Percutaneous Transluminal Angioplasty for Infrapopliteal Chronic Limb-Threatening Ischemia: A Systematic Review and Meta-analysis of Primary Patency and Binary Restenosis Rates.

PURPOSE: Percutaneous transluminal angioplasty (PTA) remains the mainstay of endovascular therapy for infrapopliteal chronic limb-threatening ischemia (CLTI), but outcomes have not been well characterized using high-quality data. The aim of this meta-analysis was to provide an updated benchmark for rates of primary patency and binary restenosis after PTA using prospectively collected, predominantly core-lab adjudicated randomized controlled trial (RCT) data. MATERIALS AND METHODS: MEDLINE, EMBASE, Cochrane Central, and ClinicalTrials.gov were queried for RCTs published through November 2022 using PTA as a control arm and including patients with infrapopliteal CLTI. Studies were excluded if >25% of patients had intermittent claudication, other vessels were included, or primary patency or binary restenosis were not outcomes. Outcomes were analyzed using random effects models. This analysis was publicly registered (PROSPERO ID#394543). No funding was utilized. RESULTS: Seventeen RCTs were included (1048 patients, 1279 lesions). Pooled primary patency rates using data from 6 RCTs were 68% at 6 months (95% confidence interval [CI]=45%-84%) and 66% at 12 months (95% CI=51%-79%). Pooled binary restenosis rates using data from 11 RCTs were 54% at 6 months (95% CI=33%-73%) and 60% at 9 to 12 months (95% CI=39%-78%). Significant heterogeneity was present in all outcomes (I2>50%, p<0.0001). Publication bias was not observed (Egger's p>0.1). CONCLUSIONS: This meta-analysis provides estimates for binary restenosis and primary patency following PTA utilizing prospectively collected, predominantly core-lab adjudicated data. Results demonstrate 1-year primary patency rates that are 10% to 20% higher than what has been historically used in power calculations. These new estimates will help facilitate more accurate power analysis for future RCTs. CLINICAL IMPACT: Rates of primary patency and binary restenosis after percutaneous transluminal angioplasty (PTA) have not been well-described using high-quality data, and investigators have been utilizing estimates of 40% to 50% and 45% to 65%, respectively, when performing power calculations for trials. This meta-analysis demonstrates using high-quality, prospectively collected, and predominantly core-lab adjudicated randomized controlled trial data that actual rates of primary patency are closer to 60% up to 1 year following PTA and provides the first meta-analysis estimate of binary restenosis rates up to 1 year after PTA. These estimates will help facilitate more accurate power calculations for future RCTs in this space.

Patient-Reported Outcomes in Venous Thromboembolism: A Systematic Review of the Literature, Current Challenges, and Ways Forward.

BACKGROUND: Venous thromboembolism (VTE) affects >1.2 million Americans annually. Although the clinical outcomes and economic burdens of VTE have been well described, the impact of VTE on patients' health status has yet to be summarized. This systematic review summarizes how patient-reported outcome measures (PROMs) have been used in VTE to date. METHODS AND RESULTS: PubMed/MEDLINE was queried for literature published through March 2023 using PROMs in a population of patients with VTE. Studies were excluded if the reference was an editorial, review, or case report, or if the study included patients with conditions other than VTE. Qualitative analyses were performed. After screening and exclusion, 136 references were identified; 5 described PROM development, 20 focused on PROM validation, and 111 used PROMs in outcomes research. The most used generic PROMs were the 36-item Short-Form Health Survey and EuroQol 5-dimensional questionnaire, and the most common disease-specific PROMs were the Venous Insufficiency Epidemiological and Economic Study-Quality of Life/Symptoms and the Pulmonary Embolism Quality of Life Questionnaire. PROMs were used to quantify the changes in health status after diagnosis, characterize the trajectory of subsequent improvement, and identify drivers of continued impairments in health status like postthrombotic syndrome and postpulmonary embolism syndrome. PROMs were also used to investigate the impact of novel treatment modalities on quality of life. CONCLUSIONS: This review demonstrates the many benefits of PROM use, including quantifying changes in health status with treatment, capturing patients' experiences with the treatment itself, and identifying complications of VTE. Incorporating PROMs into VTE care will be an essential component of evaluating the effectiveness of novel therapies and should lead to improved shared decision-making for patients with VTE.

