Single-center Retrospective Cohort Research Articles

The Impact of High Burden Idiopathic Premature Ventricular Contractions in Pediatric versus Adult Populations. A Retrospective Cohort Study.

Idiopathic premature ventricular contractions (PVCs) can occur in up to 40% of children with structurally normal hearts. The study aims to assess the impact of high-burden idiopathic PVCs on children in comparison with adults in terms of symptoms, distribution of origin, management strategies, and safety considerations. This is a single-center retrospective cohort study that included patients with frequent PVCs (> 10% burden in Holter monitoring) and categorized by age into adult group (≥ 18years) and pediatric group. Data encompassed demographic profiles, clinical symptoms, echocardiographic findings, electrocardiographic analyses, and one-year follow-up management. A total of 224 PVC cases were collected during a 2-year study (120 children and 104 adults). Syncope occurred significantly more in children than adults (15.8% vs. 0.9%, p = 0.003). In children, the right ventricular outflow tract (RVOT) free wall was the predominant site (48 patients; 40%), while the septal RVOT was most common in adults (35 patients; 33.7%). Pediatric cases exhibited significantly higher PVCs originating from the outflow tract (92.5% vs. 69.2%; p = 0.001). Nevertheless, there were no significant differences between groups regarding the safety, acute, and one-year outcomes of RF ablation. Age disparities were evident in syncope incidence and PVC origin, with no variance in PVC-induced myopathy prevalence or the safety and outcomes of RF catheter ablation between children and adults.

Comparison of Long-Term Outcomes Between Conversion to Open and Laparoscopic Subtotal Cholecystectomy in the Difficult Gallbladder: A Single-Center Retrospective Study.

A difficult laparoscopic cholecystectomy (LC) confers an increased risk of bile duct injury. Traditionally, surgeons convert to open cholecystectomy (OC) as a bailout procedure for safer dissection. Laparoscopic subtotal cholecystectomy (LSC) has recently gained favor with comparable short-term complication rates, but differences in long-term outcomes remain unknown. We sought to compare long-term biliary outcomes between OC and LSC. We performed a single-center retrospective cohort study of adults who underwent non-elective LC converted to OC or LSC due to difficult dissection from 1/1/2015 to 12/31/2019. The primary outcome was a composite measure of postoperative biliary events, and we used time-to-event analysis to compare the 2 groups. We evaluated secondary outcomes using Chi-squared or independent t-tests as appropriate. Of 1089 patients who underwent non-elective LC, 68 (6%) underwent a bailout procedure (30 OC vs 38 LSC). There were no differences in demographics or comorbidities between the groups. Most patients (84%) had acute cholecystitis. Average follow-up times were 40 ∓ 29 months in OC and 54 ∓ 21 months in LSC. Biliary events occurred in 13 total patients (19%) with OC most commonly suffering bile leak (17%) and LSC most commonly having choledocholithiasis (11%). Kaplan-Meier analysis demonstrated no significant difference in biliary events between the groups (P = 0.71). Secondary outcomes were all similar between groups, except LSC had a shorter length of stay (2.9 ∓ 2.3 vs 5.1 ∓ 3.6 days, P = 0.002). OC and LSC demonstrated comparable long-term biliary outcomes. In a difficult LC, surgeons may perform either bailout procedure to safely manage the gallbladder.

Safety and efficacy of perioperative chemotherapy combined with PD-1 inhibitor versus chemotherapy with D2 gastrectomy plus PAND in gastric cancer with PALD metastasis: A single-center retrospective cohort study.

