The influence of seasonal variation on cardiac surgery: A time-related clinical outcome predictor

Medical malpractice litigation and daylight saving time

STUDY OBJECTIVES

Daylight saving time (DST) constitutes a natural quasi-experiment to examine the influence of mild sleep loss and circadian misalignment. We investigated the acute effects of spring transition into DST and the chronic effects of DST (compared to standard time) on medical malpractice claims in the United States over 3 decades.

METHODS

We analyzed 288,432 malpractice claims from the National Practitioner Data Bank. To investigate the acute effects of spring DST transition, we compared medical malpractice incidents/decisions 1 week before spring DST transition, 1 week following spring DST transition, and the rest of the year. To investigate the chronic effects of DST months, we compared medical malpractice incidents/decisions averaged across the 7-8 months of DST vs the 4-5 months of standard time.

RESULTS

With regard to acute effects, spring DST transitions were significantly associated with higher payment decisions but not associated with the severity of medical incidents. With regard to chronic effects, the 7-8 DST months were associated with higher average payments and worse severity of incidents than the 4-5 standard time months.

CONCLUSIONS

The mild sleep loss and circadian misalignment associated with DST may influence the incidence of medical errors and decisions on medical malpractice payments both acutely and chronically.

CITATION

Gao C, Lage C, Scullin MK. Medical malpractice litigation and daylight saving time. J Clin Sleep Med. 2024;20(6):933-940.

Residential Greenness and Long-term Mortality Among Patients Who Underwent Coronary Artery Bypass Graft Surgery

BACKGROUND

Studies have reported inverse associations between exposure to residential greenness and mortality. Greenness has also been associated with better surgical recovery. However, studies have had small sample sizes and have been restricted to clinical settings. We investigated the association between exposure to residential greenness and all-cause mortality among a cohort of cardiac patients who underwent coronary artery bypass graft (CABG) surgery.

METHODS

We studied this cohort of 3,128 CABG patients between 2004 and 2009 at seven cardiothoracic departments in Israel and followed patients until death or 1st May 2021. We collected covariate information at the time of surgery and calculated the patient-level average normalized difference vegetation index (NDVI) over the entire follow-up in a 300 m buffer from the home address. We used Cox proportional hazards regression models to estimate associations between greenness and death, adjusting for age, sex, origin, socioeconomic status, type of hospital admission, peripherality, air pollution, and distance from the sea.

RESULTS

Mean age at surgery was 63.8 ± 10.6 for men and 69.5 ± 10.0 for women. During an average of 12.1 years of follow-up (37,912 person-years), 1,442 (46%) patients died. A fully adjusted Cox proportional hazards model estimated a 7% lower risk of mortality (HR: 0.93, 95% CI = [0.85, 1.00]) per 1 interquartile range width increase (0.04) in NDVI. Results were robust to the use of different buffer sizes (100 m-1,250 m from the home) and to the use of average NDVI exposure during the first versus the last 2 years of follow-up.

CONCLUSIONS

Residential greenness was associated with lower risk of mortality in CABG patients.

Influenza Season and Outcome After Elective Cardiac Surgery: An Observational Cohort Study

BACKGROUND

An asymptomatic respiratory viral infection during cardiac surgery could lead to pulmonary complications and increased mortality. For elective surgery, testing for respiratory viral infection before surgery or vaccination could reduce the number of these pulmonary complications. The aim of this study was to investigate the association between influenzalike illness (ILI) seasons and prolonged mechanical ventilation and inhospital mortality in a Dutch cohort of adult elective cardiac surgery patients.

METHODS

Cardiac surgery patients who were admitted to the intensive care unit between January 1, 2014, and February 1, 2020, were included. The primary endpoint was the duration of invasive mechanical ventilation in the ILI season compared with baseline season. Secondary endpoints were the median Pao2 to fraction of inspired oxygen ratio on days 1, 3, and 7 and postoperative inhospital mortality.

RESULTS

A total of 42,277 patients underwent cardiac surgery, 12,994 (30.7%) in the ILI season, 15,843 (37.5%) in the intermediate season, and 13,440 (31.8%) in the baseline season. No hazard rates indicative of a longer duration of invasive mechanical ventilation during the ILI season were found. No differences were found for the median Pao2 to fraction of inspired oxygen ratio between seasons. However, inhospital mortality was higher in the ILI season compared with baseline season (odds ratio 1.67; 95% CI, 1.14-2.46).