Gender Disparities in Presentation, Management, and Outcomes of Acute Pulmonary Embolism.

Pulmonary embolism (PE) is the third most common cause of cardiovascular death; however, gender disparities in PE remain understudied. All PE cases at a single institution between January 2013 and June 2019 were retrospectively reviewed. The clinical presentation, treatment modalities, and outcomes were compared between men and women using univariate and multivariate analyses adjusting for differences in baseline characteristics. A total of 1,345 patients were diagnosed with acute PE, of whom 56.3% were women (n = 757). Women had a significantly higher mean body mass index (29.4 vs 28.4) and a higher frequency of hypertension (53% vs 46%) and hormone use (6.6% vs 0%; all p <0.02). Men had a higher frequency of smoking (45% vs 33%, p <0.0001). Women had significantly lower PE severity index classifications (p = 0.0009). The rates of intensive care unit admission, vasopressor requirements, extracorporeal membrane oxygenation cannulation, and mechanical ventilation were similar between the genders. There was no significant difference in the treatment modality used between the genders. Although the risk factors and PE severity index class differed between the genders, there was no significant difference in resource utilization or treatment modality. Gender was also not a significant predictor of in-hospital mortality, moderate or severe bleeding, increased length of stay, or readmission in the study population.

Association between Hispanic or Latino ethnicity and pulmonary embolism severity, management, and in-hospital outcomes.

BACKGROUND: Hispanic and Latino patients are under-represented in existing healthcare disparities research in pulmonary embolism (PE). The goal of this study was to determine if differences in PE severity, treatment modality, or in-hospital outcomes exist for Hispanic or Latino patients with PE. METHODS: All PE cases from 2013 to 2019 at a single institution were reviewed. Clinical characteristics, imaging findings, intervention types, and in-hospital and 30-day outcomes were collected. Two cohorts were created based on patients' self-reported ethnicity. Outcomes were compared using univariate and multivariate analysis. RESULTS: A total of 1265 patients were identified with confirmed PE; 474 (37%) identified as Hispanic or Latino. Hispanic or Latino patients presented with high-risk PE significantly less often (19% vs 25%, p = 0.03). On univariate analysis, Hispanic or Latino patients had lower rates of PE-specific intervention (15% vs 19%, p = 0.03) and similar rates of inpatient mortality (6.8% vs 7.5%, p = 0.64). On ordinal regression analysis, Hispanic or Latino ethnicity was associated with lower PE severity (OR 0.69, 95% CI 0.54-0.89, p = 0.003). In subgroup analyses of intermediate and high-risk PEs, ethnicity was not a significant predictor of receipt of PE-specific intervention or in-hospital mortality. CONCLUSIONS: At this institution, Hispanic or Latino patients were less likely to present with high-risk PE but had similar rates of inpatient mortality. Future research is needed to identify if disparities in in-hospital care are driving perceived differences in PE severity and what addressable systematic factors are driving higher-than-expected in-hospital mortality for Hispanic or Latino patients.

Genomic characterization of SARS-CoV-2 from vaccine breakthrough cases in Allegheny County, Pennsylvania.

We performed whole genome sequencing on SARS-CoV-2 from 59 vaccinated individuals from southwest Pennsylvania who tested positive between February and September, 2021. A comparison of mutations among vaccine breakthrough cases to a time-matched control group identified potential adaptive responses of SARS-CoV-2 to vaccination.

Surgical Scheduling Impacts Hospital Length of Stay and Associated Healthcare Costs for Patients Undergoing Total Hip and Knee Arthroplasty.

