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

OBJECTIVE: 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. CONCLUSIONS: 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.

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.

RéSUMé: OBJECTIFS: Des rapports anecdotiques récents suggèrent qu'un nombre croissant de personnes en situation d'itinérance visitent les services d'urgence (SU) pendant les saisons froides en raison de la disponibilité insuffisante d'hébergement d'urgence. Nous avons examiné les visites mensuelles aux urgences chez les personnes en situation d'itinérance afin de déterminer s'il y a eu une augmentation significative de ces visites en 2022-2023 par rapport aux années précédentes. MéTHODES: Nous avons utilisé des données administratives de santé liées pour identifier les cohortes de personnes en situation d'itinérance en Ontario entre octobre et mars des années 2018/2019 à 2022/2023. Nous avons analysé le taux mensuel de visites aux urgences non urgentes comme mesure approximative des visites vraisemblablement attribuables à l'évitement de l'exposition au froid, en examinant les taux chez les personnes en situation d'itinérance par rapport aux patients logés. Nous avons exclu les visites pour surdose ou COVID-19. Nous avons évalué le niveau et l'importance du changement dans l'année 2022/2023 par rapport aux saisons froides précédentes en utilisant la régression de Poisson. RéSULTATS: Nous avons recensé un total de 21 588 visites non urgentes aux urgences au cours de la période d'observation chez des personnes en situation d'itinérance en Ontario. Les visites aux urgences non urgentes ont augmenté de 27 % (RR 1,24 [IC à 95 % 1,14-1,34]) en 2022­2023 par rapport aux saisons froides précédentes. À Toronto, ces visites ont augmenté de 70 % (RR 1,68 [IC à 95 % 1,57-1,80]). Parmi les patients logés, les visites aux urgences non urgentes n'ont pas changé de façon significative pendant cette période. CONCLUSIONS: Les taux de visites aux urgences attribuables vraisemblablement à l'évitement de l'exposition au froid par les personnes en situation d'itinérance ont augmenté considérablement en Ontario en 2022­2023, surtout à Toronto. Cette augmentation du nombre de visites aux urgences peut être liée à un accès inadéquat aux lits des refuges d'urgence et aux services de réchauffement dans la collectivité.

Treatment and Mortality Following Cancer Diagnosis Among People With Non-affective Psychotic Disorders in Ontario, Canada: A Retrospective Cohort Study.

BACKGROUND AND HYPOTHESIS: People with psychotic disorders have a higher risk of mortality following cancer diagnosis, compared to people without psychosis. The extent to which this disparity is influenced by differences in cancer-related treatment is currently unknown. We hypothesized that, following a cancer diagnosis, people with psychotic disorders were less likely to receive treatment and were at higher risk of death than those without psychosis. STUDY DESIGN: We constructed a retrospective cohort of cases of non-affective psychotic disorder (NAPD) and a general population comparison group, using Ontario Health (OH) administrative data. We identified cases of all cancers diagnosed between 1995 and 2019 and obtained information on cancer-related treatment and mortality. Cox proportional hazards models were used to compare the probability of having a consultation with an oncologist and receiving cancer-related treatment, adjusting for tumor site and stage. We also compared the rate of all-cause and cancer-related mortality between the two groups, adjusting for tumor site. STUDY RESULTS: Our analytic sample included 24 944 people diagnosed with any cancer. People with NAPD were less likely to receive treatment than people without psychosis (HR = 0.87, 95% CI = 0.82, 0.91). In addition, people with NAPD had a greater risk of death from any cause (HR = 1.68, 95% CI = 1.60, 1.76), compared to people without NAPD. CONCLUSIONS: The lower likelihood of receiving cancer treatment reflects disparities in accessing cancer care for people with psychotic disorders, which may partially explain the higher mortality risk following cancer diagnosis. Future research should explore mediating factors in this relationship to identify targets for reducing health disparities.

Enhancing detection of SARS-CoV-2 re-infections using longitudinal sero-monitoring: demonstration of a methodology in a cohort of people experiencing homelessness in Toronto, Canada.

