Costs of Care for Operative and Nonoperative Management of Emergency General Surgery Conditions.

OBJECTIVE: Many emergency general surgery (EGS) conditions can be managed operatively or nonoperatively, with outcomes that vary by diagnosis. We hypothesized that operative management would lead to higher in-hospital costs but to cost savings over time. BACKGROUND: EGS conditions account for $28 billion in health care costs in the United States annually. Compared with scheduled surgery, patients who undergo emergency surgery are at increased risk of complications, readmissions, and death, with accompanying costs of care that are up to 50% higher than elective surgery. Our prior work demonstrated that operative management had variable impacts on clinical outcomes depending on the EGS condition. METHODS: This was a nationwide, retrospective study using fee-for-service Medicare claims data. We included patients 65.5 years of age or older with a principal diagnosis for an EGS condition 7/1/2015-6/30/2018. EGS conditions were categorized as: colorectal, general abdominal, hepatopancreaticobiliary (HPB), intestinal obstruction, and upper gastrointestinal. We used near-far matching with a preference-based instrumental variable to adjust for confounding and selection bias. Outcomes included Medicare payments for the index hospitalization and at 30, 90, and 180 days. RESULTS: Of 507,677 patients, 30.6% received an operation. For HPB conditions, costs for operative management were initially higher but became equivalent at 90 and 180 days. For all others, operative management was associated with higher inpatient costs, which persisted, though narrowed, over time. Out-of-pocket costs were nearly equivalent for operative and nonoperative management. CONCLUSIONS: Compared with nonoperative management, costs were higher or equivalent for operative management of EGS conditions through 180 days, which could impact decision-making for clinicians, patients, and health systems in situations where clinical outcomes are similar.

Approximate balancing weights for clustered observational study designs.

In a clustered observational study, a treatment is assigned to groups and all units within the group are exposed to the treatment. We develop a new method for statistical adjustment in clustered observational studies using approximate balancing weights, a generalization of inverse propensity score weights that solve a convex optimization problem to find a set of weights that directly minimize a measure of covariate imbalance, subject to an additional penalty on the variance of the weights. We tailor the approximate balancing weights optimization problem to the clustered observational study setting by deriving an upper bound on the mean square error and finding weights that minimize this upper bound, linking the level of covariate balance to a bound on the bias. We implement the procedure by specializing the bound to a random cluster-level effects model, leading to a variance penalty that incorporates the signal-to-noise ratio and penalizes the weight on individuals and the total weight on groups differently according to the the intra-class correlation.

Paraesophageal hernia recurrence following repair: making the case for reoperative surgery in a propensity-matched cohort.

BACKGROUND: Paraesophageal hernia repairs (PEHRs) have high rates of radiographic recurrence, with some patients requiring repeat operation. This study characterizes patients who underwent PEHR to identify the factors associated with postoperative symptom improvement and radiographic recurrence. We furthermore use propensity score matching to compare patients undergoing initial and reoperative PEHR to identify the factors predictive of recurrence or need for reoperation. METHODS: After IRB approval, patients who underwent PEHR at a tertiary care center between January 2018 and December 2022 were identified. Patient characteristics, preoperative imaging, operative findings, and postoperative outcomes were recorded. A computational generalization of inverse propensity score weight was then used to construct populations of initial and redo PEHR patients with similar covariate distributions. RESULTS: A total of 244 patients underwent PEHR (78.7% female, mean age 65.4 ± 12.3 years). Most repairs were performed with crural closure (81.4%) and fundoplication (71.7%) with 14.2% utilizing mesh. Postoperatively, 76.5% of patients had subjective symptom improvement and of 157 patients with postoperative imaging, 52.9% had evidence of radiographic recurrence at a mean follow-up of 10.4 ± 13.6 months. Only 4.9% of patients required a redo operation. Hernia type, crural closure, fundoplication, and mesh usage were not predictors of radiographic recurrence or symptom improvement (P > 0.05). Propensity weight score analysis of 50 redo PEHRs compared to a matched cohort of 194 initial operations revealed lower rates of postoperative symptom improvement (P < 0.05) but no differences in need for revision, complication rates, ED visits, or readmissions. CONCLUSIONS: Most PEHR patients have symptomatic improvement with minimal complications and reoperations despite frequent radiographic recurrence. Hernia type, crural closure, fundoplication, and mesh usage were not significantly associated with recurrence or symptom improvement. Compared to initial PEHR, reoperative PEHRs had lower rates of symptom improvement but similar rates of recurrence, complications, and need for reoperation.

