Early identification of divergent performance in congenital cardiac surgery

Monitoring performance in laparoscopic gastric bypass surgery using risk-adjusted cumulative sum at 2 high-volume centers

BACKGROUND

Traditional surgical outcomes are measured retrospectively and intermittently, limiting opportunities for early intervention.

OBJECTIVES

The objective of this study was to use risk-adjusted cumulative sum (RA-CUSUM) to track perioperative surgical outcomes for laparoscopic gastric bypass. We hypothesized that RA-CUSUM could identify performance variations between surgeons.

SETTING

Two mid-Atlantic quaternary care academic centers.

METHODS

Patient-level data from the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP) were abstracted for laparoscopic gastric bypasses performed by 3 surgeons at 2 high-volume centers from 2014 to 2021. Estimated probabilities of serious complications, reoperation, and readmission were derived from the MBSAQIP risk calculator. RA-CUSUM curves were generated to signal observed-to-expected odds ratios (ORs) of 1.5 (poor performance) and .5 (superior performance). Control limits were set based on a false positive rate of 5% (α = .05).

RESULTS

We included 1192 patients: Surgeon A = 767, Surgeon B = 188, and Surgeon C = 237. Overall rates of serious complications, 30-day reoperations, and 30-day readmissions were 3.9%, 2.5%, and 5.2% respectively, with expected rates of 4.7%, 2.2%, and 5.8%. RA-CUSUM signaled lower-than-expected (OR < .5) rates of readmission and serious complication in Surgeon A, and higher-than-expected (OR > 1.5) readmission rate in Surgeon C. Surgeon A further demonstrated an early period of higher-than-expected (OR > 1.5) reoperation rate before April 2015, followed by superior performance thereafter (OR < .5). Surgeon B's performance generally reflected expected standards throughout the study period.

CONCLUSIONS

RA-CUSUM adjusts for clinical risk factors and identifies performance outliers in real-time. This approach to analyzing surgical outcomes is applicable to quality improvement, root-cause analysis, and surgeon incentivization.

A simple signaling rule for variable life-adjusted display derived from an equivalent risk-adjusted CUSUM chart

The variable life-adjusted display (VLAD) is the first risk-adjusted graphical procedure proposed in the literature for monitoring the performance of a surgeon. It displays the cumulative sum of expected minus observed deaths. It has since become highly popular because the statistic plotted is easy to understand. But it is also easy to misinterpret a surgeon's performance by utilizing the VLAD, potentially leading to grave consequences. The problem of misinterpretation is essentially caused by the variance of the VLAD's statistic that increases with sample size. In order for the VLAD to be truly useful, a simple signaling rule is desperately needed. Various forms of signaling rules have been developed, but they are usually quite complicated. Without signaling rules, making inferences using the VLAD alone is difficult if not misleading. In this paper, we establish an equivalence between a VLAD with V-mask and a risk-adjusted cumulative sum (RA-CUSUM) chart based on the difference between the estimated probability of death and surgical outcome. Average run length analysis based on simulation shows that this particular RA-CUSUM chart has similar performance as compared to the established RA-CUSUM chart based on the log-likelihood ratio statistic obtained by testing the odds ratio of death. We provide a simple design procedure for determining the V-mask parameters based on a resampling approach. Resampling from a real data set ensures that these parameters can be estimated appropriately. Finally, we illustrate the monitoring of a real surgeon's performance using VLAD with V-mask.

EM for regularized zero-inflated regression models with applications to postoperative morbidity after cardiac surgery in children

This paper proposes a new statistical approach for predicting postoperative morbidity such as intensive care unit length of stay and number of complications after cardiac surgery in children. In a recent multi-center study sponsored by the National Institutes of Health, 311 children undergoing cardiac surgery were enrolled. Morbidity data are count data in which the observations take only nonnegative integer values. Often, the number of zeros in the sample cannot be accommodated properly by a simple model, thus requiring a more complex model such as the zero-inflated Poisson regression model. We are interested in identifying important risk factors for postoperative morbidity among many candidate predictors. There is only limited methodological work on variable selection for the zero-inflated regression models. In this paper, we consider regularized zero-inflated Poisson models through penalized likelihood function and develop a new expectation-maximization algorithm for numerical optimization. Simulation studies show that the proposed method has better performance than some competing methods. Using the proposed methods, we analyzed the postoperative morbidity, which improved the model fitting and identified important clinical and biomarker risk factors.