BACKGROUND: Accurate estimation of SARS-CoV-2 re-infection is crucial to understanding the connection between infection burden and adverse outcomes. However, relying solely on PCR testing results in underreporting. We present a novel approach that includes longitudinal serologic data, and compared it against testing alone among people experiencing homelessness. METHODS: We recruited 736 individuals experiencing homelessness in Toronto, Canada, between June and September 2021. Participants completed surveys and provided saliva and blood serology samples every three months over 12 months of follow-up. Re-infections were defined as: positive PCR or rapid antigen test (RAT) results > 90 days after initial infection; new serologic evidence of infection among individuals with previous infection who sero-reverted; or increases in anti-nucleocapsid in seropositive individuals whose levels had begun to decrease. RESULTS: Among 381 participants at risk, we detected 37 re-infections through PCR/RAT and 98 re-infections through longitudinal serology. The comprehensive method identified 37.4 re-infection events per 100 person-years, more than four-fold more than the rate detected through PCR/RAT alone (9.0 events/100 person-years). Almost all test-confirmed re-infections (85%) were also detectable by longitudinal serology. CONCLUSIONS: Longitudinal serology significantly enhances the detection of SARS-CoV-2 re-infections. Our findings underscore the importance and value of combining data sources for effective research and public health surveillance.

The safety of seasonal influenza vaccination among adults prescribed immune checkpoint inhibitors: A self-controlled case series study using administrative data.

BACKGROUND: Immune checkpoint inhibitor (ICI) therapy for patients undergoing cancer treatment carries a risk of severe immune-related adverse events (IRAEs). Questions remain about whether seasonal influenza vaccination might increase the risk of developing IRAEs among these patients given that vaccines are immunomodulatory. Previous vaccine safety studies on patients with cancer prescribed ICI therapy have demonstrated conflicting results. METHODS: Using health administrative data from Ontario, Canada among adults diagnosed with cancer who had been prescribed ICI therapy and who had received an influenza vaccine from 2012 to 2019, we conducted a self-controlled case series study. The pre-vaccination control period started 42-days post-ICI initiation until 14-days prior to vaccination, the risk period was 1-42 days post-vaccination, and the post-vaccination control period was after the risk period until ICI discontinuation or a maximum period of two years. Emergency department (ED) visit(s) and/or hospitalization for any cause after ICI initiation was used to identify severe IRAEs. We fitted a fixed-effects Poisson regression model accounting for seasonality and calendar time to estimate relative incidence of IRAEs between risk and control periods. RESULTS: We identified 1133 records of cancer patients who received influenza vaccination while prescribed ICI therapy. Most were aged ≥ 66 years (73 %), were male (63 %), had lung cancer (54 %), and had received ICI therapy with a programmed cell death protein 1(PD-1) inhibitor (91 %). A quarter (26 %) experienced an ED visit and/or hospitalization during the observation period. Rates of ED visits and/or hospitalizations in the risk vs. control periods were similar, with an incidence rate ratio of 1.04 (95 % CI: 0.75-1.45). Subgroup and sensitivity analyses yielded similar results. CONCLUSION: Seasonal influenza vaccination was not associated with an increased incidence of ED visit or hospitalization among adults with cancer treated with ICI therapy and our results support further evidence of vaccine safety.

Self-reported tick exposure as an indicator of Lyme disease risk in an endemic region of Quebec, Canada.

