Theme: Epidemiology & Public Health Research Year: 2019
Background: Unstable housing is a well-established risk factor for hepatitis C (HCV) acquisition among
people who inject drugs (PWID). However, housing stability is dynamic and can fluctuate over time. Our
objective was to identify one-year housing trajectories and examine their relationship with HCV
Methods: At three-month intervals, HCV RNA-negative PWID enrolled from 2011-2016 in the HEPCO
cohort were tested for HCV and completed an interviewer-administered questionnaire. At each visit,
participants reported the accommodation they lived in the longest for each of the past three months. For
the first 12 months of follow-up (month #1 to #12), housing was categorized as either “unstable”
(hotel/motel room, rooming/boarding house, shelter, or street) or “stable”. Group-based trajectory
modeling was performed to identify trajectories of housing stability over this one-year period and to
determine the corresponding population estimates. Participants were then divided into groups based on
their most likely trajectory, and group HCV incidences were estimated using Poisson distribution (month
#1 to #63).
Results: Of the 386 included participants (mean age 40, 82% male, 52% HCV antibody-positive), 72
acquired HCV during 893 person-years of follow-up. HCV incidence was 5.2 per 100 person-years (95%CI
3.6-7.3) and median time to infection was 9.3 months (IQR 2.3-22.6). Three housing trajectories, with
population estimates, were identified over one year: sustained stability (53%), declining stability (20%),
and improving stability (27%). HCV incidence per 100 person-years was 6.0 (95%CI 4.2-8.5) for sustained
stability, 12.0 (95%CI 7.4-18.3) for declining stability, and 10.0 (95%CI 6.4-14.9) for improving stability.
Conclusion: About one in two participants followed trajectories characterized by housing instability. The
highest HCV incidence was found among PWID with declining housing stability, followed by those with
improving stability; the lowest incidence was found among those with sustained stability. PWID-targeted
interventions to improve housing conditions could play a role in preventing HCV transmission.
Disclosure of Interest Statement: This work was supported by the Canadian Institutes of Health Research
(CIHR) and the Fonds de recherche du Québec – Santé (FRQS). None of the authors has commercial
relationships that might pose a conflict of interest in connection with this work.