Propensity scores used as overlap weights provide exact covariate balance.

Overlap weighting, using weights defined as the probability of receiving the opposite treatment, is a relatively new, alternative propensity score-based weighting technique used to adjust for confounding when estimating causal treatment effects. It has preferable properties compared to inverse probability of treatment weighting, such as exact covariate balance, safeguards against extreme weights and emphasis on medical equipoise, where treatment decisions are most uncertain. In this article, we introduce the overlap weighting methodology, compare it to inverse probability of treatment weighting and provide some strategies for assessing weighting impact, through an applied example of hospital mortality. When the propensity score distributions have large separation, inverse probability of treatment weighting has been shown to produce biased and less efficient estimates of the treatment effect, making overlap weighting a preferred method in such cases.

A simplified pneumonia severity index (PSI) for clinical outcome prediction in COVID-19.

BACKGROUND: The Pneumonia Score Index (PSI) was developed to estimate the risk of dying within 30 days of presentation for community-acquired pneumonia patients and is a strong predictor of 30-day mortality after COVID-19. However, three of its required 20 variables (skilled nursing home, altered mental status and pleural effusion) are not discreetly available in the electronic medical record (EMR), resulting in manual chart review for these 3 factors. The goal of this study is to compare a simplified 17-factor version (PSI-17) to the original (denoted PSI-20) in terms of prediction of 30-day mortality in COVID-19. METHODS: In this retrospective cohort study, the hospitalized patients with confirmed SARS-CoV-2 infection between 2/28/20-5/28/20 were identified to compare the predictive performance between PSI-17 and PSI-20. Correlation was assessed between PSI-17 and PSI-20, and logistic regressions were performed for 30-day mortality. The predictive abilities were compared by discrimination, calibration, and overall performance. RESULTS: Based on 1,138 COVID-19 patients, the correlation between PSI-17 and PSI-20 was 0.95. Univariate logistic regression showed that PSI-17 had performance similar to PSI-20, based on AUC, ICI and Brier Score. After adjusting for confounding variables by multivariable logistic regression, PSI-17 and PSI-20 had AUCs (95% CI) of 0.85 (0.83-0.88) and 0.86 (0.84-0.89), respectively, indicating no significant difference in AUC at significance level of 0.05. CONCLUSION: PSI-17 and PSI-20 are equally effective predictors of 30-day mortality in terms of several performance metrics. PSI-17 can be obtained without the manual chart review, which allows for automated risk calculations within an EMR. PSI-17 can be easily obtained and may be a comparable alternative to PSI-20.

Characterization of Lymph Node Tumor Burden in Node-Positive Prostate Cancer Patients after Robotic-Assisted Radical Prostatectomy with Extended Pelvic Lymph Node Dissection.

BACKGROUND: Prostate cancer (PCa) nodal staging does not account for lymph node (LN) tumor burden. The LN anatomical compartment involved with the tumor or the quantified extent of extranodal extension (ENE) have not yet been studied in relation to biochemical recurrence-free survival (BRFS). METHODS: Histopathological slides of 66 pN1 PCa patients who underwent extended pelvic lymph node dissection were reviewed. We recorded metrics to quantify LN tumor burden. We also characterized the LN anatomical compartments involved and quantified the extent of ENE. RESULTS: The median follow-up time was 38 months. The median number of total LNs obtained per patient was 30 (IQR 23-37). In the risk-adjusted cox regression model, the following variables were associated with BRFS: mean size of the largest LN deposit per patient (log2: adjusted hazard ratio (aHR) = 1.91, p < 0.001), the mean total span of all LN deposits per patient (2.07, p < 0.001), and the mean percent surface area of the LN involved with the tumor (1.58, p < 0.001). There was no significant BRFS association for the LN anatomical compartment or the quantified extent of ENE. CONCLUSION: LN tumor burden is associated with BRFS. The LN anatomical compartments and the quantified extent of ENE did not show significant association with BRFS.

Impact of Mediating and Confounding Variables on the Volume-Outcome Association in the Treatment of Pancreatic Cancer.

