Combining cross-sectional survey and register data improved the estimate of hepatitis C prevalence among patients attending a psychiatric emergency department in Denmark

BackgroundThe prevalence of hepatitis C (HCV) among psychiatric patients is elevated compared to the background population in many studies, but the prevalence among Danish psychiatric patients is unknown. The aim of the study was to determine the HCV prevalence and the proportion of the psychiatric patient population that remains to be diagnosed and treated in a Danish setting.MethodsDuring a 5-month period, patients attending the psychiatric emergency room in Vejle, Denmark, were offered point-of-care anti-HCV testing. Previous hepatitis C tests for all patients attending the Psychiatric Department in the study period were extracted from the national laboratory database (DANVIR). We combined the survey and register data in a capture-recapture estimate of undiagnosed patients with HCV.ResultsDuring the study 24.9% (589 of 2364) patients seen at the psychiatric department attended the emergency room. The prevalence of anti-HCV among those tested in the emergency room was 1.6%. The laboratory register identified 595/2364 patients previously tested for anti-HCV with a positive prevalence of 6.1%. The undiagnosed anti-HCV positives among the 1483 never tested was estimated to 1.1%. Thus the total estimated prevalence of anti-HCV was 2.3% (54/2364, 95% CI 1.7%-3.0%) in the population, of whom 70.4% had been diagnosed, and 72.2% of diagnosed patients had received treatment or cleared HCV.ConclusionCombining survey and register data showed that the WHO target of 90% diagnosed and 80% treated was not met. To eliminate HCV in the psychiatric population, both undiagnosed and untreated patients must be targeted.