diagnosed COPD than residents of these states surveyed before Medicaid expansion (OR = 1.03; 95% CI: 0.97, 1.10; P = .276).

CONCLUSIONS: Notwithstanding increased health insurance coverage among low-income adults after Medicaid expansion, this policy did not increase the prevalence of diagnosed COPD. Access to primary care among new Medicaid enrollees and practices of diagnosing COPD in this setting should be evaluated to reduce the extent of undiagnosed COPD in socioeconomically disadvantaged groups.