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

Cohort profile: the provincial opioid agonist treatment cohort in Ontario, Canada

BACKGROUND

Opioid Agonist Treatment (OAT) is the most effective intervention for opioid use disorder (OUD), but retention has decreased due to increasingly potent drugs like fentanyl. This cohort can be used retrospectively to observe trends in service utilization, healthcare integration, healthcare costs and patient outcomes. It also facilitates the design of observational studies to mimic a prospective design.

METHODS

This study used linked administrative data from ICES to create a cohort of 137,035 individuals who received at least one prescription of methadone or buprenorphine/naloxone between 2014 and 2022. Data were linked using de-identified personal health numbers. Variables included age, sex, rurality, income, homelessness, and mental health conditions. Regional differences in OAT use, retention, and mortality were analyzed.

RESULTS

Of the cohort, 56.1% began OAT after 2014. Southern Ontario participants more often started on methadone (53.2%), while Northern Ontario patients favored buprenorphine/naloxone (62.7%). Northern patients were younger, more likely to be female, live in rural areas, and face homelessness. The death rate was higher in Southern Ontario (22.1%) than in Northern Ontario (13.2%). Retention declined over time, with 73.4% of patients remaining in treatment at the study's end.

CONCLUSIONS

The findings highlight regional disparities in OAT delivery and emphasize the need for region-specific strategies, particularly in rural areas, to improve retention and reduce mortality.

Turbulence in the system: Higher rates of left-without-being-seen emergency department visits and associations with increased risks of adverse patient outcomes since 2020

Objective

To examine risks of severe adverse patient outcomes shortly after a left-without-being-seen emergency department (LWBS ED) visit since 2020.

Methods

In this retrospective study using linked administrative data, we examined temporal trends in monthly rates of ED and LWBS visits for adults in Ontario, Canada, 2014‒2023. In patient-level analyses restricted to the first eligible LWBS ED visit, we used modified Poisson regression to compare the composite outcome of 7-day all-cause mortality or hospitalization following a LWBS ED visit for April 1, 2022‒March 31, 2023 (recent period) to April 1, 2014‒March 31, 2020 (baseline period), adjusted for age, sex, and Charlson comorbidity index.

Results

Despite fewer monthly ED visits since 2020, temporal trends revealed sustained increases in monthly LWBS rates. LWBS ED visits after April 1, 2020 exceeded the baseline period's single-month LWBS maximum of 4.0% in 15 out of 36 months. The composite outcome of 7-day all-cause mortality or hospitalization was 3.4% in the recent period versus 2.9% in the baseline period (adjusted risk ratio [aRR] 1.14, 95% confidence interval [CI] 1.11‒1.18) and remained elevated at 30 days (6.2% vs. 5.8%, respectively; aRR 1.05, 95% CI 1.03‒1.07), despite similar rates of post-ED outpatient visits (7-day recent and baseline: 38.9% and 39.7%, respectively, p = 0.38; 30-day: 59.4% and 59.7%, respectively, p = 0.05).

Conclusions

The rate of short-term mortality or hospitalization after a LWBS ED visit has recently increased, despite fewer ED visits/month and similar proportion of post-ED outpatient encounters. This concerning signal should prompt interventions to address system- and population-level causes.

Disparities in healthcare costs of people experiencing homelessness in Toronto, Canada in the post COVID-19 pandemic era: a matched cohort study

BACKGROUND

Evidence is limited about healthcare cost disparities associated with homelessness, particularly in recent years after major policy and resource changes affecting people experiencing homelessness occurred after the onset of the COVID-19 pandemic. We estimated 1-year healthcare expenditures, overall and by type of service, among a representative sample of people experiencing homelessness in Toronto, Canada, in 2021 and 2022, and compared these to costs among matched housed and low-income housed individuals.

METHODS

Data from individuals experiencing homelessness participating in the Ku-gaa-gii pimitizi-win cohort study were linked with Ontario health administrative databases. Participants (n = 640) were matched 1:5 by age, sex-assigned-at-birth and index month to presumed housed individuals (n = 3,200) and to low-income presumed housed individuals (n = 3,200). Groups were followed over 1 year to ascertain healthcare expenditures, overall and by healthcare type. Generalized linear models were used to assess unadjusted and adjusted mean cost ratios between groups.

RESULTS

Average 1-year costs were $12,209 (95% CI $9,762-$14,656) among participants experiencing homelessness compared to $1,769 ($1,453-$2,085) and $1,912 ($1,510-$2,314) among housed and low-income housed individuals. Participants experiencing homelessness had nearly seven times (6.90 [95% confidence interval [CI] 5.98-7.97]) the unadjusted mean ratio (MR) of costs as compared to housed persons. After adjustment for number of comorbidities and history of healthcare for mental health and substance use disorders, participants experiencing homelessness had nearly six times (adjusted MR 5.79 [95% CI 4.13-8.12]) the expected healthcare costs of housed individuals. The two housed groups had similar costs.

CONCLUSIONS

Homelessness is associated with substantial excess healthcare costs. Programs to quickly resolve and prevent cases of homelessness are likely to better meet the health and healthcare needs of this population while being a more efficient use of public resources.

Prescription Medication Use in Pregnancy in People with Disabilities: A Population-Based Cohort Study

Background: Individuals with disabilities may require specific medications in pregnancy. The prevalence and patterns of medication use, overall and for medications with known teratogenic risks, are largely unknown. Methods: This population-based cohort study in Ontario, Canada, 2004-2021, comprised all recognized pregnancies among individuals eligible for public drug plan coverage. Included were those with a physical (n = 44,136), sensory (n = 13,633), intellectual or developmental (n = 2,446) disability, or multiple disabilities (n = 5,064), compared with those without a disability (n = 299,944). Prescription medication use in pregnancy, overall and by type, was described. Modified Poisson regression generated relative risks (aRR) for the use of medications with known teratogenic risks and use of ≥2 and ≥5 medications concurrently in pregnancy, comparing those with versus without a disability, adjusting for sociodemographic and clinical factors. Results: Medication use in pregnancy was more common in people with intellectual or developmental (82.1%), multiple (80.4%), physical (73.9%), and sensory (71.9%) disabilities, than in those with no known disability (67.4%). Compared with those without a disability (5.7%), teratogenic medication use in pregnancy was especially higher in people with multiple disabilities (14.2%; aRR 2.03, 95% confidence interval [CI]: 1.88-2.20). Furthermore, compared with people without a disability (3.2%), the use of ≥5 medications concurrently was more common in those with multiple disabilities (13.4%; aRR 2.21, 95% CI: 2.02-2.41) and an intellectual or developmental disability (9.3%; aRR 2.13, 95% CI: 1.86-2.45). Interpretation: Among people with disabilities, medication use in pregnancy is prevalent, especially for potentially teratogenic medications and polypharmacy, highlighting the need for preconception counseling/monitoring to reduce medication-related harm in pregnancy.

Identification of homelessness using health administrative data in Ontario, Canada following a national coding mandate: a validation study

OBJECTIVES

Conducting longitudinal health research about people experiencing homelessness poses unique challenges. Identification through administrative data permits large, cost-effective studies; however, case validity in Ontario is unknown after a 2018 Canada-wide policy change mandating homelessness coding in hospital databases. We validated case definitions for identifying homelessness using Ontario health administrative databases after introduction of this coding mandate.

STUDY DESIGN AND SETTING

We assessed 42 case definitions in a representative sample of people experiencing homelessness in Toronto (n = 640) from whom longitudinal housing history (ranging from 2018 to 2022) was obtained, and a randomly selected sample of presumably housed people (n = 128,000) in Toronto. We evaluated sensitivity, specificity, positive and negative predictive values, and positive likelihood ratios to select an optimal definition, and compared the resulting true positives against false positives and false negatives to identify potential causes of misclassification.

RESULTS

The optimal case definition included any homelessness indicator during a hospital-based encounter within 180 days of a period of homelessness (sensitivity = 52.9%; specificity = 99.5%). For periods of homelessness with ≥1 hospital-based healthcare encounter, the optimal case definition had greatly improved sensitivity (75.1%) while retaining excellent specificity (98.5%). Review of false positives suggested that homeless status is sometimes erroneously carried forward in healthcare databases after an individual transitioned out of homelessness.

