Housing Status and Acute Care Use After Cancer Diagnosis.

This cohort study examines housing status and acute care use after a cancer diagnosis among individuals treated at a public hospital in San Francisco, California.

2023 Society for Academic Emergency Medicine Consensus Conference on Precision Emergency Medicine: Development of a policy-relevant, patient-centered research agenda.

OBJECTIVES: Precision medicine is data-driven health care tailored to individual patients based on their unique attributes, including biologic profiles, disease expressions, local environments, and socioeconomic conditions. Emergency medicine (EM) has been peripheral to the precision medicine discourse, lacking both a unified definition of precision medicine and a clear research agenda. We convened a national consensus conference to build a shared mental model and develop a research agenda for precision EM. METHODS: We held a conference to (1) define precision EM, (2) develop an evidence-based research agenda, and (3) identify educational gaps for current and future EM clinicians. Nine preconference workgroups (biomedical ethics, data science, health professions education, health care delivery and access, informatics, omics, population health, sex and gender, and technology and digital tools), comprising 84 individuals, garnered expert opinion, reviewed relevant literature, engaged with patients, and developed key research questions. During the conference, each workgroup shared how they defined precision EM within their domain, presented relevant conceptual frameworks, and engaged a broad set of stakeholders to refine precision EM research questions using a multistage consensus-building process. RESULTS: A total of 217 individuals participated in this initiative, of whom 115 were conference-day attendees. Consensus-building activities yielded a definition of precision EM and key research questions that comprised a new 10-year precision EM research agenda. The consensus process revealed three themes: (1) preeminence of data, (2) interconnectedness of research questions across domains, and (3) promises and pitfalls of advances in health technology and data science/artificial intelligence. The Health Professions Education Workgroup identified educational gaps in precision EM and discussed a training roadmap for the specialty. CONCLUSIONS: A research agenda for precision EM, developed with extensive stakeholder input, recognizes the potential and challenges of precision EM. Comprehensive clinician training in this field is essential to advance EM in this domain.

Incidence of Fit Test Failure During N95 Respirator Reuse and Extended Use.

Importance: The COVID-19 pandemic resulted in a widespread acute shortage of N95 respirators, prompting the Centers for Disease Control and Prevention to develop guidelines for extended use and limited reuse of N95s for health care workers (HCWs). While HCWs followed these guidelines to conserve N95s, evidence from clinical settings regarding the safety of reuse and extended use is limited. Objective: To measure the incidence of fit test failure during N95 reuse and compare the incidence between N95 types. Design, Setting, and Participants: This prospective cohort study, conducted from April 2, 2021, to July 15, 2022, at 6 US emergency departments (EDs), included HCWs who practiced N95 reuse for more than half of their clinical shift. Those who were unwilling to wear an N95 for most of their shift, repeatedly failed baseline fit testing, were pregnant, or had facial hair or jewelry that interfered with the N95 face seal were excluded. Exposures: Wearing the same N95 for more than half of each clinical shift and for up to 5 consecutive shifts. Participants chose an N95 model available at their institution; models were categorized into 3 types: dome (3M 1860R, 1860S, and 8210), trifold (3M 1870+ and 9205+), and duckbill (Halyard 46727, 46767, and 46827). Participants underwent 2 rounds of testing using a different mask of the same type for each round. Main Outcomes and Measures: The primary outcome was Occupational Safety and Health Administration-approved qualitative fit test failure. Trained coordinators conducted fit tests after clinical shifts and recorded pass or fail based on participants tasting a bitter solution. Results: A total of 412 HCWs and 824 N95s were fit tested at baseline; 21 N95s (2.5%) were withdrawn. Participants' median age was 34.5 years (IQR, 29.5-41.8 years); 252 (61.2%) were female, and 205 (49.8%) were physicians. The overall cumulative incidence of fit failure after 1 shift was 38.7% (95% CI, 35.4%-42.1%), which differed by N95 type: dome, 25.8% (95% CI, 21.2%-30.6%); duckbill, 28.3% (95% CI, 22.2%-34.7%); and trifold, 61.3% (95% CI, 55.3%-67.3%). The risk of fit failure was significantly higher for trifold than dome N95s (adjusted hazard ratio, 1.75; 95% CI, 1.46-2.10). Conclusions and Relevance: In this cohort study of ED HCWs practicing N95 reuse, fit failure occurred in 38.7% of masks after 1 shift. Trifold N95s had higher incidence of fit failure compared with dome N95s. These results may inform pandemic preparedness, specifically policies related to N95 selection and reuse practices.

