Prevalence of HCV Infection Among People Experiencing Homelessness in Madrid, Spain

Abstract

Importance: Hepatitis C virus (HCV) microelimination aims to detect and treat hidden infections, especially in at-risk groups, like people experiencing homelessness (PEH) with alcohol or drug use disorders. Point-of-care HCV RNA testing and peer support workers are crucial for identifying and preventing HCV infection among marginalized populations, contributing to overall elimination goals.

Objective: To assess risk factors, prevalence, and trends of active HCV infection among PEH in Madrid, Spain (2019-2023).

Design, setting, and participants: This cross-sectional study was conducted between 2019 and 2023 in PEH, defined as people who lacked a fixed, regular, and adequate night residence, screened on the street or in homeless shelters via mobile unit using rapid HCV antibody testing, followed by HCV-RNA testing in Madrid, Spain. Data were analyzed from January to June 2024.

Main outcomes and measures: Active HCV infection among PEH was the main outcome. Risk factors analyzed included being born outside of Spain, alcohol misuse, lacking financial income, benzodiazepine use, injection drug use (IDU; including nonactive IDU and active IDU within the last year), opioid substitution therapy participation, and sexual behavior patterns. Data were analyzed using logistic regression. P values were adjusted for multiple testing using the false discovery rate (q-values).

Results: A total of 4741 individuals were screened for HCV infection, of whom 2709 (mean [SD] age, 42.2 [12.7]; 1953 [72.2%] men) were PEH and included in analysis. A total of 363 PEH (13.4%) had test results positive for HCV antibodies, of whom 172 (47.4%) had test results positive for HCV-RNA, and 148 of these (91.9%) started HCV treatment. Overall, active HCV infection prevalence was 6.3%, and the main risk factors associated with active HCV infection included IDU, encompassing both nonactive IDU (adjusted odds ratio [aOR], 10.9; 95% CI, 6.1-19.4; q < .001) and active IDU in the last year (aOR, 27.0; 95% CI, 15.2-48.0; q < .001); a lack of financial income (aOR, 1.8; 95% CI, 1.1-2.9; q = .03); and alcohol misuse (aOR, 1.8; 95% CI, 1.3-2.6; q = .008). There was a significant decrease between 2019 and 2023 in active HCV infection prevalence across the entire population, from 7.2% to 3.4% (P = .04).

Conclusions and relevance: In this cross-sectional study of PEH in Madrid, IDU, lack of income, and alcohol misuse were primary risk factors associated with HCV infection. The significant decline in HCV rates observed across all risk groups during the study period suggests preventive policies were effective in reducing HCV prevalence among the homeless population.

Figure 1.. Flowchart of the Study Population and Results of Diagnostic Tests

HCV indicates hepatitis C virus; PEH, people experiencing homelessness.

Figure 2.. Risk Factors Associated With Active Hepatitis C Virus Infection Among the People Experiencing Homelessness

Association analysis was performed using logistic regression adjusted by patient characteristics and 1000 bootstrap repetitions. Multiple testing corrections through the Benjamini and Hochberg procedure (q-value) were performed to exclude spurious associations using the false discovery rate. aOR indicates adjusted odds ratio; NA, not applicable.

Figure 3.. Estimation of the Prevalence of Active Hepatitis C Virus (HCV) Infection in People Experiencing Homelessness Based on Key Risk Factors

Data were calculated using logistic regression adjusted by patient characteristics and 1000 bootstrap repetitions. IDU indicates injecting drug use.

Figure 4.. Estimation of Active Hepatitis C Virus (HCV) Infection Prevalence and Temporal Trend by Calendar Year Throughout the Study Period Among All Included Individuals Experiencing Homelessness

Data were calculated using logistic regression using 1000 bootstrap repetitions. The unit of study was the tests performed.