Effectiveness of the 2023-2024 Formulation of the COVID-19 Messenger RNA Vaccine.

BACKGROUND: The purpose of this study was to evaluate whether the 2023-2024 formulation of the coronavirus disease 2019 (COVID-19) messenger RNA vaccine protects against COVID-19. METHODS: Cleveland Clinic employees when the 2023-2024 formulation of the COVID-19 messenger RNA vaccine became available to employees were included. Cumulative incidence of COVID-19 over the following 17 weeks was examined prospectively. Protection provided by vaccination (analyzed as a time-dependent covariate) was evaluated using Cox proportional hazards regression, with time-dependent coefficients used to separate effects before and after the JN.1 lineage became dominant. The analysis was adjusted for the propensity to get tested, age, sex, pandemic phase when the last prior COVID-19 episode occurred, and the number of prior vaccine doses. RESULTS: Among 48 210 employees, COVID-19 occurred in 2462 (5.1%) during the 17 weeks of observation. In multivariable analysis, the 2023-2024 formula vaccinated state was associated with a significantly lower risk of COVID-19 before the JN.1 lineage became dominant (hazard ratio = .58; 95% confidence interval [CI] = .49-.68; P < .001), and lower risk but one that did not reach statistical significance after (hazard ratio = .81; 95% CI = .65-1.01; P = .06). Estimated vaccine effectiveness was 42% (95% CI = 32-51) before the JN.1 lineage became dominant, and 19% (95% CI = -1-35) after. Risk of COVID-19 was lower among those previously infected with an XBB or more recent lineage and increased with the number of vaccine doses previously received. CONCLUSIONS: The 2023-2024 formula COVID-19 vaccine given to working-aged adults afforded modest protection overall against COVID-19 before the JN.1 lineage became dominant, and less protection after.

Association Between Causative Pathogen and Occurrence of Infection-Related Glomerulonephritis in Infective Endocarditis.

Among patients with pathologically proven infective endocarditis, the association of pathogen with occurrence of infection-related glomerulonephritis (IRGN) was examined in 48 case patients with IRGN and 192 propensity score-matched controls. Bartonella was very strongly associated with IRGN (odds ratio, 38.2 [95% confidence interval, 6.7-718.8]; P < .001); other microorganisms were not.

Protection Conferred by Delta and BA.1/BA.2 Infection Against BA.4/BA.5 Infection and Hospitalization: A Retrospective Cohort Study.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 immunity has declined with subsequent waves and accrual of viral mutations. In vitro studies raise concern for immune escape by BA.4/BA.5, and a study in Qatar showed moderate protection, but these findings have yet to be reproduced. METHODS: This retrospective cohort study included individuals tested for coronavirus disease 2019 by polymerase chain reaction during Delta or BA.1/BA.2 and retested during BA.4/BA.5. The preventable fraction (PF) was calculated as ratio of the infection to the hospitalization rate for initially positive patients divided by the ratio for initially negative patients, stratified by age and adjusted for age, sex, comorbid conditions, and vaccination using logistic regression. RESULTS: A total of 20 987 patients met inclusion criteria. Prior Delta infection provided no protection against BA.4/BA.5 infection (adjusted PF, 11.9% [95% confidence interval, .8%-21.8%]); P = .04) and minimal protection against hospitalization (10.7% [4.9%-21.7%]; P = .003). In adjusted models, prior BA.1/BA.2 infection provided 45.9% (95% confidence interval, 36.2%-54.1%; P < .001) protection against BA.4/BA.5 reinfection and 18.8% (10.3%-28.3%; (P < .001) protection against hospitalization. Up-to-date vaccination provided modest protection against reinfection with BA.4/BA.5 and hospitalization. CONCLUSIONS: Prior infection with BA.1/BA.2 and up-to-date vaccination provided modest protection against infection with BA.4/BA.5 and hospitalization, while prior Delta infection provided minimal protection against hospitalization and none against infection.

Protection Against the Omicron Variant Offered by Previous Severe Acute Respiratory Syndrome Coronavirus 2 Infection: A Retrospective Cohort Study.