Operative and Nonoperative Outcomes of Emergency General Surgery Conditions: An Observational Study Using a Novel Instrumental Variable.

OBJECTIVE: To determine the effect of operative versus nonoperative management of emergency general surgery conditions on short-term and long-term outcomes. BACKGROUND: Many emergency general surgery conditions can be managed either operatively or nonoperatively, but high-quality evidence to guide management decisions is scarce. METHODS: We included 507,677 Medicare patients treated for an emergency general surgery condition between July 1, 2015, and June 30, 2018. Operative management was compared with nonoperative management using a preference-based instrumental variable analysis and near-far matching to minimize selection bias and unmeasured confounding. Outcomes were mortality, complications, and readmissions. RESULTS: For hepatopancreaticobiliary conditions, operative management was associated with lower risk of mortality at 30 days [-2.6% (95% confidence interval: -4.0, -1.3)], 90 days [-4.7% (-6.50, -2.8)], and 180 days [-6.4% (-8.5, -4.2)]. Among 56,582 intestinal obstruction patients, operative management was associated with a higher risk of inpatient mortality [2.8% (0.7, 4.9)] but no significant difference thereafter. For upper gastrointestinal conditions, operative management was associated with a 9.7% higher risk of in-hospital mortality (6.4, 13.1), which increased over time. There was a 6.9% higher risk of inpatient mortality (3.6, 10.2) with operative management for colorectal conditions, which increased over time. For general abdominal conditions, operative management was associated with 12.2% increased risk of inpatient mortality (8.7, 15.8). This effect was attenuated at 30 days [8.5% (3.8, 13.2)] and nonsignificant thereafter. CONCLUSIONS: The effect of operative emergency general surgery management varied across conditions and over time. For colorectal and upper gastrointestinal conditions, outcomes are superior with nonoperative management, whereas surgery is favored for patients with hepatopancreaticobiliary conditions. For obstructions and general abdominal conditions, results were equivalent overall. These findings may support patients, clinicians, and families making these challenging decisions.

The Conditional Effects of Multimorbidity on Operative Versus Nonoperative Management of Emergency General Surgery Conditions: A Retrospective Observational Study Using an Instrumental Variable Analysis.

OBJECTIVE: To understand how multimorbidity impacts operative versus nonoperative management of emergency general surgery (EGS) conditions. BACKGROUND: EGS is a heterogenous field, encompassing operative and nonoperative treatment options. Decision-making is particularly complex for older patients with multimorbidity. METHODS: Using an instrumental variable approach with near-far matching, this national, retrospective observational cohort study of Medicare beneficiaries examines the conditional effects of multimorbidity, defined using qualifying comorbidity sets, on operative versus nonoperative management of EGS conditions. RESULTS: Of 507,667 patients with EGS conditions, 155,493 (30.6%) received an operation. Overall, 278,836 (54.9%) were multimorbid. After adjustment, multimorbidity significantly increased the risk of in-hospital mortality associated with operative management for general abdominal patients (+9.8%; P = 0.002) and upper gastrointestinal patients (+19.9%, P < 0.001) and the risk of 30-day mortality (+27.7%, P < 0.001) and nonroutine discharge (+21.8%, P = 0.007) associated with operative management for upper gastrointestinal patients. Regardless of multimorbidity status, operative management was associated with a higher risk of in-hospital mortality among colorectal patients (multimorbid: + 12%, P < 0.001; nonmultimorbid: +4%, P = 0.003), higher risk of nonroutine discharge among colorectal (multimorbid: +42.3%, P < 0.001; nonmultimorbid: +55.1%, P < 0.001) and intestinal obstruction patients (multimorbid: +14.6%, P = 0.001; nonmultimorbid: +14.8%, P = 0.001), and lower risk of nonroutine discharge (multimorbid: -11.5%, P < 0.001; nonmultimorbid: -11.9%, P < 0.001) and 30-day readmissions (multimorbid: -8.2%, P = 0.002; nonmultimorbid: -9.7%, P < 0.001) among hepatobiliary patients. CONCLUSIONS: The effects of multimorbidity on operative versus nonoperative management varied by EGS condition category. Physicians and patients should have honest conversations about the expected risks and benefits of treatment options, and future investigations should aim to understand the optimal management of multimorbid EGS patients.