CONCLUSION

Case definitions to identify homelessness using Ontario health administrative data exhibit moderate to good sensitivity and excellent specificity. Sensitivity has more than doubled since the implementation of a national coding mandate. Mandatory collection and reporting of homelessness information within administrative data present invaluable opportunities for advancing research on the health and healthcare needs of people experiencing homelessness.

Examining the experiences of vulnerably housed patients visiting Kingston, Ontario's emergency departments: a qualitative analysis

INTRODUCTION

Vulnerably housed individuals access emergency departments (EDs) more frequently than the general population. Despite Canada's universal public health care system, vulnerably housed persons face structural barriers to care and experience discrimination from healthcare providers. This study examines how vulnerably housed persons perceive their experience of care in the ED and Urgent Care Center (UCC) in Kingston, Ontario and aims to develop strategies for improving care for this group.

METHODS

As part of a larger mixed-methods study, narratives were collected from participants attending the ED/UCC as well as community-based partner organizations, asking them to describe an experience of a recent ED visit (< 24 months). Participants could identify as members of up to three equity-deserving groups (EDGs) (for example homeless, part of an ethnic minority, having a disability, experiencing mental health issues). Coding and thematic analysis were completed for the experiences of participants who identified as being vulnerably housed (n = 171). Results were presented back to individuals with lived experience and service providers working with clients with unstable housing.

RESULTS

Participants reported judgement related to a past or presumed history of mental health or substance use and based on physical appearance. They also often felt unheard and that they were treated as less than human by healthcare providers. Lack of effective communication about the ED process, wait times, diagnosis, and treatment led to negative care experiences. Participants reported positive experiences when their autonomy in care-decision making was respected. Furthermore, having a patient-centered approach to care and addressing specific patient needs, identities and priorities led to positive care experiences.

CONCLUSIONS

The ED care experiences of vulnerably housed persons may be improved through healthcare provider training related to trauma-informed and patient-centered care and communication strategies in the ED. Another potential strategy to improve care is to have advocates accompany vulnerably housed persons to the ED. Finally, improving access to primary care may lead to reduced ED visits and better longitudinal care for vulnerably housed persons.

Disparities in diabetes processes of care among people experiencing homelessness: An opportunity for intervention

AIMS

To compare processes of diabetes care by homeless status.

METHODS

A population-based propensity matched cohort study was conducted in Ontario, Canada. People with diabetes were identified in administrative healthcare data between April 2006 and March 2019. Those with a documented history of homelessness were matched to non-homeless controls. Data on processes of care measures included glucose monitoring tests, screening for microvascular complications, and physician follow-up. Differences in processes of care were compared by homeless status using proportions, risk ratios, and rate ratios.

RESULTS

Of the 1,076,437 people with diabetes, 5219 matched pairs were identified. Homelessness was associated with fewer tests for glycated hemoglobin (RR = 0.63; 95 %CI: 0.60-0.67), LDL cholesterol (RR = 0.80; 95 %CI: 0.78-0.82), serum creatinine (RR = 0.94; 95 %CI: 0.92-0.97), urine protein quantification (RR = 0.62; 95 %CI: 0.59-0.66), and eye examinations (RR = 0.74; 95 %CI: 0.71-0.77). People with a history of homelessness were less likely to use primary care for diabetes management (RR = 0.62; 95 %CI: 0.59-0.66) or specialist care (RR = 0.87; 95 %CI: 0.83-0.91) compared to non-homeless controls.

CONCLUSIONS

Disparities in diabetes care are evident for people with a history of homelessness and contribute to excess morbidity in this population. These data provide an impetus for investment in tailored interventions to improve healthcare equity and prevent long-term complications.

Validation of case-ascertainment algorithms using health administrative data to identify people who inject drugs in Ontario, Canada

OBJECTIVES

Health administrative data can be used to improve the health of people who inject drugs by informing public health surveillance and program planning, monitoring, and evaluation. However, methodological gaps in the use of these data persist due to challenges in accurately identifying injection drug use (IDU) at the population level. In this study, we validated case-ascertainment algorithms for identifying people who inject drugs using health administrative data in Ontario, Canada.

STUDY DESIGN AND SETTING

Data from cohorts of people with recent (past 12 months) IDU, including those participating in community-based research studies or seeking drug treatment, were linked to health administrative data in Ontario from 1992 to 2020. We assessed the validity of algorithms to identify IDU over varying look-back periods (ie, all years of data [1992 onwards] or within the past 1-5 years), including inpatient and outpatient physician billing claims for drug use, emergency department (ED) visits or hospitalizations for drug use or injection-related infections, and opioid agonist treatment (OAT).

RESULTS

Algorithms were validated using data from 15,241 people with recent IDU (918 in community cohorts and 14,323 seeking drug treatment). An algorithm consisting of ≥1 physician visit, ED visit, or hospitalization for drug use, or OAT record could effectively identify IDU history (91.6% sensitivity and 94.2% specificity) and recent IDU (using 3-year look back: 80.4% sensitivity, 99% specificity) among community cohorts. Algorithms were generally more sensitive among people who inject drugs seeking drug treatment.

CONCLUSION

Validated algorithms using health administrative data performed well in identifying people who inject drugs. Despite their high sensitivity and specificity, the positive predictive value of these algorithms will vary depending on the underlying prevalence of IDU in the population in which they are applied.

Trends in emergency department visits during cold weather seasons among patients experiencing homelessness in Ontario, Canada: a retrospective population-based cohort study

PURPOSE

Recent anecdotal reports suggest increasing numbers of people experiencing homelessness are visiting emergency departments (EDs) during cold weather seasons due to inadequate shelter availability. We examined monthly ED visits among patients experiencing homelessness to determine whether there has been a significant increase in such visits in 2022/2023 compared to prior years.

METHODS

We used linked health administrative data to identify cohorts experiencing homelessness in Ontario between October and March of the 2018/2019 to 2022/2023 years. We analyzed the monthly rate of non-urgent ED visits as a proxy measure of visits plausibly attributable to avoidance of cold exposure, examining rates among patients experiencing homelessness compared to housed patients. We excluded visits for overdose or COVID-19. We assessed level and significance of change in the 2022/2023 year as compared to previous cold weather seasons using Poisson regression.

RESULTS

We identified a total of 21,588 non-urgent ED visits across the observation period among patients experiencing homelessness in Ontario. Non-urgent ED visits increased 27% (RR 1.24 [95% CI 1.14-1.34]) in 2022/2023 compared to previous cold weather seasons. In Toronto, such visits increased by 70% (RR 1.68 [95% CI 1.57-1.80]). Among housed patients, non-urgent ED visits did not change significantly during this time period.

CONCLUSION

Rates of ED visits plausibly attributable to avoidance of cold exposure by individuals experiencing homelessness increased significantly in Ontario in 2022/2023, most notably in Toronto. This increase in ED visits may be related to inadequate access to emergency shelter beds and warming services in the community.

Trends in opioid toxicities among people with and without opioid use disorder and the impact of the COVID-19 pandemic in Ontario, Canada: A population-based analysis

BACKGROUND

Across Canada, the COVID-19 pandemic occurred amidst an ongoing drug toxicity crisis. Although elevated rates of substance-related harms have been observed nationally, it remains unknown if the pandemic state of emergency led to disproportionate increases in opioid toxicities among people with opioid use disorder (OUD) compared to those without.

METHODS

We conducted a population-based repeated cross-sectional time series analysis of fatal and non-fatal opioid toxicities between January 1, 2014, and December 31, 2021, in Ontario, Canada. We used interventional autoregressive integrated moving average models to examine the impact of the pandemic on monthly rates of opioid toxicities per 100,000 Ontario residents stratified by people with and without OUD.

RESULTS

We identified 80,296 opioid toxicities of which 53.5 % occurred among people with OUD. Among 52,052 unique individuals, 60.5 % were male and 46.2 % were 25-44 years old. Between January 2014 and December 2021, the rate of opioid toxicities increased from 2.6 to 10.5 per 100,000 (rate ratio [RR]=4.07). The magnitude of this increase differed among people with OUD (0.8 to 7.4 per 100,000; RR=9.35) and without OUD (1.8 to 3.1 per 100,000; RR=1.74). We observed a significant ramp increase in the overall rate of opioid toxicities following the declaration of the pandemic emergency in March 2020 (+0.19 per 100,000 monthly, 95 % CI: 0.029, 0.36, p = 0.021). In a stratified analysis, we found a similar ramp increase among people with OUD (+0.19 per 100,000 monthly, 95 % CI: 0.10, 0.28, p < 0.001); however, this was not observed among people without OUD (p = 0.95).