Is the emergency department used as a substitute or a complement to primary care in Medicaid?

Policies to decrease low-acuity emergency department (ED) use have traditionally assumed that EDs are a substitute for unavailable primary care (PC). However, such policies can exacerbate ED overcrowding, rather than ameliorate it, if patients use EDs to complement, rather than substitute, their PC use. We tested whether Medicaid managed care enrolees visit the ED for nonemergent and PC treatable conditions to substitute for or to complement PC. Based on consumer choice theory, we modelled county-level monthly ED visit rate as a function of PC supply and used 2012-2015 New York Statewide Planning and Research Cooperative System (SPARCS) outpatient data and non-linear least squares method to test substitution vs complementarity. In the post-Medicaid expansion period (2014-2015), ED and PC are substitutes state-wide, but are complements in highly urban and poorer counties during nights and weekends. There is no evidence of complementarity before the expansion (2012-2013). Analyses by PC provider demonstrate that the relationship between ED and PC differs depending on whether PC is provided by physicians or advanced practice providers. Policies to reduce low-acuity ED use via improved PC access in Medicaid are likely to be most effective if they focus on increasing actual appointment availability, ideally by physicians, in areas with low PC provider supply. Different aspects of PC access may be differently related to low-acuity ED use.

Advance Care Planning Among Patients With Advanced Illness Presenting to the Emergency Department.

BACKGROUND: Advance care planning (ACP) benefits emergency department (ED) patients with advanced illness. Although Medicare implemented physician reimbursement for ACP discussions in 2016, early studies found limited uptake. OBJECTIVE: We conducted a pilot study to assess ACP documentation and billing to inform the development of ED-based interventions to increase ACP. METHODS: We conducted a retrospective chart review to quantify the proportion of ED patients with advanced illness with Physician Orders for Life-Sustaining Treatment (POLST) or coding of ACP discussion in the medical record. We surveyed a subset of patients via phone to evaluate ACP participation. RESULTS: Of 186 patients included in the chart review, 68 (37%) had a POLST and none had ACP discussions billed. Of 50 patients surveyed, 18 (36%) recalled prior ACP discussions. CONCLUSIONS: Given the low uptake of ACP discussions in ED patients with advanced illness, the ED may be an underused setting for interventions to increase ACP discussions and documentation.

Hospital variability in adoption of alcohol and drug screening in adult trauma patients.

BACKGROUND: Despite recommendations to screen all injured patients for substance use, single-center studies have reported underscreening. This study sought to determine if there was significant practice variability in adoption of alcohol and drug screening of injured patients among hospitals participating in the Trauma Quality Improvement Program. METHODS: This was a retrospective observational cross-sectional study of trauma patients 18 years or older in Trauma Quality Improvement Program 2017-2018. Hierarchical multivariable logistic regression modeled the odds of screening for alcohol and drugs via blood/urine test while controlling for patient and hospital variables. We identified statistically significant high and low-screening hospitals based on hospitals' estimated random intercepts and associated confidence intervals (CIs). RESULTS: Of 1,282,111 patients at 744 hospitals, 619,423 (48.3%) were screened for alcohol, and 388,732 (30.3%) were screened for drugs. Hospital-level alcohol screening rates ranged from 0.8% to 99.7%, with a mean rate of 42.4% (SD, 25.1%). Hospital-level drug screening rates ranged from 0.2% to 99.9% (mean, 27.1%; SD, 20.2%). A total of 37.1% (95% CI, 34.7-39.6%) of variance in alcohol screening and 31.5% (95% CI, 29.2-33.9%) of variance in drug screening were at the hospital level. Level I/II trauma centers had higher adjusted odds of alcohol screening (adjusted odds ratio [aOR], 1.31; 95% CI, 1.22-1.41) and drug screening (aOR, 1.16; 95% CI, 1.08-1.25) than Level III and nontrauma centers. We found 297 low-screening and 307 high-screening hospitals in alcohol after adjusting for patient and hospital variables. There were 298 low-screening and 298 high-screening hospitals for drugs. CONCLUSION: Overall rates of recommended alcohol and drug screening of injured patients were low and varied significantly between hospitals. These results underscore an important opportunity to improve the care of injured patients and reduce rates of substance use and trauma recidivism. LEVEL OF EVIDENCE: Prognostic and Epidemiological; Level III.

