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Bakr et al (Gut 2006;55:1183–7), in a large population‐based cross‐sectional survey on hepatitis C virus (HCV) infection in Egypt, found that HCV clearance rates (ie, positive HCV antibodies and negative HCV‐RNA test results) were significantly higher in women (44%) compared with men (33.7%, adjusted odds ratio (OR) 1.77).1 They conclude that these findings provide a strong evidence for a higher HCV clearance rate in women compared with men.
We have obtained different results in three published population‐based surveys (not cited by Bakr in the references) performed in Southern Italian towns.2,3,4 The overall prevalence of HCV antibody was 324/2561 (12.6%). The prevalence was slightly higher in women (13.7%) than in men (11.3%), a difference which is not statistically significant. None of the anti‐HCV‐positive patients had previously received antiviral treatment, none reported intravenous drug use, and none of them were HIV‐positive. Of those with HCV antibodies (n=324), 73.1% had chronic HCV infection (positive HCV antibody and positive HCV‐RNA test results). Nearly identical proportions of men (35/127, 27.6%) and women (52/187, 26.4%) were HCV‐RNA‐negative, indicating cleared infection.
Regardless of the difference in results, we believe that the cross‐sectional structure of all these studies (including that of Bakr) does not allow any valid conclusions in favour of or against the hypothesis of gender‐related HCV clearance. The main problem in prevalence surveys is the potential for survival bias. Bakr and coworkers are aware of this bias, as they affirm that “subjects with chronic infection will have increased mortality compared with those with cleared infection, resulting in overestimation of the population with cleared infection”. However, they failed to clarify that the survival bias could not have affected both genders similarly—that is, mortality might have been higher in women than in men with chronic HCV infection, resulting in a misleadingly higher proportion of women with presumably cleared infection.
We would like to suggest more caution before drawing any inference from prevalence surveys regarding the potential effect of gender on HCV clearance. Otherwise, conclusions may be biased.
Competing interests: None.