CONCLUSIONS

The rate of opioid toxicities accelerated across Ontario following the pandemic-related state of emergency, with the majority of this increase among people with OUD. The important differences observed among people with OUD compared with those without, highlights the critical need for improved access to harm reduction and treatment interventions among this population.

Prevalence of dementia among people experiencing homelessness in Ontario, Canada: a population-based comparative analysis

BACKGROUND

Cognitive decline in people experiencing homelessness is an increasingly recognised issue. We compared the prevalence of dementia among people experiencing homelessness to housed individuals in the general population and those living in low-income neighbourhoods.

METHODS

We conducted a population-based, cross-sectional, comparative analysis using linked health-care administrative data from Ontario, Canada. We included individuals aged 45 years or older on Jan 1, 2019, who visited hospital-based ambulatory care (eg, emergency department), were hospitalised, or visited a community health centre in 2019; and identified people experiencing homelessness if they had one or more health-care records with an indication of homelessness or unstable housing. Prevalence of dementia was ascertained as of Dec 31, 2019, using a validated case definition for Alzheimer's disease and related dementia that was modified to include diagnoses made at a community health centre. Poisson models were used to generate estimates of prevalence. Estimates were compared with Ontarians that accessed any of the same health-care services over the same time, overall (general population group), and among those who were in the lowest quintile of area-based neighbourhood income (low-income group).

FINDINGS

12 863 people experiencing homelessness, 475 544 people in the low-income comparator group, and 2 273 068 people in the general population comparator group were included in the study. Dementia prevalence was 68·7 per 1000 population among people experiencing homelessness, 62·6 per 1000 population in the low-income group, and 51·0 per 1000 population in the general population group. Descriptively, prevalence ratios between people experiencing homelessness and the comparator groups were highest within the ages of 55-64 years and 65-74 years in both sexes, ranging from 2·98 to 5·00. After adjusting for age, sex, geographical location of residence (urban vs rural), and health conditions associated with dementia, the prevalence ratio of dementia among people experiencing homelessness was 1·71 (95% CI 1·60-1·82) compared with the low-income group and 1·90 (1·79-2·03) compared with the general population group.

INTERPRETATION

People experiencing homelessness experience a high burden of dementia compared with housed populations in Ontario. Findings suggest that people experiencing homelessness might experience dementia at younger ages and could benefit from the development of proactive screening and housing interventions.

FUNDING

The Public Health Agency of Canada.

Microsimulation Models on Mental Health: A Critical Review of the Literature

OBJECTIVES

To retrieve and synthesize the literature on existing mental health-specific microsimulation models or generic microsimulation models used to examine mental health, and to critically appraise them.

METHODS

All studies on microsimulation and mental health published in English in MEDLINE, Embase, PsycINFO, and EconLit between January 1, 2010, and September 30, 2022, were considered. Snowballing, Google searches, and searches on specific journal websites were also undertaken. Data extraction was done on all studies retrieved and the reporting quality of each model was assessed using the Quality Assessment Reporting for Microsimulation Models checklist, a checklist developed by the research team. A narrative synthesis approach was used to synthesize the evidence.

RESULTS

Among 227 potential hits, 19 studies were found to be relevant. Some studies covered existing economic-demographic models, which included a component on mental health and were used to answer mental-health-related research questions. Other studies were focused solely on mental health and included models that were developed to examine the impact of specific policies or interventions on specific mental disorders or both. Most models examined were of medium quality. The main limitations included the use of model inputs based on self-reported and/or cross-sectional data, small and/or nonrepresentative samples and simplifying assumptions, and lack of model validation.

CONCLUSIONS

This review found few high-quality microsimulation models on mental health. Microsimulation models developed specifically to examine mental health are important to guide healthcare delivery and service planning. Future research should focus on developing high-quality mental health-specific microsimulation models with wide applicability and multiple functionalities.

Opioid-related overdose deaths among people experiencing homelessness, 2017 to 2021: A population-based analysis using coroner and health administrative data from Ontario, Canada

AIMS

To measure the change in proportion of opioid-related overdose deaths attributed to people experiencing homelessness and to compare the opioid-related fatalities between individuals experiencing homelessness and not experiencing homelessness at time of death.

DESIGN, SETTING AND PARTICIPANTS

Population-based, time-trend analysis using coroner and health administrative databases from Ontario, Canada from 1 July 2017 and 30 June 2021.

MEASUREMENTS

Quarterly proportion of opioid-related overdose deaths attributed to people experiencing homelessness. We also obtained socio-demographic and health characteristics of decedents, health-care encounters preceding death, substances directly contributing to death and circumstances surrounding deaths.

FINDINGS

A total of 6644 individuals (median age = 40 years, interquartile range = 31-51; 74.1% male) experienced an accidental opioid-related overdose death, among whom 884 (13.3%) were identified as experiencing homelessness at the time of death. The quarterly proportion of opioid-related overdose deaths attributed to people experiencing homelessness increased from 7.2% (26/359) in July-September 2017 to 16.8% (97/578) by April-June 2021 (trend test P < 0.01). Compared with housed decedents, those experiencing homelessness were younger (61.3 versus 53.1% aged 25-44), had higher prevalence of mental health or substance use disorders (77.1 versus 67.1%) and more often visited hospitals (32.1 versus 24.5%) and emergency departments (82.6 versus 68.5%) in the year prior to death. Fentanyl and its analogues more often directly contributed to death among people experiencing homelessness (94.0 versus 81.4%), as did stimulants (67.4 versus 51.6%); in contrast, methadone was less often present (7.8 versus 12.4%). Individuals experiencing homelessness were more often in the presence of a bystander during the acute toxicity event that led to death (55.8 versus 49.7%); and where another individual was present, more often had a resuscitation attempted (61.7 versus 55.1%) or naloxone administered (41.2 versus 28.9%).

CONCLUSIONS

People experiencing homelessness account for an increasing proportion of fatal opioid-related overdoses in Ontario, Canada, reaching nearly one in six such deaths in 2021.

Critical illness among patients experiencing homelessness: a retrospective cohort study

PURPOSE

To understand the epidemiology and healthcare use of critically ill patients experiencing homelessness compared to critically ill patients with stable housing.

METHODS

This retrospective population-based cohort study included adults admitted to any ICU in Alberta, Canada, for a 3-year period. Administrative and clinical data from the hospital, ICU and emergency department were used to examine healthcare resource use (processes of care, ICU and hospital length of stay, hospital readmission and emergency room visits). Regression was used to quantify differences in healthcare use by housing status.

RESULTS

2.3% (n = 1086) of patients admitted to the ICU were experiencing homelessness; these patients were younger, more commonly admitted for medical reasons and had fewer comorbidities compared to those with stable housing. Processes of care in the ICU were mostly similar, but healthcare use after ICU was different; patients experiencing homelessness who survived their index hospitalization were more than twice as likely to have a visit to the emergency department (OR = 2.3 times, 95% CI 2.0-2.6, < 0.001) or be readmitted to hospital (OR = 2.1, 95% CI 1.8-2.4, p < 0.001) within 30 days, and stayed 10.1 days longer in hospital (95% CI 8.6-11.6, p < 0.001), compared with those who have stable housing.

CONCLUSIONS

Patients experiencing homelessness have different characteristics at ICU admission and have similar processes of care in ICU, but their subsequent use of healthcare resources was higher than patients with stable housing. These findings can inform strategies to prepare patients experiencing homelessness for discharge from the ICU to reduce healthcare resource use after critical illness.

SARS-CoV-2 vaccination prevalence by mental health diagnosis: a population-based cross-sectional study in Ontario, Canada

BACKGROUND

Since the onset of the COVID-19 pandemic, there has been concern about the impact of SARS-CoV-2 infection among individuals with mental illnesses. We analyzed the SARS-CoV-2 vaccination status of Ontarians with and without a history of mental illness.

METHODS

We conducted a population-based cross-sectional study of all community-dwelling Ontario residents aged 19 years and older as of Sept. 17, 2021. We used health administrative data to categorize Ontario residents with a mental disorder (anxiety, mood, substance use, psychotic or other disorder) within the previous 5 years. Vaccine receipt as of Sept. 17, 2021, was compared between individuals with and without a history of mental illness.