Background: Surgical scheduling, specifically the day of the week on which surgery is performed, has been associated with various postoperative outcomes in patients undergoing lower extremity joint arthroplasty. Purpose: We sought to investigate surgical scheduling as a potential modifiable factor for patient quality metrics and related costs. Methods: In a retrospective prognostic study, all total knee and total hip arthroplasty (TKA/THA) cases that took place in 2017 to 2018 at a multihospital academic health system were queried. Patients were separated by the day of the week the surgery was performed, with Monday/Tuesday compared to Thursday/Friday. Outcomes included length of stay (LOS) (extended LOS defined as 3 days or longer), cost, and complications. Multivariable regression models measured associations between scheduling of surgery and outcomes; odds ratios (OR) and 95% confidence intervals (CIs) are reported. Results: Overall, 1,571 TKA and 992 THA patients were included (65% and 35%, respectively, performed on Monday/Tuesday and 70% and 30%, respectively, performed on Thursday/Friday). Patients undergoing TKA on Monday/Tuesday versus Thursday/Friday had higher American Society of Anesthesiologists scores (42% vs 33% with score of 3 or higher) but less often an extended LOS (31% vs 54%; adjusted OR: 2.76, 95% CI: 2.22-3.46), lower skilled nursing facility costs (unadjusted mean, $12,515 vs $14,154) and lower home health aide costs (unadjusted mean, $3,793 vs $4,192). Similar patterns were observed in THA patients. Conclusion: These results from institutional data suggest that surgical scheduling is a modifiable factor possibly associated with postoperative outcomes. Furthermore, more rigorous study is warranted.

Genomic Diversity of Hospital-Acquired Infections Revealed through Prospective Whole-Genome Sequencing-Based Surveillance.

Healthcare-associated infections (HAIs) cause mortality, morbidity, and waste of health care resources. HAIs are also an important driver of antimicrobial resistance, which is increasing around the world. Beginning in November 2016, we instituted an initiative to detect outbreaks of HAIs using prospective whole-genome sequencing-based surveillance of bacterial pathogens collected from hospitalized patients. Here, we describe the diversity of bacteria sampled from hospitalized patients at a single center, as revealed through systematic analysis of bacterial isolate genomes. We sequenced the genomes of 3,004 bacterial isolates from hospitalized patients collected over a 25-month period. We identified bacteria belonging to 97 distinct species, which were distributed among 14 groups of related species. Within these groups, isolates could be distinguished from one another by both average nucleotide identity (ANI) and principal-component analysis of accessory genes (PCA-A). Core genome genetic distances and rates of evolution varied among species, which has practical implications for defining shared ancestry during outbreaks and for our broader understanding of the origins of bacterial strains and species. Finally, antimicrobial resistance genes and putative mobile genetic elements were frequently observed, and our systematic analysis revealed patterns of occurrence across the different species sampled from our hospital. Overall, this study shows how understanding the population structure of diverse pathogens circulating in a single health care setting can improve the discriminatory power of genomic epidemiology studies and can help define the processes leading to strain and species differentiation. IMPORTANCE Hospitalized patients are at increased risk of becoming infected with antibiotic-resistant organisms. We used whole-genome sequencing to survey and compare over 3,000 clinical bacterial isolates collected from hospitalized patients at a large medical center over a 2-year period. We identified nearly 100 different bacterial species, which we divided into 14 different groups of related species. When we examined how genetic relatedness differed between species, we found that different species were likely evolving at different rates within our hospital. This is significant because the identification of bacterial outbreaks in the hospital currently relies on genetic similarity cutoffs, which are often applied uniformly across organisms. Finally, we found that antibiotic resistance genes and mobile genetic elements were abundant and were shared among the bacterial isolates we sampled. Overall, this study provides an in-depth view of the genomic diversity and evolutionary processes of bacteria sampled from hospitalized patients, as well as genetic similarity estimates that can inform hospital outbreak detection and prevention efforts.

