key: cord-0745264-j8ap7bgx
authors: Keller, Matthew; Shreffler, Jacob; Wilmes, Kathleen; Polites, Andrew; Huecker, Martin
title: Equal incidence of COVID-19 among homeless and non-homeless ED patients when controlling for confounders
date: 2021-09-25
journal: Am J Emerg Med
DOI: 10.1016/j.ajem.2021.09.057
sha: 51cdaccd1356906867a4d0eb332f44ac66215828
doc_id: 745264
cord_uid: j8ap7bgx

INTRODUCTION: The World Health Organization (WHO) declared severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) a pandemic in March 2020. Theoretically, homeless patients could have disproportionately worse outcomes from COVID-19, but little research has corroborated this claim. This study aimed to examine the demographics and incidence of COVID-19 in homeless vs non-homeless emergency department (ED) patients. METHODS: This is a retrospective study of all patients seen in the University of Louisville Hospital Emergency Department (ULH ED) from March 2019 to December 2020, excluding January and February 2020. Data was collected from the Kentucky Homeless Management Information System (HMIS) and ULH electronic health records. RESULTS: A total of 51,532 unique patients had 87,869 visits during the study period. There was a 18.1% decrease in homeless patient visits over the time period, which was similar to the decrease in non-homeless patient visits (19.2%). In the total population, 9471 individuals had known COVID-19 testing results, with a total of 610 positive (6.4% positivity rate). Of the 712 homeless ED patients, 39 tested positive (5.5% positivity rate). After adjusting for age, gender identity, race, and insurance, there was no statistically significant difference in test positivity between homeless and non-homeless patients, OR 1.23 (0.88, 1.73). Homeless patients were less likely to be admitted to either the intensive care unit (ICU) or hospital (OR = 0.55, 95% CI: OR 0.51, 0.60) as they were more likely to be discharged (OR = 1.65, 95% CI: 1.52, 1.79). CONCLUSION: Previous literature has indicated that higher disease burden, lack of access to social distancing, and poor hygiene would increase the risk of homeless individuals contracting COVID-19 and experiencing serious morbidity. However, this study found that homelessness was not an independent risk factor for COVID-19 infection.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes COVID-19, a pandemic as of March 11 th 2020, according to the World Health Organization. The infection has resulted in unprecedented changes within healthcare systems and governments. Officials learn more each day about the virus, investigating adequate treatment methods, advising hospital responses, and contemplating the effectiveness of physical distancing along with other government mandated guidelines. COVID-19 appears to cause more severe disease in older adults and people with comorbidities such as diabetes, hypertension, and cardiopulmonary disease. 1 An estimated 553,742 Americans experience homelessness on any given night. 2 Homeless patients have higher rates of substance use and mental illness compared to nonhomeless patients. 3, 4 Furthermore, homeless patients have a higher chronic disease burden resulting in significant medical morbidity and risk of premature mortality. 5 It has been speculated that COVID-19 will disproportionately affect vulnerable populations such as the homeless due to their unique challenges. 6, 7 Homeless individuals often lack access to care potentially live in unsanitary or crowded places. These challenges make it difficult for homeless individuals to comply with recommendations for social distancing, frequent hygiene, and selfquarantine. Most published studies have been small or speculative in regards to the effect of COVID-19 on the homeless population.

The Emergency Department is in a unique position to evaluate the effect of COVID-19 on the homeless by serving as a medical and social safety net, resulting in disproportionate use by homeless individuals. 8 This study aims to use data from the ED and a citywide homeless database to identify whether COVID-19 affects homeless individuals more than the general public, hypothesizing a higher incidence of COVID-19 among homeless patients.

This is a retrospective study of homeless patients in the University of Louisville Health system from March 2019 to December 2020, excluding January and February 2020; these two months were excluded so we could make a balanced comparison between the two years to understand the impact of COVID-19 on (homeless) patient volumes. This study included any patient seen in the University of Louisville Emergency department identified as homeless and excluded patients under 18 years of age were excluded. To identify homeless patients, abstractors reviewed patient visits to the ED during the selected months for any who listed current address as a local shelter/half-way house or other form of unstable housing. If the patient's address was listed as homeless, no physical address, homeless shelter, no known address, or the address of a homeless shelter, they were deemed homeless. Patients with address left blank or an email address were excluded.

Data from all homeless services provided in Louisville, Kentucky are tracked through a statewide information system called Kentucky Homeless Management Information System (HMIS). Individuals in the HMIS database fit within the definition of a "homeless individual" created by the U.S. Department of Health and Human Services (Salhi): An individual who lacks housing … [or] a stable housing situation to which they can return. Thus, all individuals listed in the HMIS were considered homeless. We cross-referenced the list of HMIS individuals with a complete list of patients seen in the ED.

During the study period, [BLINDED FOR REVIEW] used antigen and PCR testing for COVID-19. All patients with negative antigen tests had a reflex to PCR. Positive antigen and polymerase chain reaction (PCR) tests were considered positive for COVID-19. Negative PCR was considered a negative COVID-19 test. Duplicate charts and test results were removed by patient name, date of birth, and medical record number.