BACKGROUND: High-volume centers (HVC), academic centers (AC), and longer travel distances (TD) have been associated with improved outcomes for patients undergoing surgery for pancreatic adenocarcinoma (PAC). Effects of mediating variables on these associations remain undefined. The purpose of this study is to examine the direct effects of hospital volume, facility type, and travel distance on overall survival (OS) in patients undergoing surgery for PAC and characterize the indirect effects of patient-, disease-, and treatment-related mediating variables. PATIENTS AND METHODS: Using the National Cancer Database, patients with non-metastatic PAC who underwent resection were stratified by annual hospital volume (< 11, 11-19, and ≥ 20 cases/year), facility type (AC versus non-AC), and TD (≥ 40 versus < 40 miles). Associations with survival were evaluated using multiple regression models. Effects of mediating variables were assessed using mediation analysis. RESULTS: In total, 19,636 patients were included. Treatment at HVC or AC was associated with lower risk of death [hazard ratio (HR) 0.90, confidence interval (CI) 0.88-0.92; HR 0.89, CI 0.86-0.91, respectively]. TD did not impact OS. Patient-, disease-, and treatment-related variables explained 25.5% and 41.8% of the survival benefit attained from treatment at HVC and AC, reducing the survival benefit directly attributable to each variable to 4.9% and 6.4%, respectively. CONCLUSIONS: Treatment of PAC at HVC and AC was associated with improved OS, but the magnitude of this benefit was less when mediating variables were considered. From a healthcare utilization and cost-resource perspective, further research is needed to identify patients who would benefit most from selective referral to HVC or AC.

Clinical Factors and Outcomes When Real-World Heart Teams Overruled STS Risk Scores in TAVR Cases.

Objectives: This study was conducted to determine why heart teams recommended transcatheter aortic valve replacement (TAVR) versus surgical AVR (SAVR) for patients at low predicted risk of mortality (PROM) and describe outcomes of these cases. Background: Historically, referral to TAVR was based predominately on the Society of Thoracic Surgeons (STS) risk model's PROM >3%. In selected cases, heart teams had latitude to overrule these scores. The clinical reasons and outcomes for these cases are unclear. Methods: Retrospective data were gathered for all TAVR and SAVR cases conducted by 9 hospitals between 2013 and 2017. Results: Cases included TAVR patients with STS PROM >3% (n = 2,711) and ≤3% (n = 415) and SAVR with STS PROM ≤3% (n = 1,438). Leading reasons for recommending TAVR in the PROM ≤3% group were frailty (57%), hostile chest (22%), severe lung disease (16%), and morbid obesity (13%), and 44% of cases had multiple reasons. Most postoperative and 30-day outcomes were similar between TAVR groups, but the STS PROM ≤3% group had a one-day shorter length of stay (2.5 ± 3.4 vs. 3.5 ± 4.7 days; p ≤ 0.001) and higher one-year survival (91.6% vs. 86.0%, p=0.002). In patients with STS PROM ≤3%, 30-day mortality was higher for TAVR versus SAVR (2.0% vs. 0.6%; p < 0.001). Conclusions: Heart teams recommended TAVR in patients with STS PROM ≤3% primarily due to frailty, hostile chest, severe lung disease, and/or morbid obesity. Similar postoperative outcomes between these patients and those with STS PROM >3% suggest that decisions to overrule STS PROM ≤3% were merited and may have reduced SAVR 30-day mortality rate.

The CUSUM Slope Equals Observed Minus Expected Mortality and Can Be Visualized by a "Slope-Meter".

We present an additional advantage of the Risk-Adjusted CUSUM (RA-CUSUM), namely, that its slope can be quantified and is in fact equivalent to Observed (O) minus Expected (E) mortality. That is, the height of the RA-CUSUM is the O minus E deaths, which measures performance since the start of the series, and the slope of the RA-CUSUM is the O minus E mortality which measures performance during a chosen interval. We present a useful graphical tool (Slope-Meter) to allow approximation of this mortality difference by the viewer.

Comparison of 26-mm Evolut and 23-mm Sapien 3 Valves in TAVR for Small Aortic Annulus.