Diabetes Is Predictive of Postoperative Outcomes and Readmission Following Posterior Lumbar Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The present study analyzes complication rates and episode-based costs for patients with and without diabetes mellitus (DM) following posterior lumbar fusion (PLF). METHODS: PLF cases at a single institution from 2008 to 2016 were queried (n = 3226), and demographic and perioperative data were analyzed. Patients with and without the diagnosis of DM were compared using chi-square, Student's t test, and multivariable regression modeling. RESULTS: Patients with diabetes were older (63.10 vs 56.48 years, P < .001) and possessed a greater number of preoperative comorbidities (47.84% of patients had Elixhauser Comorbidity Index >0 vs 42.24%, P < .001) than did patients without diabetes. When controlling for preexisting differences, diabetes remained a significant risk factor for prolonged length of stay (OR = 1.59, 95% CI 1.26-2.01, P < .001), intensive care unit stay (OR = 1.52, 95% CI 1.07-2.17, P = .021), nonhome discharge (OR = 1.86, 95% CI 1.46-2.37, P < .001), 30-day readmission (OR = 2.15, 95% CI 1.28-3.60, P = .004), 90-day readmission (OR = 1.65, 95% CI 1.05-2.59, P = .031), 30-day emergency room visit (OR = 2.15, 95% CI 1.27-3.63, P = .004), and 90-day emergency room visit (OR = 2.27, 95% CI 1.41-3.65, P < .001). Cost modeling controlling for overall comorbidity burden demonstrated that diabetes was associated with a $1709 increase in PLF costs (CI $344-$3074, P = .014). CONCLUSIONS: The present findings indicate a correlation between diabetes and a multitude of postoperative adverse outcomes and increased costs, thus illustrating the substantial medical and financial burdens of diabetes for PLF patients. Future studies should explore preventive measures that may mitigate these downstream effects.

The Impact of Diabetes on Outcomes and Health Care Costs Following Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: Retrospective cohort study. OBJECTIVES: Anterior cervical discectomy and fusion (ACDF) is commonly used to treat an array of cervical spine pathology and is associated with good outcomes and low complication rates. Diabetes mellitus (DM) is a common comorbidity for patients undergoing ACDF, but the literature is equivocal about the impact it has on outcomes. Because DM is a highly prevalent comorbidity, it is crucial to determine if it is an associated risk factor for outcomes after ACDF procedures. METHODS: Patients at a single institution from 2008 to 2016 undergoing ACDF were compared on the basis of having a prior diagnosis of DM versus no DM. The 2 cohorts were compared utilizing univariate tests and multivariate logistic and linear regressions. RESULTS: Data for 2470 patients was analyzed. Diabetic patients had significantly higher Elixhauser scores (P < .0001). Univariate testing showed diabetic patients were more likely to suffer from sepsis (0.82% vs 0.10%, P = .03) and bleeding complications (3.0% vs 1.5%, P = .04). In multivariate analyses, diabetic patients had higher rates of non-home discharge (odds ratio [OR] = 1.37, 95% confidence interval [CI] = 1.07-1.75, P = .013) and prolonged length of stay (OR = 1.95, 95% CI = 1.25-3.05, P = .003), but similar complication (OR = 1.46, 95% CI = 0.85-2.52, P = .17), reoperation (OR = 0.77, 95% CI = 0.33-1.81, P = .55), and 90-day readmission (OR = 1.53, 95% CI = 0.97-2.43) rates compared to nondiabetic patients. Direct cost was also shown to be similar between the cohorts after adjusting for patient, surgical, and hospital-related factors (estimate = -$30.25, 95% CI = -$515.69 to $455.18, P = .90). CONCLUSIONS: Diabetic patients undergoing ACDF had similar complication, reoperation, and readmission rates, as well as similar cost of care compared to nondiabetic patients.

Whole-Genome Sequencing Surveillance and Machine Learning of the Electronic Health Record for Enhanced Healthcare Outbreak Detection.