BACKGROUND: Previous infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) provides strong protection against future infection. There is limited evidence on whether such protection extends to the Omicron variant. METHODS: This retrospective cohort study included 635 341 patients tested for SARS-CoV-2 via polymerase chain reaction from 9 March 2020 to 1 March 2022. Patients were analyzed according to the wave in which they were initially infected. The primary outcome was reinfection during the Omicron period (20 December 2021-1 March 2022). We used a multivariable model to assess the effects of prior infection and vaccination on hospitalization. RESULTS: Among the patients tested during the Omicron wave, 30.6% tested positive. Protection of prior infection against reinfection with Omicron ranged from 18.0% (95% confidence interval [CI], 13.0-22.7) for patients infected in wave 1 to 69.2% (95% CI, 63.4-74.1) for those infected in the Delta wave. In adjusted models, previous infection reduced hospitalization by 28.5% (95% CI, 19.1-36.7), whereas full vaccination plus a booster reduced it by 59.2% (95% CI, 54.8-63.1). CONCLUSIONS: Previous infection offered less protection against Omicron than was observed in past waves. Immunity against future waves will likely depend on the degree of similarity between variants.

Veno-arterial extracorporeal membrane oxygenation versus standard medical management for massive pulmonary embolism.

PURPOSE: There is limited research on the use and outcomes of veno-arterial extracorporeal membrane oxygenation (VA-ECMO) treatment for massive pulmonary embolism (PE). This study compared VA-ECMO treatment for massive PE versus patients treated medically. MATERIALS AND METHODS: Patients diagnosed with massive PE at one hospital system were reviewed. VA-ECMO and non-ECMO groups were compared by t test and Chi-square. Mortality risk factors were identified by logistic regression. Survival was assessed by Kaplan Meier and propensity matching of groups. RESULTS: Ninety-two patients were included (22 VA-ECMO and 70 non-ECMO). Age (OR 1.08, 95% CI 1.03-1.13), arterial SBP (OR 0.97, 95% CI 0.94-0.99), albumin (OR 0.3, 95% CI 0.1-0.8), and phosphorus (OR 2.0, 95% CI 1.4-3.17) were independently associated with 30-day mortality. Alkaline phosphate (OR 1.03, 95% CI 1.01-1.05) and SOFA score (OR 1.3, 95% CI 1.06-1.51) were associated with 1-year mortality. Propensity matching showed no difference in 30-day (59% VA-ECMO versus 72% non-ECMO, p = 0.363) or 1-year survival (50% VA-ECMO versus 64% non-ECMO, p = 0.355). CONCLUSIONS: Patients treated with VA-ECMO for massive PE and medically treated patients have similar short- and long-term survival. Further research is needed to define clinical recommendations and benefits of intensive therapy such as VA-ECMO in this critically ill population.

Necessity of Coronavirus Disease 2019 (COVID-19) Vaccination in Persons Who Have Already Had COVID-19.

BACKGROUND: The aim was to evaluate the necessity of coronavirus disease 2019 (COVID-19) vaccination in persons with prior COVID-19. METHODS: Employees of the Cleveland Clinic working in Ohio on 16 December 2020, the day COVID-19 vaccination was started, were included. Anyone who tested positive for COVID-19 at least once before the study start date was considered previously infected. One was considered vaccinated 14 days after receiving the second dose of COVID-19 mRNA vaccine. Cumulative incidences of COVID-19, symptomatic COVID-19, and hospitalizations for COVID-19 were examined over the next year. RESULTS: Among 52 238 employees, 4718 (9%) were previously infected and 36 922 (71%) were vaccinated by the study's end. Cumulative incidence of COVID-19 was substantially higher throughout for those previously uninfected who remained unvaccinated than for all other groups, lower for the vaccinated than unvaccinated, and lower for those previously infected than those not. Incidence of COVID-19 increased dramatically in all groups after the Omicron variant emerged. In multivariable Cox proportional hazards regression, both prior COVID-19 and vaccination were independently associated with significantly lower risk of COVID-19. Among previously infected subjects, a lower risk of COVID-19 overall was not demonstrated, but vaccination was associated with a significantly lower risk of symptomatic COVID-19 in both pre-Omicron (HR, .60; 95% CI, .40-.90) and Omicron (HR, .36; 95% CI, .23-.57) phases. CONCLUSIONS: Both previous infection and vaccination provide substantial protection against COVID-19. Vaccination of previously infected individuals does not provide additional protection against COVID-19 for several months, but after that provides significant protection at least against symptomatic COVID-19.

Coronavirus Disease 2019 Vaccine Boosting in Previously Infected or Vaccinated Individuals.