BACKGROUND: Patients with small aortic annuli (SAA) are prone to higher post-transcatheter aortic valve replacement (TAVR) transvalvular gradients and development of prosthesis-patient mismatch (PPM). In many patients with SAA, the choice of TAVR valve commonly involves choosing between the 26-mm Medtronic Evolut 2 (ME26) or the 23-mm Edwards Sapien 3 valve (ES23). We compared echocardiographic and clinical outcomes in patients with SAA undergoing TAVR with either valve. METHODS: We queried the Providence St. Joseph Health Society of Thoracic Surgeons/American College of Cardiology Transcatheter Valve Therapy Registry database for patients undergoing TAVR with either the ES23 or ME26 between July 2015 and December 2018 at 11 hospitals. Post-TAVR echocardiographic and clinical results in-hospital, at 1 month, and at 1 year were examined. High gradient (HG) was defined as mean gradient (MG) ≥20 mm Hg. RESULTS: We identified 1162 patients with SAA undergoing TAVR with either the ME26 (n = 233) or ES23 valve (n = 929). Baseline characteristics between groups were similar. At 1 month, the ME26 was associated with a lower MG than the ES23 (7.7 ± 4.7 mm Hg vs 13.1 ± 4.9 mm Hg; P<.001) and moderate or severe PPM (11% and 3% vs 27% and 13%; P<.001). Occurrence of HG at 1 year was lower with the ME26 valve vs the ES23 valve (0% vs 15%; P<.001). In-hospital and follow-up clinical outcomes to 1 year were similar for both groups. CONCLUSION: TAVR in SAA with the ME26 is associated with lower incidence of HG or PPM compared with the ES23. While clinical outcomes at 1 year were similar, the long-term implications of these findings remain unknown.

Calibration Factors for STS Risk Model Predictions: Why, How and When They Are Used.

The Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database is the world's premier adult cardiac surgery outcomes registry. This tutorial explains the following: how STS updates the risk models that are used to calculate the predicted risks of adverse events in the registry; why STS on a quarterly basis adjusts or "calibrates" the observed-to-expected ratios to equal 1 (O/E = 1), thereby effectively making the annual number of adverse events predicted by the model match the annual number of adverse events observed in the entire registry; the differences between the calibrated and uncalibrated O/E ratios; and how and when to use each.

Remdesivir and Mortality in Patients With Coronavirus Disease 2019.

BACKGROUND: The impact of remdesivir (RDV) on mortality rates in coronavirus disease 2019 (COVID-19) is controversial, and the mortality effect in subgroups of baseline disease severity has been incompletely explored. The purpose of this study was to assess the association of RDV with mortality rates in patients with COVID-19. METHODS: In this retrospective cohort study we compared persons receiving RDV with those receiving best supportive care (BSC). Patients hospitalized between 28 February and 28 May 2020 with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 infection were included with the development of COVID-19 pneumonia on chest radiography and hypoxia requiring supplemental oxygen or oxygen saturation ≤94% with room air. The primary outcome was overall survival, assessed with time-dependent Cox proportional hazards regression and multivariable adjustment, including calendar time, baseline patient characteristics, corticosteroid use, and random effects for hospital. RESULTS: A total of 1138 patients were enrolled, including 286 who received RDV and 852 treated with BSC, 400 of whom received hydroxychloroquine. Corticosteroids were used in 20.4% of the cohort (12.6% in RDV and 23% in BSC). Comparing persons receiving RDV with those receiving BSC, the hazard ratio (95% confidence interval) for death was 0.46 (.31-.69) in the univariate model (P < .001) and 0.60 (.40-.90) in the risk-adjusted model (P = .01). In the subgroup of persons with baseline use of low-flow oxygen, the hazard ratio (95% confidence interval) for death in RDV compared with BSC was 0.63 (.39-1.00; P = .049). CONCLUSION: Treatment with RDV was associated with lower mortality rates than BSC. These findings remain the same in the subgroup with baseline use of low-flow oxygen.

Is the 21-Gene Recurrence Score on Core Needle Biopsy Equivalent to Surgical Specimen in Early-Stage Breast Cancer? A Comparison of Gene Expression Between Paired Core Needle Biopsy and Surgical Specimens.