BACKGROUND: Most hospitals use traditional infection prevention (IP) methods for outbreak detection. We developed the Enhanced Detection System for Healthcare-Associated Transmission (EDS-HAT), which combines whole-genome sequencing (WGS) surveillance and machine learning (ML) of the electronic health record (EHR) to identify undetected outbreaks and the responsible transmission routes, respectively. METHODS: We performed WGS surveillance of healthcare-associated bacterial pathogens from November 2016 to November 2018. EHR ML was used to identify the transmission routes for WGS-detected outbreaks, which were investigated by an IP expert. Potential infections prevented were estimated and compared with traditional IP practice during the same period. RESULTS: Of 3165 isolates, there were 2752 unique patient isolates in 99 clusters involving 297 (10.8%) patient isolates identified by WGS; clusters ranged from 2-14 patients. At least 1 transmission route was detected for 65.7% of clusters. During the same time, traditional IP investigation prompted WGS for 15 suspected outbreaks involving 133 patients, for which transmission events were identified for 5 (3.8%). If EDS-HAT had been running in real time, 25-63 transmissions could have been prevented. EDS-HAT was found to be cost-saving and more effective than traditional IP practice, with overall savings of $192 408-$692 532. CONCLUSIONS: EDS-HAT detected multiple outbreaks not identified using traditional IP methods, correctly identified the transmission routes for most outbreaks, and would save the hospital substantial costs. Traditional IP practice misidentified outbreaks for which transmission did not occur. WGS surveillance combined with EHR ML has the potential to save costs and enhance patient safety.

Barriers to Collection and Use of Patient-Reported Outcomes A Multi-Institutional Survey of Surgeons and Care Teams.

BACKGROUND: Currently there is a lack of insight into what total joint replacement (TJR) surgeons and care teams perceive to be the greatest barriers to collection and use of patient reported outcomes (PROs). The goal of this study was to provide insight on this topic using a multi-institutional survey. METHODS: A thorough literature review on PROs adoption and utilization was conducted to generate a 26-question survey. This survey was disseminated to joint replacement surgeons, associate providers (e.g., nurse practitioners and physician assistants), and other non-clinical health care staff involved in PRO collection at three institutions. Data from all respondents were analyzed qualitatively and using chi-square tests. RESULTS: Of 37 responses, 24 (65%) were from orthopedic surgeons and 13 (35%) from other clinical and administrative staff. Seventy-one percent of surgeons thought that integration into clinical workflow was the greatest barrier to initial implementation of PROs, while the greatest long-term limitations were accessibility (50%), patient engagement and compliance (50%), ability to represent their health in PROs (54%), and consistency across providers (50%). For PROs to be clinically useful, surgeons required that they should be linked to the EMR interface (65%), immediately available (59%), and are trended over time (59%). Fifty-four percent of surgeons across institutions believed administrative leadership was ultimately responsible for successful PROs implementation, while 46% of other staff believed that responsibility fell to surgeons and clinical staff. CONCLUSION: Surgeons perceive that the greatest barriers to PRO collection are workflow integration initially, and patient engagement, compliance, and ability to represent their health in PROs over the long term. Stakeholders inconsistently report which group is responsible for successful implementation.

Orthopedic Surgeon and Care Team Perceptions and Use of Patient-Reported Outcomes in Total Joint Replacement Patients.

