Current Self-reported Pain Before and After Cure of Hepatitis C Among Persons Who Actively Inject Drugs.

Background: Questions remain on the relationship between pain and hepatitis C virus cure among persons who inject drugs (PWID). This study aimed to explore whether achieving hepatitis C virus cure reduced pain severity.

Methods: Prespecified secondary analysis utilized data from a pragmatic clinical trial of care delivery models that enrolled PWIDs between 2016 and 2018 and treated with sofosbuvir/velpatasvir. Current pain severity (0-100) was assessed before and after treatment and 5-point Likert pain scales were used to determine moderate or greater current pain at baseline; the duration and etiology of current pain were not assessed. We used generalized mixed-effects linear models to test whether achieving sustained virologic response (SVR), that is, cure, was associated with lower numeric pain scores (primary outcome) posttreatment, adjusting for potential confounders (age, sex, intervention assignment, time/visit, and baseline pain severity category) and to examine changes in pain over time. Adjusted means estimated from a fitted model for pain severity at each visit were compared between participants who did and did not achieve SVR, both for the sample overall and for the subsample of participants who reported moderate or greater pain at baseline.

Results: Of the 501 participants who were randomized, treated with DAAs and had SVR data, moderate or greater pain was reported at baseline in 174 (34.7%) of participants. Numeric pain severity did not significantly differ by SVR status at any study visit except for the week 48 visit from baseline, when the estimated pain score was significantly higher for those who failed treatment (38.0 vs 26.3, P = 0.033). Among the subsample with baseline moderate or greater pain, pain severity scores were significantly lower in subsequent visits compared to the baseline visit, with the exception of week 48 among participants who did not achieve SVR.

Conclusions: Among PWID, achieving SVR did not improve pain severity. However, participants who failed treatment had significantly greater pain at the visit immediately following visit for SVR, which may relate to adverse psychological effects of treatment failure. Among those with baseline moderate or greater pain, pain scores declined post treatment, suggesting that treatment itself (irrespective of SVR) may be associated with improved pain.