Monitoring the performance of intensive care units using the variable life-adjusted display: a simulation study to explore its applicability and efficiency

RATIONALE, AIMS AND OBJECTIVES

Graphical monitoring tools are needed for real-time quality evaluation in intensive care unit. The variable life-adjusted display (VLAD) provides a directly interpretable assessment indicating whether the overall performance is better or worse than expected on the basis of the predicted risk of failure. The aim of this study is to quantify the ability of VLAD charts to early recognize a worsening in clinical performance.

METHODS

A Monte Carlo experiment simulating the sequence of successes and failures of an intensive care unit is performed; the predicted mortality is calculated by means of the Simplified Acute Physiology Score 3 admission score. From a given position in the admissions sequence, we increased the probability of death; we calculated: (i) the surveillance system delay in responding to the mortality increase; (ii) the percentage of cases where the VLAD has been able to give an alarm within the first 5, 10, 20 and 60 deaths occurred after the increase of probability of death; and (iii) the percentage of false declarations of increase (anticipated alarms).

RESULTS

The frequency distribution of the alarm delays shows VLAD was not always able to early detect mortality increase. Only a very small number of anticipated alarms were given.

CONCLUSIONS

Variable life-adjusted display ability to signal is mild and strictly correlated with the institution volume of activity. Therefore, the use of VLAD seems to be not always advisable, and an integration between VLAD and other well-documented tools as CUSUM charts could be preferable.

Hyperglycemia and the outcome of pediatric cardiac surgery patients requiring peritoneal dialysis

OBJECTIVE

To study the nature of the association between glycemia and ICU mortality in pediatric cardiac surgery patients treated with peritoneal dialysis (PD).

MATERIALS AND METHODS

Retrospective observational study in the ICU of a tertiary hospital involving forty pediatric cardiac surgery patients treated with PD. We selected patients requiring PD, extracted glucose measurements and nutritional intake data during ICU stay and calculated mean and maximum blood glucose values i) during ICU stay; ii) during dependence on PD; and iii) during independence from PD. We statistically assessed the relationship between glycemia-related variables and ICU mortality.

MEASUREMENTS AND RESULTS

Twenty-two patients treated with PD died (mortality 55%). In the PD cohort, 9725 blood glucose measurements were performed (every 3.3 hours on average). The mean glycemia during dependence on PD was significantly higher in non-survivors than survivors (p<0.0001), but not during independence from PD (p=0.49). The area under the receiver operator characteristic curve for the mean glycemia during dependence on PD was significantly greater than that obtained during independence from PD. Even after adjustment for severity of illness using multivariate logistic analysis, the mean glycemia and calorie intake during PD were significant and independent predictors of ICU mortality.

CONCLUSIONS

A higher mean blood glucose concentration during PD, but not during PD-free periods was associated with greater ICU mortality. Mean glycemia and calorie intake during PD were significant and independent predictors of ICU mortality.

Monitoring the occurrence of wound infections after cardiac surgery

The aim of this study was to demonstrate the use of a graphical method for real-time monitoring of the occurrence of surgical wound infection following cardiac surgery. This included developing and incorporating a risk scoring system so that variations in case-mix could be duly accounted for in the monitoring process. We analysed routinely collected data from a London teaching hospital. These data consisted of records for 2146 patients who had undergone cardiac surgery between April 2000 and March 2004 and whose surgical wounds were followed up as part of the local surveillance programme. The risk model was developed using logistic regression analysis with surgical wound infection diagnosed before hospital discharge as the outcome measure. Factors included in the model were the number of surgical wounds, patient age, operations that combined bypass surgery and valve replacement, renal disease and the number of days between hospital admission and surgery. The model was a good predictor of outcomes recorded within an independent data set (Chi-squared=3.81, P=0.58) and we incorporated it into a graphical tool for monitoring outcomes. The risk model and the associated graphical monitoring method could be valuable tools to assist with infection management. If used in real-time, problems with the care process can be quickly identified allowing timely remedial action to be taken.