BACKGROUND: The recent shift toward value-based health care and bundled payments in orthopedic surgery has increased the use patient-reported outcomes (PROs) in standard clinical care. Such assessments of patient function and satisfaction are particularly important among total joint arthroplasty (TJA) patients to monitor postoperative health. PURPOSE: The purpose of this study was to assess orthopedic care team perceptions of current and future PRO usage and compare current rates and modes of PRO collection between three urban, academic health care systems. METHODS: A literature search was conducted on current PRO uses and barriers to their adoption to generate a 26-question survey. The survey was disseminated to orthopedic surgeons and care team members at three academic health care institutions (institutions A, B, and C). Responses were analyzed for qualitative and quantitative insights. RESULTS: Among institutions A, B, and C, PRO collection generally declined from baseline (60%, 90%, 89%) to 6 weeks (67%, 82%, 71%) and 3 months postoperatively (44%, 36%, 47%). However, there were large variations in reported PRO collection intervals among institutions. Respondents reported assessing patient baseline functional status as the most useful current application of PROs and cited the prediction of patient benefit from TJA as the most useful future application for PROs. Though respondents were largely optimistic about PRO utility in clinical care, a small minority remained skeptical. CONCLUSIONS: Perceptions of PRO utilization and collection intervals varied considerably among respondents. For PROs to be an accurate and useful clinical tool, standardization and thorough understanding of PRO collection among orthopedic care team members is essential.

Emergence of an early SARS-CoV-2 epidemic in the United States.

The emergence of the COVID-19 epidemic in the United States (U.S.) went largely undetected due to inadequate testing. New Orleans experienced one of the earliest and fastest accelerating outbreaks, coinciding with Mardi Gras. To gain insight into the emergence of SARS-CoV-2 in the U.S. and how large-scale events accelerate transmission, we sequenced SARS-CoV-2 genomes during the first wave of the COVID-19 epidemic in Louisiana. We show that SARS-CoV-2 in Louisiana had limited diversity compared to other U.S. states and that one introduction of SARS-CoV-2 led to almost all of the early transmission in Louisiana. By analyzing mobility and genomic data, we show that SARS-CoV-2 was already present in New Orleans before Mardi Gras, and the festival dramatically accelerated transmission. Our study provides an understanding of how superspreading during large-scale events played a key role during the early outbreak in the U.S. and can greatly accelerate epidemics.

Pre-hospital antiplatelet medication use on COVID-19 disease severity.

OBJECTIVE: To evaluate the association between pre-hospitalization antiplatelet medication use and COVID-19 disease severity. DESIGN: Retrospective cohort study. SETTING: Inpatient units at The Mount Sinai Hospital. PATIENTS: Adults age ≥18 admitted between March 1, 2020 and April 9, 2020 with confirmed COVID-19 infection with at least 28 days follow-up. MEASUREMENTS: We captured baseline demographic, pre-hospitalization antiplatelet medication use, and clinical encounter data for all patients who met inclusion criteria. The primary endpoint was peak score on a 6-point modified ordinal scale (MOS), which is based on World Health Organization blueprint R&S groups, used to grade severity of illness through clinical outcomes of interest. Scores indicate the following: 1 - COVID-19 infection not requiring hospitalization, 2 - requiring hospitalization but not supplemental oxygen, 3 - hospitalization requiring supplemental oxygen, 4 - hospitalization requiring high-flow nasal cannula (HFNC) or non-invasive positive pressure ventilation (NIPPV), 5 - hospitalization requiring intubation or extracorporeal membrane oxygenation (ECMO), 6 - death. Multivariable adjusted partial proportional odds model (PPOM) was performed to examine the association between pre-hospitalization antiplatelet medication use and likelihood of each MOS score. MAIN RESULTS: Of 762 people admitted with COVID-19, 239 (31.4%) used antiplatelet medications pre-hospitalization while 523 (68.6%) did not. Antiplatelet users were older and had more co-morbidities at baseline. Before adjusting for covariates, patients who used antiplatelet medications pre-hospitalization were more likely than non-users to have peak MOS score 6 (death, OR 1.75, 95% CI 1.21-2.52), peak MOS score ≥5 (intubation/ECMO or death, OR 1.4, 95% CI 1.00-1.98) and peak MOS score ≥4 (HFNC, NIPPV, intubation/ECMO or death, OR 1.40, 95% CI 1.01-1.94). On multivariable adjusted PPOM analysis controlling for 13 covariates, there were no longer any significant differences in peak MOS scores between users and non-users. CONCLUSIONS: After adjusting for covariates, pre-hospital antiplatelet use was not associated with COVID-19 severity in hospitalized patients.