Using Balancing Weights to Target the Treatment Effect on the Treated when Overlap is Poor.

Inverse probability weights are commonly used in epidemiology to estimate causal effects in observational studies. Researchers often focus on either the average treatment effect or the average treatment effect on the treated with inverse probability weighting estimators. However, poor overlap in the baseline covariates between the treated and control groups can produce extreme weights that can result in biased treatment effect estimates. One alternative to inverse probability weights are overlap weights, which target the population with the most overlap on observed covariates. Although estimates based on overlap weights produce less bias in such contexts, the causal estimand can be difficult to interpret. An alternative to model-based inverse probability weights are balancing weights, which directly target imbalances during the estimation process, rather than model fit. Here, we explore whether balancing weights allow analysts to target the average treatment effect on the treated in cases where inverse probability weights lead to biased estimates due to poor overlap. We conduct three simulation studies and an empirical application. We find that balancing weights often allow the analyst to still target the average treatment effect on the treated even when overlap is poor. We show that although overlap weights remain a key tool, more familiar estimands can sometimes be targeted by using balancing weights.

Radiation, Lymph Node Dissection, or Both: Management of Lymph Node Micrometastases from Merkel Cell Carcinoma.

BACKGROUND: Regional lymph node micrometastases from Merkel cell carcinoma (MCC) can be treated with completion lymph node dissection (CLND) and/or radiation therapy (RT). It is unclear how these options compare in terms of survival benefits for patients. PATIENTS AND METHODS: This retrospective cohort study used data from years 2012-2019 of the National Cancer Database. Patients with MCC and clinically negative, but pathologically positive, lymph node metastases who received RT to and/or CLND of the regional lymph node basin were included. Inverse probability weight balancing was performed using covariates followed by Cox proportional hazards modeling for survival analysis. RESULTS: A total of 962 patients were included [median (interquartile range) age, 74 (67-80) years, 662 (68.8%) male patients, 926 (96.3%) white patients]. The majority (63%, n = 606) had a CLND only, while 18% (n = 173) had RT only, and 19% (n = 183) had both CLND and RT. From 2016 to 2019, usage of RT only increased from 10% to 31.8%. Multivariate analysis demonstrated that treatment modality was not associated with survival [RT versus CLND, hazard ratio (HR) 0.842, 95% confidence interval (CI) 0.621-1.142, p = 0.269, RT+CLND versus CLND, HR 1.029, 95% CI 0.775-1.367, p = 0.844]. This persisted after balancing weights (RT versus CLND, HR 0.837, 95% CI 0.614-1.142, p = 0.262, RT+CLND versus CLND, HR 1.085, 95% CI 0.801-1.470, p = 0.599). CONCLUSIONS: The usage of RT for nodal micrometastasis in MCC is increasing as compared with CLND. This strategy appears to be safe, with no significant difference in survival outcomes.

Impact of Medicaid expansion on outcomes after abdominal aortic aneurysm repair.

