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Title: Joint Modeling of HCV and HIV Co-Infection among Injecting Drug Users in Italy and Spain Using Individual Cross-Sectional Data
Authors: Del Fava, Emanuele
Shkedy, Ziv
Hens, Niel
Aerts, Marc
Suligoi, Barbara
Camoni, Laura
Vallejo, Fernando
Wiessing, Lucas
Kretzschmar, Mirjam
Issue Date: 2011
Citation: Statistical Communications in Infectious Diseases, 3(1) (ART N°3), p. 1-30.
Abstract: The aim of the analysis presented in this paper is to study co-infection with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) in injecting drug users (IDUs) using a joint modeling approach that makes use of multivariate statistical methods for current status data. Using marginal models, we estimate association measures between HCV and HIV infections at individual level, i.e., odds ratios and correlation coefficients, and we regress them against some risk factors, e.g., the length of the injecting career, the age at first injection, the ever sharing of syringes, and the frequency of current injecting. In addition, we fit random-effects models that take into account the individual heterogeneity in the acquisition of the infections. For our analysis, we use cross-sectional data from two independent serological surveys, one carried out in Italy(IT) in 2005 on 856 subjects, and the other in three Spanish(ES)cities between 2001 and 2003, on 589 subjects. We found that the infections are positively associated within individualse.g., ORIT=2.56 with 95% confidence interval (CI) (1.43, 6.68) and ORES= 2.42, with 95% CI (1.41, 4.30). We found that the odds ratio and the correlation between HCV and HIV infections increase positively with the length of the injecting career. Moreover, they are found to be significantly positive in case IDUs have never shared syringes or report low injecting frequencies. The variance of the individual random effects is positivee.g., σb²=0.34 (0.14, 0.62) indicating that there is significant individual heterogeneity in the acquisition of the infections. Our results show that a significant association between HCV and HIV infections within IDUs is related to significant individual heterogeneity in the acquisition of the infections. Indeed, the association between these infections in IDUs who report ever sharing syringes is not significant, which can be explained by a higher homogeneity in their behaviors and, therefore, in their acquisition of the infections.
URI: http://hdl.handle.net/1942/12288
DOI: 10.2202/1948-4690.1010
ISSN: 1948-4690
Category: A2
Type: Journal Contribution
Appears in Collections: Research publications

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