Viral hepatitis and HIV risk among older vs younger people who inject drugs in Kenya

Author: Lindsey Riback, Mercy Nyakowa, Chenshu Zhang, Sarah Masyuko, Rose Wafula, Nazila Ganatra, Matthew Akiyama, Lindsey Riback

Theme: Epidemiology & Public Health Research Year: 2023

Background: Hepatitis C (HCV) risk is associated with more years injecting among people who inject drugs (PWID), but data are limited on age group differences in injection practices among PWID in resource-limited countries. We compared baseline HCV and HIV prevalence and related risk factors between younger (<30 years old) and older (≥30) Kenyan PWID.

Methods: We are recruiting 3,500 PWID from needle and syringe programs (NSP) sites in Kenya. Participants are recruited using respondent driven sampling, complete biobehavioral surveys, and receive HIV, HCV, and HBV testing. We conducted this analysis using chi-square tests for categorical variables and t-tests for continuous variables.

Results: Among the 1526 participants enrolled thus far, most are male (89.9%) and 34.4 years old (SD=±8.6) on average. One-third, 529 (34.7%) are between the ages of 18 and 29, while 997 (65.3%) ≥30 years. Older age was significantly associated with HCV (26.2% vs 10.0%, p<0.001), HBV (1.9% vs 0.4%, p=0.02) and HIV (15.4% vs 4.9%, p<0.001). The older cohort reported injecting at a later age (31.5 vs 21.9, p<0.001), and injected more times on average in the last 30 days (60.3 vs 48.2, p<0.001). Older PWID were more likely to have ever injected someone else (60.9% vs. 49.4%, p<0.001) and more likely to use injection equipment after someone at their last injection; needles (11.9% vs 6.1%, p<0.001), cotton (13.7% vs 7.6%, p<0.001) and cookers (13.7% vs 8.5%, p=0.003). Older PWID reported visiting NSPs more often on average in the last month (16.2 vs 10.7, p<0.001)

Conclusion: Higher viral hepatitis and HIV prevalence among older PWID is likely attributable to more years injecting; however, older PWID also reported higher injection frequency and equipment sharing. While these risks might be mitigated by more frequent NSP use, these findings highlight the need better understand age‐specific risk to inform tailored harm reduction interventions.

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