New patterns emerge after a sustained increase in the incidence of hepatitis C virus infection from 2004 to 2017: a joinpoint regression analysis.

OBJECTIVES

Hepatitis C virus (HCV) infection continues to be a major public health concern in China. There is little information available in the literature about age- and sex-specific HCV incidence trends. The goal of this study was to examine recent trends in HCV incidence rates in Hunan, China, according to age and gender.

STUDY DESIGN

A descriptive study was implemented with a joinpoint analysis.

METHODS

Based on the annual reported incidence data of hepatitis C in Hunan, China, from 2004 to 2017, we performed a joinpoint regression analysis to examine trends in the annual percentage change (APC) and the average annual percentage change (AAPC) in the incidence of HCV infection throughout the study period; we stratified the analysis by gender and age. The software calculates the APC, AAPC and the 95% confidence intervals for each trend segment and tests whether the slope for each segment has a significant difference from the prior segment using a Z test.

RESULTS

From 2004 to 2017, the overall incidence rate of HCV infection rose from 0.93 per 100,000 to 20.88 per 100,000 (AAPC, 25.2%). In particular, women aged ≥65 years had the fastest increasing rate (AAPC, 29.9%). The incidence of different demographic groups showed no significant difference in increasing trends before 2013. However, new patterns emerged after 2013: the incidence of people aged 0-14 years was no longer significantly elevated; a significant yearly decline occurred in the incidence of HCV in people aged 15-29 years; the incidence of HCV in people aged ≥30 years continued to increase, with significantly slower increasing rates than before; and women aged ≥65 years showed a significantly higher yearly increase in incidence than that in men in the same age group (APC, 11.1% in women versus 5.3% in men).

CONCLUSION

The overall increasing rate of HCV infection significantly slowed after 2007 and 2013. The differences in incidence trends among demographic groups have obviously increased in the last 5 years, and the reasons underlying these different trends urgently require further study. People in older age groups, especially women aged ≥65 years, still experienced increases in incidence rates in the last 5 years. This finding indicates that programmes for the prevention and control of HCV infection in older people require continued strengthening.