Patient safety and human factors in pediatric cardiac surgery

The patient safety movement and human factors studies are becoming an increasingly important part of everyday clinical practice. Pediatric cardiac surgery is a high-risk field that is very much dependent on safe practices and continuous research into improvement of outcomes. This article reviews the main research frameworks, methods used, and current findings in the area of patient safety and human factors within pediatric cardiac surgery.

Providing feedback to hospital doctors about prescribing errors; a pilot study

OBJECTIVE

To assess the feasibility and acceptability of obtaining data on prescribing error rates in routine practice, and presenting feedback on such errors to medical staff.

SETTING

One clinical directorate of a London teaching trust.

METHODS

Ward pharmacists recorded all prescribing errors identified in newly written medication orders on one day each fortnight between February and May 2005. We examined prescribing errors reported on the trust's medication incident database for the same period.

MAIN OUTCOME MEASURES

Prescribing errors identified and recorded by ward pharmacists, prescribing errors reported as incident reports; prescribing error rates per clinical specialty; lead consultants' views on receiving feedback on errors for their specialty.

RESULTS

During eight data collection days, 4,995 new medication orders were examined. Of these, 462 (9.2%; 95% confidence interval 8.5 -10.1%) contained at least one prescribing error. There were 474 errors in total. Pharmacists indicated that they would have reported 19 (4%) of the prescribing errors as medication incidents. Eight prescribing errors were reported for the entire four-month study period on non-data collection days. Feedback was presented to lead clinicians of 10 clinical specialties. This included graphical summaries showing how the specialty compared with others, and a list of errors identified. This information was well-received by clinicians.

CONCLUSION

Prescribing errors identified by ward pharmacists can be systematically fed back at the level of the clinical specialty; this is acceptable to the consultants involved. Incident report data is subject to gross under-reporting. Routinely providing feedback for each consultant team or for individual prescribers will require more focussed data collection.

Real-time monitoring of coronary care mortality: a comparison and combination of two monitoring tools

BACKGROUND

Quality control in clinical care is becoming increasingly more prevalent, resulting in a need for tools that can be readily used by clinical teams for monitoring their own performance. The aim of this study was to devise a practical and effective scheme for monitoring coronary care mortality in real-time.

METHODS

We obtained data for 2153 consecutive patients admitted after acute myocardial infarction between 1st September and 30th November 1995 to one of 20 acute hospitals in West Yorkshire participating in the NHS R and D funded EMMACE-1 study. We developed control charts for each centre to monitor 30-day mortality. These control charts used two complementary tools: the Risk-Adjusted Cumulative Sum chart (CUSUM) and a new 'Rocket Tail' chart based upon the Variable Life-Adjusted Display (VLAD). We also combined information from each of these to devise a further chart.

RESULTS

Control charts are shown for two centres in order to illustrate the important features of the different but complimentary monitoring tools. The Risk-Adjusted CUSUM is shown to be useful for detecting isolated runs of unsatisfactory outcome results but is not 'intuitive', and does not give any indication of the preceding history of outcomes. The Rocket Tail chart is shown to give a good summary of outcome history and also how overall performance compares with what would be expected for the case-mix. A chart that combines both approaches appeals to the advantages of each.

CONCLUSIONS

We propose a visual approach to health-care monitoring that beneficially combines and extends the different information of the previously used CUSUM and VLAD charts.

Anesthetic Management and Outcome of Complex Late Arterial-Switch Operations for Patients With Transposition of the Great Arteries and a Systemic Right Ventricle

OBJECTIVE

For patients with transposition of the great arteries and a systemic right ventricle, complex late arterial-switch operations (double switch, switch conversion, Senning-Rastelli) after the newborn period have been described recently to restore the morphologic left ventricle to the systemic circulation. The purpose of this study was to describe the anesthetic management and perioperative outcome of this group of patients and to compare them with a control group of patients who had primary arterial-switch operations in the neonatal period.

DESIGN

Retrospective database and medical record review with 3:1 control:case ratio.

SETTING

Tertiary care academic children's hospital.

PARTICIPANTS

Patients undergoing complex late-arterial switch operations after the newborn period.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Thirteen patients were identified in the complex late-switch group and 43 in neonatal arterial-switch group. There were no perioperative deaths, no new gross neurologic deficits, and all patients were discharged home in both groups. Anesthetic and bypass times were significantly longer in the late-switch group (745 v 558 minutes, p < 0.001, and 382 v 243 minutes, p < 0.001, respectively). Transfusion requirements were similar between the groups. The incidence of arrhythmia (92% v 9%, p < 0.001), use of pacing systems (69% v 9%, p < 0.001), cardioversion (15% v 0%, p = 0.05), and pharmacologic treatment of arrhythmias (69% v 0%, p < 0.01) intraoperatively were significantly higher in the complex late-switch group.