368 Background: Gastric cancer with para-aortic lymph node (PALD) metastasis is associated with a poor prognosis. When the metastasis is limited to the PALD, preoperative systemic therapy combined with D2 gastrectomy plus para-aortic lymph node dissection (PAND) may enhance survival. The benefit of perioperative chemotherapy combined with immune checkpoint inhibitors for these patients is unknown. Methods: A total of 133 patients with gastric cancer and limited No.16a2/b1 lymph node metastasis underwent perioperative systemic therapy combined with D2 gastrectomy plus PAND. Patients receiving chemotherapy combined with a PD-1 inhibitor were assigned to Group A (n=62), while those receiving chemotherapy alone were assigned to Group B (n=71). Pathological response, safety, efficacy, and survival outcomes were compared between the two groups. Results: Adverse events occurred at comparable rates between the two groups. No treatment-related deaths occurred in either group. In Group A, all patients (100%) achieved R0 resection, compared to 70 patients (98.6%) in Group B. Group A showed significantly better pathological outcomes than Group B, with higher rates of pathological complete response (pCR) (37.1% vs. 4.2%, P < 0.001), and major pathological response (MPR) (58.1% vs. 22.5%, P < 0.001). Group A showed a higher 2-year overall survival (OS) rate compared to Group B (90.3% vs. 62.9%, P = 0.011). The median overall survival (mOS) in Group B was 35.0 months, while follow-up data for Group A are currently insufficient to assess mOS. Conclusions: The addition of a PD-1 inhibitor to chemotherapy significantly improves the pathological response rate and prognosis in gastric cancer patients with PALD. Notably, the combination did not increase adverse events. These findings suggest that combining PD-1 inhibitor with chemotherapy could be a promising strategy for improving outcomes in this patient population, though further prospective studies are necessary to confirm long-term survival benefits. Postoperative outcomes and pathological response. Variable Group A (n=62) % Group A (n=71) % P Value Vascular tumor embolus 0.005 Negative 43 69.4% 32 45.1% Positive 19 30.6% 39 54.9% Nerve infiltration 0.004 Negative 44 71.0% 33 46.5% Positive 18 29.0% 38 53.5% No.16a2/b1 0.057 Negative 53 85.5% 51 71.8% Positive 9 14.5% 20 28.2% Tumor resection 0.970 Distal 26 41.9% 30 42.3% Total 36 58.1% 41 57.7% Serum CEA (U/mL） 0.805 Normal 56 90.3% 65 91.5% >5 6 9.7% 6 8.5% Serum CA125 (U/mL) 0.280 Normal 30 48.4% 41 57.7% >35 32 51.6% 30 42.3% Serum CA199 (U/mL) 0.783 Normal 56 90.3% 65 91.5% >37 6 9.7% 6 8.5% pT-stage <0.001 ≤T2 37 59.7% 19 26.8% ＞T2 25 40.3% 52 73.2% pN-stage 0.001 N0/1 42 67.7% 27 38.0% N2/3 20 32.3% 44 62.0% TRG ＜0.001 0 23 37.1% 3 4.2% 1 13 21.0% 13 18.3% 2 22 35.5% 47 66.2% 3 4 6.5% 8 11.3% pCR 23 37.1% 3 4.2% ＜0.001 MPR 36 58.1% 16 22.5% ＜0.001

Clinical Urinary Tract Infections in Kidney Transplant Recipients With Initially Asymptomatic Bacteriuria: A Single-Center Retrospective Cohort Study.

Management of asymptomatic bacteriuria in kidney transplant recipients remains uncertain. Our main objective was to evaluate whether patient- or episode-related factors could help identify episodes of asymptomatic bacteriuria associated with a higher risk of being followed by a symptomatic urinary tract infection. A single-center, retrospective cohort study. Consecutive patients who received a kidney transplantation between January 1, 2008, and April 26, 2016, and experienced≥1 episode of asymptomatic bacteriuria during the first 3 years posttransplantation. Recipient age, sex, diabetes, donor type, retransplant, urological abnormalities, thymoglobulin for induction, time since transplant, presence of ureteral stent, prior acute rejection, leukocyturia, hematuria, urinary nitrites, bacterial strain, prior urinary tract infection, resistance to antibiotics, antibiotic treatment. The primary outcome was the occurrence of symptomatic urinary tract infection. The secondary outcome was antibiotic treatment of asymptomatic bacteriuria. A Cox regression survival analysis model accounting for recurrent events and a logistic regression model. From a cohort of 508 patients, we included 597 episodes of asymptomatic bacteriuria detected in 119 outpatients. Antibiotics were prescribed in 26% of these episodes. Overall, 56 (9%) of episodes were followed by a symptomatic urinary tract infection. Pretransplant diabetes (hazard ratio [HR], 4.28; 95% confidence intervals [CI], 2.40-7.61), leukocyturia or hematuria (HR, 2.24; 95% CI, 1.27-3.96), and the presence of a ureteral stent (HR, 3.40; 95% CI, 1.33-8.70) were associated with development of a clinical urinary tract infection in patients with asymptomatic bacteriuria. The small number of events limits complete multivariable adjustment. It also prevents us from drawing a definite conclusion about the importance of a number of independent variables as risk factors for the outcome. The benefit of treating episodes ofasymptomatic bacteriuria with high-risk characteristics should be investigated in future trials.

532 Profile of patients with rheumatoid arthritisassociated interstitial lung disease: a single-center retrospective cohort study

532 Profile of patients with rheumatoid arthritisassociated interstitial lung disease: a single-center retrospective cohort study

Advantages of Robotic Total Mesorectal Excision With Partial Prostatectomy Compared With Open Surgery for Rectal Cancer: A Single-Center Retrospective Cohort Study.