RESULTS

Our sample included 11 900 868 adult Ontario residents. The proportion of individuals not fully vaccinated (2 doses) was higher among those with substance use disorders (37.7%) or psychotic disorders (32.6%) than among those with no mental disorders (22.9%), whereas there were similar proportions among those with anxiety disorders (23.5%), mood disorders (21.5%) and other disorders (22.1%). After adjustment for age, sex, neighbourhood income and homelessness, individuals with psychotic disorders (adjusted prevalence ratio 1.19, 95% confidence interval [CI] 1.18-1.20) and substance use disorders (adjusted prevalence ratio 1.35, 95% CI 1.34-1.35) were more likely to be partially vaccinated or unvaccinated relative to individuals with no mental disorders.

INTERPRETATION

Our study found that psychotic disorders and substance use disorders were associated with an increased prevalence of being less than fully vaccinated. Efforts to ensure such individuals have access to vaccinations, while challenging, are critical to ensuring the ongoing risks of death and other adverse consequences of SARS-CoV-2 infection are mitigated in this high-risk population.

Trends in hospital coding for people experiencing homelessness in Canada, 2015-2020: a descriptive study

BACKGROUND

In 2018, hospitals were mandated to record homelessness using International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Canada (ICD-10-CA code Z59.0). We sought to answer whether the coding mandate affected the volume of patients identified as experiencing homelessness in acute inpatient hospitalizations and if there was any geographic variation.

METHODS

We conducted a serial cross-sectional study describing 6 fiscal years (2015/16 to 2020/21) of hospital administrative data from the Hospital Morbidity Database. We reported frequencies and percentages of hospitalizations with a Z59.0 diagnostic code and disaggregated by several types of Canadian geographies. Controlling for fiscal quarter (coded Q1 to Q4) and province or territory, adjusted logistic regression models quantified the odds of Z59.0 being coded during hospital stays.

RESULTS

The frequency and percentage of people experiencing homelessness in hospitalization records across Canada increased from 6934 (0.12%) in 2015/16 to 21 529 (0.41%) in 2020/21. Trends varied by province and territory. Recording of the Z59.0 code increased following the mandate (adjusted odds ratio 2.29, 95% confidence interval 2.25-2.32), relative to the pre-mandate period.

INTERPRETATION

The 2018 coding mandate coincided with an increase in the use of the Z59.0 code to document homelessness in health care administrative data; however, trends varied by jurisdiction. The ICD-10-CA code Z59.0 presents a promising opportunity for standardized and routinely collected data to identify people experiencing homelessness in hospital administrative data.

Assessing the coverage and timeliness of coronavirus vaccination among people experiencing homelessness in Wales, UK: a population-level data-linkage study

BACKGROUND

People experiencing homelessness have elevated morbidity, increasing their risk of COVID-19 related complications and mortality. Achieving high vaccination coverage in a timely manner among homeless populations was therefore important during the mass vaccination programme in Wales to limit adverse outcomes. However, no systematic monitoring of vaccinations among people experiencing homelessness in Wales has been undertaken.

METHODS

Retrospective cohort analysis was conducted using de-identified administrative data. Study cohort members were adults (≥ 18 years old) living in Wales on the 2 December 2020 and who had recently experienced homelessness, defined as experiencing homelessness between 1 July 2020 and 2 December 2020. The outcome of interest was first coronavirus vaccine dose. Follow-up started on 2 December 2020, and ended if the participant died, had a break in address history > 30 days, reached the end of follow up (30 November 2021), or had the outcome of interest. Median-time-to-vaccination was used as a crude measure of 'timeliness' of vaccine uptake. To account for competing risk of death prior to vaccination, vaccine coverage was described using cumulative incidence at 350-days, and at 50-day increments over follow-up (2 December 2020 to 17 November 2021). As a benchmark, all time-to-event measures were generated for the adult population in Wales with similar baseline individual and residential characteristics as the study cohort.

RESULTS

1,595 people with recent experiences of homelessness were identified and included in analysis. The study cohort were disproportionately male (68.8%) and concentrated in the most deprived areas in Wales. Median time-to-vaccination for the study cohort was 196 days (95% CI.: 184-209 days), compared to 141 days (95% CI.: 141-141 days) among the matched adult population in Wales. Cumulative incidence of vaccination after 350-days of follow-up was 60.4% (95% CI.: 57.8-62.8%) among the study cohort, compared to 81.4% (95% CI.: 81.3-81.5%) among the matched adult population. Visual analysis of cumulative incidence over time suggests that vaccine inequality, i.e., difference between study cohort and matched adult population, peaked after 200-days of follow-up, and declined slightly until last follow-up at 350-days.

CONCLUSIONS

Despite being prioritised for vaccination, people experiencing homelessness in Wales appear to have been under-engaged, leading to lower vaccination coverage and greater time unvaccinated, potentially increasing their risk of COVID-19 complications and mortality.

The Association of Homelessness With Rates of Diabetes Complications: A Population-Based Cohort Study

OBJECTIVE

To estimate the rates of diabetes complications and revascularization procedures among people with diabetes who have experienced homelessness compared with a matched cohort of nonhomeless control subjects.

RESEARCH DESIGN AND METHODS

A propensity-matched cohort study was conducted using administrative health data from Ontario, Canada. Inclusion criteria included a diagnosis of diabetes and at least one hospital encounter between April 2006 and March 2019. Homeless status was identified using a validated administrative data algorithm. Eligible people with a history of homelessness were matched to nonhomeless control subjects with similar sociodemographic and clinical characteristics. Rate ratios (RRs) for macrovascular complications, revascularization procedures, acute glycemic emergencies, skin/soft tissue infections, and amputation were calculated using generalized linear models with negative binomial distribution and robust SEs.

RESULTS

Of 1,076,437 people who were eligible for inclusion in the study, 6,944 were identified as homeless. A suitable nonhomeless match was found for 5,219 individuals. The rate of macrovascular complications was higher for people with a history of homelessness compared with nonhomeless control subjects (RR 1.85, 95% CI 1.64-2.07), as were rates of hospitalization for glycemia (RR 5.64, 95% CI 4.07-7.81) and skin/soft tissue infections (RR 3.78, 95% CI 3.31-4.32). By contrast, the rates of coronary revascularization procedures were lower for people with a history of homelessness (RR 0.76, 95% CI 0.62-0.94).

CONCLUSIONS

These findings contribute to our understanding of the impact of homelessness on long-term diabetes outcomes. The higher rates of complications among people with a history of homelessness present an opportunity for tailored interventions to mitigate these disparities.

Cold-related injuries among patients experiencing homelessness in Toronto: a descriptive analysis of emergency department visits

PURPOSE

Homelessness increases the risk of cold-related injuries. We examined emergency department visits for cold-related injuries in Toronto over a 4-year period, comparing visits for patients identified as homeless to visits for patients not identified as homeless.

METHODS

This descriptive analysis of visits to emergency departments in Toronto between July 2018 and June 2022 used linked health administrative data. We measured emergency department visits with cold-related injury diagnoses among patients experiencing homelessness and those not identified as homeless. Rates were expressed as a number of visits for cold-related injury per 100,000 visits overall. Rate ratios were used to compare rates between homeless vs. not homeless groups.

RESULTS

We identified 333 visits for cold-related injuries among patients experiencing homelessness and 1126 visits among non-homeless patients. In each of the 4 years of observation, rate ratios ranged between 13.6 and 17.6 for cold-related injuries overall, 13.7 and 17.8 for hypothermia, and 10.3 and 18.3 for frostbite. Rates per 100,000 visits in the fourth year (July 2021 to June 2022) were significantly higher than in the pre-pandemic period. Male patients had higher rates, regardless of homelessness status; female patients experiencing homelessness had higher rate ratios than male patients experiencing homelessness.

CONCLUSION

Patients experiencing homelessness visiting the emergency department are much more likely to be seen for cold-related injuries than non-homeless patients. Additional efforts are needed to prevent cold-related exposure and consequent injury among people experiencing homelessness.

Predictors and Consequences of Homelessness: Protocol for a Cohort Study Design Using Linked Routine Data

BACKGROUND

Homelessness is a global burden, estimated to impact more than 100 million people worldwide. Individuals and families experiencing homelessness are more likely to have poorer physical and mental health than the general population. Administrative data is being increasingly used in homelessness research.