Cluster Analysis of the Highest Users of Medical, Behavioral Health, and Social Services in San Francisco.

BACKGROUND: In the City and County of San Francisco, frequent users of emergent and urgent services across different settings (i.e., medical, mental health (MH), substance use disorder (SUD) services) are referred to as high users of multiple systems (HUMS). While often grouped together, frequent users of the health care system are likely a heterogenous population composed of subgroups with differential management needs. OBJECTIVE: To identify subgroups within this HUMS population using a cluster analysis. DESIGN: Cross-sectional study of HUMS patients for the 2019-2020 fiscal year using the Coordinated Care Management System (CCMS), San Francisco Department of Public Health's integrated data system. PARTICIPANTS: We calculated use scores based on nine types of urgent and emergent medical, MH, and SUD services and identified the top 5% of HUMS patients. Through k-medoids cluster analysis, we identified subgroups of HUMS patients. MAIN MEASURES: Subgroup-specific demographic, comorbidity, and service use profiles. KEY RESULTS: The top 5% of HUMS patients in the study period included 2657 individuals; 69.7% identified as men and 66.5% identified as non-White. We detected 5 subgroups: subgroup 1 (N = 298, 11.2%) who were relatively younger with prevalent MH and SUD comorbidities, and MH services use; subgroup 2 (N = 478, 18.0%), who were experiencing homelessness, with multiple comorbidities, and frequent use of medical services; subgroup 3 (N = 449, 16.9%), who disproportionately self-identified as Black, with prolonged homelessness, multiple comorbidities, and persistent HUMS status; subgroup 4 (N = 690, 26.0%), who were relatively older, disproportionately self-identified as Black, with prior homelessness, multiple comorbidities, and frequent use of medical services; and subgroup 5 (N=742, 27.9%), who disproportionately self-identified as Latinx, were housed, with medical comorbidities and frequent medical service use. CONCLUSIONS: Our study highlights the heterogeneity of HUMS patients. Interventions must be tailored to meet the needs of these diverse patient subgroups.

Extended-Release Naltrexone and Case Management for Treatment of Alcohol Use Disorder in the Emergency Department.

STUDY OBJECTIVE: To assess the feasibility of initiating treatment for alcohol use disorder with extended-release naltrexone and case management services in the emergency department (ED) and measure the intervention's impact on daily alcohol consumption and quality of life. METHODS: This is a 12-week prospective open-label single-arm study of a multimodal treatment for alcohol use disorder consisting of monthly extended-release naltrexone injections and case management services initiated at an urban academic ED. Participants were actively drinking adult patients in ED with known or suspected alcohol use disorder and an AUDIT-C score more than 4. The main feasibility outcomes included the rates of participant enrollment, retention in the study, and continuing treatment after study completion. Efficacy outcomes were the change in daily alcohol consumption (drinks per day; 14 g ethanol per drink), measured by a 14-day timeline followback, and the change in quality of life measured with a single-item Kemp quality of life scale. RESULTS: One hundred seventy-nine patients were approached, and 32 were enrolled (18%). Of the 32 enrolled patients, 25 (78%) completed all visits, and 22 (69%) continued naltrexone after the trial. The mean baseline daily alcohol consumption was 7.6 drinks per day (interquartile range, 4.5, 13.4), and the mean quality of life was 3.6 (SD 1.7) on a 7-point scale. The median daily alcohol consumption change was -7.5 drinks per day (Hodges-Lehmann 95% confidence interval -8.6, -5.9). The mean quality of life change was 1.2 points (95% confidence interval 0.5, 1.9; P<.01). CONCLUSION: We found that initiation of treatment of alcohol use disorder with extended-release naltrexone and case management is feasible in an ED setting and observed significant reductions in drinking with improved quality of life in the short term. Multicenter randomized controlled trials are needed to further validate these findings.

Implementation of a Leave-behind Naloxone Program in San Francisco: A One-year Experience.