Robotic total mesorectal excision (TME) with resection of adjacent organs has been increasingly used for locally advanced rectal cancer; however, few studies have focused on robotic TME with partial prostatectomy. Therefore, this study aimed to demonstrate the advantages of robotic TME with partial prostatectomy compared with open surgery for rectal cancer. This retrospective cohort study examined consecutive patients with rectal cancer who underwent robotic or open TME with partial prostatectomy at a high-volume center in Japan from April 2003 to March 2022. The patients were divided into robotic (n = 14) and open (n = 11) surgery groups. The short- and long-term outcomes of these patients were compared. More transabdominal partial prostatectomies were performed in the robotic surgery group than in the open surgery group (71.4% vs. 9.1%, p = 0.001). Moreover, sphincter-preserving surgery was performed in 35.7% of patients in the robotic surgery group. The robotic surgery group had shorter operative times (401 min vs. 435 min, p = 0.047), less blood loss (56 mL vs. 484 mL, p < 0.001), lower complication rates (28.6% vs. 72.7%, p = 0.047), and shorter postoperative hospital stays (8 days vs. 18 days, p < 0.001) than the open surgery group. No significant differences were observed in the positive radial margin rate (7.1% vs. 9.1%, p = 1.000) or long-term outcomes between the two groups. Compared with open surgery, robotic TME with partial prostatectomy facilitates transabdominal partial prostatectomy, resulting in more sphincter-preserving surgeries and better short-term outcomes.

Abstract TP129: Both English and non-English speaking patients with large-vessel occlusion receive timely access to thrombectomy

Introduction: An equitable health system requires access to clinical advances across society. In stroke, mechanical thrombectomy (MT) has revolutionized the field by providing an acute therapy with unprecedented reduction in morbidity and mortality. Its benefit depends heavily on the duration between stroke onset and cerebral reperfusion. As such, patient factors associated with delays in care can influence outcomes after MT and lead to health inequities. Communication is paramount to a neurological evaluation. In a predominantly English-speaking medical system, we hypothesized that patients with a primary language other than English who presented to the hospital with large-vessel occlusion ischemic stroke (LVO) might experience delays in care resulting in longer times to MT. Methods: We conducted a single-center retrospective cohort study to investigate the impact of primary language on door-to-puncture time (DTP) among patients with LVO who presented to a single comprehensive stroke center between 01/2020 and 05/2024 and underwent MT. We employed non-parametric statistics to compare patient demographics and clinical outcomes and a LASSO approach to identify independent predictors of DTP. Results: Of the 413 patients who underwent MT, 52 (13%) were non-English-speaking (Table 1). In the overall cohort, patients were on average 71 years of age and majority male (57%). They presented to the hospital 8.1 hours after last known well with a mean NIHSS of 19. Compared with the English-speaking cohort, non-English-speaking patients presented earlier to the hospital after last known well (6.1 hours versus 8.1 hours, p = 0.110), were more likely to receive thrombolysis (33% versus 14%, p &lt; 0.001), and had higher rates of hypertension (63% versus 44%, p &lt; 0.008) and lower rates of congestive heart failure (12% versus 30%, p = 0.005). Neither DTP (60 minutes versus 60 minutes, p = 0.900) nor door to needle time (time to administration of thrombolytic, 43 minutes versus 47 minutes, p = 0.600) differed between non-English and English-speaking patients. Regression analysis identified a history of dyslipidemia (decreased DTP 8 min, 95% CI 2-14 min) and having received IV thrombolysis (increased DTP 13 min, 95% CI 5-21 min), but not primary language, as independent predictors of DTP. Conclusions: Our comprehensive stroke center promotes an equitable health system by providing a timely opportunity for MT after LVO irrespective of patient language.

Risk factors that predict for presence of clinically significant, noncalcified plaque in younger adults.

Coronary artery calcium (CAC) scoring may be a useful tool for assessing cardiovascular disease in young adults, particularly in those with risk factors such as hypertension, dyslipidemia, or smoking. In this study, we aimed to address the risk factors for developing noncalcified plaque in young adults by assessing total plaque burden. A single-center retrospective cohort study was conducted among 1026 consecutive patients aged 18-45 years who underwent CAC scoring and coronary computed tomography (CT) angiograms for clinical indications. CAC scores and total plaque scores (TPS) were calculated using standard scoring protocols. Multiple logistic regression analysis was conducted to identify independent risk factors of significant, noncalcified plaque in subjects where CAC = 0. This single-center retrospective cohort study included 1026 patients aged 18-45 years who underwent CAC scoring and coronary CT angiograms for clinical indications. The mean age of the population was 38.8 years old. Sixty-three patients had a CAC score of 0 and a TPS >0. Of the patients with noncalcified plaque burden, 15% had a stenosis >50%, and 10% had a stenosis >70%. The odds of a subject having noncalcified plaque presence and CAC absent were significantly associated with being Hispanic, having diabetes, and having hyperlipidemia. In young adults aged 18-45 years old, we found diabetes, hyperlipidemia, and being of Hispanic origin to be significantly associated with noncalcified plaque burden.

Factors Associated with Prolonged Mechanical Ventilation in Late Repair of Tetralogy of Fallot.

