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OBJECTIVES: Patient-centered medical homes (PCMHs) represent a widespread model of healthcare transformation. Despite evidence that PCMHs can improve care quality, the mechanisms by which they improve outcomes are relatively unexamined. We aimed to assess the mechanisms linking certification as a Health Care Home (HCH), a statewide PCMH initiative, with asthma care quality and outcomes. We compared direct certification effects versus indirect clinical effects (via improved care process).

STUDY DESIGN: This was an observational study using statewide patient-level data on asthma care quality and asthma outcomes.

METHODS: This study examined care quality for 296,662 adults and children with asthma in 501 HCH-certified and non-HCH clinics in Minnesota from 2010 to 2013. Using endogenous treatment effects models, we assessed the effects of HCH certification on care process (patient education using asthma action plans [AAPs]) and outcomes (asthma controlled; having no exacerbations) and asthma education’s effect on outcomes. We used logistic regression to formally decompose direct (certification) versus indirect (via education/AAPs) effects.

RESULTS: Adults’ adjusted rates of process and outcomes targets were double for HCH versus non-HCH clinics; children’s rates were also significantly higher for HCHs. Tests of the indirect/care process effect showed that rates of meeting outcomes targets were 7 to 9 times higher with education using an AAP. Decomposition indicated that the indirect effect (via education/AAPs) constituted 16% to 35% of the total HCH effect on outcomes.

CONCLUSIONS: HCHs were …