BACKGROUND: Lyme disease (LD) and other tick-borne diseases are emerging across Canada. Spatial and temporal LD risk is typically estimated using acarological surveillance and reported human cases, the former not considering human behavior leading to tick exposure and the latter occurring after infection. OBJECTIVES: The primary objective was to explore, at the census subdivision level (CSD), the associations of self-reported tick exposure, alternative risk indicators (predicted tick density, eTick submissions, public health risk level), and ecological variables (Ixodes scapularis habitat suitability index and cumulative degree days > 0 °C) with incidence proportion of LD. A secondary objective was to explore which of these predictor variables were associated with self-reported tick exposure at the CSD level. METHODS: Self-reported tick exposure was measured in a cross-sectional populational health survey conducted in 2018, among 10,790 respondents living in 116 CSDs of the Estrie region, Quebec, Canada. The number of reported LD cases per CSD in 2018 was obtained from the public health department. Generalized linear mixed-effets models accounting for spatial autocorrelation were built to fulfill the objectives. RESULTS: Self-reported tick exposure ranged from 0.0 % to 61.5 % (median 8.9 %) and reported LD incidence rates ranged from 0 to 324 cases per 100,000 person-years, per CSD. A positive association was found between self-reported tick exposure and LD incidence proportion (ß = 0.08, CI = 0.04,0.11, p < 0.0001). The best-fit model included public health risk level (AIC: 144.2), followed by predicted tick density, ecological variables, self-reported tick exposure and eTick submissions (AIC: 158.4, 158.4, 160.4 and 170.1 respectively). Predicted tick density was the only significant predictor of self-reported tick exposure (ß = 0.83, CI = 0.16,1.50, p = 0.02). DISCUSSION: This proof-of-concept study explores self-reported tick exposure as a potential indicator of LD risk using populational survey data. This approach may offer a low-cost and simple tool for evaluating LD risk and deserves further evaluation.

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.

Professional characteristics, attitudes, and practices associated with stress and quality of life among Canadian animal health workers.

Objective: To describe the knowledge, attitudes, and practices (KAP) towards COVID-19 of Canadian companion animal health workers (AHW); to measure their perceived stress and quality of life (QoL); and to explore professional risk factors associated with stress and QoL. Sample: We sampled 436 companion animal veterinarians and technicians. Procedure: The study had cross-sectional and cohort components. It was conducted online in August to December 2020, and repeated in May to July 2021, using a questionnaire assessing the respondents' professional characteristics, COVID-19 KAP, perceived stress, and QoL. Results: Overall, AHW had sufficient knowledge of COVID-19 transmission, and reported having adopted good preventive practices. Since the beginning of the pandemic, participants reported increases in new clients (76%), in refusal of new clients (53%), and in pet euthanasia (24%). Increased client refusal and pet euthanasia were associated with greater stress and poorer professional QoL, whereas perceived susceptibility to and adoption of measures against COVID-19 were associated with lower stress and better QoL. Conclusion and clinical relevance: For AHW, professional characteristics were associated with stress and professional QoL. This information is important for developing strategies to cope with the ongoing shortage of AHW and with future public health crises.

Caractéristiques professionnelles, attitudes et pratiques associées au stress et à la qualité de vie des travailleurs en santé animale au Canada. Objectif: Décrire les connaissances, attitudes et pratiques (KAP) envers la COVID-19 des travailleurs canadiens en santé des animaux de compagnie (AHW); mesurer leur stress perçu et leur qualité de vie (QoL); et explorer les facteurs de risque professionnels associés au stress et à la QoL. Échantillonnage: Nous avons échantillonné 436 médecins vétérinaires et techniciens en pratique des animaux de compagnie. Procédure: L'étude avait des composantes transversale et de cohorte. Elle a été menée en ligne d'août à décembre 2020, et répétée de mai à juillet 2021, à l'aide d'un questionnaire évaluant les caractéristiques professionnelles des répondants, leurs KAP envers la COVID-19, leur stress perçu et leur QoL. Résultats: Dans l'ensemble, les AHW avaient une connaissance suffisante de la transmission de la COVID-19 et ont déclaré avoir adopté de bonnes pratiques de prévention. Depuis le début de la pandémie, les participants ont signalé une augmentation du nombre de nouveaux clients (76 %), du refus de nouveaux clients (53 %) et de l'euthanasie des animaux de compagnie (24 %). L'augmentation du refus des clients et de l'euthanasie des animaux de compagnie était associée à un plus grand stress et à une QoL professionnelle plus faible, tandis que la perception du risque et l'adoption de mesures contre le COVID-19 étaient associées à un stress plus faible et à une meilleure QoL. Conclusion et pertinence clinique: Pour les AHW, les caractéristiques professionnelles étaient associées au stress et à la QoL. Ces informations sont importantes pour développer des stratégies pour faire face à la pénurie continue d'AHW et aux futures crises de santé publique.(Traduit par Dr Serge Messier).