Emergence of an early SARS-CoV-2 epidemic in the United States.

The emergence of the early COVID-19 epidemic in the United States (U.S.) went largely undetected, due to a lack of adequate testing and mitigation efforts. The city of New Orleans, Louisiana experienced one of the earliest and fastest accelerating outbreaks, coinciding with the annual Mardi Gras festival, which went ahead without precautions. To gain insight into the emergence of SARS-CoV-2 in the U.S. and how large, crowded events may have accelerated early transmission, we sequenced SARS-CoV-2 genomes during the first wave of the COVID-19 epidemic in Louisiana. We show that SARS-CoV-2 in Louisiana initially had limited sequence diversity compared to other U.S. states, and that one successful introduction of SARS-CoV-2 led to almost all of the early SARS-CoV-2 transmission in Louisiana. By analyzing mobility and genomic data, we show that SARS-CoV-2 was already present in New Orleans before Mardi Gras and that the festival dramatically accelerated transmission, eventually leading to secondary localized COVID-19 epidemics throughout the Southern U.S.. Our study provides an understanding of how superspreading during large-scale events played a key role during the early outbreak in the U.S. and can greatly accelerate COVID-19 epidemics on a local and regional scale.

Emergence in late 2020 of multiple lineages of SARS-CoV-2 Spike protein variants affecting amino acid position 677.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein (S) plays critical roles in host cell entry. Non-synonymous substitutions affecting S are not uncommon and have become fixed in a number of SARS-CoV-2 lineages. A subset of such mutations enable escape from neutralizing antibodies or are thought to enhance transmission through mechanisms such as increased affinity for the cell entry receptor, angiotensin-converting enzyme 2 (ACE2). Independent genomic surveillance programs based in New Mexico and Louisiana contemporaneously detected the rapid rise of numerous clade 20G (lineage B.1.2) infections carrying a Q677P substitution in S. The variant was first detected in the US on October 23, yet between 01 Dec 2020 and 19 Jan 2021 it rose to represent 27.8% and 11.3% of all SARS-CoV-2 genomes sequenced from Louisiana and New Mexico, respectively. Q677P cases have been detected predominantly in the south central and southwest United States; as of 03 Feb 2021, GISAID data show 499 viral sequences of this variant from the USA. Phylogenetic analyses revealed the independent evolution and spread of at least six distinct Q677H sub-lineages, with first collection dates ranging from mid-August to late November 2020. Four 677H clades from clade 20G (B.1.2), 20A (B.1.234), and 20B (B.1.1.220, and B.1.1.222) each contain roughly 100 or fewer sequenced cases, while a distinct pair of clade 20G clusters are represented by 754 and 298 cases, respectively. Although sampling bias and founder effects may have contributed to the rise of S:677 polymorphic variants, the proximity of this position to the polybasic cleavage site at the S1/S2 boundary are consistent with its potential functional relevance during cell entry, suggesting parallel evolution of a trait that may confer an advantage in spread or transmission. Taken together, our findings demonstrate simultaneous convergent evolution, thus providing an impetus to further evaluate S:677 polymorphisms for effects on proteolytic processing, cell tropism, and transmissibility.

Quorum sensing provides a molecular mechanism for evolution to tune and maintain investment in cooperation.

