Weekend Effect Research Articles

Measurement report: Airborne measurements of NOx fluxes over Los Angeles during the RECAP-CA 2021 campaign

Abstract. Nitrogen oxides (NOx≡NO+NO2) are involved in most atmospheric photochemistry, including the formation of tropospheric ozone (O3). While various methods exist to accurately measure NOx concentrations, it is still a challenge to quantify the source and flux of NOx emissions. We present airborne measurements of NOx and winds used to infer the emission of NOx across Los Angeles. The measurements were obtained during the research aircraft campaign RECAP-CA (Re-Evaluating the Chemistry of Air Pollutants in CAlifornia) in June 2021. Geographic allocations of the fluxes are compared to the NOx emission inventory from the California Air Resources Board (CARB). We find that the NOx fluxes have a pronounced weekend effect and are highest in the eastern part of the San Bernardino Valley. The comparison of the RECAP-CA and the modeled CARB NOx fluxes suggests that the modeled emissions are higher than expected near the coast and in Downtown Los Angeles and lower than expected further inland in the eastern part of the San Bernardino Valley.

Comparison between Spatially Resolved Airborne Flux Measurements and Emission Inventories of Volatile Organic Compounds in Los Angeles.

Los Angeles is a major hotspot for ozone and particulate matter air pollution in the United States. Ozone and PM2.5 in this region have not improved substantially for the past decade, despite a reduction in vehicular emissions of their precursors, NOx and volatile organic compounds (VOCs). This reduction in "traditional" sources has made the current emission mixture of air pollutant precursors more uncertain. To map and quantify emissions of a wide range of VOCs in this urban area, we performed airborne eddy covariance measurements with wavelet analysis. VOC fluxes measured include tracers for source categories, such as traffic, vegetation, and volatile chemical products (VCPs). Mass fluxes were dominated by oxygenated VOCs, with ethanol contributing ∼29% of the total. In terms of OH reactivity and aerosol formation potential, terpenoids contributed more than half. Observed fluxes were compared with two commonly used emission inventories: the California Air Resources Board inventory and the combination of the Biogenic Emission Inventory System with the Fuel-based Inventory of Vehicle Emissions combined with Volatile Chemical Products (FIVE-VCP). The comparison shows mismatches regarding the amount, spatial distribution, and weekend effects of observed VOC emissions with the inventories. The agreement was best for typical transportation related VOCs, while discrepancies were larger for biogenic and VCP-related VOCs.

The Reduction of After-Hours and Weekend Effects in Upper Gastro-intestinal Bleeding Mortality During the COVID-19 Pandemic Compared to the Pre-Pandemic Period.

In upper gastrointestinal bleeding (UGIB), admissions after normal working hours and during weekends may be associated with increased mortality. To assess the evolution of the after-hours and weekend effects during the COVID-19 pandemic as a result of progressive improved management despite management challenges during the pandemic. We performed an observational study of patients admitted for UGIB at a tertiary academic center between March 2020 and December 2021, compared to the corresponding timeframe before the pandemic. Admissions were assessed based on regular hours versus after-hours and weekdays versus weekends. We stratified patients based on demographic data, etiology, prognostic scores, the time between symptom onset and admission, as and between admission and endoscopy. The outcomes included mortality, rebleeding rate, the requirement for surgery and transfusion, and hospitalization days. 802 cases were recorded during the pandemic, and 1006 cases before the pandemic. The overall mortality rate was 12.33%. Patients admitted after hours and during weekends had a higher mortality rate compared to those admitted during regular hours and weekdays (15.18% versus 10.22%, and 15.25% versus 11.16%), especially in cases of non-variceal bleeding. However, the difference in mortality rates was reduced by 2/3 during the pandemic, despite the challenges posed by COVID-19 infection. This suggests that there was an equalization effect of care in UGIB, regardless of the admission time. The differences observed in mortality rates for after-hours and weekend admissions seem to be primarily related to a higher proportion of patients who did not undergo endoscopy, while the proportion of severe cases remained similar. Blood requirements, hospital days, and rebleeding rate were similar between the two groups. Admissions during weekends and after-hours have been associated with increased mortality, particularly in cases of non-variceal bleeding. However, the impact of this association was significantly reduced during the pandemic.