BACKGROUND: The purpose of this study was to determine whether boosting previously infected or vaccinated individuals with a vaccine developed for an earlier variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protects against the Omicron variant. METHODS: Employees of Cleveland Clinic, previously infected with or vaccinated against coronavirus disease 2019 (COVID-19) and working the day the Omicron variant was declared a variant of concern, were included. The cumulative incidence of COVID-19 was examined over 2 months during an Omicron variant surge. Protection provided by boosting was evaluated using Cox proportional hazards regression. Analyses were adjusted for time since proximate SARS-CoV-2 exposure. RESULTS: Among 39 766 employees, 8037 (20%) previously infected and the remaining previously vaccinated, COVID-19 occurred in 6230 (16%) during the study. Risk of COVID-19 increased with time since proximate SARS-CoV-2 exposure, and boosting protected those >6 months since prior infection or vaccination. In multivariable analysis, boosting was independently associated with lower risk of COVID-19 among those vaccinated but not previously infected (hazard ratio [HR], .43; 95% confidence interval [CI], .41-.46) as well as those previously infected (HR, .66; 95% CI, .58-.76). Among those previously infected, receipt of 2 compared with 1 dose of vaccine was associated with higher risk of COVID-19 (HR, 1.54; 95% CI, 1.21-1.97). CONCLUSIONS: Administering a COVID-19 vaccine not designed for the Omicron variant >6 months after prior infection or vaccination protects against Omicron variant infection. There is no advantage to administering more than 1 dose of vaccine to previously infected persons.

Decreased frequency of transplantation and lower post-transplant survival free of re-transplantation in LVAD patients with the new heart transplant allocation system.

PURPOSE: To evaluate the effect of the new heart transplant (HT) allocation system in left ventricular assist device (LVAD) supported patients listed as bridge to transplantation (BTT). METHODS: Adult patients who were listed for HT between October 18, 2016 and October 17, 2019, and were supported with an LVAD, enrolled in the UNOS database were included in this study. Patients were classified in the old or new system if they were listed or transplanted before or after October 18, 2018, respectively. RESULTS: A total of 3261 LVAD patients were listed for transplant. Of these, 2257 were classified in the old and 1004 in the new system. The cumulative incidence of death or removal from the transplant list due to worsening clinical status at 360-days after listing was lower in the new system (4% vs. 7%, P = .011). LVAD Patients listed in the new system had a lower frequency of transplantation within 360-days of listing (52% vs. 61%, P < .001). A total of 1843 LVAD patients were transplanted, 1004 patients in the old system and 839 patients in the new system. The post-transplant survival at 360 days was similar between old and new systems (92.3% vs. 90%, P = .08). However, LVAD patients transplanted in the new system had lower frequency of the combined endpoint, freedom of death or re-transplantation at 360 days (92.2% vs. 89.6%, P = .046). CONCLUSION: The new HT allocation system has affected the LVAD-BTT population significantly. On the waitlist, LVAD patients have a decreased cumulative frequency of transplantation and a concomitant decrease in death or delisting due to worsening status. In the new system, LVAD patients have a decreased survival free of re-transplantation at 360 days post-transplant.

Clinical and Echocardiographic Characteristics of Bartonella Infective Endocarditis: An 8-Year Single-Centre Experience in the United States.

BACKGROUND: Infective endocarditis due to Bartonella species is rare. The clinical and echocardiographic characteristics are not well defined. We aimed to investigate the clinical and echocardiographic findings of Bartonella endocarditis in the contemporary era. METHODS: The infective endocarditis (IE) registry and echocardiographic database at our institution were retrospectively analysed to evaluate the clinical and echocardiographic features of Bartonella endocarditis. RESULTS: Between January 2008 and December 2015, there were 11 patients with Bartonella IE (0.84% among a total of 1,308 cases of definite IE): median age 54 (30-69) years, all male, 9 Caucasian, 10 had a history of cat exposure, 10 had a pre-existing valvulopathy including 6 patients with a prosthetic valve with prosthesis age range between 3 to 5 years and 1 patient with implantable cardioverter defibrillator (ICD). Bartonella henselae was responsible for all the cases. Echocardiographic evidence of IE was found in 6 of 11 patients on transthoracic echocardiography (TTE), and 6 of 8 on transoesophageal echocardiography (TEE). Bartonella IE was associated with significant valvular destruction and dysfunction on echocardiography. Nine (9) patients were managed surgically with excellent outcomes, including two patients who failed initial medical therapy. Two (2) patients who were managed medically had progression of valvular dysfunction. At a median follow-up of 6 months, there were no deaths attributable to IE or other cardiovascular causes. CONCLUSION: In a contemporary single-centre cohort in the United States, Bartonella IE remains rare, but should be considered when pathogen could not be identified in patients with suspected IE, especially those with prosthetic valves or bicuspid aortic valve (BAV). The vast majority of patients with Bartonella IE were managed surgically with excellent outcomes.