OBJECTIVE: Lack of insurance has been independently associated with an increased risk of in-hospital mortality after abdominal aortic aneurysm repair, possibly due to worse control of comorbidities and delays in diagnosis and treatment. Medicaid expansion has improved insurance rates and access to care, potentially benefiting these patients. We sought to assess the association between Medicaid expansion and outcomes after abdominal aortic aneurysm repair. METHODS: A retrospective analysis of Healthcare Cost and Utilization Project State Inpatient Databases data from 14 states between 2012 and 2018 was conducted. The sample was restricted to first-record abdominal aortic aneurysm repairs in adults under age 65 in states that expanded Medicaid on January 1, 2014 (Medicaid expansion group) or had not expanded before December 31, 2018 (non-expansion group). The Medicaid expansion and non-expansion groups were compared between pre-expansion (2012-2013) and post-expansion (2014-2018) time periods to assess baseline demographic and operative differences. We used difference-in-differences multivariable logistic regression adjusted for patient factors, open vs endovascular repair, and standard errors clustered by state. Our primary outcome was in-hospital mortality. Outcomes were stratified by insurance type. RESULTS: We examined 8995 patients undergoing abdominal aortic aneurysm repair, including 3789 (42.1%) in non-expansion states and 5206 (57.9%) in Medicaid expansion states. Rates of Medicaid insurance were unchanged in non-expansion states but increased in Medicaid expansion states post-expansion (non-expansion: 10.9% to 9.8%; P = .346; expansion: 9.7% to 19.7%; P < .001). One in 10 patients from both non-expansion and Medicaid expansion states presented with ruptured aneurysms, which did not change over time. Rates of open repair decreased in both non-expansion and Medicaid expansion states over time (non-expansion: 25.1% to 19.2%; P < .001; expansion: 25.2% to 18.4%; P < .001). On adjusted difference-in-differences analysis between expansion and non-expansion states pre-to post-expansion, Medicaid expansion was associated with a 1.02% absolute reduction in in-hospital mortality among all patients (95% confidence interval, -1.87% to -0.17%; P = .019). Additionally, among patients who were either on Medicaid or were uninsured (ie, the patients most likely to be impacted by Medicaid expansion), a larger 4.17% decrease in in-hospital mortality was observed (95% confidence interval, -6.47% to -1.87%; P < .001). In contrast, no significant difference-in-difference in mortality was observed for privately insured patients. CONCLUSIONS: Medicaid expansion was associated with decreased in-hospital mortality after abdominal aortic aneurysm repair among all patients and particularly among patients who were either on Medicaid or were uninsured. Our results provide support for improved access to care for patients undergoing abdominal aortic aneurysm repair through Medicaid expansion.

Conditional Effects of Race on Operative and Nonoperative Outcomes of Emergency General Surgery Conditions.

INTRODUCTION: Many emergency general surgery (EGS) conditions can be managed both operatively or nonoperatively; however, it is unknown whether the decision to operate affects Black and White patients differentially. METHODS: We identified a nationwide cohort of Black and White Medicare beneficiaries, hospitalized for common EGS conditions from July 2015 to June 2018. Using near-far matching to adjust for measurable confounding and an instrumental variable analysis to control for selection bias associated with treatment assignment, we compare outcomes of operative and nonoperative management in a stratified population of Black and White patients. Outcomes included in-hospital mortality, 30-day mortality, nonroutine discharge, and 30-day readmissions. An interaction test based on a t test was used to determine the conditional effects of operative versus nonoperative management between Black and White patients. RESULTS: A total of 556,087 patients met inclusion criteria, of which 59,519 (10.7%) were Black and 496,568 (89.3%) were White. Overall, 165,932 (29.8%) patients had an operation and 390,155 (70.2%) were managed nonoperatively. Significant outcome differences were seen between operative and nonoperative management for some conditions; however, no significant differences were seen for the conditional effect of race on outcomes. CONCLUSIONS: The decision to manage an EGS patient operatively versus nonoperatively has varying effects on surgical outcomes. These effects vary by EGS condition. There were no significant conditional effects of race on the outcomes of operative versus nonoperative management among universally insured older adults hospitalized with EGS conditions.

A guide to regression discontinuity designs in medical applications.

We present a practical guide for the analysis of regression discontinuity (RD) designs in biomedical contexts. We begin by introducing key concepts, assumptions, and estimands within both the continuity-based framework and the local randomization framework. We then discuss modern estimation and inference methods within both frameworks, including approaches for bandwidth or local neighborhood selection, optimal treatment effect point estimation, and robust bias-corrected inference methods for uncertainty quantification. We also overview empirical falsification tests that can be used to support key assumptions. Our discussion focuses on two particular features that are relevant in biomedical research: (i) fuzzy RD designs, which often arise when therapeutic treatments are based on clinical guidelines, but patients with scores near the cutoff are treated contrary to the assignment rule; and (ii) RD designs with discrete scores, which are ubiquitous in biomedical applications. We illustrate our discussion with three empirical applications: the effect CD4 guidelines for anti-retroviral therapy on retention of HIV patients in South Africa, the effect of genetic guidelines for chemotherapy on breast cancer recurrence in the United States, and the effects of age-based patient cost-sharing on healthcare utilization in Taiwan. Complete replication materials employing publicly available data and statistical software in Python, R and Stata are provided, offering researchers all necessary tools to conduct an RD analysis.