Investigating Weekend Effect in the Management of Upper and Lower Extremity Degloving Injuries.

Weekend presentation has been associated with adverse outcomes in emergent conditions, including stroke, myocardial infarction, and critical limb ischemia. We examine whether a weekend effect exists in the management of and outcomes after extremity degloving injuries. The cohort included adults presenting with open extremity degloving injuries to a tertiary level one trauma center between June 2018 and May 2022. We collected demographics, comorbidities, injury information, interventions, and complications. Propensity score weighting was used to minimize confounding differences between those presenting on weekends (Sat-Sun) versus weekdays (Mon-Fri). Weighted regressions were used to examine differences in interventions by day of presentation. Multivariable weighted regressions accounting for differences in interventions received were used to examine whether weekend presentation was associated with amputation risk, complications, or functional deficits. Ninety-five patients with 100 open extremity degloving injuries were included. In total, 39% of injuries were weekend-presenting. There was a higher rate of noninsulin-dependent diabetes among patients presenting on weekends (P = 0.03). Weekend-presenting injuries had higher median Injury Severity Scores (P = 0.04). Propensity-weighted regression analysis revealed differences in interventions received on weekends, including lower rates of pedicled and free flaps and bone graft, and increased rates of negative-pressure wound therapy (P ≤ 0.02). Multivariable regression analysis revealed weekend presentation was a significant independent risk factor for amputation of the affected extremity [odds ratio 2.27, 95% CI (1.01-5.33), P = 0.05]. Weekend presentation may impact interventions received and amputation risk in patients presenting with open extremity degloving injuries.

TCT-355 The Weekend Effect on Cardiac Arrest Admissions—Is There Room for Improvement? An Insight From the National Inpatient Sample

TCT-355 The Weekend Effect on Cardiac Arrest Admissions—Is There Room for Improvement? An Insight From the National Inpatient Sample

Black Carbon in a City of the Atacama Desert before and after the Start of the COVID-19 Lockdown: Ground Measurements and MERRA-2 Reanalysis

In this study, the temporal variations of black carbon (BC) were analyzed from November 2019 to September 2021, in Tacna, Peru. Ground measurements obtained with a photoacoustic extinctiometer (PAX BC) and NASA’s MERRA-2 reanalysis data (MERRA-2 BC) were used. The seasonal concentrations of PAX BC (mean ± standard deviation) were as follows: 0.70 ± 0.35, 0.73 ± 0.46, 0.70 ± 0.39, and 0.85 ± 0.46 µg m−3, for spring, summer, autumn, and winter, respectively; while MERRA-2 BC values were 0.12 ± 0.11, 0.06 ± 0.02, 0.06 ± 0.02, and 0.11 ± 0.06 µg m−3, for the same seasons. We found a large discrepancy between these two techniques, as the PAX BC measurements were an order of magnitude higher than the MERRA-2 BC values. In addition, MERRA-2 did not record urban pollution events and did not present the BC weekend effect. The most frequent wind direction (81%) was from the southwest and the sources of greatest contamination were located to the northeast and southeast. The Mann–Kendall test confirmed a downward trend in PAX BC one week (37%) and two weeks (30%) after the start of the COVID-19 lockdown, and no trend in MERRA-2 BC. These results suggest that MERRA-2 underestimates the BC emissions from local sources.

Clinical Outcomes according to Timing to Non Invasive Ventilation Initiation in COPD Patients with Acute Respiratory Failure: A Retrospective Cohort Study.