Research establishing factors associated with duration of mechanical ventilation after Tetralogy of Fallot repair, is mainly based on population presenting at early infancy. There are fewer reports regarding repair after infancy, during childhood and preadolescence. To compare two groups of late TOF repair based on post-operative invasive mechanical ventilation duration and explore associations with pre-operative clinical markers of severity of right ventricular outflow tract obstruction. A single-center retrospective cohort study based on medical charts review of patients older than 12months who underwent primary complete TOF repair between 2017 and 2023. Patients younger than 12months or those who had distinct anatomical variants were excluded. Pre-operative characteristics reflecting the severity of right ventricular outflow tract obstruction were collected, including baseline oxygen saturation, the occurrence of hypercyanotic spells, maximum right ventricular outflow tract pressure gradient. Perioperative variables included repair type, cardiopulmonary bypass and aortic cross-clamp duration, and rates of residual lesions. 280 patients from 27 countries were screened; 181 remained eligible and were significantly older than previously reported. 129 (71%) were extubated early post-operatively, while 52 (29%) had a longer ventilation course. In a multivariate analysis, only baseline oxygen saturation and repair type maintained a significant association with length of mechanical ventilation. In distinctly older patients undergoing TOF repair, those with lower base line saturation undergoing a non-valve preserving repair are more likely to have a longer course of mechanical ventilation. Other clinical markers reflecting the severity of right ventricular outflow tract obstruction were not independently associated with mechanical ventilation duration.

Potential of 6-mm-diameter fully covered self-expandable metal stents for unresectable malignant distal biliary obstruction: a propensity score-matched study.

To date, only thinner-diameter metal stents have been evaluated for unresectable malignant distal biliary obstruction (UR-MDBO). This study investigated the outcomes and optimal cohorts for a 6-mm-diameter fully covered self-expandable metal stent (FCSEMS) compared with those for a 10-mm-diameter FCSEMS. This single-center retrospective cohort study included patients who underwent initial transpapillary metal stenting for UR-MDBO. Propensity score matching (1:1) analysis was performed. Of 133/68 patients who underwent 6-mm/10-mm-diameter FCSEMS deployment, 59 in each group were selected. The median time to recurrent biliary obstruction was not significantly different between the groups (p=0.46). In contrast, use of the 6-mm-diameter FCSEMS resulted in a significantly reduced incidence of stent-related adverse events (AEs) (p=0.016), especially cholecystitis (p=0.032), and patients aged <70 years were particularly affected by this significant reduction. Among the patients in the end-stage cohort who were unable to continue chemotherapy after FCSEMS deployment, the free rate of stent-related events, including recurrent biliary obstruction and stent-related AEs, was significantly higher in the 6-mm group (p=0.027). For UR-MDBO, a 6-mm-diameter FCSEMS can be an optimal and safe option in the younger cohort with a relatively high risk of AEs and in the end-stage cohort requiring safer drainage without interference from stent-related events during times of poor prognosis.

P-391. Infections in Gender-Affirming Surgery: A Single-center Experience with Gender-affirming Vaginoplasty

Abstract Background There are an estimated 1.3 million transgender adults in the US and about 25% undergo some form of gender-affirming surgery (GAS). Data on infectious complications following GAS is limited. We describe the epidemiology and incidence of infections following gender-affirming vaginoplasty (GAV). We also describe HIV screening and pre-exposure prophylaxis (PrEP) use in this population as transwomen are disproportionately affected by HIV and have the highest prevalence compared to any other group of US adults. Methods In this single-center retrospective cohort study, we identified 398 patients aged ≥18 years who underwent GAV at Oregon Health &amp; Science University from 2016 to 2023. We reviewed medical records up to 6 months from the initial surgery and used standardized criteria to diagnose surgical site infections (SSI), urinary tract infections (UTI), and sexually transmitted infections (STI). Data around HIV screening and PrEP use was also obtained. Results 381 patients underwent primary vaginoplasty and 17 underwent revision of the primary surgery. 332 had standard penile inversion, 64 had robotic vaginoplasty, and 2 patients had intestinal vaginoplasty. UTI was the most common postoperative complication (incidence 13.8 per 100 individuals; n=55), followed by SSI (incidence 5.5 per 100 individuals; n=22). We identified 4 episodes of bacteremia related to surgery- all due to E coli- and one case of pelvic abscess. Only 2 STIs were identified and neither involved the neogenitalia- 1 was primary syphilis and the other was gonococcal urethritis. 16 patients had positive HIV serostatus. All 16 were prescribed ART and 11/16 had an undetectable viral load at the time of surgery. Only 22.5% of HIV seronegative patients had screening within a year before surgery and only 6% were on PrEP at the time of surgery. Conclusion In our study, UTIs and SSIs were the most common infections post-GAV. Serious infections were rare. We also identified a significant gap in HIV screening and PrEP uptake in this especially vulnerable group. Transgender surgery programs should incorporate HIV screening and counseling around PrEP. Disclosures Monica K. Sikka, MD, F2G: Grant/Research Support Christopher Evans, MD, ViiV: Grant/Research Support

374. Early Discontinuation of Empiric Antibiotics for Febrile Neutropenia in Pediatric Allogeneic Haploidentical Hematopoietic Cell Transplant Recipients