Emergency Surgery, Multimorbidity and Hospital-Free Days: A Retrospective Observational Study.

INTRODUCTION: Analyzing hospital-free days (HFDs) offers a patient-centered approach to health services research. We hypothesized that, within emergency general surgery (EGS), multimorbidity would be associated with fewer HFDs, whether patients were managed operatively or nonoperatively. METHODS: EGS patients were identified using national Medicare claims data (2015-2018). Patients were classified as multimorbid based on the presence of a Qualifying Comorbidity Set and stratified by treatment: operative (received surgery within 48 h of index admission) and nonoperative. HFDs were calculated through 180 d, beginning on the day of index admission, as days alive and spent outside of a hospital, an Emergency Department, or a long-term acute care facility. Univariate comparisons were performed using Kruskal-Wallis tests and risk-adjusted HFDs were compared between multimorbid and nonmultimorbid patients using multivariable zero-inflated negative binomial regression models. RESULTS: Among 174,891 operative patients, 45.5% were multimorbid. Among 398,756 nonoperative patients, 59.2% were multimorbid. Multimorbid patients had fewer median HFDs than nonmultimorbid patients among operative and nonoperative cohorts (P < 0.001). At 6 mo, among operative patients, multimorbid patients had 6.5 fewer HFDs (P < 0.001), and among nonoperative patients, multimorbid patients had 7.9 fewer HFDs (P < 0.001). When length of stay was included as a covariate, nonoperative multimorbid patients still had 7.9 fewer HFDs than nonoperative, nonmultimorbid patients (P < 0.001). CONCLUSIONS: HFDs offer a patient-centered, composite outcome for claims-based analyses. For EGS patients, multimorbidity was associated with less time alive and out of the hospital, especially when patients were managed nonoperatively.

National Cohort Study of Resource Utilization in Older Adults With Emergency General Surgery Conditions.

INTRODUCTION: Prior studies have sought to describe Emergency General Surgery (EGS) burden, but a detailed description of resource utilization for both operative and nonoperative management of EGS conditions has not been undertaken. METHODS: Patient and hospital characteristics were extracted from Medicare data, 2015-2018. Operations, nonsurgical procedures, and other resources (i.e., radiology) were defined using Current Procedural Terminology codes. RESULTS: One million eight hundred two thousand five hundred forty-five patients were included in the cohort. The mean age was 74.7 y and the most common diagnoses were upper gastrointestinal. The majority of hospitals were metropolitan (75.1%). Therapeutic radiology services were available in 78.4% of hospitals and operating rooms or endoscopy suites were available in 92.5% of hospitals. There was variability in resource utilization across EGS subconditions, with hepatobiliary (26.4%) and obstruction (23.9%) patients most frequently undergoing operation. CONCLUSIONS: Treatment of EGS diseases in older adults involves several interventional resources. Changes in EGS models, acute care surgery training, and interhospital care coordination may be beneficial to the treatment of EGS patients.

Delayed time to radiation and overall survival in Merkel cell carcinoma.