Nighttime and non-working days are characterized by a shortage of dedicated staff and available resources. Previous studies have highlighted that patients admitted during the weekend had higher mortality than patients admitted on weekdays ("weekend effect"). However, most studies have focused on specific conditions and controversial results were reported. We conducted an observational, monocentric, retrospective cohort study, based on data collected prospectively to evaluate the impact of the timing of NIV initiation on clinical outcomes in COPD patients with acute respiratory failure (ARF). A total of 266 patients requiring NIV with a time gap between diagnosis of ARF and NIV initiation <48 h were included. Interestingly, 39% of patients were not acidotic (pH = 7.38 ± 0.09 vs. 7.26 ± 0.05, p = 0.003) at the time of NIV initiation. The rate of NIV failure (need for intubation and/or all-cause in-hospital death) was similar among three different scenarios: "daytime" vs. "nighttime", "working" vs. "non-working days", "nighttime or non-working days" vs. "working days at daytime". Patients starting NIV during nighttime had a longer gap to NIV initiation compared to daytime (219 vs. 115 min respectively, p = 0.01), but this did not influence the NIV outcome. These results suggested that in a training center for NIV management, the failure rate did not increase during the "silent" hours.

Weekend Effect on Clinical Outcomes of Acute Lower Gastrointestinal Bleeding: A Large Multicenter Cohort Study in Japan

Introduction: Weekend admissions showed increased mortality in several medical conditions. This study aimed to examine the weekend effect on acute lower gastrointestinal bleeding (ALGIB) and its mortality and other outcomes. Methods: This retrospective cohort study (CODE BLUE-J Study) was conducted at 49 Japanese hospitals between January 2010 and December 2019. In total, 8,120 outpatients with acute hematochezia were enrolled and divided into weekend admissions and weekday admissions groups. Multiple imputation (MI) was used to handle missing values, followed by propensity score matching (PSM) to compare outcomes. The primary outcome was mortality; the secondary outcomes were rebleeding, length of stay (LOS), blood transfusion, thromboembolism, endoscopic treatment, the need for interventional radiology, and the need for surgery. Colonoscopy and computed tomography (CT) management were also evaluated. Results: Before PSM, there was no significant difference in mortality (1.3% vs. 0.9%, p = 0.133) between weekend and weekday admissions. After PSM with MI, 1,976 cases were matched for each admission. Mortality was not significantly different for weekend admissions compared with weekday admissions (odds ratio [OR] 1.437, 95% confidence interval [CI] 0.785–2.630; p = 0.340). No significant difference was found with other secondary outcomes in weekend admissions except for blood transfusion (OR 1.239, 95% CI 1.084–1.417; p = 0.006). Weekend admission had a negative effect on early colonoscopy (OR 0.536, 95% CI 0.471–0.609; p < 0.001). Meanwhile, urgent CT remained significantly higher in weekend admissions (OR 1.466, 95% CI 1.295–1.660; p < 0.001). Conclusion: Weekend admissions decrease early colonoscopy and increase urgent CT but do not affect mortality or other outcomes except transfusion.

Explicit incentives increase citizen science recordings

AbstractFrom tracking land‐use change to biodiversity loss, citizen science data have become a cornerstone for conservation. However, policymakers must understand the “data‐generating process” to make good use of existing citizen science data and encourage the production of useful new data. We analyze data from the two largest German online platforms for ecological observations to explore and quantify the effect of explicit incentives on volunteer recordings, created by a large‐scale prize competition on one of the platforms. We find 10% more recordings during the prize competition. Moreover, the effects of weather and weekends are attenuated during the competition period. Finally, the diversity of recorded species decreases. Our study shows the first statistical evidence that using explicit incentives increases the quantity of citizen science data. It highlights the need to further study the effect of explicit incentives on data quality and the engagement of citizens for conservation.

42780 A National Analysis of the Weekend Effect in Children Diagnosed with Dermatomyositis using the Kids’ Inpatient Database

42780 A National Analysis of the Weekend Effect in Children Diagnosed with Dermatomyositis using the Kids’ Inpatient Database

Estimating the epidemic reproduction number from temporally aggregated incidence data: A statistical modelling approach and software tool.