Changes in heart transplant waitlist and posttransplant outcomes in patients with restrictive and hypertrophic cardiomyopathy with the new heart transplant allocation system.

Historically, patients with restrictive (RCM) and hypertrophic cardiomyopathy (HCM) experienced longer wait-times for heart transplant (HT) and increased waitlist mortality. Recently, a new HT allocation system was implemented in the United States. We sought to determine the impact of the new HT system on RCM/HCM patients. Adult patients with RCM/HCM listed for HT between November 2015 and September 2019 were identified from the UNOS database. Patients were stratified into two groups: old system and new system. We identified 872 patients who met inclusion criteria. Of these, 608 and 264 were classified in the old and new system groups, respectively. The time in the waitlist was shorter (25 vs. 54 days, P < .001), with an increased frequency of HT in the new system (74% vs. 68%, P = .024). Patients who were transplanted in the new system had a longer ischemic time, increased use of temporary mechanical circulatory support and mechanical ventilation. There was no difference in posttransplant survival at 9 months (91.1% vs. 88.9%) (p = .4). We conclude that patients with RCM/HCM have benefited from the new HT allocation system, with increased access to HT without affecting short-term posttransplant survival.

Increased frequency of heart transplantation, shortened waitlist time and preserved post-transplant survival in adults with congenital heart disease, on the new heart transplant allocation system.

Historically, adult congenital patients have longer waitlist time and worse outcomes on the heart transplant waitlist as well as poorer early post-transplant survival. A new heart transplantation allocation system was implemented in the United States on October 18, 2018. The effect of the new allocation system on adult congenital patients is unknown. Adult congenital patients listed for transplantation between November 1, 2015 and September 30, 2019 registered in the United Network for Organ Sharing were included in the study. October 18, 2018 was used as the limit to distribute listed and transplanted patients into old and new groups. A total of 399 patients were listed for heart transplant only, 284 in the old system and 115 in the new system. Clinical characteristics were similar between both groups. The cumulative incidence of poor outcome on the transplant list was similar in both groups (P = .23), but the cumulative incidence of transplant was higher in the new system group (P < .009) and was associated with a shorter waitlist time. The one-year post-transplant outcome was similar between old and new groups (P = .37). The new allocation system has benefited adult congenital patients with increased cumulative frequency of transplantation without worsening short-term survival after transplantation.

Distribution of Transmission Potential During Nonsevere COVID-19 Illness.

BACKGROUND: Patients recovering from coronavirus disease 2019 (COVID-19) often continue to test positive for the causative virus by polymerase chain reaction (PCR) even after clinical recovery, thereby complicating return-to-work plans. The purpose of this study was to evaluate transmission potential of COVID-19 by examining viral load with respect to time. METHODS: Health care personnel (HCP) at Cleveland Clinic diagnosed with COVID-19, who recovered without needing hospitalization, were identified. Threshold cycles (Ct) for positive PCR tests were obtained and viral loads calculated. The association of viral load with days since symptom onset was examined in a multivariable regression model, which was reduced by stepwise backward selection to only keep variables significant at a level of .05. Viral loads by day since symptom onset were predicted using the model and transmission potential evaluated by examination of a viral load-time curve. RESULTS: Over 6 weeks, 230 HCP had 528 tests performed. Viral loads declined by orders of magnitude within a few days of symptom onset. The only variable significantly associated with viral load was time since onset of symptoms. Of the area under the curve (AUC) spanning symptom onset to 30 days, 96.9% lay within the first 7 days, and 99.7% within 10 days. Findings were very similar when validated using split-sample and 10-fold cross-validation. CONCLUSIONS: Among patients with nonsevere COVID-19, viral loads in upper respiratory specimens peak by 2 or 3 days from symptom onset and decrease rapidly thereafter. The vast majority of the viral load-time AUC lies within 10 days of symptom onset.

A Direct Comparison of Enhanced Saliva to Nasopharyngeal Swab for the Detection of SARS-CoV-2 in Symptomatic Patients.