CONCLUSIONS

Patients undergoing cardiac surgery during the ILI season were at increased risk of inhospital mortality compared with patients in the baseline season. No evidence was found that this difference is caused by direct postoperative pulmonary complications.

Acuity Is Seasonal in a Tertiary Care Burn Center

Supply and demand dictate resource allocation in large academic institutions. Classic teaching is that burns is a seasonal specialty with winter being the "busiest" time of year. Resident allocation during the winter and summer months, however, is traditionally low due to the holidays and travel peaks. Our objective was to evaluate our acuity-defined as patient complexity-based on seasons, in order to petition for appropriate mid-level provider allocation. We performed a retrospective review of all admissions to an accredited, large academic burn center. All patients admitted between January 1, 2009 and December 31, 2018 were eligible for inclusion. Demographics, length of stay, injury characteristics, and mortality were evaluated. Thirteen thousand four hundred fifty-eight patients were admitted during this study period. Most patients were admitted during the summer. Patients admitted to the intensive care unit were more likely to be admitted in the winter, although this was not statistically significant. Winter admissions had the longest lengths of stay, and the highest incidence of inhalation injury. Female and elderly patients were more likely admitted during the winter. There was a significant difference in mortality between summer and winter seasons. Acuity is seasonal in our large academic burn center and resource allocation should align with the needs of the patients. This data may help large centers petition their institutions for more consistent experienced mid-level providers, specifically during critical seasons.

An Analysis of Medical Malpractice Litigations in Coronary Artery Bypass Grafting from 1994-2019

BACKGROUND

Cardiothoracic surgery is one of the more highly litigated medical specialties, and coronary artery bypass grafting (CABG) constitutes a substantial portion of cardiothoracic surgery cases. Therefore, understanding litigations relating to CABG would be of benefit to surgeons working to uphold the standards of care that their patients seek and minimize their own legal liability. This study analyzed CABG litigations to identify predictive factors of litigation and verdict type.

METHODS

This study utilized the Westlaw legal database to compile litigations from 1994-2019 across the United States, and resulted in 307 total litigations. After individual screening, 211 litigations met the criteria for inclusion, and were analyzed for demographic, clinical, chronological, and verdict characteristics.

RESULTS

Litigations were present in 33 U.S. states, with California, New York, and Florida having the most litigations. Defendant verdicts were reached in 67.78% of litigations, followed by 20.38% of plaintiff verdicts and 11.85% of settlements. Plaintiff verdicts were associated with the incidence of myocardial infarction during hospitalization. The winter season had the most litigations (42.18%), and the most defendant verdicts (37.76%). Patient mortality occurred in 47.39% of litigations. The most common alleged reason for litigation was a procedural error (55.45%).

CONCLUSIONS

Defendant verdicts were significantly associated with an alleged reason of procedural errors, an alleged reason of a failure to monitor, and congestive heart failure present in patients. The common nature of defendant verdicts, and the significantly greater occurrence of defendant verdicts during the highly-litigated winter season, suggest that surgeons frequently satisfy the legal standard of care.

Seasonality of mortality and in-hospital complications in hip fracture surgery: Retrospective cohort research using a nationwide inpatient database

AIM

Among older patients undergoing hip fracture surgery, previous studies have shown a seasonal variation of in-hospital surgical complications. However, little is known about seasonal effects on mortality and systemic complications after hip fracture surgery. In the present study, we evaluated whether mortality and in-hospital systemic complications are influenced by seasonal differences.

METHODS

We enrolled patients from a nationwide database who underwent hip fracture surgery between 2010 and 2018. The primary outcome was in-hospital mortality. The secondary outcomes were in-hospital systemic complications. The association between the seasonality and in-hospital outcomes was investigated using multivariable Cox, logistic regression and causal mediation analysis.

RESULTS

With 425 856 patients (mean age 83.5 years; 79% women), overall in-hospital mortality was 5324 (1.2%). Fall and winter were associated with a higher mortality than spring (hazard ratio [HR] 1.16; P < 0.001; HR 1.14; P = 0.001, respectively). Across all the seasons, there were 36 834 overall systemic complications (8.6%), with respiratory infection being the most frequent (18 637 [4.4%]). Among these complications, only respiratory infection showed seasonal variation, with a higher prevalence in fall and winter. The mediated effect of respiratory infection on mortality was significantly higher in fall and winter compared with spring (fall, HR 1.06, proportion mediated 36.7%; winter, HR 1.14, proportion mediated 55.0%; all P < 0.001).

