Hepatitis C Virus Genotype Distribution in Istanbul, Türkiye: Temporal Trends and Demographic Patterns

Hepatitis C virus (HCV) genotype distribution varies across geographic regions and populations and may change over time. This study examined the current distribution and temporal trends of HCV genotypes, and their patterns by demographic characteristics and nationality, at a tertiary care hospital in Istanbul, Türkiye. We retrospectively evaluated 188 patients who underwent HCV genotyping between June 2019 and December 2024. Genotype distribution was assessed according to age, sex, and year, while temporal trends were analyzed using the Cochran–Armitage trend test and binomial logistic regression. GT1b was the predominant subtype (54.8%), followed by GT3 (19.1%), GT1a (10.1%), and GT4 (5.9%); mixed-genotype results were detected in 5.9% of cases. Genotype distribution differed significantly by age group and sex (Monte Carlo p = 0.044 and p = 0.002, respectively), but not by year (p = 0.128). After Holm adjustment, GT1a was more frequent among males, whereas GT1b was more frequent among females. No significant linear temporal trends were observed for GT1a, GT1b, GT3, GT4, or mixed-genotype results. Genotype patterns also varied descriptively across nationality groups. These findings underscore the importance of up-to-date regional data and continued genotype surveillance for monitoring changes in HCV epidemiology.