BACKGROUND: Clinically localized Merkel cell carcinoma (MCC) is commonly treated with surgical excision and radiotherapy. The relationship between time to adjuvant radiotherapy and overall survival (OS) remains understudied. METHODS: This retrospective study used data from the National Cancer Database (2006-2019). Patients with clinically localized MCC who received surgical excision and adjuvant radiotherapy were included. Multivariate regressions were used to account for various patient and tumor factors. The primary outcome was 5-year OS, and the secondary outcome was time from diagnosis to adjuvant radiation (TTR). RESULTS: Of the 1965 patients included, most were male (n = 1242, 63.2%) and white (n = 1915, 97.5%), and the median age was 74 years (interquartile range [IQR]: 66-81). The median TTR was 83 days (IQR: 65-106). A total of 83.6% of patients received radiotherapy to the primary site, 21.3% to the draining nodal basin, 17.1% to both, and 12.2% whose target location of radiotherapy was not recorded in the data. TTR of ≥79 days (the 45th percentile) was associated with worse OS on both univariate and multivariate analyses (log-rank p = 0.0014; hazard ratio [HR]: 1.258, 95% confidence interval [CI]: 1.055-1.500, p = 0.010). This persisted on sub-analyses of patients <80 years old (n = 1407; HR: 1.380, 95% CI: 1.080-1.764, p = 0.010) and of patients with Charlson comorbidity index (CCI) of 0 (n = 1411; HR: 1.284, 95% CI: 1.034-1.595, p = 0.024). Factors associated with delayed TTR included greater age (p = 0.039), male sex (p = 0.04), CCI > 1 (p = 0.036), academic facility (p < 0.001), rural county (p = 0.034), AJCC T2 stage (p = 0.010), negative margins (p = 0.017), 2+ pathologically positive regional nodes (p = 0.011), and margin size >2 cm (p = 0.015). CONCLUSIONS: Delayed radiotherapy (≥79 days) was associated with worse OS of MCC patients. Further study in controlled cohorts is needed to ascertain this relationship.

Preoperative MRI and Its Impact on Surgical Outcomes in Patients with Triple Negative Breast Cancer Treated with Primary Surgery: Did New Margin Guidelines or Cavity Shave Margins Practice Diminish the Role of Preoperative MRI?

BACKGROUND: Results of an earlier retrospective study from our institution suggested that patients with triple negative breast cancer (TNBC) who had preoperative MRI may have had an improved local recurrence rate (LRR) after breast conserving surgery (BCS). We aimed to clarify the impact of preoperative MRI on surgical outcomes in an expanded TNBC cohort treated by BCS in a contemporary era. METHODS: Our study cohort comprised 648 patients with TNBC who underwent BCS between 2009 and 2018. Demographic and clinical characteristics were compared between those with (n = 292, 45.1%) and without (n = 356, 54.9%) preoperative MRI. Multivariable logistic regression was performed to assess the association of preoperative MRI with surgical outcomes. RESULTS: The crude LRR of 3.5% was lower than previously reported. Univariable analyses demonstrated that the LRR and re-excision rates in the MRI and no-MRI groups were 3.4 and 3.7%, 21.6% and 27.2%, p = 0.876 and p = 0.10, respectively. Multivariable logistic regression analyses demonstrated that preoperative MRI was not associated with a lower LRR: odds ratio (OR) = 1.42 (p = 0.5). During our study period, new margin guidelines and shave margins practice were adopted in 2014 and 2015. To account for their effects, the year of diagnosis/surgery and other clinical variables were adjusted in multivariable logistic regression and inverse probability weighting models to demonstrate that preoperative MRI remained associated with a lower re-excision risk, OR 0.56, p = 0.04l; and a lower re-excision rate, 23.15% versus 36.0%, p < 0.01, respectively. CONCLUSIONS: Our findings suggested that patients with TNBC anticipating BCS may benefit from preoperative MRI.

Lymph Node Evaluation after Neoadjuvant Chemotherapy for Patients with Gastric Cancer.

BACKGROUND: Adequate lymphadenectomy with at least 16 nodes retrieved at the time of gastrectomy is a quality measure recommended to ensure adequate staging. The minimum nodal retrieval recommended after receipt of neoadjuvant chemotherapy (NACT) is less defined. METHODS: Patients with clinical stages 1 to 3 gastric adenocarcinoma who received NACT and surgical resection were identified from the 2004-2015 National Cancer Database. The optimal nodal harvest number was calculated with Cox spline regression modeling. Cohorts with a nodal harvest higher or lower than this number were 1:1 propensity score-matched. Overall survival (OS) was analyzed using Kaplan-Meier survival estimates. RESULTS: Among 4337 patients receiving NACT, the optimal minimal nodal harvest at gastrectomy was 23 nodes. Compared with the patients who had fewer than 23 nodes retrieved, the patients with at least 23 nodes examined (n = 1073, 24.7%) were more likely to be female (26.1% vs 22%; p = 0.006) and non-white (29.3% vs 18.5%; p < 0.0001), to have a Charlson-Deyo score of 0 (71.5% vs 66.8%; p = 0.005), and to have undergone resection at an academic facility (67.9% vs 51.5%; p < 0.0001). The patients with at least 23 nodes examined had higher proportions of high-grade tumor (62% vs 57.4%; p = 0.030), pT3 or pT4 tumor (56.3% vs 48.7%; p < 0.0001), body tumor (21.3% vs 12.5%; p < 0.0001), or antrum/pylorus tumor (15.3% vs 11.4%; p < 0.0001). The patients with at least 23 nodes were more likely to have lymph node metastases identified (61% vs 51%; p < 0.0001). After matching, the patients with at least 23 nodes (n = 990) demonstrated an improved 5-year OS (57.9% vs 49%; p = 0.001). CONCLUSIONS: The extent of lymphadenectomy during gastrectomy for gastric adenocarcinoma should not be reduced after NACT because adequate lymph node retrieval remains important for prognostication.