The time-varying reproduction number (Rt) is an important measure of epidemic transmissibility that directly informs policy decisions and the optimisation of control measures. EpiEstim is a widely used opensource software tool that uses case incidence and the serial interval (SI, time between symptoms in a case and their infector) to estimate Rt in real-time. The incidence and the SI distribution must be provided at the same temporal resolution, which can limit the applicability of EpiEstim and other similar methods, e.g. for contexts where the time window of incidence reporting is longer than the mean SI. In the EpiEstim R package, we implement an expectation-maximisation algorithm to reconstruct daily incidence from temporally aggregated data, from which Rt can then be estimated. We assess the validity of our method using an extensive simulation study and apply it to COVID-19 and influenza data. For all datasets, the influence of intra-weekly variability in reported data was mitigated by using aggregated weekly data. Rt estimated on weekly sliding windows using incidence reconstructed from weekly data was strongly correlated with estimates from the original daily data. The simulation study revealed that Rt was well estimated in all scenarios and regardless of the temporal aggregation of the data. In the presence of weekend effects, Rt estimates from reconstructed data were more successful at recovering the true value of Rt than those obtained from reported daily data. These results show that this novel method allows Rt to be successfully recovered from aggregated data using a simple approach with very few data requirements. Additionally, by removing administrative noise when daily incidence data are reconstructed, the accuracy of Rt estimates can be improved.

Quantification of carbon monoxide emissions from African cities using TROPOMI

Abstract. Carbon monoxide (CO) is an air pollutant that plays an important role in atmospheric chemistry and is mostly emitted by forest fires and incomplete combustion in, for example, road transport, residential heating, and industry. As CO is co-emitted with fossil fuel CO2 combustion emissions, it can be used as a proxy for CO2. Following the Paris Agreement, there is a need for independent verification of reported activity-based bottom-up CO2 emissions through atmospheric measurements. CO can be observed daily at a global scale with the TROPOspheric Monitoring Instrument (TROPOMI) satellite instrument with daily global coverage at a resolution down to 5.5 × 7 km2. To take advantage of this unique TROPOMI dataset, we develop a cross-sectional flux-based emission quantification method that can be applied to quantify emissions from a large number of cities, without relying on computationally expensive inversions. We focus on Africa as a region with quickly growing cities and large uncertainties in current emission estimates. We use a full year of high-resolution Weather Research and Forecasting (WRF) simulations over three cities to evaluate and optimize the performance of our cross-sectional flux emission quantification method and show its reliability down to emission rates of 0.1 Tg CO yr−1. Comparison of the TROPOMI-based emission estimates to the Dynamics–Aerosol–Chemistry–Cloud Interactions in West Africa (DACCIWA) and Emissions Database for Global Atmospheric Research (EDGAR) bottom-up inventories shows that CO emission rates in northern Africa are underestimated in EDGAR, suggesting overestimated combustion efficiencies. We see the opposite when comparing TROPOMI to the DACCIWA inventory in South Africa and Côte d'Ivoire, where CO emission factors appear to be overestimated. Over Lagos and Kano (Nigeria) we find that potential errors in the spatial disaggregation of national emissions cause errors in DACCIWA and EDGAR respectively. Finally, we show that our computationally efficient quantification method combined with the daily TROPOMI observations can identify a weekend effect in the road-transport-dominated CO emissions from Cairo and Algiers.

Weekend Effect of Air Pollutants in a Tropical Brazilian Metropolis

Weekend Effect of Air Pollutants in a Tropical Brazilian Metropolis

Research Progress on the Change Trend and Pollution Characteristics of Ambient Air Quality

In order to understand the change trend of ambient air quality, as well as the pollution characteristics of the main pollutants in the ambient air PM2.5, PM10, CO, etc., the weekend effect and the Spring Festival and National Day holiday pollution characteristics, this paper summarizes and summarizes the relevant environmental pollution related research, so as to provide scientific reference for effective prevention and control of air pollution.