A registry-based population study of the HLA in Québec, Canada.

As part of the worldwide effort to better characterize HLA diversity in populations, we have studied the population of Québec in Canada. This province has been defined by a complex history with multiple founder effects and migration patterns. We analyzed the typing data of 3806 individuals registered in Héma-Québec's Registry, which covered most administrative regions in Québec. Typing information was resolved at the second field level of resolution by next-generation sequencing (NGS) or by Sanger sequencing. We used the HLA-net.eu GENE[RATE] tools to estimate allele and two-locus haplotype frequencies for HLA-A, -B, -C, -DRB1, -DQB1, and -DPB1, as well as Hardy-Weinberg equilibrium (HWE), selective neutrality, and linkage disequilibrium. The chord genetic distance was also calculated between administrative regions and was visualized using non-metric multidimensional scaling (NMDS) analysis. While most individual regions were in HWE, HWE was rejected for the province considered as a whole. Some regions exhibited signatures of selection, mostly toward an excess of heterozygotes. Allele and haplotype frequencies revealed outlier regions that strongly differed from the other regions. NMDS plots also showed differences between regions. The administrative regions of the province of Québec displayed heterogeneity in their HLA profiles. This heterogeneity was attributable to differing allele and haplotype specificities by region. In particular, regions 02-Saguenay-Lac-Saint-Jean and 01-Bas-St-Laurent diverged from the rest of the regions. The urban regions 06-Montréal and 13-Laval were very diversified in their HLA profiles. Together, these results will help optimize donor recruitment strategies in Québec.

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.

RéSUMé: OBJECTIF: L'itinérance augmente le risque de blessures liées au froid. Nous avons examiné les visites aux urgences pour des blessures liées au froid à Toronto sur une période de quatre ans, en comparant les visites de patients en situation d'itinérance aux visites de patients pas en situation d'itinérance. MéTHODES: Cette analyse descriptive des visites aux services d'urgence à Toronto entre juillet 2018 et juin 2022 a utilisé des données administratives de santé liées. Nous avons mesuré les visites aux services d'urgence avec un diagnostic de blessure liée au froid parmi les patients en situation d'itinérance et ceux pas en situation d'itinérance. Les taux ont été exprimés en nombre de visites pour les blessures liées au froid par 100 000 visites au total. Le rapport de taux ont été utilisés pour comparer les taux entre les groupes en situation d'itinérance et ceux pas en situation d'itinérance. RéSULTATS: Nous avons identifié 333 visites pour des blessures liées au froid chez les patients en situation d'itinérance et 1126 chez les patients pas en situation d'itinérance. Au cours de chacune des quatre années d'observation, les rapports de taux variaient entre 13,6 et 17,6 pour l'ensemble des blessures liées au froid, 13,7 et 17,8 pour l'hypothermie et 10,3 et 18,3 pour les engelures. Les taux par 100 000 visites au cours de la quatrième année (de juillet 2021 à juin 2022) étaient considérablement plus élevés que pendant la période précédant la pandémie. Les patients de sexe masculin affichaient des taux plus élevés, peu importe leur statut d'itinérance; les patients de sexe féminin en situation d'itinérance affichaient des rapports de taux plus élevés que les patients de sexe masculin en situation d'itinérance. CONCLUSION: Les patients en situation d'itinérance qui se rendent à l'urgence sont beaucoup plus susceptibles d'être vus pour des blessures liées au froid que les autres. Des efforts supplémentaires sont nécessaires pour prévenir l'exposition au froid et les blessures qui en découlent chez les personnes en situation d'itinérance.

The burden of psychiatric disorders associated with orofacial cleft pathology among children in Ontario, Canada.

