Date Published: October 3, 2018
Publisher: Public Library of Science
Author(s): Jorge Valencia La Rosa, Pablo Ryan, Alejandro Alvaro-Meca, Jesús Troya, Guillermo Cuevas, Jorge Gutiérrez, Santiago Moreno, Jason Blackard.
Harm reduction strategies have been shown to decrease the incidence of human immunodeficiency virus (HIV) infection in people who inject drugs (PWID), but the results have been inconsistent when it comes to prevention of hepatitis C virus (HCV) infection. We aimed to examine the rate of HCV seroconversion among people who use drugs (PWUD) followed at a mobile harm reduction unit (MHRU) to evaluate if a low-threshold methadone substitution program (LTMSP) is associated with a low HCV seroconversion rate and subsequently identify barriers for elimination.
A cohort of PWUD have been followed at a MRHU in Madrid between 2013 and 2016. Individuals who were negative for HCV antibodies at baseline and who had at least one retest for HCV antibodies were eligible. Kaplan-Meier methods were employed to estimate the global incidence density.
During the study period, 946 PWUD were screened for HCV at least once. At baseline 127 PWUD were negative for HCV antibodies and had at least one follow-up HCV antibodies test. The baseline HCV prevalence was 33%. After a median 0.89 (IQR 0.3–1.5) years of follow-up and 135 person-years of risk for HCV infection, 28 subjects seroconverted. The incidence density for HCV seroconversion for this sample was 20.7 cases (95% CI: 14.3–29.7) per 100 person-years. Injecting drugs in the last year was strongly associated to HCV seroconversion (AHR 15.5, 95%CI 4.3–55.8, p < 0.001). Methadone status was not associated to HCV seroconversion. A high incidence of HCV infection was found among PWUD at a MHRU in Madrid. In this setting opiate substitutive treatment (OST) as a LTMSP does not appear to protect against HCV seroconversion.
According to the World Health Organization (WHO), viral hepatitis was the seventh highest cause of mortality in 2015, being responsible for an estimated 1.3 million deaths per year from acute infection and hepatitis-related liver cancer and cirrhosis). Of those deaths, approximately 30% are attributable tohepatitis C virus(HCV). World Health Organization estimates that worldwide, there were about 1.75 million new HCV infections in 2015 ).
For the present observational study, we pooled data from a cohort of PWUD who actively consumed heroin and/or cocaine, either smoked or injected, and were being followed at a MHRU located in the outskirts of Madrid, Spain.Data are available from the Subdirección General de Adicciones (Madrid, Spain) Institutional Data Access for researchers who meet the criteria for confidential data.When entering the MHRU, clients sign different documents, which include informed consents for blood tests, standard follow-up at the Unit, and inclusion of information in a database for purposes of analysis. The database is anonymized with an alphanumeric code unique for each client, so that no person can be identified and linked to the registered information. In these circumstances, no additional approval from an Ethics Committee was required.
During the study period, 946 PWUD were seen at the MHRU and had performed at least an HCV antibodies test as part of the individual, initial intervention in our MHRU. HCV and HIV antibodies prevalence of the initial sample were 33.3% and 4.8%, respectively.
In this study, we found that the HCV incidence density forPWUD actively followed in a MHRU of Madrid (Spain) between January 2013 and December 2016 remains unacceptably high despite the availability of newer antivirals and the universal treatment for HCV infection in our country. Furthermore, the use of injected drugs in the last year is an independent robust predictor of HCV seroconversion, and the OST as a LTMSP was not associated with lower HCV seroconversion rates.
The incidence of HCV remains high in PWUD actively followed at a MHRU in Madrid, despite a LTMSP and other current harm reduction strategies. In particular, OST as a LTMSP was not a protective factor to HCV seroconversion. The findings of this investigation may not necessarily be generalizable to all PWUD or who live in other communities or countries with different characteristics but it points to the need of different measures to limit the continuous spread of HCV among PWUD.