BACKGROUND: Molecular testing on surgical specimens predicts disease recurrence and benefit of adjuvant chemotherapy in hormone receptor-positive (HR+), human epidermal growth factor receptor 2-negative (HER2-) early-stage breast cancer (EBC). Testing on core biopsies has become common practice despite limited evidence of concordance between core/surgical samples. In this study, we compared the gene expression of the 21 genes and the recurrence score (RS) between paired core/surgical specimens. METHODS: Eighty patients with HR+/HER2- EBC were evaluated from two publicly available gene expression datasets (GSE73235, GSE76728) with paired core/surgical specimens without neoadjuvant systemic therapy. The expression of the 21 genes was compared in paired samples. A microarray-based RS was calculated and a value ≥ 26 was defined as high-RS. The concordance rate and kappa statistic were used to evaluate the agreement between the RS of paired samples. RESULTS: Overall, there was no significant difference and a high correlation in the gene expression levels of the 21 genes between paired samples. However, CD68 and RPLP0 in GSE73235, AURKA, BAG1, and TFRC in GSE76728, and MYLBL2 and ACTB in both datasets exhibited weak to moderate correlation (r < 0.5). There was a high correlation of the microarray-based RS between paired samples in GSE76728 (r = 0.91, 95% confidence interval [CI] 0.81-0.96) and GSE73235 (r = 0.82, 95% CI 0.71-0.89). There were no changes in RS category in GSE76728, whereas 82% of patients remained in the same RS category in GSE73235 (κ = 0.64). CONCLUSIONS: Gene expression levels of the 21-gene RS showed a high correlation between paired specimens. Potential sampling and biological variability on a set of genes need to be considered to better estimate the RS from core needle biopsy.

Continuous Monitoring of Risk-Adjusted Outcomes: Excess Deaths vs Lives Saved.

Reporting of risk-adjusted surgical outcomes is commonly used to compare providers and track changes over time. Preferred graphical methods use the relationship of the observed to the expected values of outcome events, including their ratio (O/E), and the cumulative sum (CUSUM) of their differences over time, called Risk-Adjusted CUSUM (RA-CUSUM) or Variable Life Adjusted Display (VLAD). We demonstrate these methods using operative mortality data for 7255 isolated coronary artery bypass graft patients from January 2014 to June 2017. RA-CUSUM and VLAD are excellent techniques to display risk-adjusted outcomes and, unlike O/E, can provide continuous monitoring as performance varies over time.

Early cost-utility analysis of tissue-engineered heart valves compared to bioprostheses in the aortic position in elderly patients.

OBJECTIVES: Aortic valve disease is the most frequent indication for heart valve replacement with the highest prevalence in elderly. Tissue-engineered heart valves (TEHV) are foreseen to have important advantages over currently used bioprosthetic heart valve substitutes, most importantly reducing valve degeneration with subsequent reduction of re-intervention. We performed early Health Technology Assessment of hypothetical TEHV in elderly patients (≥ 70 years) requiring surgical (SAVR) or transcatheter aortic valve implantation (TAVI) to assess the potential of TEHV and to inform future development decisions. METHODS: Using a patient-level simulation model, the potential cost-effectiveness of TEHV compared with bioprostheses was predicted from a societal perspective. Anticipated, but currently hypothetical improvements in performance of TEHV, divided in durability, thrombogenicity, and infection resistance, were explored in scenario analyses to estimate quality-adjusted life-year (QALY) gain, cost reduction, headroom, and budget impact. RESULTS: Durability of TEHV had the highest impact on QALY gain and costs, followed by infection resistance. Improved TEHV performance (- 50% prosthetic valve-related events) resulted in lifetime QALY gains of 0.131 and 0.043, lifetime cost reductions of €639 and €368, translating to headrooms of €3255 and €2498 per hypothetical TEHV compared to SAVR and TAVI, respectively. National savings in the first decade after implementation varied between €2.8 and €11.2 million (SAVR) and €3.2-€12.8 million (TAVI) for TEHV substitution rates of 25-100%. CONCLUSIONS: Despite the relatively short life expectancy of elderly patients undergoing SAVR/TAVI, hypothetical TEHV are predicted to be cost-effective compared to bioprostheses, commercially viable and result in national cost savings when biomedical engineers succeed in realising improved durability and/or infection resistance of TEHV.

Neoadjuvant Chemotherapy Improves Survival in Patients with Clinical T4b Colon Cancer.