INTRODUCTION: In response to the ongoing opioid overdose crisis, US officials urged the expansion of access to naloxone for opioid overdose reversal. Since then, emergency medical services' (EMS) dispensing of naloxone kits has become an emerging harm reduction strategy. METHODS: We created a naloxone training and low-barrier distribution program in San Francisco: Project FRIEND (First Responder Increased Education and Naloxone Distribution). The team assembled an advisory committee of stakeholders and subject-matter experts, worked with local and state EMS agencies to augment existing protocols, created training curricula, and developed a naloxone-distribution data collection system. Naloxone kits were labeled for registration and data tracking. Emergency medical technicians and paramedics were asked to distribute naloxone kits to any individuals (patient or bystander) they deemed at risk of experiencing or witnessing an opioid overdose, and to voluntarily register those kits. RESULTS: Training modalities included a video module (distributed to over 700 EMS personnel) and voluntary, in-person training sessions, attended by 224 EMS personnel. From September 25, 2019-September 24, 2020, 1,200 naloxone kits were distributed to EMS companies. Of these, 232 kits (19%) were registered by EMS personnel. Among registered kits, 146 (63%) were distributed during encounters for suspected overdose, and 103 (44%) were distributed to patients themselves. Most patients were male (n = 153, 66%) and of White race (n = 124, 53%); median age was 37.5 years (interquartile range 31-47). CONCLUSION: We describe a successful implementation and highlight the feasibility of a low-threshold, leave-behind naloxone program. Collaboration with multiple entities was a key component of the program's success.

Analysis of Emergency Department Encounters Among High Users of Health Care and Social Service Systems Before and During the COVID-19 Pandemic.

Importance: Although the general US population had fewer emergency department (ED) visits during the COVID-19 pandemic, patterns of use among high users are unknown. Objectives: To examine natural trends in ED visits among high users of health and social services during an extended period and assess whether these trends differed during COVID-19. Design, Setting, and Participants: This retrospective cohort study combined data from 9 unique cohorts, 1 for each fiscal year (July 1 to June 30) from 2012 to 2021, and used mixed-effects, negative binomial regression to model ED visits over time and assess ED use among the top 5% of high users of multiple systems during COVID-19. Data were obtained from the Coordinated Care Management System, a San Francisco Department of Public Health platform that integrates medical and social information with service use. Exposures: Fiscal year 2020 was defined as the COVID-19 year. Main Outcomes and Measures: Measured variables were age, gender, language, race and ethnicity, homelessness, insurance status, jail health encounters, mental health and substance use diagnoses, and mortality. The main outcome was annual mean ED visit counts. Incidence rate ratios (IRRs) were used to describe changes in ED visit rates both over time and in COVID-19 vs non-COVID-19 years. Results: Of the 8967 participants, 3289 (36.7%) identified as White, 3005 (33.5%) as Black, and 1513 (16.9%) as Latinx; and 7932 (88.5%) preferred English. The mean (SD) age was 46.7 (14.2) years, 6071 (67.7%) identified as men, and 7042 (78.5%) had experienced homelessness. A statistically significant decrease was found in annual mean ED visits among high users for every year of follow-up until year 8, with the largest decrease occurring in the first year of follow-up (IRR, 0.41; 95% CI, 0.40-0.43). However, during the pandemic, ED visits decreased 25% beyond the mean reduction seen in prepandemic years (IRR, 0.75; 95% CI, 0.72-0.79). Conclusions and Relevance: In this study, multiple cohorts of the top 5% of high users of multiple health care systems in San Francisco had sustained annual decreases in ED visits from 2012 to 2021, with significantly greater decreases during COVID-19. Further research is needed to elucidate pandemic-specific factors associated with these findings and understand how this change in use was associated with health outcomes.

Association of Shelter-in-Place Hotels With Health Services Use Among People Experiencing Homelessness During the COVID-19 Pandemic.