Abstract Background Febrile neutropenia (FN) occurs in 80-90% of haploidentical hematopoietic cell transplants (haplo-HCT), but most patients do not have documented infections. Empiric antibiotics are frequently continued until neutrophil recovery, even when there is no evidence of infection. Shorter antibiotic courses to decrease antibiotic exposure have been studied in adult HCT recipients and have demonstrated safety compared to conventional management. In 2017 we implemented a strategy to discontinue antibiotics at ≤ 72 h in stable haplo-HCT patients with FN and no evidence of infection. In this study, we evaluate the implementation and outcomes of this practice.Figure 1.A. Mean antibiotic-free days across the study period. B. Individual antibiotic-free days in EAD and LAD Methods This single-center retrospective cohort included patients &amp;lt; 24 years old who underwent haplo-HCT from 2010 to 2022 with ≥ 1 episode of FN and no documented infection. They were classified by time period as follows: late antibiotic discontinuation (LAD) vs. early antibiotic discontinuation &amp;lt; 72 h (EAD). The primary outcome was antibiotic-free days. The secondary outcomes were subsequent breakthrough bloodstream infection (BSI), intensive care unit (ICU) admission, septic shock, mortality, and practice fidelity (adherence) and sustainability.Figure 2.Fidelity to implemented practice across time Results We included 230 patients (117 in LAD, 113 in EAD). No differences in age, sex, or race were observed. A higher proportion of patients received myeloablative conditioning regimens in LAD (p &amp;lt; 0.01, Table 1). There were more antibiotic-free days after EAD implementation (Figure 1), but no differences in the incidence of breakthrough bloodstream infections (EAD: 6.1%, LAD: 5.1%, p= 0.81) or other adverse clinical outcomes. There was no infection-related mortality in either group (Table 1). The fidelity (adherence) to recommended practice of discontinuing antibiotics ≤72 hours was 61.6%, with increase over time (Figure 2). Conclusion Implementation of EAD strategy for FN in haplo-HCT patients led to an increase in antibiotic-free days during the first 30 days post-HCT. Adverse clinical outcomes were infrequent in both groups and did not significantly increase after EAD. Prospective multicenter studies are required to evaluate the safety of EAD strategies. Disclosures Diego R. Hijano, MD, MSc, FDA: Grant/Research Support|Merck: Grant/Research Support|National Institute of Health: Grant/Research Support Gabriela Maron, MD, MS, Astellas Inc: Grant/Research Support|NIH: Grant/Research Support|SymBio Pharma: Advisor/Consultant|SymBio Pharma: Grant/Research Support

P-357. Maximizing Value in Public Healthcare: Assessing the Financial Return on Investment in Surgical Infection Prevention at a Philanthropic Teaching Hospital Serving Exclusively Public Patients

Abstract Background This study aimed to evaluate the cost-effectiveness of hospitals’ continuous investments in HAI prevention, focusing specifically, on the prevention of SSIs. The objective was to estimate the impact of SSIs on hospital profitability.Figure 1The infection prevention programs to prevent Surgical Site Infections (SSIs) The infection prevention programs to prevent Surgical Site Infections (SSIs) Methods A single-center retrospective cohort study was conducted between January 2019 and September 2023, involving patients undergoing arthroplasty, small bowel surgeries, cholecystectomy, herniorrhaphy, and open fracture reduction. The cost of each infection was obtained in the literature. The study compared SSI incidence between 2019-2022 and 2023. The hospital implemented a Value Management Office (VMO) in 2022 to accelerate the dissemination of value-based healthcare, with a focus on IPP, including measures to prevent SSIs. The infection prevention programs to prevent SSI consisted of maximum adherence to antimicrobial prophylaxis, SSI rate feedback for surgical team with root cause, auditing surgical procedures, reinforcing good practices in the operating room and improvement of the materials and sterilization center.Table 1Comparison of Surgical Site Infection Rates: Baseline Period (2019-2022) vs. Current Period (2023)Comparison of Surgical Site Infection Rates: Baseline Period (2019-2022) vs. Current Period (2023) Results During the baseline period, January 2019 to December 2022, 9,235 patients were included, being 59% female and a mean age of 51 years. 368 were diagnosed with SSI and the mortality rate was 1.4%. When an SSI occurs, the length of stay is longer (p=0.001) and the risk of death doubles (RR=2.1; p=0.033). The analysis shows a remarkable 64% decrease in SSI rates, from 4% in 2019-2022 to 1.4% in 2023. This translates into 63 prevented infections and 2 fewer deaths. The study attributes this success to implemented preventive measures because there was no significant difference in terms of the duration of the surgery (p= 0.411) and age of patients in each group (p=0.843). Additionally, the reduced SSI rate led to shorter hospital stays and an estimated monthly cost savings of US$52,160-US$93,865.Table 2Impact of Surgical Site Infections on Mortality Risk and Extended Hospital StayImpact of Surgical Site Infections on Mortality Risk and Extended Hospital Stay Conclusion Investing in interventions aimed at reducing adverse events, such as SSIs, is essential for enhancing patient care and safety. This study highlights the significant financial returns associated with investing in infection prevention: 52,160 to 93,865 USD, particularly in reducing surgical infections.Table 3Reduction in Costs, Hospital Stay Duration, and Prevented Deaths Associated with Surgical Site InfectionsReduction in Costs, Hospital Stay Duration, and Prevented Deaths Associated with Surgical Site Infections Disclosures All Authors: No reported disclosures

