BACKGROUND: The Department of Veterans Affairs is the largest US provider of hepatitis C treatment. Although antiviral regimens are becoming simpler, hepatitis C antivirals are not typically prescribed by primary care providers. The Veterans Affairs Extension for Community Health Outcomes (VA-ECHO) program was launched to promote primary care-based hepatitis C treatment using videoconferencing-based specialist support. We aimed to assess whether primary care provider participation in VA-ECHO was associated with hepatitis C treatment and sustained virologic response. METHODS: We identified 4173 primary care providers (n = 152 sites) responsible for 38,753 patients with chronic hepatitis C infection. A total of 6431 patients had a primary care provider participating in VA-ECHO; 32,322 patients had an unexposed primary care provider. Exposure was modeled as a patient-level time-varying covariate. Patients became exposed after primary care provider participation in >= 1 VA-ECHO session. Multivariable Cox proportional hazards frailty modeling assessed the association between VA-ECHO exposure and hepatitis C treatment. Among treated patients, modified Poisson regression assessed the relationship between exposure and sustained virologic response. RESULTS: After adjustment, exposed patients received significantly higher rates of antiviral treatment compared with unexposed patients (adjusted hazard ratio, 1.20; 95% confidence interval, 1.10-1.32; P <. 01). The rate of primary care provider-initiated antiviral medication was 21.4% among treated patients reviewed on VA-ECHO teleconferences compared with 2.5% among unexposed patients (P <. 01). No difference in adjusted rates of sustained virologic response was observed for patients with exposed primary care providers (P = .32), with similar crude rates for primary care providers versus specialists. CONCLUSIONS: National implementation of VA-ECHO was positively associated with hepatitis C treatment initiation by primary care providers, without differences in sustained virologic response. Published by Elsevier Inc.