Unstable Housing May Be a Barrier to HCV Treatment Among People Who Inject Drugs

Sarah Kimball, MPH

Credit: New York University

Unstable housing may lead to poorer treatment outcomes among people who inject drugs (PWID) with hepatitis C virus (HCV) versus those with stable housing, according to findings from a recent systematic review and meta-analysis.¹

Results specifically pointed to the potential negative impact of unstable housing on direct-acting antiviral (DAA) initiation in this patient population, although studies assessing treatment gaps pertaining to adherence, completion, success, and reinfection were limited.¹

“Prior systematic reviews have demonstrated that people who inject drugs have similar DAA treatment outcomes compared to non-PWID; however, no reviews have looked at treatment outcomes among PWID who are unstably housed compared to those who are stably housed,” Sarah Kimball, MPH, doctoral student concentrating in epidemiology at New York University School of Global Public Health, and colleagues wrote.¹ “Given the unique challenges of unstable housing, it is necessary to better understand current treatment outcomes to develop future interventions.”

According to the World Health Organization (WHO), globally, an estimated 50 million people have chronic HCV infection, with about 1 million new infections occurring per year. In 2016, the WHO outlined a plan for the elimination of viral hepatitis as a public health problem by 2030, including a 90% reduction in incidence and a 65% reduction in mortality compared with a 2015 baseline. Although DAAs are able to cure 95% of infections, access remains an issue, underscoring the importance of understanding factors that may be hindering treatment among vulnerable or underserved patient populations.^2,3

To determine the extent to which HCV DAA treatment outcomes differ between PWID with and without stable housing, investigators searched Web of Science, Medline via PubMed, Embase, CINAHL Complete, PsychInfo, and Cochrane Library for studies that collected quantitative data, included current or former PWID with chronic HCV, collected current housing information, tested outcomes in standard clinical settings, and were written in English. Studies were limited to those published from 2014 onward and that stratified HCV treatment outcomes by housing status.¹

Investigators excluded studies if they used interferon-based treatments; did not evaluate outcomes for an existing HCV treatment model; and occurred in prisons, jails, or in-patient hospital settings. Individual studies were assessed for risk of bias using the Newcastle-Ottawa Scale (NOS) and the NIH Quality Assessment Tool.¹

The primary outcomes were HCV treatment initiation, adherence, completion, success, and reinfection. For each outcome, investigators recorded the raw and adjusted effect measures, covariates controlled for, and sample size.¹

The initial search yielded 473 studies, 8 of which met inclusion criteria. All of the studies took place in urban environments except for a cross-sectional survey that was conducted in a national sample. Regarding location, 3 studies were based in the United States, 2 in Australia, 1 in Canada, 1 in Norway, and 1 in the Czech Republic. Regarding study design, 3 studies were cross-sectional, 3 were retrospective cohort studies, and 2 were prospective cohort studies.¹

Investigators noted the studies generally received quality ratings of “poor” or “fair” using the NOS and NIH assessments, pointing to a lack of clear definitions of housing status, reliance on self-report data for diagnosis of HCV and treatment outcomes, and small sample sizes.¹

A total of 4 studies measured HCV treatment initiation, the only outcome with sufficient measures for meta-analysis. Of these studies, 3 were cross-sectional studies and 1 was a retrospective cohort study, with results showing reduced odds of treatment initiation in the group with unstable housing. Investigators noted only 3 studies were significant, and of those that provided adjusted odds ratios (aOR), 2 remained significant after adjustment (aOR, 0.42; 95% CI, 0.22-0.82 and aOR, 0.39; 95% CI, 0.19-0.80).¹

Using a random-effects model, investigators found those with unstable housing had 0.40 (95% CI, 0.26-0.62) times the odds of initiating treatment compared to those with stable housing. The I2 was 0% but was not precise (95% CI, 0.0%-84.7%) and was based on a small number of studies that were from different countries, used different recruitment methods, and had different definitions of PWID and housing status.¹

Success measurements were available in 4 studies, including 2 prospective cohort studies and 2 retrospective cohort studies. However, despite similar settings, the measures had inconsistent definitions and analyses that made them incompatible for meta-analysis. Upon analysis of the individual study outcomes, investigators noted 3 of the studies found lower odds of treatment success for those with unstable housing compared to stable housing, although only 1 result was significant (OR, 0.27; 95% CI, 0.08-0.95).¹

Investigators pointed out other outcomes beyond treatment initiation were not amenable for meta-analysis due to a limited number of studies or differing outcome definitions and had “very low” certainty using the GRADE criteria. However, even treatment initiation had “low” certainty using the GRADE criteria. Due to limited measurements, investigators were unable to perform statistical tests such as funnel plots to check for reporting bias.¹

“In order to reach HCV elimination targets, we must reach highly burdened populations such as PWID experiencing unstable housing. As previous studies have found, lack of safe and secure housing may negatively impact HCV treatment outcomes, although our conclusions are limited by lack of evidence,” investigators concluded.¹

References:

1. ^{Kimball S, Reynoso M, McKnight C, et al. Hepatitis C treatment outcomes among people who inject drugs experiencing unstable versus stable housing: Systematic review and meta-analysis. Plos One. https://doi.org/10.1371/journal.pone.0302471}
2. ^{World Health Organization. Hepatitis C Virus. Newsroom. April 9, 2024. Accessed May 7, 2024. https://www.who.int/news-room/fact-sheets/detail/hepatitis-c}
3. ^{World Health Organization. WHO releases first-ever global guidance for country validation of viral hepatitis B and C elimination. June 25, 2021. Accessed May 7, 2024. https://www.who.int/news/item/25-06-2021-who-releases-first-ever-global-guidance-for-country-validation-of-viral-hepatitis-b-and-c-elimination}