CONCLUSIONS

Patients presenting for complex late corrective operations for transposition of the great arteries require long and complex anesthetics. Despite these challenges, perioperative outcomes are excellent.

Cardiac ECMO for biventricular hearts after paediatric open heart surgery

OBJECTIVE

To delineate predictors of hospital survival in a large series of children with biventricular physiology supported with extracorporeal membrane oxygenation (ECMO) after open heart surgery.

RESULTS

81 children were placed on ECMO after open heart surgery. 58% (47 of 81) were transferred directly from cardiopulmonary bypass to ECMO. Hospital survival was 49% (40 of 81) but there were seven late deaths among these survivors (18%). Factors that improved the odds of survival were initiation of ECMO in theatre (64% survival (30 of 47)) rather than the cardiac intensive care unit (29% survival (10 of 34)) and initiation of ECMO for reactive pulmonary hypertension. Important adverse factors for hospital survival were serious mechanical ECMO circuit problems, renal support, residual lesions, and duration of ECMO.

CONCLUSIONS

Hospital survival of children with biventricular physiology who require cardiac ECMO is similar to that found in series that include univentricular hearts, suggesting that successful cardiac ECMO is critically dependent on the identification of hearts with reversible ventricular dysfunction. In our experience of postoperative cardiac ECMO, the higher survival of patients cannulated in the operating room than in the cardiac intensive care unit is due to early effective support preventing prolonged hypoperfusion and the avoidance of a catastrophic cardiac arrest.

Survival after surgery or therapeutic catheterisation for congenital heart disease in children in the United Kingdom: analysis of the central cardiac audit database for 2000-1

OBJECTIVES

To analyse simple national statistics and survival data collected in the central cardiac audit database after treatment for congenital heart disease and to provide long term comparative statistics for each contributing centre.

DESIGN

Prospective, longitudinal, observational, national cohort survival study.

SETTING

UK central cardiac audit database.

MAIN OUTCOME MEASURES

Survival at 30 days and one year after treatment in the year April 2000-March 2001, assessed by using both volunteered life status and independently validated life status through the Office for National Statistics, using the patient's unique NHS number, or the general register offices of Scotland and Northern Ireland. Institutional results following a group of six benchmark operations and three benchmark catheterisation procedures.

RESULTS

Since April 2000 data have been received from all 13 UK tertiary centres performing cardiac surgery or therapeutic cardiac catheterisation in children with congenital heart disease. Altogether 3666 surgical procedures and 1828 therapeutic catheterisations were performed. Central tracking of mortality identified 469 deaths, 194 occurring within 30 days and 275 later. Forty two of the 194 deaths within 30 days were detected by central tracking but not by volunteered data. For surgery overall, survival at 30 days was 94.9%, falling to 91.2% at one year; this effect was most marked for infants. For therapeutic catheterisation survival at 30 days was 99.1%, falling to 98.1% at one year. Survival of individual centres or individual operators did not differ from the national average after benchmark procedures.

CONCLUSIONS

Independent data validation is essential for accurate survival analysis. One year survival gives a more realistic view of outcome than traditional perioperative mortality. Currently no detectable difference exists in survival between any of the 13 UK tertiary congenital heart disease centres, but confidence intervals for small centres are wide, limiting our power to detect underperformance from analysis of a single year's data. Appropriately resourced, focused national audit is capable of accurate data collection on which nationwide, long term quality control can be based.

Quality assurance of paediatric cardiac surgery: a prospective 6-year analysis

OBJECTIVE

To audit effective quality assurance methods to monitor outcomes following paediatric cardiac surgery at a single institution.

METHODS

All patients undergoing cardiac surgery from January 1996 to December 2001 were enrolled prospectively. Patients were stratified by complexity of surgical procedure into four groups, with Category 4 being the most complex procedure. Outcome measures included death, length of admission and morbidity from complications.