Importance: Some jurisdictions used hotels to provide emergency noncongregate shelter and support services to reduce the risk of COVID-19 infection among people experiencing homelessness (PEH). A subset of these shelter-in-place (SIP) hotel guests were high users of acute health services, and the association of hotel placement with their service use remains unknown. Objective: To evaluate the association of SIP hotel placements with health services use among a subset of PEH with prior high acute health service use. Design, Setting, and Participants: This study used a matched retrospective cohort design comparing health services use between PEH with prior high service use who did and did not receive a SIP hotel placement, from April 2020 to April 2021. The setting was 25 SIP hotels in San Francisco, California, with a daily capacity of 2500 people. Participants included PEH who were among the top 10% high users of acute medical, mental health, and substance use services and who had 3 or more emergency department (ED) visits in the 9 months before the implementation of the SIP hotel program. Data analysis for this study was performed from February 2021 to May 2022. Exposures: SIP hotel placement with on-site supportive services. Main Outcomes and Measures: The primary outcomes were ED visits, hospitalizations and bed days, psychiatric emergency visits, psychiatric hospitalizations, outpatient mental health and substance use visits, and outpatient medical visits. Results: Of 2524 SIP guests with a minimum of 90-day stays, 343 (13.6%) met criteria for high service use. Of 686 participants with high service use (343 SIP group; 343 control), the median (IQR) age was 54 (43-61) years, 485 (70.7%) were male, 283 (41.3%) were Black, and 337 (49.1%) were homeless for more than 10 years. The mean number of ED visits decreased significantly in the high-user SIP group (1.84 visits [95% CI, 1.52-2.17 visits] in the 90 days before SIP placement to 0.82 visits [95% CI, 0.66-0.99 visits] in the 90 days after SIP placement) compared with high-user controls (decrease from 1.33 visits [95% CI, 1.39-1.58 visits] to 1.00 visits [95% CI, 0.80-1.20 visits]) (incidence rate ratio [IRR], 0.60; 95% CI, 0.47-0.75; P < .001). The mean number of hospitalizations decreased significantly from 0.41 (95% CI, 0.30-0.51) to 0.14 (95% CI, 0.09-0.19) for SIP guests vs 0.27 (95% CI, 0.19-0.34) to 0.22 (95% CI, 0.15-0.29) for controls (IRR, 0.41; 95% CI, 0.27-063; P < .001). Inpatient hospital days decreased significantly from a mean of 4.00 (95% CI, 2.44-5.56) to 0.81 (95% CI, 0.40-1.23) for SIP guests vs 2.27 (95% CI, 1.27-3.27) to 1.85 (95% CI, 1.06-2.65) for controls (IRR, 0.25; 95% CI, 0.12-0.54; P < .001), as did psychiatric emergency visits, from a mean of 0.03 (95% CI, 0.01-0.05) to 0.01 (95% CI, 0.00-0.01) visits for SIP guests vs no change in the control group (IRR, 0.25; 95% CI, 0.11-0.51; P < .001). Conclusions and Relevance: These findings suggest that in a population of PEH with high use of acute health services, SIP hotel placement was associated with significantly reduced acute care use compared with high users without a placement.

Mortality Among People Experiencing Homelessness in San Francisco During the COVID-19 Pandemic.

Importance: There has been recent media attention on the risk of excess mortality among homeless individuals during the COVID-19 pandemic, yet data on these deaths are limited. Objectives: To quantify and describe deaths among people experiencing homelessness in San Francisco during the COVID-19 pandemic and to compare the characteristics of these deaths with those in prior years. Design, Setting, and Participants: A cross-sectional study tracking mortality among people experiencing homelessness from 2016 to 2021 in San Francisco, California. All deceased individuals who were homeless in San Francisco at the time of death and whose deaths were processed by the San Francisco Office of the Chief Medical Examiner were included. Data analysis was performed from August to October 2021. Exposure: Homelessness, based on homeless living status in an administrative database. Main Outcomes and Measures: Descriptive statistics were used to understand annual trends in demographic characteristics, cause and manner of death (based on autopsy), substances present in toxicology reports, geographic distribution of deaths, and use of health and social services prior to death. Total estimated numbers of people experiencing homelessness in San Francisco were assessed through semiannual point-in-time counts. The 2021 point-in-time count was postponed owing to the COVID-19 pandemic. Results: In San Francisco, there were 331 deaths among people experiencing homelessness in the first year of the COVID-19 pandemic (from March 17, 2020, to March 16, 2021). This number was more than double any number in previous years (eg, 128 deaths in 2016, 128 deaths in 2017, 135 deaths in 2018, and 147 deaths in 2019). Most individuals who died were male (268 of 331 [81%]). Acute drug toxicity was the most common cause of death in each year, followed by traumatic injury. COVID-19 was not listed as the primary cause of any deaths. The proportion of deaths involving fentanyl increased each year (present in 52% of toxicology reports in 2019 and 68% during the pandemic). Fewer decedents had contacts with health services in the year prior to their death during the pandemic than in prior years (13% used substance use disorder services compared with 20% in 2019). Conclusions and Relevance: In this cross-sectional study, the number of deaths among people experiencing homelessness in San Francisco increased markedly during the first year of the COVID-19 pandemic. These findings may guide future interventions to reduce mortality among individuals experiencing homelessness.

Understanding the association between frequent emergency department use and jail incarceration: A cross-sectional analysis.

