The effect of hepatitis C treatment response on medical costs: a longitudinal analysis in an integrated care setting.

BACKGROUND: Studies suggest that chronic hepatitis C patients who achieve sustained virologic response (SVR) have lower risks of liver-related morbidity and mortality. Given the substantial costs and complexity of hepatitis C virus (HCV) antiviral treatment, post-treatment benefits are important to understand.
OBJECTIVE: To determine whether health care costs and utilization for up to 5 years after treatment differed between patients who achieved SVR and those who did not.
METHODS: Kaiser Permanente Medical Care Program patients receiving HCV treatment with pegylated interferon and ribavirin (Peg-IFN/RBV) from 2002 to 2007 were retrospectively analyzed, excluding those with human immunodeficiency virus (HIV) or chronic hepatitis B. Health care utilization and costs for up to 5 years after treatment completion were derived from electronic records. We compared mean annual cost and overall post-treatment costs (standardized to year-2007 dollars), and yearly utilization counts between the SVR and non-SVR groups, adjusting for pretreatment costs, age, sex, baseline cirrhosis, and race using gamma and Poisson regression models.
RESULTS: The 1,924 patients eligible for inclusion were a mean age of 50 years; 63% male; 58% white, non-Hispanic; 62% with genotype 1; and 48% who had achieved SVR. The mean duration of post-treatment time was 3 years, and patients without SVR incurred significantly higher health care costs than patients with SVR. For each post-treatment year, total adjusted costs were significantly higher in the non-SVR group than in the SVR group, with rate ratios (RRs) and 95% CIs ranging from 1.26 (95% CI, 1.13-1.40) to 1.64 (95% CI, 1.38-1.96), driven mostly by hospital and outpatient pharmacy costs. When all post-treatment years were considered collectively, the non-SVR group had significantly higher costs overall (RR=1.41; 95% CI, 1.17-1.69) and in each category of costs. The adjusted difference in yearly total mean costs was $2,648 (95% CI, 737-4,560). In post-treatment years 2-5, adjusted liver-specific laboratory test rates were 1.8 to 2.3 times higher in the non-SVR group than in the SVR group (each year, P less than 0.001). During post-treatment years 1-5, adjusted yearly liver-related hospitalization rates were up to 2.45 times higher (95% CI, 1.56-3.85), and medicine/GI clinic visit rates were up to 1.39 times higher (95% CI, 1.23-1.54) in the non-SVR group compared with the SVR group.
CONCLUSION: Health care utilization and costs after HCV antiviral therapy with Peg-IFN/RBV, particularly for liver-related tests, outpatient drugs, and hospitalizations, were significantly lower for patients who achieved SVR than for those without SVR. Our observations are consistent with the potentially lower risk of severe liver disease among patients with SVR.