RESULTS

A total of 1815 patients underwent 1973 surgical procedures. Of these, 1447 (73.3%) were cardiopulmonary bypass procedures, and 543 (27.5%) were more complex (Category 3 and 4) procedures. Median patient age was 3.5 years (range, 1 day-20 years) and patient weight 15.0 kg (range, 900 g to 90 kg). Sixty-six patients (3.6%) died during the study period. Of the procedures in 1996, 22.7% were classified as complex compared with 29.2% of procedures in 2001. The annual surgical mortality ranged from 1.9-4.7% (P = 0.20), and when mortality was adjusted for complexity of surgery, there was no significant yearly variation in the mortality rate (P = 0.57). Analysis of individual surgeon's results showed no significant difference in the mortality rate by complexity of surgery performed (P = 0.90). Mean ventilation times did not change significantly over time (P = 0.79). The yearly incidence of significant neurological complications ranged from 0.6% to 4.5% and the incidence of arrhythmias from 4.2% to 8.0%. No difference was detected between the years.

CONCLUSIONS

Stratifying complexity of surgery proved valuable in monitoring surgical outcomes and detecting differences in performance over time as large subgroups were created for analysis.

Intraoperative Transesophageal Echocardiography in Pediatric Congenital Cardiac Surgery: A Two-Center Observational Study

Transesophageal echocardiography (TEE) is a monitoring and diagnostic tool for the care of children undergoing cardiac surgery. We analyzed reports from 865 routine TEE examinations performed between January 1994 and March 2002 in patients younger than 17-yr-old who were undergoing surgery for congenital heart disease. Patients' median age was 36 mo (range, 1 day-16 yr). The primary end-point of the study was the incidence of surgical and medical management decisions changed as a result of TEE findings; secondary end-points were diagnostic impact (diagnostic exclusions and new diagnoses) and surgical outcome. Fifty percent of the examinations were performed by anesthesiologists with an advanced level of training in perioperative TEE; all of the examiners had an experience of >or=>500 TEE examinations. Supervision by an anesthesiologist with an advanced level of training was requested in 36.7% of cases; supervision by a cardiologist was requested in 3.8%. Surgical alterations of management were reported in 12.7% of cases and included the need for a repeat bypass run in 7.3%; medical alterations of management were required in 19.4% of cases. We observed a diagnostic impact of TEE in 18.5% of cases and a suboptimal but acceptable surgical outcome in 27.6%; TEE findings predicted postoperative difficulties in 4.0%. Our results confirm the utility of routine TEE to assess repair of congenital heart defects. Furthermore, this service was competently performed by a regular team of cardiac anesthesiologists appropriately trained in TEE.

IMPLICATIONS

Transesophageal echocardiography (TEE) is an essential monitoring and diagnostic device for the care of children undergoing cardiac surgery. The surgical and medical impact of TEE is demonstrated in a large series of patients. This service can be performed by appropriately trained cardiac anesthesiologists.

Anesthetic and perioperative outcome of teenagers and adults with congenital heart disease

OBJECTIVE

To compare the perioperative outcome of patients >or=13 years old undergoing surgery for congenital heart disease in a children's hospital by a dedicated congenital heart surgery and anesthesia team with procedure-matched younger control patients.

DESIGN

Retrospective medical record review study. From October 1997 to July 2000, medical records of all patients >12 years old requiring cardiopulmonary bypass were reviewed. A control group of patients <or=5 years old was reviewed, and 2 patients were matched to each older patient by diagnosis and surgical procedure. Data are reported as mean +/- SD. Older (study) patients were compared with younger (control) patients using t-test or chi square, with p <or= 0.05 significant.

SETTING

Medical school-affiliated tertiary-care children's hospital.

PARTICIPANTS

Patients undergoing congenital heart surgery.

MEASUREMENTS AND MAIN RESULTS

The study group (older patients) comprised 85 patients, and the control group (younger patients) comprised 170 patients. There were no intraoperative deaths. All major complications-cardiopulmonary resuscitation, neurologic injury, massive hemorrhage with sternotomy, femoral cannulation for emergent bypass, and severe episodes of hypotension on induction of anesthesia-occurred in older patients undergoing repeat sternotomy.

CONCLUSION

Mortality and major morbidity were low in both groups; however, all major intraoperative incidents occurred in older repeat sternotomy patients, suggesting increased perioperative risk for adverse outcomes in these patients.