CONCLUSIONS

We found a significantly higher mortality in fall and winter after hip fracture surgery. Specifically, in winter, the increased in-hospital death was largely attributed to the increased incidence of respiratory infection. Geriatr Gerontol Int 2021; 21: 398-403.

Winter LVAD implantation is associated with adverse clinical outcomes

BACKGROUND

The seasonal variation of incidence and severity of heart failure is well known. However, the impact of seasonal variation on clinical outcomes following left ventricular assist device (LVAD) implantation remains unknown.

METHODS

We retrospectively reviewed consecutive patients who received LVAD implantation between January 2014 and December 2016 along with their first year of post-implant outcomes. Clinical outcomes were compared between those with winter LVAD implantation (between October and March) and those with non-winter LVAD implantation.

RESULTS

168 patients with a median age of 57 years and 130 males were included. There was no seasonal difference in the number of LVAD implantations. One-year survival free from major adverse events was significantly lower in the winter implant group (n = 88) compared to the non-winter group (n = 80) (44% vs 61%) with an adjusted hazard ratio of 1.81 (95% confidence interval 1.11-2.90, p = 0.014), largely due to a higher rate of heart failure readmission in the winter implant patients (incidence rate ratio 2.29, 95% confidence interval 0.89-5.84).

CONCLUSION

Patients who underwent LVAD implantation during the winter season had a higher heart failure readmission rate. A detailed mechanism and therapeutic strategy given our findings warrant further investigation.

What Influence Does the Time of Year Have on Postoperative Complications Following Total Knee Arthroplasty?

BACKGROUND

The time of year might influence the occurrence of surgical complications. Therefore, this study investigated correlations between the time-of-year and 30-day postoperative complication rates following primary total knee arthroplasty (TKA). Specifically, we determined (1) postoperative complication rates across all quarters; and (2) time-of-year influence on complications using univariate and multivariate regression analyses.

METHODS

CPT code 27447 identified 147,473 TKAs from the NSQIP database. Readmissions, reoperations, as well as medical and surgical complications occurring within 30 postoperative days were assessed. All TKAs were divided into 4 cohorts based on the quarter-of-the-year (Q1-Q4) during which the surgery was performed. Chi-Square, ANOVA, linear regression, as well as univariate and multivariate analyses were performed to compare complication rates. A P < .05 was set for statistical significance.

RESULTS

Q3 had a higher risk of superficial infection when compared to Q1 (OR 1.37; 95% CI 1.12-1.69; P = .002). There was a lower risk of pneumonia between Q2 and Q1 (OR: 0.7; 95% CI 0.54-0.90; P = .007) as well as Q4 and Q1 (OR 0.76; 95% CI 0.6-0.96; P = .017). Blood transfusion was lower in Q2, Q3, and Q4 compared to Q1 (P = .02, P < .001, and P < .001).

CONCLUSION

This study provides a baseline analysis correlating the time of year and outcomes of TKA. However, since seasonality and weather can vary greatly in the United States by geographic region and time of year, future studies should be performed at a more granular level using hospital-specific data correlating weather and region to TKA outcomes.

Seasonal Influence on Postoperative Complications after Total Knee Arthroplasty

Purpose

This study is aimed at investigating whether inpatient complications and surgical site infections (SSIs) occurred more commonly in patients undergoing total knee arthroplasty (TKA) during the summer season.

Materials and Methods

A total of 725 patients who underwent unilateral or bilateral TKA were included in this study. A total of 241 patients (33.2%) underwent TKA between May and August. Our outcomes of interest were the incidence of postoperative complications and length of stay.

Results

May–August surgeries were associated with a higher risk of postoperative inpatient complications (p=0.003). May–August surgeries (odds ratio [OR], 2.13; 95% confidence interval [CI], 1.18 to 3.85), postoperative transfusion (OR, 2.46; 95% CI, 1.43 to 4.26), postoperative special care unit stay (OR, 4.68; 95% CI, 1.99 to 11.0) and chronic kidney disease (OR, 3.27; 95% CI, 1.15 to 9.28) were associated with a higher odds of developing inpatient complications. No association was present between summer surgeries and SSIs (p=0.486).