An Internally Validated Prognostic Risk-Score Model for Disease-Specific Survival in Clinical Stage I and II Merkel Cell Carcinoma.

BACKGROUND: Merkel cell carcinoma (MCC) is a rare cutaneous malignancy for which factors predictive of disease-specific survival (DSS) are poorly defined. METHODS: Patients from six centers (2005-2020) with clinical stage I-II MCC who underwent sentinel lymph node (SLN) biopsy were included. Factors associated with DSS were identified using competing-risks regression analysis. Risk-score modeling was established using competing-risks regression on a training dataset and internally validated by point assignment to variables. RESULTS: Of 604 patients, 474 (78.5%) and 128 (21.2%) patients had clinical stage I and II disease, respectively, and 189 (31.3%) had SLN metastases. The 5-year DSS rate was 81.8% with a median follow-up of 31 months. Prognostic factors associated with worse DSS included increasing age (hazard ratio [HR] 1.03, p = 0.046), male sex (HR 3.21, p = 0.021), immune compromise (HR 2.46, p = 0.013), presence of microsatellites (HR 2.65, p = 0.041), and regional nodal involvement (1 node: HR 2.48, p = 0.039; ≥2 nodes: HR 2.95, p = 0.026). An internally validated, risk-score model incorporating all of these factors was developed with good performance (AUC 0.738). Patients with ≤ 4.00 and > 4.00 points had 5-year DSS rates of 89.4% and 67.2%, respectively. Five-year DSS for pathologic stage I/II patients with > 4.00 points (n = 49) was 79.8% and for pathologic stage III patients with ≤ 4.00 points (n = 62) was 90.3%. CONCLUSIONS: A risk-score model, including patient and tumor factors, based on DSS improves prognostic assessment of patients with clinically localized MCC. This may inform surveillance strategies and patient selection for adjuvant therapy trials.

Multimorbidity Confers Greater Risk for Older Patients in Emergency General Surgery Than the Presence of Multiple Comorbidities: A Retrospective Observational Study.

BACKGROUND: Little is known about the impact of multimorbidity on outcomes for older emergency general surgery patients. OBJECTIVE: The aim was to understand whether having multiple comorbidities confers the same amount of risk as specific combinations of comorbidities (multimorbidity) for a patient undergoing emergency general surgery. RESEARCH DESIGN: Retrospective observational study using state discharge data. SUBJECTS: Medicare beneficiaries who underwent an operation for an emergency general surgery condition in New York, Florida, or Pennsylvania (2012-2013). MEASURES: Patients were classified as multimorbid using Qualifying Comorbidity Sets (QCSs). Outcomes included in-hospital mortality, hospital length of stay and discharge status. RESULTS: Of 312,160 patients, a large minority (37.4%) were multimorbid. Non-QCS patients did not have a specific combination of comorbidities to satisfy a QCS, but 64.1% of these patients had 3+ comorbid conditions. Multimorbidity was associated with increased in-hospital mortality (10.5% vs. 3.9%, P <0.001), decreased rates of discharge to home (16.2% vs. 37.1%, P <0.001), and longer length of stay (10.4 d±13.5 vs. 6.7 d±9.3, P <0.001) when compared with non-QCS patients. Risks varied between individual QCSs. CONCLUSIONS: Multimorbidity, defined by satisfying a specific QCS, is strongly associated with poor outcomes for older patients requiring emergency general surgery in the United States. Variation in risk of in-hospital mortality, discharge status, and length of stay between individual QCSs suggests that multimorbidity does not carry the same prognostic weight as having multiple comorbidities-the specifics of which are important in setting expectations for individual, complex patients.