BACKGROUND: Individuals with orofacial cleft (OFC) may be at a higher risk of developing psychiatric disorders (PD) than the general population. We determined the risk of psychiatric diagnoses in children with OFC in Canada. METHODS: This population-based retrospective cohort study used health administrative data from the province of Ontario, Canada. Children with OFC who were born between April 1, 1994, and March 31, 2017, in Ontario were matched to five non-OFC children based on sex, date of birth, and mother's age. We determined the rate of events and time-to-event for first diagnosis of PD in children aged ≥ 3 years (y), and for intellectual developmental delay (IDD) from birth. Risk factors for PD and IDD were assessed using 1-way ANOVA for means, Kruskal-Wallis for medians, and the χ2 test for categorical variables. OUTCOMES: There were 3051 children with OFC (matched to 15,255 controls), of whom 2515 patients with OFC (12,575 controls) had a complete follow-up to the third birthday. Children with OFC were more likely to have PD than controls (54.90 vs. 43.28 per 1000 patient-years, P < .001), with a mean age to first diagnosis of 8.6 ± 4.2 y. The cleft palate group had the highest risk (HR 1.33, 95% CI 1.18-1.49). Children with OFC also had a higher risk of IDD than non-OFC children (27.78 vs. 3.46 per 1000 patient-years, p < .001). INTERPRETATION: Children born with OFC in Ontario had a higher risk of psychiatric diagnosis and IDD compared to controls. Further research is also required to better understand the predictors of variation in risk, including geographic location and the presence of congenital abnormalities, and identify potential areas for intervention. EVIDENCE RATING SCALE FOR PROGNOSTIC/RISK STUDIES: Level II.

Early mortality in patients with cancer treated with immune checkpoint inhibitors in routine practice.

BACKGROUND: We sought to estimate the proportion of patients with cancer treated with immune checkpoint inhibitors (ICI) who die soon after starting ICI in the real world and examine factors associated with early mortality (EM). METHODS: We conducted a retrospective cohort study using linked health administrative data from Ontario, Canada. EM was defined as death from any cause within 60 days of ICI initiation. Patients with melanoma, lung, bladder, head and neck, or kidney cancer treated with ICI between 2012 and 2020 were included. RESULTS: A total of 7126 patients treated with ICI were evaluated. Fifteen percent (1075 of 7126) died within 60 days of initiating ICI. The highest mortality was observed in patients with bladder and head and neck tumors (approximately 21% each). In multivariable analysis, previous hospital admission or emergency department visit, prior chemotherapy or radiation therapy, stage 4 disease at diagnosis, lower hemoglobin, higher white blood cell count, and higher symptom burden were associated with higher risk of EM. Conversely, patients with lung and kidney cancer (compared with melanoma), lower neutrophil to lymphocytes ratio, and with higher body mass index were less likely to die within 60 days post ICI initiation. In a sensitivity analysis, 30-day and 90-day mortality were 7% (519 of 7126) and 22% (1582 of 7126), respectively, with comparable clinical factors associated with EM identified. CONCLUSIONS: EM is common among patients treated with ICI in the real-world setting and is associated with several patient and tumor characteristics. Development of a validated tool to predict EM may facilitate better patient selection for treatment with ICI in routine practice.

Incidence of SARS-CoV-2 Infection Among People Experiencing Homelessness in Toronto, Canada.

