Medicare Disabled Patients with Hepatitis C: Determinants of Quality of Care Receipt, Peg-Interferon Treatment Initiation, and Risk of Metabolic and Vascular Disorders

Abstract

Background: Due to years of undetected hepatitis C virus (HCV) infection, the burden of liver and extrahepatic disorders will continue to increase in the US. HCV patients receiving Social Security Disability Benefits represent~70% of HCV patients in Medicare and are an understudied population facing numerous barriers to HCV management. We explored pre-treatment quality of care (QC) patterns, determined the factors associated with differential QC receipt and peg-interferon treatment initiation, and examined the effectiveness of peg-interferon therapy for ?24 weeks at reducing metabolic/vascular risk in Medicare disabled HCV patients. Methods: Medicare claims (2006-2009) linked to the Area Health Resource Files were used. We used a random forest model of conditional inference trees to aggregate QC indicators into high, good, fair, and low QC groupings. Ordinal partial proportional odds regression modelled the receipt of differential QC levels. Modified Poisson regressions, propensity-score weighted for the level of QC received, examined the association between treatment initiation and patient- and county-level characteristics. Poisson regression with weights for treatment selection, discontinuation, and informative censoring due to mortality quantified the effect of peg-interferon treatment on the risk of incident mild, severe, or mild and severe metabolic/vascular events, compared to the untreated. Results: We identified 1,936 patients with continuous enrolment, of whom 10.4% initiated peg-interferon. The five strongest QC metrics predicting treatment included "having received liver biopsy", "HCV genotype testing", "visit to specialist", "confirmation of HCV viremia", and "iron overload testing". While county of residence had no effect on QC receipt, residence in rural counties with high screening capacity was associated with higher prevalence ratio [PR] of treatment initiation (PR=1.42, p=0.09). High QC (PR=5.61, p<0.01) and good QC (PR=2.46, p<0.01) were associated with higher treatment rates. Multiple comorbidities were associated with lower odds of QC receipt (OR=0.76, p=0.05) and treatment initiation (PR=0.27, p<0.01). Over two years of follow-up, there was no difference in metabolic/vascular risk between those treated≥24 weeks (n=43) and untreated (n=879) patients. Conclusion: As barriers to eradicating the HCV infection would likely persist even with novel interferon-free regimens, future research should use our findings to better characterize and optimize treatment in HCV patients with disabilities.