The impact of hospital volume on racial disparities in resected rectal cancer.

BACKGROUND: Although high volume centers (HVC) equate to improved outcomes in rectal cancer, the impact of surgical volume related to race is less defined. METHODS: Patients who underwent surgical resection for stage I-III rectal adenocarcinoma were divided into cohorts based on race and hospital surgical volume. Outcomes were analyzed following 1:1 propensity-score matching using logistic, Poisson, and Cox regression analyses with marginal effects. RESULTS: Fifty-four thousand one hundred and eighty-four (91.5%) non-Black and 5043 (8.5%) Black patients underwent resection of rectal cancer. Following 1:1 matching of non-Black (N = 5026) and Black patients, 5-year overall survival (OS) of Black patients was worse (72% vs. 74.4%, average marginal effects [AME] 0.66, p = 0.04) than non-Black patients. When compared to non-Black patients managed at HVCs, Black patients had worse OS (70.1% vs. 74.7%, AME 1.55, p = 0.03), but this difference was not significant when comparing OS between non-Black and Black patients managed at HVCs (72.3% vs. 74.7%, AME 0.62, p = 0.06). Length of stay was longer among Black and HVC patients across all cohorts. There was no difference across cohorts in 90-day mortality. CONCLUSIONS: Although racial disparities exist in rectal cancer, this disparity appears to be ameliorated when patients are managed at HVCs.

Association of type II diabetes mellitus with characteristics and outcomes for patients undergoing sentinel lymph node biopsy for cutaneous melanoma.

BACKGROUND AND OBJECTIVES: Type II diabetes mellitus (T2DM) can lead to an immunosuppressed state, but whether T2DM is associated with worse outcomes for patients with melanoma has not been well studied. METHODS: Consecutive patients diagnosed with clinical stage I-II cutaneous melanoma who underwent sentinel lymph node biopsy at a single institution (2007-2016) were identified. Melanoma characteristics and recurrence/survival outcomes were compared between patients with and without T2DM at the time of melanoma diagnosis. RESULTS: Of 1128 patients evaluated, 111 (9.8%) had T2DM (n = 94 [84.7%] non-insulin dependent [NID-T2DM]; n = 17 [15.3%] insulin dependent [ID-T2DM]). T2DM patients were more likely to be older (odds ratio [OR] 1.04, p < 0.001), male (OR 2.15, p = 0.003), have tumors >1.0 mm (OR 1.88, p = 0.023), and have microsatellitosis (OR 2.29, p = 0.030). Five-year cumulative incidence of melanoma recurrence was significantly higher for patients with ID-T2DM (46.7% ID-T2DM vs. 25.7% NID-T2DM vs. 17.1% no T2DM, p < 0.001), and on multivariable analysis, ID-T2DM was independently associated with melanoma recurrence (hazard ratio 2.57, p = 0.015). No difference in 5-year disease-specific survival was observed between groups. CONCLUSIONS: ID-T2DM appears to be associated with more advanced melanoma and increased risk for melanoma recurrence. Further study as to whether this reflects differences in tumor biology or host factors is warranted.

An introduction to spillover effects in cluster randomized trials with noncompliance.

In some cluster randomized trials, subjects may not comply with their assigned treatment status. Such treatment noncompliance can create opportunities for spillover effects within clusters. Little research has focused on what can be learned in such context. This article provides a non-technical review of recent work on the complications that arise in cluster randomized trials where some units within treated clusters do not comply with treatment but the treatment spillovers over to these units. We motivate concepts using a hypothetical vaccine cluster randomized trial. We review that standard instrumental variable methods cannot recover the complier average causal effect in the presence of these spillovers. In fact, we review that without additional assumptions, little can be learned about compliance effects or spillover effects. We discuss one additional assumption that allows for bounds on a key causal effect. We also outline an estimator for these bounds.