OBJECTIVE

The objective of this study is to combine administrative health care data and social housing data to better understand the consequences and predictors associated with being homeless.

METHODS

We will be linking health and social care administrative databases from Northern Ireland, United Kingdom. We will conduct descriptive analyses to examine trends in homelessness and investigate risk factors for key outcomes.

RESULTS

The results of our analyses will be shared with stakeholders, reported at conferences and in academic journals, and summarized in policy briefing notes for policymakers.

CONCLUSIONS

This study will aim to identify predictors and consequences of homelessness in Northern Ireland using linked housing, health, and social care data. The findings of this study will examine trends and outcomes in this vulnerable population using routinely collected health and social care administrative data.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/42404.

Co-occurring homelessness, justice involvement, opioid dependence and psychosis: a cross-sectoral data linkage study

BACKGROUND

Administrative data offer unique opportunities for researching experiences which pose barriers to participation in primary research and household surveys. Experiencing multiple social disadvantages is associated with very poor health outcomes, but little is known about how often this occurs and what combinations are most common. We linked administrative data across public services to create a novel population cohort containing information on experiences of homelessness, justice involvement, opioid dependence and psychosis.

METHODS

We securely linked administrative data from (i) a population register derived from general practitioner registrations; (ii) local authority homelessness applications; (iii) prison records; (iv) criminal justice social work reports; (v) community dispensing for opioid substitution therapy; and (vi) a psychosis clinical register, for people aged ≥18 years resident in Glasgow, Scotland between 01 April 2010 and 31 March 2014. We estimated period prevalence and compared demographic characteristics for different combinations.

RESULTS

Of 536 653 individuals in the cohort, 28 112 (5.2%) had at least one of the experiences of interest during the study period and 5178 (1.0%) had more than one. Prevalence of individual experiences varied from 2.4% (homelessness) to 0.7% (psychosis). The proportion of people with multiple co-occurring experiences was highest for imprisonment (50%) and lowest for psychosis (14%). Most combinations showed a predominance of men living in the most deprived areas of Scotland.

CONCLUSIONS

Cross-sectoral record linkage to study multiple forms of social disadvantage showed that co-occurrence of these experiences was relatively common. Following this demonstration of feasibility, these methods offer opportunities for evaluating the health impacts of policy and service change.

Factors associated with high health care spending among patients with schizophrenia

INTRODUCTION

Understanding the reasons for the wide variation in health care spending among patients with schizophrenia may benefit the development of interventions aimed at improving patient outcomes and health care spending efficiency. The aim of our study was to determine factors associated with high health care spending in the patient population.

METHODS

A serial cross-sectional study used the administrative health records of residents of Alberta, Canada between 1 January 2008 and 31 December 2017 and provincial costing methodologies to calculate total health care spending and sector-specific costs. Factors that modified the odds of being a high cost (i.e. 95th percentile or higher) patient with schizophrenia were estimated using generalized estimating equations.

RESULTS

This study captured 242 818 person-years of observations among 38 177 unique patients with schizophrenia. Increased odds of being a high-cost patient were associated with younger age (18-29 years), male sex, unstable housing status and requiring care from multiple medical specialties. The strongest estimated associations between high cost status and comorbidity were for metastatic cancer (OR = 2.26) and cirrhosis (OR = 2.07). In contrast, polypharmacy was associated with a decreased odds of being high cost compared with untreated patients.

CONCLUSION

Factors associated with being a high-cost patient are the result of complex interactions between individual, structural and treatment-related factors. Efforts to improve patient outcomes and address rising health care costs must consider the value of allocating resources towards early detection and support of patients with schizophrenia along with the prevention/management of comorbidity.

Impact of Ontario's Harmonized Heat Warning and Information System on emergency department visits for heat-related illness in Ontario, Canada: a population-based time series analysis

INTERVENTION

Ontario's Harmonized Heat Warning and Information System (HWIS) brings harmonized, regional heat warnings and standard heat-health messaging to provincial public health units prior to periods of extreme heat.

RESEARCH QUESTION

Was implementation of the harmonized HWIS in May 2016 associated with a reduction in emergency department (ED) visits for heat-related illness in urban locations across Ontario, Canada?

METHODS

We conducted a population-based interrupted time series analysis from April 30 to September 30, 2012-2018, using administrative health and outdoor temperature data. We used autoregressive integrated moving average models to examine whether ED rates changed following implementation of the harmonized HWIS, adjusted for maximum daily temperature. We also examined whether effects differed in heat-vulnerable groups (≥65 years or <18 years, those with comorbidities, those with a recent history of homelessness), and by heat warning region.

RESULTS

Over the study period, heat alerts became more frequent in urban areas (6 events triggered between 2013 and 2015 and 14 events between 2016 and 2018 in Toronto, for example). The mean rate of ED visits was 47.5 per 100,000 Ontarians (range 39.7-60.1) per 2-week study interval, with peaks from June to July each year. ED rates were particularly high in those with a recent history of homelessness (mean rate 337.0 per 100,000). Although rates appeared to decline following implementation of HWIS in some subpopulations, the change was not statistically significant at a population level (rate 0.04, 95% CI: -0.03 to 0.1, p=0.278).

CONCLUSION

In urban areas across Ontario, ED encounters for heat-related illness may have declined in some subpopulations following HWIS, but the change was not statistically significant. Efforts to continually improve HWIS processes are important given our changing Canadian climate.

"Bring the Hoses to Where the Fire Is!": Differential Impacts of Marginalization and Socioeconomic Status on COVID-19 Case Counts and Healthcare Costs

OBJECTIVES

Local health leaders and the Director General of the World Health Organization alike have observed that COVID-19 "does not discriminate." Nevertheless, the disproportionate representation of people of low socioeconomic status among those infected resembles discrimination. This population-based retrospective cohort study examined COVID-19 case counts and publicly funded healthcare costs in Ontario, Canada, with a focus on marginalization.

METHODS

Individuals with their first positive severe acute respiratory syndrome coronavirus 2 test from January 1, 2020 to June 30, 2020, were linked to administrative databases and matched to negative/untested controls. Mean net (COVID-19-attributable) costs were estimated for 30 days before and after diagnosis, and differences among strata of age, sex, comorbidity, and measures of marginalization were assessed using analysis of variance tests.

RESULTS

We included 28 893 COVID-19 cases (mean age 54 years, 56% female). Most cases remained in the community (20 545, 71.1%) or in long-term care facilities (4478, 15.5%), whereas 944 (3.3%) and 2926 (10.1%) were hospitalized, with and without intensive care unit, respectively. Case counts were skewed across marginalization strata with 2 to 7 times more cases in neighborhoods with low income, high material deprivation, and highest ethnic concentration. Mean net costs after diagnosis were higher for males ($4752 vs $2520 for females) and for cases with higher comorbidity ($1394-$7751) (both P < .001) but were similar across levels of most marginalization dimensions (range $3232-$3737, all P ≥ .19).

CONCLUSIONS

This study suggests that allocating resources unequally to marginalized individuals may improve equality in outcomes. It highlights the importance of reducing risk of COVID-19 infection among marginalized individuals to reduce overall costs and increase system capacity.

Drug Overdoses During the COVID-19 Pandemic Among Recently Homeless Individuals

AIMS

To examine how weekly rates of emergency department (ED) visits for drug overdoses changed among individuals with a recent history of homelessness (IRHH) and their housed counterparts during the pre-pandemic, peak, and re-opening periods of the first wave of the COVID-19 pandemic, using corresponding weeks in 2019 as a historical control.

DESIGN

Population-based retrospective cohort study conducted between September 30, 2018 and September 26, 2020.

SETTING

Ontario, Canada.

PARTICIPANTS

A total of 38 617 IRHH, 15 022 369 housed individuals, and 186 858 low-income housed individuals matched on age, sex, rurality, and comorbidity burden.

MEASUREMENTS

ED visits for drug overdoses of accidental and undetermined intent.

