Validation study of health administrative data algorithms to identify individuals experiencing homelessness and estimate population prevalence of homelessness in Ontario, Canada

Abstract

ObjectivesTo validate case ascertainment algorithms for identifying individuals experiencing homelessness in health administrative databases between 2007 and 2014; and to estimate homelessness prevalence trends in Ontario, Canada, between 2007 and 2016.DesignA population-based retrospective validation study.SettingOntario, Canada, from 2007 to 2014 (validation) and 2007 to 2016 (estimation).ParticipantsOur reference standard was the known housing status of a longitudinal cohort of housed (n=137 200) and homeless or vulnerably housed (n=686) individuals. Two reference standard definitions of homelessness were adopted: the housing episode and the annual housing experience (any homelessness within a calendar year).Main outcome measuresSensitivity, specificity, positive and negative predictive values and positive likelihood ratios of 30 case ascertainment algorithms for detecting homelessness using up to eight health service databases.ResultsSensitivity estimates ranged from 10.8% to 28.9% (housing episode definition) and 18.5% to 35.6% (annual housing experience definition). Specificities exceeded 99% and positive likelihood ratios were high using both definitions. The most optimal algorithm estimates that 59 974 (95% CI 55 231 to 65 208) Ontarians (0.53% of the adult population) experienced homelessness in 2016, a 67.3% increase from 2007.ConclusionsIn Ontario, case ascertainment algorithms for identifying homelessness had low sensitivity but very high specificity and positive likelihood ratio. The use of health administrative databases may offer opportunities to track individuals experiencing homelessness over time and inform efforts to improve housing and health status in this vulnerable population.

Heterogeneity in testing, diagnosis and outcome in SARS-CoV-2 infection across outbreak settings in the Greater Toronto Area, Canada: an observational study

“…67 We could not estimate testing per capita or test positivity proportion among people using shelters given low sensitivity in identifying this population in the testing data. 26 However, our data suggest that a minimum of 13.2% of people using shelters had been tested by May 20, 2020 (Appendix 3, Supplementary Figure 1C), suggesting that higher diagnoses per capita among people using shelters may be partially explained by increased testing. Work is underway to improve the sensitivity of algorithms to identify people experiencing homelessness.…”

“…Individuals with a record of emergency department visit or hospital admission in the past year and with a "homelessness" indicator at the time of the service (via linkage to health administrative data) were identified as people experiencing homelessness. 26 We estimated the population size of long-term care home residents using the total long-term care home bed capacity in the GTA, assuming complete occupancy. 8,27 Population denominators for people using shelters were sourced from public reports [28][29][30][31][32][33][34][35] (Appendix 1, available at www.cmajopen.ca/ content/8/4/E627/suppl/DC1).…”

Cardiovascular disease in homeless versus housed individuals: a systematic review of observational and interventional studies

“…8 Context-specific data and context-specific solutions are likely to be most beneficial in the homeless population, and as with other areas of healthcare, better use of routine electronic health record data is required. 25 The 'diseases of the West' and 'diseases of affluence' paradigms persisted for many decades in global health and public health respectively, leading to neglect of non-communicable diseases and their management for several generations in those settings and populations where burden and need were greatest. 26 Health service interventions for homeless people still largely focus on infectious diseases, substance abuse, mental illness and crisis management.…”

“… 8 Context-specific data and context-specific solutions are likely to be most beneficial in the homeless population, and as with other areas of healthcare, better use of routine electronic health record data is required. 25 …”

Testing, infection and complication rates of COVID-19 among people with a recent history of homelessness in Ontario, Canada: a retrospective cohort study

“…Leveraging a validated case definition for homelessness 21 and population-level health administrative databases, we aimed to describe rates of SARS-CoV-2 testing, test positivity and hospital admission, intensive care receipt and mortality related to COVID-19 among people with a recent history of homelessness and to compare these rates with those for the community-dwelling population in Ontario, Canada.…”