The ongoing coronavirus disease 2019 (COVID-19) pandemic has resulted in shortages of nasopharyngeal swabs (NPS) and viral transport media, necessitating the search for alternate diagnostic specimens, such as saliva. We directly compared matched saliva and NPS specimens from symptomatic patients suspected of having COVID-19. An enhanced saliva specimen (i.e., strong sniff, elicited cough, and collection of saliva/secretions) was collected without transport medium prior to collection of NPS from 224 patients with symptoms deemed consistent with COVID-19. Both specimens were tested with the CDC 2019 nCoV real-time RT-PCR diagnostic panel (4 February 2020 version), with the NPS result used as the reference standard. For the 216 patients included in the final analysis, there was 100% positive agreement (38/38 positive specimens) and 99.4% negative agreement (177/178 negative specimens). The one discrepant specimen had the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) confirmed in the saliva specimen using an alternate FDA EUA assay. The overall mean difference in cycle threshold (CT ) values for the positive NPS and saliva specimens was -3.61 (95% confidence interval [CI], -5.78 to -1.44; P = 0.002). An enhanced saliva specimen performed as well as NPS for the qualitative detection of SARS-CoV-2 in symptomatic patients, although the overall mean viral load in saliva was lower.

Matched retrospective study of infective endocarditis among solid organ transplant recipients compared to non-transplant: Seven-year experience in a US Referral Center.

BACKGROUND: Infective endocarditis (IE) is a rare complication following solid organ transplant (SOT); data on the clinical features and outcomes of IE in SOT recipients in the modern era are limited. METHODS: We conducted a single-center retrospective cohort study of IE diagnosed from 1/2008-12/2014 in SOT recipients, who were matched by age and microorganism to cases of IE in non-SOT, to describe the clinical features and outcomes. RESULTS: There were 14 cases of IE identified in SOT recipients matched to 56 non-SOT controls. Median time from transplant to IE was 1017 days (IQR 379-1830). Compared to non-SOT patients, SOT patients were more likely to be undergoing current hemodialysis (16% vs 36%) and to possess indwelling central venous catheters within the 30 days prior to diagnosis of IE (27% vs 50%). No SOT patients had documented drug use as a risk factor for IE whereas 6 (11%) non-SOT did. Enterococcus was the most common etiologic agent and was isolated in 50% of cases; only one fungal infection was identified, a mixed infection with Candida. Thirty-day mortality was 14% in SOT patients, significantly higher versus no deaths in non-SOT (P = .037). CONCLUSIONS: The present study illustrates a change in epidemiology of IE in SOT patients characterized by IE that generally occurs more than one-year post-transplant, is due to bacterial infection rather than fungus, and appears to be health care associated. Multicenter studies are merited to explore transplant-specific risk factors for IE in the special population of SOT patients.

Contemporary Outcomes of Pulmonary Valve Endocarditis: A 16-Year Single Centre Experience.

BACKGROUND: Limited data exist regarding the clinical characteristics and contemporary outcomes of patients with pulmonary valve (PoV) infective endocarditis (IE). METHODS: This is a retrospective cohort study of patients with a confirmed diagnosis of IE affecting the PoV at our centre between January 2002 and October 2018. Electronic medical records were reviewed to gather the clinical and echocardiographic variables. The population was subdivided according to risk factor profiles: group 1: miscellaneous risk factors; group 2: patients with congenital heart disease (CHD); and group 3: patients who inject drugs (PWID). The primary outcome was all-cause mortality. RESULTS: Out of 2,124 cases of IE during the study period, 24 (1.1%) patients had PoV IE. The majority of cases of PoV IE occurred in patients with prosthetic valves (54.2%). Coagulase-negative Staphylococci species were the most common micro-organisms. Seventy-five per cent (75%) of the patients required surgical management. The median follow-up was 2.8 years (interquartile range: 0.2-5.3 years). Patients with miscellaneous risk factors were older (p<0.01), and had higher rates of hypertension (p=0.01) and hyperlipidaemia (p=0.04). There was a statistically significant difference in survival between the groups (p=0.03), mainly driven by better outcomes of patients with CHD, compared to those with miscellaneous risk factors. CONCLUSIONS: In a contemporary 16-year series, a high proportion of patients with PoV IE required surgical management. Patients with PoV IE and CHD had better survival, compared to patients with miscellaneous risk factors at a median follow-up of 2.8 years.

2018 Infectious Diseases Society of America Clinical Practice Guideline for the Management of Outpatient Parenteral Antimicrobial Therapy.