Weekend versus Weekday Procedures for Total Hip Arthroplasties

AbstractThe “weekend effect” is the phenomenon that claims increased adverse outcomes for weekend procedures compared to weekday procedures. However, there is significant controversy regarding such disparities in elective orthopaedic surgeries. With the increasing demand for hip arthroplasty projected over the next 20 years, it is important to investigate a possible “weekend effect” to optimize outcomes and cost-effectiveness. In this study, we investigate the association between weekday versus weekend total hip arthroplasty (THA) and postoperative outcomes using the Healthcare Cost and Utilization Project (HCUP) data. We performed a retrospective analysis of the HCUP database between 2002 and 2020 comparing THAs done Monday to Friday versus THAs done Saturday to Sunday. Data collected included patient demographics and comorbidities, hospital length of stay, admission to procedure time, discharge disposition, mortality, and outcome data through postoperative day 30. THAs performed on weekends were associated with significantly increased length of stay, total charges, admission-to-procedure time, and mortality compared to those on weekdays. Our findings suggest that the development of nationwide programs to standardize care and weekend case management for THA patients can potentially help reduce health care costs, improve operative outcomes, and reduce the discrepancy between weekend and weekday surgeries.

Effect of weekend versus weekday admission on the mortality of acute ischemic stroke patients in China: an analysis of data from the Chinese acute ischemic stroke treatment outcome registry.

Due to disparities in medical resources in rural and urban areas as well as in different geographic regions in China, the effect of weekend versus weekday admission on the outcomes of acute ischemic stroke (AIS) patients is unknown. Our aim was to investigate whether the outcomes of AIS patients differ according to the day of admission in China. The data were extracted from the Chinese Acute Ischemic Stroke Treatment Outcome Registry (CASTOR), a multicenter prospective study database of patients diagnosed with AIS. The chi-square test (χ2) and logistic regression were used to assess mortality for weekday and weekend admissions among AIS patients stratified by rural or urban status and geographic region (including the eastern, northeastern, central, and western regions). In total, 9,256 patients were included in this study. Of these patients, 57.2% were classified as urban, and 42.8% were classified as rural. A total of 6,760 (73%) patients were admitted on weekdays, and 2,496 (27%) were admitted on weekends. There was no significant difference in the mortality rate among patients admitted on weekends compared with those admitted on weekdays in urban (7.5% versus 7.4%) or rural areas (8.8% versus 8.1%; p > 0.05). The mortality rate was the highest among patients admitted on weekends and weekdays (11.6% versus 10.3%) in the northeastern area, without statistical significance before and after adjusting for the patients' background characteristics (p > 0.05). In addition, regression analysis revealed that the mortality of patients admitted on weekdays was more likely to be influenced by regional subgroup, hospital level and intravenous thrombolysis than that of patients admitted on weekends. The weekend effect was not observed in the mortality of patients with AIS regardless of rural-urban status or geographic region in China.

Differences in mechanical thrombectomy for acute ischemic stroke on weekdays versus nights/ weekends in a Japanese primary stroke core center.

The term "weekend effect" refers to an increase in the mortality rate for hospitalizations occurring on weekends versus weekdays. In this study, we investigated whether such an effect exists in patients undergoing mechanical thrombectomy for acute ischemic stroke with large vessel occlusion (currently the standard treatment for this condition) at a single center in Japan. We surveyed 151 patients who underwent mechanical thrombectomy for acute ischemic stroke with large vessel occlusion (75 and 76 patients were treated during daytime and nighttime, respectively) from January 2019 to June 2021. The items evaluated in this analysis were the rate of modified Rankin Scale ≤2 or prestroke scale, mortality, and procedural treatment time. The rates of modified Rankin Scale ≤2 or prestroke scale and mortality at 90 days after treatment did not differ significantly between daytime and nighttime (41.3% vs. 29.0%, p=0.11; 14.7% vs. 11.8%, p=0.61, respectively). The door-to-groin time tended to be shorter during daytime versus nighttime (57 [IQR: 42.5-70] min vs. 70 [IQR: 55-82]) min, p=0.0507). This study did not reveal differences in treatment outcome between daytime and nighttime in patients undergoing mechanical thrombectomy for acute ischemic stroke with large vessel occlusion. Therefore, the "weekend effect" was not observed in our institution.