FINDINGS

Average rates of ED visits for drug overdoses between January and September 2020 were higher among IRHH compared with housed individuals (rate ratio [RR], 148.0; 95% CI, 142.7-153.5) and matched housed individuals (RR, 22.3; 95% CI, 20.7-24.0). ED visits for drug overdoses decreased across all groups by ~20% during the peak period (March 17 to June 16, 2020) compared with corresponding weeks in 2019. During the re-opening period (June 17 to September 26, 2020), rates of ED visits for drug overdoses were significantly higher among IRHH (RR, 1.56; 95% CI, 1.44-1.69), matched housed individuals (RR, 1.25; 95% CI, 1.08-1.46), and housed individuals relative to equivalent weeks in 2019 (RR, 1.07; 95% CI, 1.02-1.11). The relative increase in drug overdose ED visits among IRHH was larger compared with both matched housed individuals (P = 0.01 for interaction between group and year) and housed individuals (P < 0.001) during this period.

CONCLUSIONS

Recently homeless individuals in Ontario, Canada experienced disproportionate increases in ED visits for drug overdoses during the re-opening period of the COVID-19 pandemic compared with housed people.

Hospitalizations During the COVID-19 Pandemic Among Recently Homeless Individuals: a Retrospective Population-Based Matched Cohort Study

BACKGROUND

Hospitalizations fell precipitously among the general population during the COVID-19 pandemic. It remains unclear whether individuals experiencing homelessness experienced similar reductions.

OBJECTIVE

To examine how overall and cause-specific hospitalizations changed among individuals with a recent history of homelessness (IRHH) and their housed counterparts during the first wave of the COVID-19 pandemic, using corresponding weeks in 2019 as a historical control.

DESIGN

Population-based cohort study conducted in Ontario, Canada, between September 30, 2018, and September 26, 2020.

PARTICIPANTS

In total, 38,617 IRHH, 15,022,368 housed individuals, and 186,858 low-income housed individuals matched on age, sex, rurality, and comorbidity burden.

MAIN MEASURES

Primary outcomes included medical-surgical, non-elective (overall and cause-specific), elective surgical, and psychiatric hospital admissions.

KEY RESULTS

Average rates of medical-surgical (rate ratio: 3.8, 95% CI: 3.7-3.8), non-elective (10.3, 95% CI: 10.1-10.4), and psychiatric admissions (128.1, 95% CI: 126.1-130.1) between January and September 2020 were substantially higher among IRHH compared to housed individuals. During the peak period (March 17 to June 16, 2020), rates of medical-surgical (0.47, 95% CI: 0.47-0.47), non-elective (0.80, 95% CI: 0.79-0.80), and psychiatric admissions (0.86, 95% CI: 0.84-0.88) were significantly lower among housed individuals relative to equivalent weeks in 2019. No significant changes were observed among IRHH. During the re-opening period (June 17-September 26, 2020), rates of non-elective hospitalizations for liver disease (1.41, 95% CI: 1.23-1.69), kidney disease (1.29, 95% CI: 1.14-1.47), and trauma (1.19, 95% CI: 1.07-1.32) increased substantially among IRHH but not housed individuals. Distinct hospitalization patterns were observed among IRHH even in comparison with more medically and socially vulnerable matched housed individuals.

CONCLUSIONS

Persistence in overall hospital admissions and increases in non-elective hospitalizations for liver disease, kidney disease, and trauma indicate that the COVID-19 pandemic presented unique challenges for recently homeless individuals. Health systems must better address the needs of this population during public health crises.

Categorization of Opioid Use Among Pregnant People and Association With Overdose or Death

Importance

Early identification of people who use opioids in pregnancy may improve health outcomes for pregnant people and infants. However, characterization of diverse circumstances surrounding type of opioid use and indications for opioid use are lacking.

Objective

To develop clinically distinct groups of people who use opioids in pregnancy and to evaluate their association with drug overdose or death up to 1 year post partum.

Design, Setting, and Participants

This is a population-based, repeated cross-sectional study conducted in Ontario, Canada, with participants who used opioids in pregnancy who had a live birth or stillbirth between January 1, 2014, and December 31, 2019, identified in health administrative databases. Data were analyzed from August 2020 to January 2021.

Exposures

Prenatal opioid use.

Main Outcomes and Measures

Latent class analysis (LCA), based on prenatal opioid use and 19 socioeconomic and medical characteristics, first identified clinically distinct groups of opioid users. Then, within the optimally derived LCA-derived group, adjusted relative risks (aRRs) were generated for the outcome of drug overdose or all-cause death within 1 year post partum, adjusting for birthing parent age and year of delivery.

Results

The analysis included 31 241 people with prenatal opioid use (mean [SD] age, 30.0 [5.6] years; 86.1% [26 908 individuals] Canadian-born; 30.6% [9574 individuals] lived in low-income neighborhoods). LCA generated a 5-group model that optimally distinguished opioid users in pregnancy as follows: short-term analgesia with low comorbidity (group 1), analgesia in young people (group 2), medication for opioid use disorder or unregulated opioid use (group 3), pain management with comorbidity (group 4), and mixed opioid use plus high social and medical needs (group 5). The overall risk of postpartum drug overdose or death was 1.5%. Using the 5-group model, compared with people in group 1, the aRR of overdose or death was highest among those in group 5 (aRR, 14.0; 95% CI, 10.1-19.5), followed by group 3 (aRR, 4.6; 95% CI, 3.3-6.5), group 2 (aRR, 3.3; 95% CI, 2.2-4.7), and group 4 (aRR, 3.2; 95% CI, 2.3-4.4).

Conclusions and Relevance

In this cross-sectional study, distinct groups of people with opioid use in pregnancy were associated with increasing degrees of risk of postpartum drug overdose or death. Group characteristics can be used to identify people with high risk and inform harm reduction, home visiting programs, and other interventions.

COVID-19 vaccine coverage and factors associated with vaccine uptake among 23 247 adults with a recent history of homelessness in Ontario, Canada: a population-based cohort study

BACKGROUND

People experiencing homelessness face a high risk of SARS-CoV-2 infection and transmission, as well as health complications and death due to COVID-19. Despite being prioritised for receiving the COVID-19 vaccine in many regions, little data are available on vaccine uptake in this vulnerable population. Using population-based health-care administrative data from Ontario, Canada-a region with a universal, publicly funded health system-we aimed to describe COVID-19 vaccine coverage (ie, the estimated percentage of people who have received a vaccine) and determinants of vaccine receipt among individuals with a recent history of homelessness.

METHODS

We conducted a retrospective, population-based cohort study of adults (aged ≥18 years) with a recent experience of homelessness, inadequate housing, or shelter use as recorded in routinely collected health-care databases between June 14, 2020, and June 14, 2021 (a period within 6 months of Dec 14, 2020, when COVID-19 vaccine administration was initiated in Ontario). Participants were followed up from Dec 14, 2020, to Sept 30, 2021, for the receipt of one or two doses of a COVID-19 vaccine using the province's real-time centralised vaccine information system. We described COVID-19 vaccine coverage overall and within predefined subgroups. Using modified Poisson regression, we further identified sociodemographic factors, health-care usage, and clinical factors associated with receipt of at least one dose of a COVID-19 vaccine.

FINDINGS

23 247 individuals with a recent history of homelessness were included in this study. Participants were predominantly male (14 752 [63·5%] of 23 247); nearly half were younger than 40 years (11 521 [49·6%]) and lived in large metropolitan regions (12 123 [52·2%]); and the majority (18 226 [78·4%]) visited a general practitioner for an in-person consultation during the observation period. By Sept 30, 2021, 14 271 (61·4%; 95% CI 60·8-62·0) individuals with a recent history of homelessness had received at least one dose of a COVID-19 vaccine and 11 082 (47·7%; 47·0-48·3) had received two doses; in comparison, over the same period, 86·6% of adults in the total Ontario population had received a first dose and 81·6% had received a second dose. In multivariable analysis, factors positively associated with COVID-19 uptake were one or more outpatient visits to a general practitioner (adjusted risk ratio [aRR] 1·37 [95% CI 1·31-1·42]), older age (50-59 years vs 18-29 years: 1·18 [1·14-1·22], ≥60 years vs 18-29 years: 1·27 [1·22-1·31]), receipt of an influenza vaccine in either of the two previous influenza seasons (1·25 [1·23-1·28]), being identified as homeless via a visit to a community health centre versus exclusively a hospital-based encounter (1·13 [1·10-1·15]), receipt of one or more SARS-CoV-2 tests between March 1, 2020, and Sept 30, 2021 (1·23 [1·20-1·26]), and the presence of chronic health conditions (one condition: 1·05 [1·03-1·08]; two or more conditions: 1·11 [1·08-1·14]). By contrast, living in a smaller metropolitan region (aRR 0·92 [95% CI 0·90-0·94]) or rural location (0·93 [0·90-0·97]) versus large metropolitan regions were associated with lower uptake.