BACKGROUND: Frequent emergency department (ED) use and incarceration can be driven by underlying structural factors and social needs. If frequent ED users are at increased risk for incarceration, ED-based interventions could be developed to mitigate this risk. The objective of this study was to determine whether frequent ED use is associated with incarceration. METHODS: We conducted a retrospective cross-sectional study of 46,752 individuals in San Francisco Department of Public Health's interagency, integrated Coordinated Care Management System (CCMS) during fiscal year 2018-2019. The primary exposure was frequency of ED visits, and the primary outcome was presence of any county jail incarceration during the study period. We performed descriptive and multivariable analysis to determine the association between the frequency of ED use and jail encounters. RESULTS: The percentage of those with at least one episode of incarceration during the study period increased with increasing ED visit frequency. Unadjusted odds of incarceration increased with ED use frequency: odds ratio (OR) = 2.14 (95% confidence interval [CI] = 1.94-2.35) for infrequent use, OR = 4.98 (95% CI = 4.43-5.60) for those with frequent ED use, and OR = 12.33 (95% CI = 9.59-15.86) for those with super-frequent ED use. After adjustment for observable confounders, the odds of incarceration for those with super-frequent ED use remained elevated at 2.57 (95% CI = 1.94-3.41). Of those with super-frequent ED use and at least one jail encounter, 18% were seen in an ED within 30 days after release from jail and 25% were seen in an ED within 30 days prior to arrest. CONCLUSIONS: Frequent ED use is independently associated with incarceration. The ED may be a site for intervention to prevent incarceration among frequent ED users by addressing unmet social needs.

Effect of extended-release naltrexone on alcohol consumption: a systematic review and meta-analysis.

AIMS: The aims of this study were to (1) estimate the effect of extended-release naltrexone compared with placebo on alcohol consumption in patients with alcohol use disorder (AUD) and (2) conduct pre-planned subgroup analyses to test whether being abstinent when initiating treatment (lead-in abstinence) or the duration of treatment improves treatment efficacy. DESIGN: Systematic review and random-effects meta-analysis of blinded randomized placebo-controlled trials reporting the effect extended-release naltrexone on alcohol consumption. SETTING: Outpatient clinics. PARTICIPANTS: Seven trials evaluating a total of 1500 adults with AUD receiving monthly injections of either placebo or extended-release naltrexone at doses of 150-400 mg for 2-6 months and some form of behavioral therapy. MEASUREMENTS: Pooled weighted mean difference (WMD) in drinking days per month and heavy drinking days per month. FINDINGS: The WMD was -2.0 [95% confidence interval (CI) = -3.4, -0.6; P = 0.03] in favor of extended-release naltrexone for drinking days per month and -1.2 (95% CI = -0.2, -2.1; P = 0.02) for heavy drinking days per month, indicating that treatment resulted in two fewer drinking days per month and 1.2 fewer heavy drinking days per month compared with placebo. Trials not requiring lead-in abstinence and those lasting longer than 3 months reported larger reductions in heavy drinking days per month; WMD -2.0 (95% CI = -3.52, -0.48; P = 0.01) and -1.9 (95% CI = -3.2, -0.5; P = 0.01), respectively. In all cases, the I2 statistics (0-7.2%) did not suggest substantial heterogeneity. CONCLUSIONS: Extended-release naltrexone reduces drinking days and heavy drinking days per month compared with placebo. Reductions are larger with a longer duration of treatment.

Using a "Big Events" framework to understand emergency department use among women experiencing homelessness or housing instability in San Francisco during the COVID-19 pandemic.

BACKGROUND: The COVID-19 pandemic created a major public health crisis that disrupted economic systems, social networks and individual behaviors, which led to changes in patterns of health care use. Factors associated with emergency department (ED) visits during the pandemic among especially high-risk individuals are unknown. We used a "Big Events" approach, which considers major disruptions that create social instability, to investigate ED use in people experiencing homelessness or housing instability, many of whom use drugs. METHODS: Between July and December 2020, we conducted a community-based San Francisco study to compare homeless and unstably housed (HUH) women who did and did not use an ED during the first 10 months of the pandemic. RESULTS: Among 128 study participants, 34% had ≥1 ED visit during the pandemic. In adjusted analysis, factors significantly associated with ED use included experiencing homelessness, cocaine use and increased difficulties receiving drug use treatment during the pandemic. CONCLUSION: These findings build on the "Big Events" approach to considering risk pathways among people who use drugs. They suggest the importance of ensuring access to housing and low-barrier non-COVID health services, including drug treatment, alongside crisis management activities, to reduce the health impacts of public health crises.