P-1138. Quantifying Antibiotic Prescribing in Children with Tracheostomies

Abstract Background Prolonged or unnecessary antibiotic prescribing is associated with adverse outcomes. Children with tracheostomies are at risk for antibiotic overprescribing. We sought to quantify and characterize systemic antibiotic prescribing among children with tracheostomies, and to identify predictors of higher prescribing. Methods This single-center retrospective cohort study included children with tracheostomies 2 months-18 years old cared for between 2010-2018. Detailed demographic, clinical, and antibiotic prescribing data were extracted from the medical record. Patient-level antibiotic prescribing was quantified using antibiotic courses initiated and DOT per child per year of enrollment. Group-level prescribing was summarized using total antibiotic courses and days of therapy (DOT) per 1000 person-days. Antibiotics prescribed for &amp;gt; 1 day were classified by spectrum of activity and stratified by setting and year. Clinical predictors of patient-level prescribing were identified using backward stepwise multivariable analyses within a generalized linear model. Results The 548 children with tracheostomies (47.6% with baseline ventilator use) were prescribed a median 8 antibiotic courses per child per year (IQR: 4-16) for a total median exposure of 49.3 DOT per child per year (IQR: 22.6-123.2) or 183.7 DOTs per 1000 person-days. Most courses (73.9%) were broad-spectrum, with vancomycin, piperacillin-tazobactam, and ampicillin-clavulanate being the top 3 most frequently-prescribed antibiotic courses. Azithromycin and gentamicin represented a high proportion of all DOTs (azithromycin 25.4%, gentamicin 13.0%). Annual antibiotic prescribing decreased 34.5% from 2010-2018. In adjusted analysis to identify predictors, ventilator use at baseline was associated with fewer DOT per child per year, while higher patient complexity and more ICU hospital days were risk factors for higher DOT. Conclusion Children with tracheostomies have high antibiotic use, and are predominantly prescribed broad-spectrum antibiotics. Chronic ventilator use was a protective factor against higher prescribing. This data may inform antimicrobial stewardship work. Disclosures All Authors: No reported disclosures

P-616. Sociodemographic and Clinical Factors Affecting Vaccination after Pediatric Solid Organ Transplantation at Duke University

Abstract Background Pediatric solid organ transplant (SOT) recipients are at increased risk for vaccine preventable illnesses (VPI). They frequently receive vaccines after transplantation when immunosuppressive medications and cytopenias may impact their immune response to routine childhood vaccines. Current guidelines recommend monitoring vaccine-specific serologies to ensure optimal vaccine responses and to guide the need for repeat doses. Methods In this single-center retrospective cohort study, a multivariate logistic regression model was used to determine the sociodemographic and clinical factors associated with delays in starting post-transplant vaccines and adherence to post-vaccine serologic monitoring among 199 pediatric patients who received a SOT at Duke University between 2014-2023. The prevalence of cytopenias at the time of post-transplant vaccination was also described. Results Out of 150 children eligible for post-transplant vaccines (Table1), 48 (32%) failed to start catch-up vaccines within 2 years of transplantation. Older children (OR=0.877, 0.83-0.927) and children with private insurance (OR=0.458, 0.211-0.993) had significantly decreased odds of early catch-up vaccines (Table 2). Hepatitis B serologies were obtained in 23% of patients after post-transplant vaccination, but titers against the remaining non-live childhood vaccines were only obtained in 1-8% of children (Table 3). Approximately 53% of all children had neutropenia or lymphopenia (less than 1500 x 10^6 cells/L) at the time of post-transplant vaccination, with heart and intestinal/multi-visceral transplant recipients having the highest rates at ∼75% (Table 4). Conclusion These findings identify pediatric SOT recipients most at risk for delayed post-transplant vaccines. The associations between vaccine delay and private insurance and older age warrant further investigation. The extremely low rates of vaccine-specific serologic monitoring and the high prevalence of cytopenias at the time of vaccination raise concerns that pediatric SOT recipients are insufficiently protected from VPI. Future work will determine the impact of cytopenias on vaccine response and will address inequities in vaccination among pediatric SOT recipients. Disclosures All Authors: No reported disclosures

P-76. Risk factors associated with Gram-negative early hip and knee prosthetic joint infections: a single-center retrospective cohort study