Patterns and outcomes of weekend admission for acute ischemic stroke

Background and objectivesThe “weekend effect” describes worse care delivery during off-hours or weekends and has been demonstrated in multiple sub-specialties. Off-hours care for acute ischemic stroke (AIS) has been associated with poorer outcomes. However, there is less data about the “weekend effect” on endovascular thrombectomy (ET) outcomes. MethodsWe used Medicare 100% sample datasets and included all AIS admissions from 2018-2019, using validated International Classification of Diseases, 10th Revision, Clinical Modification codes to identify AIS and comorbidities. Medicare provides the date of admission for all hospitalizations, and the day of the week was determined and assigned to weekend (Saturday or Sunday) or weekday (Monday through Friday). We defined 3 major outcomes: inpatient mortality, discharge home (vs. other destination), and 30-day mortality. ResultsAmong 471427 AIS admissions,13.0% and 12.9% of all AIS admissions occurred on a Saturday and Sunday, respectively, less than the expected 14.3% occurring on any given day (p-value <0.0001). AIS admissions on a weekend were less likely to receive IV thrombolysis (13.6% on Saturday and 12.9% on Sunday) and ET (13.1% on Saturday and 13.2% on Sunday), p-value <0.0001. Among all AIS admissions, weekend admission was associated with worse outcomes, including higher odds of inpatient mortality (adjusted OR 1.04 [95% CI 1.01-1.08, p<0.0001]), lower odds of discharge home (0.94 [0.93-0.96, p<0.0001]), and higher odds of 30-day mortality (1.06 [1.04-1.08, p<0.0001]). However, among AIS patients treated with ET, there was no association of weekend admission with outcomes. ConclusionsIn this national and contemporary dataset, we observed that the proportion of thrombolysis and ET cases was less over the weekend, and outcomes (inpatient mortality, 30-day mortality and odds of discharge home) were worse overall. We did not observe this association among AIS patients undergoing ET on a weekend vs. weekday.

Admission on weekends does not increase mortality after hip fracture: a meta-analysis of 1.4 million patients.

The "weekend" effect resulting in increased complication rates in patients admitted on weekends has been noted in many diseases. This systematic review and meta-analysis aimed to collate adjusted data from published studies to assess if admission on weekends as compared to weekdays increases mortality rates in hip fracture patients. Databases of PubMed, CENTRAL, Scopus, Web of Science, and Embase were searched up to 31st December 2022 for studies comparing mortality between weekend versus weekday admission of hip fracture patients. Adjusted hazard ratios (HR) were pooled. Fourteen studies including 1,487,986 patients were analyzed. Most studies were from Europe and North America. Results showed no difference in mortality rates of hip fracture patients admitted on weekends versus weekdays (HR: 1.00 95% 0.96, 1.04 I2 = 75%). There was no publication bias and results did not change on the leave-one-out analysis. Subgroup analysis based on sample size and treatment did not change outcomes. This meta-analysis has shown no apparent weekend effect in cases of hip fractures. Patients admitted on weekends had similar mortality rates as compared to those admitted on weekdays. Current data has high heterogeneity and is mostly from developed countries.

Weekend effect in emergency laparotomy: a propensity score-matched analysis.

The 'weekend effect' is the term given to the observed discrepancy regarding patient care and outcomes on weekends compared to weekdays. This study aimed to determine whether the weekend effect exists within Aotearoa New Zealand (AoNZ) for patients undergoing emergency laparotomy (EL), given recent advances in management of EL patients. A cohort study was conducted across five hospitals, comparing the outcomes of weekend and weekday acute EL. A propensity-score matched analysis was used to remove potential confounding patient characteristics. Of the 487 patients included, 132 received EL over the weekend. There was no statistically significant difference between patients undergoing EL over the weekend compared to weekdays. Mortality rates were comparable between the weekday and weekend cohorts (P = 0.464). These results suggest that modern perioperative care practice in New Zealand obviates the 'weekend' effect.