The Efficacy and Safety of Treating Hepatitis C in Patients With a Diagnosis of Schizophrenia
Tolerability of interferon amongst patients with schizophrenia (PWS) is of significance given a higher rate of HCV infection within this group. Approaching one in five adults tested amongst a sample of 931 patients with severe mental illness attending US inpatient and outpatient psychiatric facilities were found to have HCV.[3] Screening of patients treated with Clozapine, an atypical antipsychotic reserved for patients with refractory schizophrenia, revealed a prevalence of 4.1%.[4]
Prevalence rates of HCV amongst PWS are higher than controls even in the absence of a self-reported history of substance misuse.[10]
Our cohort demonstrates PWS to be good candidates for treatment with interferon containing regimens. It is well tolerated, with only 4% of PWS discontinuing treatment due to psychiatric illness. Despite a rate of cirrhosis twice that of controls, SVR rates were numerically higher amongst both genotype 1- and genotype 2/3-infected PWS.
This intriguing finding is not unique, with a prior study showing a higher SVR rate amongst genotype 2/3 PWS compared with controls.[9] We hypothesize that this may be explained by better compliance with treatment. Amongst our PWS, none discontinued treatment due to the lack of compliance with prescribed medication. Those PWS undergoing treatment had been identified by their treating psychiatrist as stable, and this may in part be due to good compliance with prescribed psychiatric medication.
The increased time from referral to treatment amongst PWS may reflect closer scrutiny of likelihood of treatment success, including compliance. Thus, the PWS we treat are likely a selected cohort with good compliance. We suggest that the well-established relationship between compliance and SVR rates[11,12] may explain our better than expected SVR rates amongst PWS.
In addition to the effects of patient selection on compliance, there is evidence to show that PWS and concomitant diabetes demonstrate improved compliance with oral hypoglycaemic medications,[13] and have lower HbA1c levels,[14] than matched diabetic controls without schizophrenia. This may be as a result of frequent contact and supervision by community psychiatric nurses.
Studies involving direct observed therapy in patients with HCV showed a greater proportion of patients achieving SVR,[15] and one may speculate that psychiatric input designed to aid compliance with antipsychotic medication may have a similar effect. A weakness of our study is a lack of data on the degree of psychiatric support and whether this was predictive of achieving SVR, an area worthy of further research.
Whilst clinical trials of new interferon-free regimens have classified PWS as ineligible for treatment with interferon,[16] there is no convincing data to support this. Whilst these regimens are likely to be better tolerated, cost dictates that they will not be available to all and we would advocate not excluding PWS from treatment with Interferon.
In conclusion, given the disproportionately high rates of chronic hepatitis C in PWS and the good SVR rates reported, we suggest that targeted treatment for this patient group can be safely considered.
No comments:
Post a Comment