As selection frequently favors noncooperating defectors in mixed populations with cooperators, mechanisms that promote cooperation stability clearly exist. One potential mechanism is bacterial cell-to-cell communication, quorum sensing (QS), which can allow cooperators to prevent invasion by defectors. However, the impact of QS on widespread maintenance of cooperation in well-mixed conditions has not been experimentally demonstrated over extended evolutionary timescales. Here, we use wild-type (WT) Vibrio campbellii that regulates cooperation with QS and an unconditional cooperating (UC) mutant to examine the evolutionary origins and dynamics of novel defectors during a long-term evolution experiment. We found that UC lineages were completely outcompeted by defectors, whereas functioning QS enabled the maintenance of cooperative variants in most WT populations. Sequencing evolved populations revealed multiple luxR mutations that swept the UC lineages. However, the evolution of mutant lineages with reduced levels of bioluminescence (dims) occurred in many WT lineages. These dim variants also decreased other cooperative phenotypes regulated by QS, including protease production, indicating they result from changes to QS regulation. This diminished investment phenotype optimizes a tradeoff between cooperative input and growth output and suggests that decreasing the cost of QS could be a favorable strategy for maintaining the cooperative behaviors it regulates.

Metric Selection, Metric Targets, and Risk Adjustment Should be Considered in the Design of Gainsharing Models for Bundled Payment Programs in Total Joint Arthroplasty.

BACKGROUND: Under bundled payment models, gainsharing presents an important mechanism to ensure engagement and reward innovation. We hypothesized that metric selection, metric targets, and risk adjustment would impact surgeons' performance in gainsharing models. METHODS: Patients undergoing total joint arthroplasty at an urban health system from 2017 to September 2018 were included. Gainsharing metrics included the following: length of stay, % discharge-to-home, 90-day readmission rate, % of patients with episode spend under target price, and % of patients with patient-reported outcomes (PROs) collected. Four scenarios were created to evaluate how metric selection/adjustment impacted surgeons' performance designation: scenario 1 used "aspirational targets" (>60th percentile), scenario 2 used "acceptable targets" (>50th percentile), scenario 3 risk-adjusted surgeon performance prior to comparing aspirational targets, and scenario 4 included a PRO collection metric. Number of metrics achieved determined performance tier, with higher tiers getting a greater share of the gainsharing pool. RESULTS: In total, 2776 patients treated by 12 surgeons met inclusion criteria (mean length of stay 3.0 days, readmission rate 4.0%, discharge-to-home 74%, episode spend under target price 85%, PRO collection 56%). Lowering of metric targets (scenario 1 vs. 2) resulted in a 75% increase in the number of high performers and 98% of the gainsharing pool being eligible for distribution. Risk adjustment (scenario 3) caused 50% of providers to move to higher performance tiers and potential payments to increase by 28%. Adding the PRO metric did not change performance. CONCLUSION: Quality metric/target selection and risk adjustment profoundly impact surgeons' performance in gainsharing contracts. This impacts how successful these contracts can be in driving innovation and dis-incentivizing the "cherry picking" of patients. LEVEL OF EVIDENCE: Level III.

One gene, multiple ecological strategies: A biofilm regulator is a capacitor for sustainable diversity.

Many bacteria cycle between sessile and motile forms in which they must sense and respond to internal and external signals to coordinate appropriate physiology. Maintaining fitness requires genetic networks that have been honed in variable environments to integrate these signals. The identity of the major regulators and how their control mechanisms evolved remain largely unknown in most organisms. During four different evolution experiments with the opportunist betaproteobacterium Burkholderia cenocepacia in a biofilm model, mutations were most frequently selected in the conserved gene rpfR RpfR uniquely integrates two major signaling systems-quorum sensing and the motile-sessile switch mediated by cyclic-di-GMP-by two domains that sense, respond to, and control the synthesis of the autoinducer cis-2-dodecenoic acid (BDSF). The BDSF response in turn regulates the activity of diguanylate cyclase and phosphodiesterase domains acting on cyclic-di-GMP. Parallel adaptive substitutions evolved in each of these domains to produce unique life history strategies by regulating cyclic-di-GMP levels, global transcriptional responses, biofilm production, and polysaccharide composition. These phenotypes translated into distinct ecology and biofilm structures that enabled mutants to coexist and produce more biomass than expected from their constituents grown alone. This study shows that when bacterial populations are selected in environments challenging the limits of their plasticity, the evolved mutations not only alter genes at the nexus of signaling networks but also reveal the scope of their regulatory functions.