INTERPRETATION

In Ontario, COVID-19 vaccine coverage among adults with a recent history of homelessness has lagged and, as of Sept 30, 2021, was 25 percentage points lower than that of the general adult population in Ontario for a first dose and 34 percentage points lower for a second dose. With high usage of outpatient health services among individuals with a recent history of homelessness, better utilisation of outpatient primary care structures might offer an opportunity to increase vaccine coverage in this population. Our findings underscore the importance of leveraging existing health and service organisations that are accessed and trusted by people who experience homelessness for targeted vaccine delivery.

FUNDING

The Public Health Agency of Canada.

TRANSLATION

For the French translation of the abstract see Supplementary Materials section.

Identifying subgroups of adult high-cost health care users: a retrospective analysis

BACKGROUND

Few studies have categorized high-cost patients (defined by accumulated health care spending above a predetermined percentile) into distinctive groups for which potentially actionable interventions may improve outcomes and reduce costs. We sought to identify homogeneous groups within the persistently high-cost population to develop a taxonomy of subgroups that may be targetable with specific interventions.

METHODS

We conducted a retrospective analysis in which we identified adults (≥ 18 yr) who lived in Alberta between April 2014 and March 2019. We defined "persistently high-cost users" as those in the top 1% of health care spending across 4 data sources (the Discharge Abstract Database for inpatient encounters; Practitioner Claims for outpatient primary care and specialist encounters; the Ambulatory Care Classification System for emergency department encounters; and the Pharmaceutical Information Network for medication use) in at least 2 consecutive fiscal years. We used latent class analysis and expert clinical opinion in tandem to separate the persistently high-cost population into subgroups that may be targeted by specific interventions based on their distinctive clinical profiles and the drivers of their health system use and costs.

RESULTS

Of the 3 919 388 adults who lived in Alberta for at least 2 consecutive fiscal years during the study period, 21 115 (0.5%) were persistently high-cost users. We identified 9 subgroups in this population: people with cardiovascular disease (n = 4537; 21.5%); people receiving rehabilitation after surgery or recovering from complications of surgery (n = 3380; 16.0%); people with severe mental health conditions (n = 3060; 14.5%); people with advanced chronic kidney disease (n = 2689; 12.7%); people receiving biologic therapies for autoimmune conditions (n = 2538; 12.0%); people with dementia and awaiting community placement (n = 2520; 11.9%); people with chronic obstructive pulmonary disease or other respiratory conditions (n = 984; 4.7%); people receiving treatment for cancer (n = 832; 3.9%); and people with unstable housing situations or substance use disorders (n = 575; 2.7%).

INTERPRETATION

Using latent class analysis supplemented with expert clinical review, we identified 9 policy-relevant subgroups among persistently high-cost health care users. This taxonomy may be used to inform policy, including identifying interventions that are most likely to improve care and reduce cost for each subgroup.

Intellectual/developmental disabilities among people incarcerated in federal correctional facilities in Ontario, Canada: Examining prevalence, health and correctional characteristics

BACKGROUND

There is little research with people who experience intellectual/developmental disabilities and imprisonment.

METHODS

The study linked health and correctional data to examine prevalence of intellectual/developmental disabilities and health and correctional characteristics among adults experiencing their first federal incarceration between 1 January 2002 and 31 December 2011 (n = 9278) and two non-incarcerated groups (n = 10,086,802).

RESULTS

The prevalence of intellectual/developmental disabilities was 2.1% in the incarcerated group and 0.9% in the non-incarcerated group. Before incarceration, those with, versus without, intellectual/developmental disabilities were at greater risk of traumatic brain injury, mental illness, and substance use disorders. While incarcerated, those with intellectual/developmental disabilities were more likely to incur serious institutional disciplinary charges. Post-incarceration, persons with intellectual/developmental disabilities were at greater risk of emergency department visits, and psychiatric and acute hospitalizations, than the non-incarcerated groups.

CONCLUSIONS

People with intellectual/developmental disabilities are overrepresented in Canadian federal correctional institutions. The authors offer strategies to support people prior to, during, and post-incarceration.

A population level study of SARS-CoV-2 prevalence amongst people experiencing homelessness in Wales, UK

Introduction

Prior research into the prevalence of SARS-CoV-2 infection amongst people experiencing homelessness (PEH) largely relates to people in communal forms of temporary accommodation in contexts where this type of accommodation remained a major part of the response to homelessness during the COVID-19 pandemic. Little is known about the prevalence of SARS-CoV-2 amongst PEH more broadly, and in a policy and practice context that favoured self-contained accommodation, such as Wales, UK.

Objective

Describe the prevalence of SARS-CoV-2 amongst PEH in Wales, UK, using routinely collected administrative data from the Secure Anonymised Information Linkage Databank.

Methods

Routinely collected data were used to identify PEH in Wales between 1st March 2020 and 1st March 2021. Using SARS-CoV-2 pathology testing data, prevalence rates were generated for PEH and three comparator groups: (1) the not-homeless population; (2) a cohort 'exact matched' for age, sex, local authority and area deprivation; and (3) a matched comparison group created using these same variables and Propensity Score Matching (PSM). Three logistic regressions were run on samples containing each of the comparator groups to explore the effect of experiencing homelessness on testing positive for SARS-CoV-2.

Results

The prevalence of SARS-CoV-2 infection amongst PEH was 5.0%, compared to the not-homeless population at 5.6%. For the exact matched and PSM match comparator groups, prevalence was 6.9% and 6.7%, respectively. Logistic regression found that SARS-CoV-2 infection was 0.9 times less likely amongst PEH compared to people not experiencing homelessness from the general population. The odds of SARS-CoV-2 infection for PEH was 0.75 and 0.73 where the 'not-homeless' comparators were from the exact match and PSM samples, respectively.

Conclusion

Our analysis revealed that a year into the COVID-19 pandemic, the prevalence of SARS-CoV-2 amongst PEH in Wales was lower than the general population. A policy response to homelessness that moved away from communal accommodation may be partly responsible for the reduced SAR-CoV-2 infection amongst PEH.

Opportunity to inform social needs within a hospital setting using data-driven patient engagement

Background

High-risk patients account for a disproportionate amount of healthcare use, necessitating the development of care delivery solutions aimed specifically at reducing this use. These interventions have largely been unsuccessful, perhaps due to a lack of attention to patients’ social needs and engagement of patients in developing solutions.

Methods

The project team used a combination of administrative data, information culled from charts and interviews with high-risk patients to understand social needs, the current experience of addressing social needs in the hospital, and patient preferences and identified opportunities for improvement. Interviews were conducted in March and April 2020, and patients were asked to reflect on their experiences both before and during the COVID-19 pandemic.

Results

A total of 4579 patients with 26 168 visits to the emergency department and 2904 inpatient admissions in the previous year were identified. Qualitative analysis resulted in three themes: (1) the interaction between social needs, demographics, and health; (2) the hospital’s role in addressing social needs; and (3) the impact of social needs on experiences of care. Themes related to experiences before and during COVID-19 did not differ. Three opportunities were identified: (1) training for staff related to stigma and trauma, (2) improved documentation of social needs and (3) creation of navigation programmes.

Discussion

Certain demographic factors were clearly associated with an increased need for social support. Unfortunately, many factors identified by patients as mediating their need for such support were not consistently captured. Going forward, high-risk patients should be included in the development of quality improvement initiatives and programmes to address social needs.

Does Housing Improve Health Care Utilization and Costs? A Longitudinal Analysis of Health Administrative Data Linked to a Cohort of Individuals With a History of Homelessness

BACKGROUND

Individuals who are homeless have complex health care needs, which contribute to the frequent use of health services. In this study, we investigated the relationship between housing and health care utilization among adults with a history of homelessness in Ontario.

METHODS

Survey data from a 4-year prospective cohort study were linked with administrative health records in Ontario. Annual rates of health encounters and mean costs were compared across housing categories (homeless, inconsistently housed, housed), which were based on the percentage of time an individual was housed. Generalized estimating equations were applied to estimate the average annual effect of housing status on health care utilization and costs.