Conclusions

The results of this study show that overall complication rates following TKA exhibit a seasonal trend, with a peak during the summer months. These results may have some implication in clinical practice and stricter approaches to hospital guidelines during the summer months.

Red cell distribution width and coronary artery bypass surgery

OBJECTIVES

The red cell distribution width (RDW) has been identified as an independent risk factor with regard to prognosis in patients with coronary artery disease with or without heart failure. We sought to investigate the role of RDW in patients undergoing isolated coronary artery bypass graft surgery (CABG).

METHODS

Analysis of consecutive patients on a validated prospective cardiac surgery database was performed for patients undergoing isolated CABG. Univariate and multivariate analysis was performed for in hospital mortality, long-term survival, length of hospital stay, length of intensive care unit stay and creatinine kinase muscle-brain (CKMB) release.

RESULTS

Overall mortality was 2.1% for all cases, N = 8615. Median follow up was 5.8 years. Univariate analysis demonstrated that the RDW has a significant effect on CKMB release, P = 0.001, in-hospital mortality, P < 0.0001, and long-term survival, P < 0.0001, but no significant effect on the ITU length of stay, P = 0.9, or hospital length of stay, P = 0.2. Multivariate analysis revealed that the RDW was a significant factor determining in-hospital mortality and long-term survival, but had no significant effect on CKMB release, ITU or hospital length of stay. Confounding factor analysis revealed that in the absence of anaemia, the RDW was still a significant factor determining in-hospital mortality and long-term survival.

CONCLUSIONS

The RDW is a significant factor determining in-hospital mortality and long-term survival in patients undergoing isolated CABG. The mechanism of association requires further study.

To everything there is a season: impact of seasonal change on admissions, acuity of injury, length of stay, throughput, and charges at an accredited, regional burn center

PURPOSE

Although previous studies have investigated the impact of weather and temporal factors on incidence of trauma admissions, there is a paucity of data describing the effect of seasonal change on burn injury. The purpose of this study was to examine the impact of the changing seasons on admissions to and resource utilization at an accredited burn center, with the goal of optimizing patient throughput and matching supply with demand.

METHODS

We performed a retrospective review of all burn admissions to an accredited, regional burn center, from Summer 2009 through Spring 2010. Patients were segregated into the seasonal cohorts of Summer, Fall, Winter, and Spring, based on admission date. Patient demographics included age, gender, mechanism of injury, and total body surface area (TBSA) injured. Main outcome measures included length of intensive care unit (ICU) stay, length of stay (LOS), and hospital charges, which served as a proxy for resource utilization (nursing, wound, and critical care; access to operating room (OR); inpatient rehabilitation). Groups were compared by T tests, with statistical significance assigned to P values <0.05.

RESULTS

Seven hundred thirty patients were admitted to the burn center during this annual period, with a mean age of 31.6 years and a TBSA of 8.9%. Although Spring had the greatest the number of admissions at 219 (30%), patients from Summer and Winter had the largest burns, longest length of ICU and hospital stays, and highest hospital charges (P < 0.05). Furthermore, variability of these parameters, as measured by standard deviation, was greatest during Summer and Winter, serving to reduce throughput via uneven demand on resources. Highest throughput occurred during the Spring, which had the highest admission-to-LOS ratio. No differences were observed in age, gender, and incidence of electrical injuries, across the 4 seasons.

CONCLUSIONS

Summer and winter were the peak seasons of resource utilization at our burn center, in terms of length and variability of ICU and hospital stays, as well as total hospital charges. Such seasonal change may be related to acuity of burn injury but not number of burn admissions. To improve operational efficiency and maximize patient throughput, resource allocation should be structured to anticipate seasonal changes, so that supply of services matches demand.

