title: Major decline of hepatitis C virus incidence rate over two decades in a cohort of drug users.
abstract: Injecting drug users (DU) are at high risk for hepatitis C virus (HCV) and HIV infections. To examine the prevalence and incidence of these infections over a 20-year period (1985-2005), the authors evaluated 1276 DU from the Amsterdam Cohort Studies who had been tested prospectively for HIV infection and retrospectively for HCV infection. To compare HCV and HIV incidences, a smooth trend was assumed for both curves over calendar time. Risk factors for HCV seroconversion were determined using Poisson regression. Among ever-injecting DU, the prevalence of HCV antibodies was 84.5% at study entry, and 30.9% were co-infected with HIV. Their yearly HCV incidence dropped from 27.5/100 person years (PY) in the 1980s to 2/100 PY in recent years. In multivariate analyses, ever-injecting DU who currently injected and borrowed needles were at increased risk of HCV seroconversion (incidence rate ratio 29.9, 95% CI 12.6, 70.9) compared to ever-injecting DU who did not currently inject. The risk of HCV seroconversion decreased over calendar time. The HCV incidence in ever-injecting DU was on average 4.4 times the HIV incidence, a pattern seen over the entire study period. The simultaneous decline of both HCV and HIV incidence probably results from reduced risk behavior at the population level.
authors.affiliation: Department of Human Retrovirology, Academic Medical Center, and Health Service of Amsterdam, Nieuwe Achtergracht 100, 1018 WT Amsterdam, The Netherlands. cvdberg@ggd.amsterdam.ml
authors.forename: Charlotte H S B
authors.initials: CH
authors.lastname: van den Berg
authors.forename: Colette
authors.initials: C
authors.lastname: Smit
authors.forename: Margreet
authors.initials: M
authors.lastname: Bakker
authors.forename: Ronald B
authors.initials: RB
authors.lastname: Geskus
authors.forename: Ben
authors.initials: B
authors.lastname: Berkhout
authors.forename: Suzanne
authors.initials: S
authors.lastname: Jurriaans
authors.forename: Roel A
authors.initials: RA
authors.lastname: Coutinho
authors.forename: Katja C
authors.initials: KC
authors.lastname: Wolthers
authors.forename: Maria
authors.initials: M
authors.lastname: Prins
mesh_terms: D000328:Adult; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000453:epidemiology*; D006526:Hepatitis C / Q000150:complications / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D008297:Male; D016485:Needle Sharing; D018671:Needle-Exchange Programs; D009426:Netherlands / Q000453:epidemiology; D012307:Risk Factors; D012698:Serologic Tests; D015819:Substance Abuse, Intravenous / Q000150:complications / Q000453:epidemiology*