Abstract Background Prosthetic joint infection (PJI) is a devastating complication of total joint arthroplasty, occurring in 1-2% of all prosthetic joint surgeries. While rare, Gram-negative (GN) bacteria are important causes of PJIs and can be difficult to treat due to increasing antimicrobial resistance. We looked at cases of early PJIs due to GN bacteria in our institution to identify potential risk factors. Methods We conducted a retrospective cohort study using the Center for Disease Control’s National Healthcare Safety Network data report of surgical site infections (SSI) for our institution between January 1, 2011 and June 1, 2023. Procedure codes HPRO and KPRO were used to identify total hip (THA) and knee (TKA) arthroplasty cases. Welch two sample t-test and Chi-square tests were used for between-group comparisons of continuous and categorical outcomes, respectively. Multiple logistic regression was used to identify risk factors and estimate adjusted odds ratios (aOR) for GN PJIs. Results Our cohort included 17,725 arthroplasty cases, of which 174 developed a SSI of the implanted joint ≤90 days of index surgery, with a cumulative incidence of 0.98%. Of the SSI cases, 34 (20%) isolated GN bacteria while 140 (80%) were caused by other organisms. The most common GN bacteria were E. coli (11), Klebsiella species (8), P. aeruginosa (8). Patients with GN infections were older, with a median age of 70 (IQR 61-76) compared to 65 (IQR 58-70) in the non-GN infections group (p = 0.090). Duration of index surgery was longer in GN infections, with a median duration of 204 minutes (IQR 121-304) compared to 151 minutes (IQR 110-219, p=0.019). There were no differences between GN bacterial infections and infections due to other organisms for sex, American Society of Anesthesiologists physical status score, surgical risk score, body mass index, or history of diabetes. In the logistic regression, age and duration were associated with increased odds of GN infection with an aOR of 1.04 for age (p=0.05) and 1.05 for duration (p=0.003). Conclusion The cumulative incidence of SSI of prosthetic hip and knee arthroplasties was low at &amp;lt; 1% with GN infections making up a minority of cases. Age at time of index surgery and duration of surgery were significantly associated with an increased risk of GN bacterial infection. Disclosures All Authors: No reported disclosures

P-2303. Active Surveillance and Antimicrobial Prophylaxis to Prevent Hyperammonemia Syndrome in Lung Transplant Recipients: A Single Center Cohort Study

Abstract Background Hyperammonemia syndrome (HS) is a life-threatening complication primarily affecting lung transplant recipients (LTR) and is associated with M. hominis and/or Ureaplasma spp infection. We implemented an active surveillance and prophylaxis protocol to improve outcomes associated with HS in LTR. Herein, we evaluate the impact of our protocol on outcomes of HS. Methods This is a single-center retrospective cohort study of adult LTR performed from 1/1/2019 to 1/31/2024. Our surveillance and prophylaxis protocol was implemented on 8/1/2022 and included PCR testing for M. hominis and Ureaplasma spp on post-operative bronchoscopy samples, measurement of serum ammonia levels, and azithromycin prophylaxis in our LTR. Comparisons between groups were performed using Chi-square or Fischer’s exact test for categorical variables and Student’s t test or Mann-Whitney U for continuous variables. Results One hundred and thirty-four adults received a lung transplant during the study period. Baseline characteristics are shown in Table 1. In total, 9 LTR (6.7%) were diagnosed with M. hominis or Ureaplasma spp. infection (Table 2). Of these, 3 LTR met criteria for definite HS (3/134, 2.2%) of whom two died. An additional 3 LTR had disseminated infection due to M. hominis without evidence of HS. Following protocol implementation, 31/37 (83.8%) LTR had PCR testing for M. hominis and Ureaplasma spp. (Table 2). Ammonia levels were sent within 3 days of transplantation in 20/37 (54.1%) LTR. All patients received prophylaxis with azithromycin (or alternative agent) for at least 5 days or until PCR returned negative. Three LTR had either M. hominis or Ureaplasma spp infection detected following protocol implementation; none developed HS. One LTR developed disseminated M. hominis infection. However, screening was delayed by 10 days and prophylaxis was stopped after 5 days, prior to screening results being known. Conclusion The prevalence of HS in our cohort is similar to published reports. Adherence to our protocol was high for azithromycin prophylaxis and PCR testing, but low for ammonia levels. Importantly, no case of definite HS occurred following protocol implementation. Additional studies to determine optimal screening and prophylaxis strategies for HS are needed. Disclosures Kapil K. Saharia, MD, MPH, Eurofins Viracor: Advisor/Consultant

P-1943. Risk Factors for Coronavirus disease 2019 (COVID-19)-Associated Pulmonary Aspergillosis (CAPA) in Critically Ill Patients: The Predictive Value of KL-6 for CAPA and Mortality