We first compared unique patient visits within the homeless population and non-homeless population. We made comparisons for admissions data utilizing chi-square tests and an independent samples T-test for age. We calculated and present odds ratios with 95% Cis for chisquare findings. Next, we calculated percentage change in total visits between groups. Finally, we analyzed COVID-19 testing and positivity rates between groups; for this, we present an adjusted odds ratio after controlling for race, age, gender identity, and insurance status. IBM SPSS Statistics Version 27 was utilized for analyses.

The total number of unique [BLINDED FOR REVIEW] ED patients from March 2019 to Dec 2020, excluding Jan and Feb 2020 was 51,532. The total number of homeless patients to the [BLINDED FOR REVIEW] ED from March 2019 to Dec 2020, excluding Jan and Feb 2020 was 3911 (7.6% of ED patients). Table 1 provides demographics of homeless versus non-homeless patients during the study period. 

A total of 51,532 unique patients had 87,869 visits during the study period. There was a decrease in homeless patient visits over the time period of 18.1%, which was similar to the decrease in non-homeless patient visits (19.2%).

Analysis found that in our sample, 9,471 individuals had known COVID-19 testing results. In the [BLINDED FOR REVIEW] ED, 610 were positive (6.4% positivity rate). Of the 712 homeless individuals tested for COVID-19, 39 were positive (5.5% positivity rate). After adjusting for age, gender identity, race, and insurance there was not a statistically significant difference between homeless status and positive COVID tests, OR: 1.23 (0.88, 1.73).

This study aimed to identify whether COVID-19 affects homeless individuals disproportionately compared to the general public. All previous literature indicates that the higher disease burden, lack of access to social distancing, and poor hygiene would increase the risk of homeless individuals contracting COVID-19 and experiencing serious morbidity. While the rate of COVID-19 positive testing in homeless patients was higher than nonhomeless, adjustment for demographic parameters yielded no statistically significant difference between groups.

Approximately 1.4 million persons access emergency shelters or transitional housing each year. 2 These environments have increased risk for spreading communicable diseases. Apart from studies showing increased incidence of COVID-19 in homeless shelters, this is one of the first studies to examine the rate of COVID-19 among homeless and non-homeless individuals. 9, 10 During COVID-19 outbreaks in homeless shelters in San Francisco, researchers found a 66% J o u r n a l P r e -p r o o f positivity rate among shelter residents compared to the community incidence of 5.7%. 9 Other literature was speculative and warned of impending crisis among the homeless population. 11 Thi study's lack of increased incidence of COVID-19 among homeless patients, despite increased risk factors, might be explained by the increased sun exposure, more time spent outdoors, and decreased person-to-person contact. Research on the protective effect of vitamin D against COVID-19 infection has conflicting conclusions. One study from University of Chicago found increased risk of COVID-19 infection among vitamin D insufficient patients and black individuals, while another study from the UK demonstrated COVID-19 infection had no link with ethnicity or vitamin D levels. 12, 13 A meta-analysis found no difference in infection rate by vitamin D levels, but those with deficiency were more likely to have severe cases. 14 Homeless individuals may actually practice relative socially distancing by spending the majority of their days outdoors and in general having less employment. Some speculate that consistent baseline exposure to unhygienic environments bolsters the immune system (Herzberg Motivation Hygiene Theory).

[BLINDE FOR REVIEW] performed COVID-19 testing on all symptomatic patients in the ED and all admitted patients regardless of symptoms. Studies have shown a high incidence of asymptomatic COVID-19 at some homeless sites. 15, 10 Homeless individuals may have fewer symptoms with COVID-19 infection and thus be less likely to seek testing. Consequently, the true prevalence of COVID-19 in the homeless patients who utilize our ED could be underestimated.

With the numerous risk factors that homeless patients face, one could expect a higher admission rate among the homeless population for COVID-19. However, homeless patients in our study were less likely to be admitted to either the ICU or hospital. This contrasts with previous studies demonstrating homelessness as an independent risk factor for admission. 5 The lower homeless admission rate, in light of SARS-CoV-2 screening of all admitted patients, could indicate a relative undercapture of COVID-positive homeless patients.

This study has several limitations. First, this is a retrospective, single center study. With data from only one ED, it is difficult to capture population data on all homeless individuals in the city. Homeless patients are known to visit multiple EDs which could lead to COVID-19 positive individuals being missed. However, as the only academic hospital in the city, ULH serves a large portion of the indigent population. Second, the demographics and climate of Louisville's population may differ from other areas of the country. Compared to northern cities, Louisville does not experience freezing outdoor temperatures for as much of the year. Third, possible confounding variables were not examined, such as patient access to PPE, access to primary care providers, BMI, vitamin D status, amount of time spend outside, or coexisting substance use. Each of these factors could potentially confound the comparison between homeless and nonhomeless individuals.

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