The Effect of HCV on Methadone Dose During Pregnancy

Pregnancy is a time of high patient motivation to initiate treatment for opioid use disorder (OUD). Hepatic drug metabolism can be altered by pregnancy and hepatitis C virus (HCV) infection. We aimed to examine the impact of HCV during pregnancy on methadone dosing. Retrospective chart review of all pregnant patients with OUD admitted for initiation of methadone from 1/2020-6/2022. Associations were examined using Student's T-tests, chi-squared tests, Fisher's exact tests and univariate and multivariate linear regression. We identified 191 pregnancies initiated on methadone, of which 188 were screened for HCV. 111 (59.0%) were HCV Antibody (Ab)+, of whom 108 were tested for HCV RNA and 66 (61.1%) were HCV RNA+. The median viral load was 498,500 IU/mL (range 19-46,000,000 IU/mL). Fibrosis-4 (Fib4) score, an estimate of liver fibrosis, was available for 97 pregnancies. The average Fib4 score was 0.36 (SD 0.69), and only five individuals had Fib4 scores > 1.45. White race (p < 0.001) and injection drug use (p < 0.001) were associated with being HCV RNA+. HCV RNA+ individuals had higher Fib4 scores (p = 0.022). We found no association between being HCV RNA+ and stable methadone dose achieved during hospitalisation (p = 0.105) in univariate analysis or a multivariate linear regression model (p = 0.567). There was no correlation between viral load or Fib4 score and stable methadone dose. No patient had a Fib4 score > 3.25. Our data suggest that HCV-specific alterations are unnecessary for methadone dosing in pregnancy and that fibrotic liver damage is rare in this population. However, further research is warranted for the subset of pregnant patients with advanced fibrosis.