Importance: People experiencing homelessness are at high risk of SARS-CoV-2 infection. Incident infection rates have yet to be established in these communities and are needed to inform infection prevention guidance and related interventions. Objective: To quantify the SARS-CoV-2 incident infection rate among people experiencing homelessness in Toronto, Canada, in 2021 and 2022 and to assess factors associated with incident infection. Design, Setting, and Participants: This prospective cohort study was conducted among individuals aged 16 years and older who were randomly selected between June and September 2021 from 61 homeless shelters, temporary distancing hotels, and encampments in Toronto, Canada. Exposures: Self-reported housing characteristics, such as number sharing living space. Main Outcomes and Measures: Prevalence of prior SARS-CoV-2 infection in summer 2021, defined as self-reported or polymerase chain reaction (PCR)- or serology-confirmed evidence of infection at or before the baseline interview, and SARS-CoV-2 incident infection, defined as self-reported or PCR- or serology-confirmed infection among participants without history of infection at baseline. Factors associated with infection were assessed using modified Poisson regression with generalized estimating equations. Results: The 736 participants (415 of whom did not have SARS-CoV-2 infection at baseline and were included in the primary analysis) had a mean (SD) age of 46.1 (14.6) years; 486 (66.0%) self-identified as male. Of these, 224 (30.4% [95% CI, 27.4%-34.0%]) had a history of SARS-CoV-2 infection by summer 2021. Of the remaining 415 participants with follow-up, 124 experienced infection within 6 months, representing an incident infection rate of 29.9% (95% CI, 25.7%-34.4%), or 5.8% (95% CI, 4.8%-6.8%) per person-month. Report after onset of the SARS-CoV-2 Omicron variant was associated with incident infection, with an adjusted rate ratio (aRR) of 6.28 (95% CI, 3.94-9.99). Other factors associated with incident infection included recent immigration to Canada (aRR, 2.74 [95% CI, 1.64-4.58]) and alcohol consumption over the past interval (aRR, 1.67 [95% CI, 1.12-2.48]). Self-reported housing characteristics were not significantly associated with incident infection. Conclusions and Relevance: In this longitudinal study of people experiencing homelessness in Toronto, SARS-CoV-2 incident infection rates were high in 2021 and 2022, particularly once the Omicron variant became dominant in the region. Increased focus on homelessness prevention is needed to more effectively and equitably protect these communities.

A Cross-sectional Study of Community-level Physician Retention and Diabetes Management in Rural Ontario.

OBJECTIVE: Our aim in this study was to determine the impact of community-level physician retention on the quality of diabetes care in rural Ontario. METHODS: Using administrative data, we compared diabetes quality of care. We defined retention as the proportion of physicians in a community from one year to the next. We grouped retention level by tertile and added a category for those communities with no physician. RESULTS: Residents of high-retention communities were more likely to have had glycated hemoglobin (odds ratio [OR], 1.10; 95% confidence interval [CI], 1.06 to 1.14) and low-density lipoprotein (OR, 1.17; 95% CI, 1.13 to 1.22) testing, but less likely to have had testing for urine albumin-to-creatine ratio (OR, 0.86; 95% CI, 0.83 to 0.89) or to have received an angiotensin-converting enzyme inhibitor or angiotensin-2 receptor blocker (OR, 0.91; 95% CI, 0.86 to 0.95) or a statin (OR, 0.91; 95% CI, 0.87 to 0.96), when compared with low-retention communities. Communities with no residing physician had care that was equivalent to or better than that in high-retention communities. CONCLUSIONS: Community-level physician retention, based on a 2-year time frame, was significantly related to quality of diabetes care. A closer look at models of care in communities with no residing physician is warranted. Community-level physician retention can be used to assess the impact of physician shortages on diabetes management in rural communities.

HLA and red blood cell antigen genotyping in SARS-CoV-2 convalescent plasma donors.

Aim: More data is required regarding the association between HLA allele and red blood cell (RBC) antigen expression in regard to SARS-CoV-2 infection and COVID-19 susceptibility. Methods: ABO, RhD, 37 other RBC antigens and HLA-A, B, C, DRB1, DQB1 and DPB1 were determined using high throughput platforms in 90 Caucasian convalescent plasma donors. Results: The AB group was significantly increased (1.5×, p = 0.018) and some HLA alleles were found to be significantly overrepresented (HLA-B*44:02, C*05:01, DPB1*04:01, DRB1*04:01 and DRB1*07:01) or underrepresented (A*01:01, B51:01 and DPB1*04:02) in convalescent individuals compared with the local bone marrow registry population. Conclusion: Our study of infection-susceptible but non-hospitalized Caucasian COVID-19 patients contributes to the global understanding of host genetic factors associated with SARS-CoV-2 infection and severity.

Epilepsy Surgery in Adult Stroke Survivors with New-Onset Drug-Resistant Epilepsy.