Abstract Background Coronavirus Disease 2019 (COVID-19) is an acute respiratory viral illness that can be complicated by secondary invasive fungal infections, such as COVID-19-Associated Pulmonary Aspergillosis (CAPA). Krebs von den Lungen-6 (KL-6), a mucinous high-molecular-weight glycoprotein found on the surface of type II alveolar epithelial cells, has been known as a biomarker indicative of respiratory epithelial damage. This study aims to evaluate the risk factors for CAPA in critically ill COVID-19 patients, with a focus on the predictive value of KL-6. Overall 30-day survival rates between patients with and without CAPA Methods This single-center retrospective cohort study included critically ill COVID-19 patients (those requiring high-flow respiratory support or mechanical ventilation) admitted from January 2021 through June 2023. CAPA diagnosis was established based on the 2020 European Confederation of Medical Mycology and the International Society for Human and Animal Mycology consensus criteria. The study investigated factors associated with CAPA and compared overall 30-day mortality for patients with and without CAPA. Results Among 238 critically ill COVID-19 patients, 25 (10.5%) were diagnosed with CAPA. Notably, patients with CAPA exhibited significantly higher median serum peak levels of KL-6 (787.4 vs. 290.2 U/mL, P&amp;lt; 0.001), with a cutoff value of 392.9 U/mL determined by the Youden index. Multivariable analysis revealed that a peak KL-6 level ≥ 392.9 U/mL was strongly associated with CAPA (adjusted odds ratio 8.62, 95% confidence interval [CI] 2.43-31.69). Additionally, inotropics/vasopressor support, diabetes mellitus, and tocilizumab were identified as factors associated with the development of CAPA. The overall 30-day mortality was significantly higher in patients with CAPA (60.8%) compared to those without (45.2%) (P=0.020), with the difference persisting after adjustment (adjusted hazard ratio 2.06, 95% CI 1.05-4.03). Furthermore, along with older age, lacticemia, and diabetes mellitus, elevated KL-6 was also associated with increased mortality. Conclusion Our study suggests that KL-6 may be a significant predictor of both the development of CAPA and mortality among critically ill patients with COVID-19. Disclosures All Authors: No reported disclosures

Prognostic significance of left atrial volume index in patients with severe aortic stenosis after transcatheter aortic valve

Abstract Background Transcatheter aortic valve replacement (TAVR) is an important approach for patients with severe aortic stenosis (AS), but its mortality remains high and its prognostic factors are not fully understood. Methods This single-center retrospective cohort study enrolled 553 consecutive severe AS patients who underwent TAVR between April 2012 and October 2019. Patients with biological valve decay after surgery, moderate to severe mitral stenosis, and inadequate echocardiographic image were excluded. The primary outcome was mortality at 4 years after TAVR. Results Over the follow-up time, 64 patients (12.8%) died. Compared to the Survivors, the Non-survivors were older, less females, higher STS scores, larger left atrial volume index (LAVi) and lower serum albumin level. Results from univariate and multivariate cox regression analysis showed that the age (HR, 1.072; 95% CI 1.023-1.124, p =0.004), the LAVi level (HR, 1.023; 95% CI 1.013-1.033, p &amp;lt;0.001) and the serum level of albumin (HR, 0.862; 95% CI 0.796-0.934, p &amp;lt;0.001) were the independent risk factors for estimation of 4-year mortality after TAVR. Moreover, the mortality in patients with the highest category of LAVi (&amp;gt;48 ml/m2) was significantly higher than others, and its multivariable HR was 4.796 (95% CI, 1.137-20.238). In addition, Kaplan-Meier analysis revealed a reduced survival probability according to the highest category of LAVi (p =0.003). Conclusion LAVi was an independent predictor of mortality in patients with severe AS after TAVR, and LAVi could be used as a risk stratificationtool for long-term clinical outcome of post-TAVR patients.

Psychosocial Determinants and Outcomes of Expedited Liver Transplant Evaluations: Insights From a Retrospective Cohort Analysis.

As the burden of chronic liver disease and the demand for liver transplants (LT) grows, understanding the interplay between access to care and patient outcomes is increasingly important. In this study, we explored patient characteristics and transplant outcomes in patients undergoing LT evaluations, with a focus on identifying risk factors for expedited LT evaluation. This single-center retrospective cohort study included patients who underwent LT evaluation for deceased donor LT between October 2017 and July 2021. Patients were categorized by context: expedited (inpatient) and routine (outpatient) LT evaluation groups. The outcome measures included waitlist status, pre-LT mortality, and post-LT complications. Of 602 patients, 26% underwent expedited LT evaluation. Patients who underwent expedited evaluation were more likely to have a history of ascites (P < 0.001), hepatic encephalopathy (P < 0.001), and spontaneous bacterial peritonitis (P < 0.001) and had a higher model for end-stage liver disease sodium scores (P < 0.001). Both mortality (35% versus 17%, P < 0.001) and LT (39% versus 22%, P < 0.001) were more common in the expedited group; post-LT mortality was similar up to 2 y. Perceived financial concerns and social security disability income were risk factors for expedited LT evaluation. In addition, greater proximity to the LT center (95% confidence interval, 1.1-6.3; P = 0.025) and speaking a primary language other than English (95% confidence interval, 1.0-10.7; P = 0.042) were risk factors for expedited LT evaluation in women but not in men. Expedited LT evaluations were associated with more severe illness and higher pre-LT mortality; however, post-LT outcomes were comparable with those of routine evaluations. Identifying psychosocial risk factors may enhance equity and access to LT evaluations, particularly for women who face unique challenges in this context.