An electronic tool for visual feedback to monitor the adherence to quality indicators in intensive care medicine

Evidence-based medicine is often inadequately implemented in intensive care units (ICU); the aim of this study was to improve its implementation via a technical feedback system, using key performance indicators (KPI). The study evaluated 205 patients treated in a cardiac surgical ICU over a 6-month period (3 months before and 3 months after implementation of the feedback system). KPI adherence rates for sedation, delirium and pain monitoring, and completion of a weaning protocol before and after the implementation of the feedback system, were compared. Adherence rates for pain and delirium monitoring, and implementation of the weaning protocol, were significantly increased by the intervention. Adherence to KPIs for sedation, which were high at baseline, could not be further improved. Daily display of KPI implementation had a positive effect on adherence to standard operating procedures. Adherence to guidelines may be improved by using this feedback system as part of the clinical routine.

Sampling time error in EuroSCORE II

Seasonal variation in mortality after cardiac surgery exists. EuroSCORE II accrued data over a 12-week period from May to July 2010. We investigated whether the accrual period for EuroSCORE II had a different mortality rate compared with the rest of the year. We found in a study population of 18,706 that the accrual period of EuroSCORE II may introduce bias into the predicted mortality, potentially reducing the accuracy of the new model.

Academic season does not influence cardiac surgical outcomes at US Academic Medical Centers

BACKGROUND

Previous studies have demonstrated the influence of academic season on outcomes in select surgical populations. However, the influence of academic season has not been evaluated nationwide in cardiac surgery. We hypothesized that cardiac surgical outcomes were not significantly influenced by time of year at both cardiothoracic teaching hospitals and non-cardiothoracic teaching hospitals nationwide.

STUDY DESIGN

From 2003 to 2007, a weighted 1,614,394 cardiac operations were evaluated using the Nationwide Inpatient Sample database. Patients undergoing cardiac operations at cardiothoracic teaching and non-cardiothoracic teaching hospitals were identified using the Association of American Medical College's Graduate Medical Education Tracking System. Hierarchic multivariable logistic regression analyses were used to estimate the effect of academic quarter on risk-adjusted outcomes.

RESULTS

Mean patient age was 65.9 ± 10.9 years. Women accounted for 32.8% of patients. Isolated coronary artery bypass grafting was the most common operation performed (64.7%), followed by isolated valve replacement (19.3%). The overall incidence of operative mortality and composite postoperative complication rate were 2.9% and 27.9%, respectively. After accounting for potentially confounding risk factors, timing of operation by academic quarter did not independently increase risk-adjusted mortality (p = 0.12) or morbidity (p = 0.24) at academic medical centers.

CONCLUSIONS

Risk-adjusted mortality and morbidity for cardiac operations were not associated with time of year in the US at teaching and nonteaching hospitals. Patients should be reassured of the safety of performance of cardiac operations at academic medical centers throughout a given academic year.

Seasonal variation influences outcomes following lung cancer resections

OBJECTIVE

The effect of seasonal variation on postoperative outcomes following lung cancer resections is unknown. We hypothesized that postoperative outcomes following surgical resection for lung cancer within the United States would not be impacted by operative season.

METHODS

From 2002 to 2007, 182507 isolated lung cancer resections (lobectomy (n = 147 937), sublobar resection (n = 21650), and pneumonectomy (n = 13916)) were evaluated using the Nationwide Inpatient Sample (NIS) database. Patients were stratified according to operative season: spring (n = 47382), summer (n = 46131), fall (n = 45370) and winter (n = 43624). Multivariate regression models were applied to assess the effect of operative season on adjusted postoperative outcomes.

RESULTS

Patient co-morbidities and risk factors were similar despite the operative season. Lobectomy was the most common operation performed: spring (80.0%), summer (81.3%), fall (81.8%), and winter (81.1%). Lung cancer resections were more commonly performed at large, high-volume (>75th percentile operative volume) centers (P < 0.001). Unadjusted mortality was lowest during the spring (2.6%, P < 0.001) season compared with summer (3.1%), fall (3.0%) and winter (3.2%), while complications were most common in the fall (31.7%, P < 0.001). Hospital length of stay was longest for operations performed in the winter season (8.92 ± 0.11 days, P < 0.001). Importantly, multivariable logistic regression revealed that operative season was an independent predictor of in-hospital mortality (P < 0.001) and of postoperative complications (P < 0.001). Risk-adjusted odds of in-hospital mortality were increased for lung cancer resections occurring during all other seasons compared with those occurring in the spring.

CONCLUSIONS

Outcomes following surgical resection for lung cancer are independently influenced by time of year. Risk-adjusted in-hospital mortality and hospital length of stay were lowest during the spring season.