RESULTS

Over the study period, the proportion of individuals who were housed increased from 37% to 69%. The unadjusted rates of ambulatory care visits, prescription medications, and laboratory tests were highest during person-years spent housed or inconsistently housed and the rate of emergency department visits was lowest during person-years spent housed. Following adjustment, the rate of prescription claims remained higher during person-years spent housed or inconsistently housed compared with the homeless. Rate ratios for other health care encounters were not significant (P>0.05). An interaction between time and housing status was observed for total health care costs; as the percentage of days housed increased, the average costs increased in year 1 and decreased in years 2-4.

CONCLUSIONS

These findings highlight the effects of housing on health care encounters and costs over a 4-year study period. The rate of prescription medications was higher during person-years spent housed or inconsistently housed compared with the homeless. The cost analysis suggests that housing may reduce health care costs over time; however, future work is needed to confirm the reason for the reduction in total costs observed in later years.

Hard-to-Reach Populations and Administrative Health Data: A Serial Cross-sectional Study and Application of Data to Improve Interventions for People Experiencing Homelessness

BACKGROUND

Intervention studies with vulnerable groups in the emergency department (ED) suffer from lower quality and an absence of administrative health data. We used administrative health data to identify and describe people experiencing homelessness who access EDs, characterize patterns of ED use relative to the general population, and apply findings to inform the design of a peer support program.

METHODS

We conducted a serial cross-sectional study using administrative health data to examine ED use by people experiencing homelessness and nonhomeless individuals in the Niagara region of Ontario, Canada from April 1, 2010 to March 31, 2018. Outcomes included number of visits; unique patients; group proportions of Canadian Triage and Acuity Scale (CTAS) scores; time spent in emergency; and time to see an MD. Descriptive statistics were generated with t tests for point estimates and a Mann-Whitney U test for distributional measures.

RESULTS

We included 1,486,699 ED visits. The number of unique people experiencing homelessness ranged from 91 in 2010 to 344 in 2017, trending higher over the study period compared with nonhomeless patients. Rate of visits increased from 1.7 to 2.8 per person. People experiencing homelessness presented later with higher overall acuity compared with the general population. Time in the ED and time to see an MD were greater among people experiencing homelessness.

CONCLUSIONS

People experiencing homelessness demonstrate increasing visits, worse health, and longer time in the ED when compared with the general population, which may be a burden on both patients and the health care system.

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

BACKGROUND

People with a recent history of homelessness are believed to be at high risk of infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and, when infected, complications of coronavirus disease 2019 (COVID-19). We describe and compare testing for SARS-CoV-2, test positivity and hospital admission, receipt of intensive care and mortality rates related to COVID-19 for people with a recent history of homelessness versus community-dwelling people as of July 31, 2020.

METHODS

We conducted a population-based retrospective cohort study in Ontario, Canada, between Jan. 23 and July 31, 2020, using linked health administrative data among people who either had a recent history of homelessness or were dwelling in the community. People were included if they were eligible for provincial health care coverage and not living in an institutionalized facility on Jan. 23, 2020. We examined testing for SARS-CoV-2, test positivity and complication outcomes of COVID-19 (hospital admission, admission to intensive care and death) within 21 days of a positive test result. Extended multivariable Cox proportional hazard models were used to estimate adjusted hazard ratios (HRs) in 3 time periods: preshutdown (Jan. 23-Mar. 13), peak (Mar. 14-June 16) and reopening (June 17-July 31).

RESULTS

People with a recent history of homelessness (n = 29 407) were more likely to be tested for SARS-CoV-2 in all 3 periods compared with community-dwelling people (n = 14 494 301) (preshutdown adjusted HR 1.61, 95% confidence interval [CI] 1.22-2.11; peak adjusted HR 2.95, 95% CI 2.88-3.03; reopening adjusted HR 1.45, 95% CI 1.39-1.51). They were also more likely to have a positive test result (peak adjusted HR 3.66, 95% CI 3.22-4.16; reopening adjusted HR 1.76, 95% CI 1.15-2.71). In the peak period, people with a recent history of homelessness were over 20 times more likely to be admitted to hospital for COVID-19 (adjusted HR 20.35, 95% CI 16.23-25.53), over 10 times more likely to require intensive care for COVID-19 (adjusted HR 10.20, 95% CI 5.81-17.93) and over 5 times more likely to die within 21 days of their first positive test result (adjusted HR 5.73, 95% CI 3.01-10.91).

INTERPRETATION

In Ontario, people with a recent history of homelessness were significantly more likely to be tested for SARS-CoV-2, to have a positive test result, to be admitted to hospital for COVID-19, to receive intensive care for COVID-19 and to die of COVID-19 compared with community-dwelling people. People with a recent history of homelessness should continue to be considered particularly vulnerable to SARS-CoV-2 infection and its complications.

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

BACKGROUND

Congregate settings have been disproportionately affected by coronavirus disease 2019 (COVID-19). Our objective was to compare testing for, diagnosis of and death after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection across 3 settings (residents of long-term care homes, people living in shelters and the rest of the population).

METHODS

We conducted a population-based prospective cohort study involving individuals tested for SARS-CoV-2 in the Greater Toronto Area between Jan. 23, 2020, and May 20, 2020. We sourced person-level data from COVID-19 surveillance and reporting systems in Ontario. We calculated cumulatively diagnosed cases per capita, proportion tested, proportion tested positive and case-fatality proportion for each setting. We estimated the age- and sex-adjusted rate ratios associated with setting for test positivity and case fatality using quasi-Poisson regression.

RESULTS

Over the study period, a total of 173 092 individuals were tested for and 16 490 individuals were diagnosed with SARS-CoV-2 infection. We observed a shift in the proportion of cumulative cases from all cases being related to travel to cases in residents of long-term care homes (20.4% [3368/16 490]), shelters (2.3% [372/16 490]), other congregate settings (20.9% [3446/16 490]) and community settings (35.4% [5834/16 490]), with cumulative travel-related cases at 4.1% (674/16490). Cumulatively, compared with the rest of the population, the diagnosed cases per capita was 64-fold and 19-fold higher among long-term care home and shelter residents, respectively. By May 20, 2020, 76.3% (21 617/28 316) of long-term care home residents and 2.2% (150 077/6 808 890) of the rest of the population had been tested. After adjusting for age and sex, residents of long-term care homes were 2.4 (95% confidence interval [CI] 2.2-2.7) times more likely to test positive, and those who received a diagnosis of COVID-19 were 1.4-fold (95% CI 1.1-1.8) more likely to die than the rest of the population.

INTERPRETATION

Long-term care homes and shelters had disproportionate diagnosed cases per capita, and residents of long-term care homes diagnosed with COVID-19 had higher case fatality than the rest of the population. Heterogeneity across micro-epidemics among specific populations and settings may reflect underlying heterogeneity in transmission risks, necessitating setting-specific COVID-19 prevention and mitigation strategies.

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

OBJECTIVES

To identify: (i) risk of cardiovascular disease (CVD) in homeless versus housed individuals and (ii) interventions for CVD in homeless populations.

METHODS

We conducted a systematic literature review in EMBASE until December 2018 using a search strategy for observational and interventional studies without restriction regarding languages or countries. Meta-analyses were conducted, where appropriate and possible. Outcome measures were all-cause and CVD mortality, and morbidity.

RESULTS

Our search identified 17 articles (6 case-control, 11 cohort) concerning risk of CVD and none regarding specific interventions. Nine were included to perform a meta-analysis. The majority (13/17, 76.4%) were high quality and all were based in Europe or North America, including 765 459 individuals, of whom 32 721 were homeless. 12/17 studies were pre-2011. Homeless individuals were more likely to have CVD than non-homeless individuals (pooled OR 2.96; 95% CI 2.80 to 3.13; p<0.0001; heterogeneity p<0.0001; I²=99.1%) and had increased CVD mortality (age-standardised mortality ratio range: 2.6-6.4). Compared with non-homeless individuals, hypertension was more likely in homeless people (pooled OR 1.38-1.75, p=0.0070; heterogeneity p=0.935; I²=0.0%).

CONCLUSIONS

Homeless people have an approximately three times greater risk of CVD and an increased CVD mortality. However, there are no studies of specific pathways/interventions for CVD in this population. Future research should consider design and evaluation of tailored interventions or integrating CVD into existing interventions.