BACKGROUND: Despite its effectiveness, surgery for drug-resistant epilepsy is underutilized. However, whether epilepsy surgery is also underutilized among patients with stroke-related drug-resistant epilepsy is unclear. Therefore, our objectives were to estimate the rates of epilepsy surgery assessment and receipt among patients with stroke-related drug-resistant epilepsy and to identify factors associated with these outcomes. METHODS: We used linked health administrative databases to conduct a population-based retrospective cohort study of adult Ontario, Canada residents discharged from an Ontario acute care institution following the treatment of a stroke between January 1, 1997, and December 31, 2020, without prior evidence of seizures. We excluded patients who did not subsequently develop drug-resistant epilepsy and those with other epilepsy risk factors. We estimated the rates of epilepsy surgery assessment and receipt by March 31, 2021. We planned to use Fine-Gray subdistribution hazard models to identify covariates independently associated with our outcomes, controlling for the competing risk of death. RESULTS: We identified 265,081 patients who survived until discharge following inpatient stroke treatment, 1,902 (0.7%) of whom subsequently developed drug-resistant epilepsy (805 women; mean age: 67.0 ± 13.1 years). Fewer than six (≤0.3%) of these patients were assessed for or received epilepsy surgery before the end of follow-up (≤55.5 per 100,000 person-years). Given that few outcomes were identified, we could not proceed with the multivariable analyses. CONCLUSIONS: Patients with stroke-related drug-resistant epilepsy are infrequently considered for epilepsy surgery that could reduce morbidity and mortality.

Navigator programme for hospitalised adults experiencing homelessness: protocol for a pragmatic randomised controlled trial.

INTRODUCTION: People experiencing homelessness suffer from poor outcomes after hospitalisation due to systemic barriers to care, suboptimal transitions of care, and intersecting health and social burdens. Case management programmes have been shown to improve housing stability, but their effects on broad posthospital outcomes in this population have not been rigorously evaluated. The Navigator Programme is a Critical Time Intervention case management programme that was developed to help homeless patients with their postdischarge needs and to link them with community-based health and social services. This randomised controlled trial examines the impact of the Navigator Programme on posthospital outcomes among adults experiencing homelessness. METHODS AND ANALYSIS: This is a pragmatic randomised controlled trial testing the effectiveness of the Navigator Programme at an urban academic teaching hospital and an urban community teaching hospital in Toronto, Canada. Six hundred and forty adults experiencing homelessness who are admitted to the hospital will be randomised to receive support from a Homeless Outreach Counsellor for 90 days after hospital discharge or to usual care. The primary outcome is follow-up with a primary care provider (physician or nurse practitioner) within 14 days of hospital discharge. Secondary outcomes include postdischarge mortality or readmission, number of days in hospital, number of emergency department visits, self-reported care transition quality, and difficulties meeting subsistence needs. Quantitative outcomes are being collected over a 180-day period through linked patient-reported and administrative health data. A parallel mixed-methods process evaluation will be conducted to explore intervention context, implementation and mechanisms of impact. ETHICS AND DISSEMINATION: Ethics approval was obtained from the Unity Health Toronto Research Ethics Board. Participants will be required to provide written informed consent. Results of the main trial and process evaluation will be reported in peer-reviewed journals and shared with hospital leadership, community partners and policy makers. TRIAL REGISTRATION NUMBER: NCT04961762.

Dissecting the impact of molecular T-cell HLA mismatches in kidney transplant failure: A retrospective cohort study.