BACKGROUND: In 2016, the National Comprehensive Cancer Network included neoadjuvant chemotherapy as a treatment option for patients with clinical T4b colon cancer. However, there is little published data on the survival impact of neoadjuvant chemotherapy for locally advanced colon cancer. METHODS: Adult patients with non-metastatic clinically staged T3 or T4 colon cancer who underwent surgical resection were identified from the National Cancer Data Base between 2006 and 2014. Treatment was categorized as neoadjuvant chemotherapy followed by surgery and surgery followed by adjuvant chemotherapy. Overall survival was compared between the two groups using propensity score matching. RESULTS: Of 27,575 patients that met inclusion criteria, 26,654 (97%) were treated with surgery followed by adjuvant chemotherapy and 921 (3%) received neoadjuvant chemotherapy followed by surgery. After propensity score matching, patients with T4b colon cancer treated with neoadjuvant chemotherapy had a 23% lower risk of death at 3 years compared to patients that had adjuvant chemotherapy (HR 0.77, 95% CI 0.60-0.98; p = 0.04). However, neoadjuvant chemotherapy did not demonstrate a similar significant benefit for patients with T3 and T4a disease. CONCLUSIONS: Patients with clinical T4b colon cancer treated with neoadjuvant chemotherapy may have an improved survival compared to those who receive adjuvant chemotherapy. Further prospective investigation is warranted.

Bioprosthetic Aortic Valve Durability: A Meta-Regression of Published Studies.

To compare structural valve deterioration (SVD) among bioprosthetic aortic valve types, a PubMed search found 54 papers containing SVD-free curves extending to at least 10 years. The curves were digitized and fit to Weibull distributions, and the mean times to valve failure (MTTF) were calculated. Twelve valve models were collapsed into four valve types: Medtronic (Medtronic, Minneapolis, MN) and Edwards (Edwards Lifesciences, Irvine, CA) porcine; and Sorin (Sorin Group [now LivaNova], London, United Kingdom) and Edwards pericardial. Meta-regression found MTTF was associated with the patient's age, publication year, SVD definition, and valve type. Sorin pericardial valves had significantly lower risk-adjusted MTTF (higher SVD risk), and there were no significant differences in MTTF among the other three valve types.

A method to estimate the mean lifetime survival increase of statin therapy.

AIM: To propose a method for estimating the lifetime advantage of statins. METHODS: Kaplan-Meier survival curves from published 4S and LIPID studies with 5.8- and 6.1-year follow-up were digitized. Gompertz distributions were fit up to the end of the trials, and then extrapolated out to the end of the patients' predicted lifetimes for each study. RESULTS: The method results in a 9.9 (95% CI: 8.7-11.9) and 2.8 (95% CI: 2.3-3.3) years' increases for the statin groups for 4S and LIPID studies, respectively. CONCLUSION: Previous analysis of the same data was limited by the trials' relatively short run time. As such, we propose a method for correctly estimating the true effect of statin therapy in terms of total lifetime extension.

Surveillance of guideline practices for duodenoscope and linear echoendoscope reprocessing in a large healthcare system.

BACKGROUND AND AIMS: To assess the adequacy of currently recommended duodenoscope and linear echoendoscope (DLE) automatic endoscope reprocessing (AER) and high-level disinfection (HLD), we collected daily post-reprocessing surveillance cultures of 106 DLEs in 21 Providence and Affiliate Hospitals. METHODS: Daily qualitative surveillance of dried, post-HLD DLEs was conducted for a minimum of 30 days at each facility. Positivity rates for any microbial growth and growth of high-concern pathogens were reported. Potential effects of DLE manufacturer, age, and AER processor on culture-positivity rate were assessed. RESULTS: Microbial growth was recovered from 201 of 4032 specimens (5%) or 189 of 2238 encounters (8.4%), including 23 specimens (.6%) or 21 encounters (.9%) for a high-concern pathogen. Wide variations in culture-positivity rate were observed across facilities. No striking difference in culture-positivity rate was seen among 8 DLE models, 3 DLE manufacturers, DLE age, manual or bedside cleanser, or automatic flushing system use. However, there was suggestive evidence that Custom Ultrasonics AER (Warminster, Pa, USA) had a lower culture-positivity rate than Medivators AER (Cantel Medical Corp., Little Falls, NJ, USA) for high-concern pathogen growth (0/1079 vs 21/2735 specimens or 0/547 vs 20/1582 encounters). Two endoscopes grew intestinal flora on several occasions despite multiple HLD. No multidrug-resistant organism was detected. CONCLUSIONS: In this multicenter DLE surveillance study, microbial growth was recovered in 5.0% of specimens (8.4% of encounters), with most being environmental microbes. Enteric bacterial flora was recovered in .6% of specimens (.9% of encounters), despite compliance with 2014 U.S. guidelines and manufacturers' recommendations for cleaning and HLD process. The observed better performance of Custom Ultrasonics AER deserves further investigation.