A panel of experts was convened by the Infectious Diseases Society of America (IDSA) to update the 2004 clinical practice guideline on outpatient parenteral antimicrobial therapy (OPAT) [1]. This guideline is intended to provide insight for healthcare professionals who prescribe and oversee the provision of OPAT. It considers various patient features, infusion catheter issues, monitoring questions, and antimicrobial stewardship concerns. It does not offer recommendations on the treatment of specific infections. The reader is referred to disease- or organism-specific guidelines for such support.

2018 Infectious Diseases Society of America Clinical Practice Guideline for the Management of Outpatient Parenteral Antimicrobial Therapy.

A panel of experts was convened by the Infectious Diseases Society of America to update the 2004 clinical practice guideline on outpatient parenteral antimicrobial therapy (OPAT) [1]. This guideline is intended to provide insight for healthcare professionals who prescribe and oversee the provision of OPAT. It considers various patient features, infusion catheter issues, monitoring questions, and antimicrobial stewardship concerns. It does not offer recommendations on the treatment of specific infections. The reader is referred to disease- or organism-specific guidelines for such support.

Stroke Risk Following Infection in Patients with Continuous-Flow Left Ventricular Assist Device.

BACKGROUND: Infection has been associated with stroke in patients with left ventricular assist devices (LVAD); however, little data exist on the timing, type and mortality impact of infection-related stroke. METHODS: Prospectively collected data of HeartMate II (N = 332) and HeartWare (N = 70) LVAD patients from a single center were reviewed. Only strokes (ischemic or hemorrhagic) that occurred within 6 weeks following a LVAD infection were considered in analyses. The association between LVAD infections (wound, pump pocket, driveline and/or bloodstream infection [BSI]), specific pathogens and ischemic and hemorrhagic strokes was evaluated using multivariable logistic regression analysis. The impact of infection-related stroke on cumulative survival was assessed using Kaplan-Meier analysis. RESULTS: Of 402 patients, LVAD infection occurred in 158 (39%) including BSI in 107 (27%), driveline infection in 67 (17%), wound infection in 31 (8%) and pump pocket infection in 24 (6%). LVAD infection-related stroke occurred in 20/158 (13%) patients in a median of 4 days (0-36 days) from documented infection. In multivariable analysis, ischemic stroke was associated with wound infection (aOR 9.0, 95% CI 2.4-34.0, P = 0.001) and BSI (aOR 7.7, 95% CI 0.9-66.0, P = 0.064), and hemorrhagic stroke was associated with BSI in 100% of cases (P = 0.01). There was no association with driveline or pump pocket infection. The cumulative survival rate among patients with infection-related stroke was significantly lower compared to those with LVAD infection but no stroke (log-rank P < 0.001). There was a trend toward shorter stroke-free survival among patients with LVAD infection. CONCLUSIONS: LVAD infections, particularly BSI, are significantly associated with stroke, and infection-related stroke conferred significantly lower cumulative survival.

Emergency department visits during outpatient parenteral antimicrobial therapy: a retrospective cohort study.

Objectives: Patients receiving outpatient parenteral antimicrobial therapy (OPAT) may require emergency department (ED) visits to manage complications. This study's purpose was to identify risk factors for ED visits during OPAT and risk factors for hospitalization among patients with ED visits. Methods: All OPAT courses initiated between 1 January 2013 and 1 January 2017 at Cleveland Clinic were identified. The first OPAT course per patient was included. For these, ED visits within 30 days were identified. Reasons and risk factors for these visits were sought, as were risk factors for hospitalization among patients visiting the ED. Results: Among 8263 patients on OPAT, 381 (4.6%) had at least one ED visit, an additional 1133 (14%) were hospitalized and an additional 50 (0.6%) died, within 30 days. One hundred and ninety-three ED visits (51%) were OPAT related. In a multivariable subdistribution proportional hazards competing risks regression model, prior ED visit (preceding year) was most strongly associated with ED visits (HR 2.29, 95% CI 1.76-2.98, P = 8.1 × 10-10). Eighty-five visits (22%) led to hospitalization. Compared with non-OPAT-related reasons, visits for vascular access complications were associated with lower odds of hospitalization (OR 0.36, 95% CI 0.14-0.83, P = 0.022) and visits for worsening infection with higher odds (OR 18.95, 95% CI 5.50-79.85, P = 1.2 × 10-7). Conclusions: Compared with patients without, patients with prior ED visit have a 2.3-fold higher hazard of an ED visit within 30 days of OPAT initiation. Visits for worsening infection are much more likely to result in hospitalization than those for vascular access complications.