Introduction: Kidney transplantation is the optimal treatment in end-stage kidney disease, but de-novo donor specific antibody development continues to negatively impact patients undergoing kidney transplantation. One of the recent advances in solid organ transplantation has been the definition of molecular mismatching between donors and recipients' Human Leukocyte Antigens (HLA). While not fully integrated in standard clinical care, cumulative molecular mismatch at the level of eplets (EMM) as well as the PIRCHE-II score have shown promise in predicting transplant outcomes. In this manuscript, we sought to study whether certain T-cell molecular mismatches (TcEMM) were highly predictive of death-censored graft failure (DCGF). Methods: We studied a retrospective cohort of kidney donor:recipient pairs from the Scientific Registry of Transplant Recipients (2000-2015). Allele level HLA-A, B, C, DRB1 and DQB1 types were imputed from serologic types using the NMDP algorithm. TcEMMs were then estimated using the PIRCHE-II algorithm. Multivariable Accelerated Failure Time (AFT) models assessed the association between each TcEMM and DCGF. To discriminate between TcEMMs most predictive of DCGF, we fit multivariable Lasso penalized regression models. We identified co-expressed TcEMMs using weighted correlation network analysis (WGCNA). Finally, we conducted sensitivity analyses to address PIRCHE and IMGT/HLA version updates. Results: A total of 118,309 donor:recipient pairs meeting the eligibility criteria were studied. When applying the PIRCHE-II algorithm, we identified 1,935 distinct TcEMMs at the population level. A total of 218 of the observed TcEMM were independently associated with DCGF by AFT models. The Lasso penalized regression model with post selection inference identified a smaller subset of 86 TcEMMs (56 and 30 TcEMM derived from HLA Class I and II, respectively) to be highly predictive of DCGF. Of the observed TcEMM, 38.14% appeared as profiles of highly co-expressed TcEMMs. In addition, sensitivity analyses identified that the selected TcEMM were congruent across IMGT/HLA versions. Conclusion: In this study, we identified subsets of TcEMMs highly predictive of DCGF and profiles of co-expressed mismatches. Experimental verification of these TcEMMs determining immune responses and how they may interact with EMM as predictors of transplant outcomes would justify their consideration in organ allocation schemes and for modifying immunosuppression regimens.

Virtual family physician care during COVID-19: a mixed methods study using health administrative data and qualitative interviews.

BACKGROUND: The onset of the COVID-19 pandemic necessitated a rapid shift in primary health care from predominantly in-person to high volumes of virtual care. The pandemic afforded the opportunity to conduct a deep regional examination of virtual care by family physicians in London and Middlesex County, Ontario, Canada that would inform the foundation for virtual care in our region post-pandemic. OBJECTIVES: (1) to determine volumes of in-person and virtual family physicians visits and characteristics of the family physicians and patients using them during the early COVID-19 pandemic; (2) to determine how virtual visit volumes changed over the pandemic, compared to in-person; and (3) to explore family physicians' experience in virtual visit adoption and implementation. METHODS: We conducted a concurrent mixed-methods study of family physicians from March to October 2020. The quantitative component examined mean weekly number of total, in-person and virtual visits using health administrative data. Differences in outcomes according to physician and practice characteristics for pandemic periods were compared to pre-pandemic. The qualitative study employed Constructivist Grounded Theory, conducting semi-structured family physicians interviews; analyzing data iteratively using constant comparative analysis. We mapped themes from the qualitative analysis to quantitative findings. RESULTS: Initial volumes of patients decreased, driven by fewer in-person visits. Virtual visit volumes increased dramatically; family physicians described using telephone almost entirely. Rural family physicians reported video connectivity issues. By early second wave, total family physician visit volume returned to pre-pandemic volumes. In-person visits increased substantially; family physicians reported this happened because previously scarce personal protective equipment became available. Patients seen during the pandemic were older, sicker, and more materially deprived. CONCLUSION: These results can inform the future of virtual family physician care including the importance of continued virtual care compensation, the need for equitable family physician payment models, and the need to attend to equity for vulnerable patients. Given the move to virtual care was primarily a move to telephone care, the modality of care delivery that is acceptable to both family physicians and their patients must be considered.

Multiplex PCR assay targeting Trichomonas vaginalis: need for biological evaluation and interpretation.

In a retrospective study, we used sequencing to investigate Trichomonas vaginalis-positive specimens (genital, rectal and pharyngeal) with the Allplex™ STI Essential or the Anyplex™-II-STI-7 assays. Our results confirm that majority of T. vaginalis-positive genital and pharyngeal specimens contained T. vaginalis DNA and actually T. tenax DNA, respectively.