Original Article
Acute Risk Change: An Innovative Measure of Operative Adverse Events and Perioperative Team Performance

https://doi.org/10.1053/j.jvca.2018.01.014Get rights and content

Objectives

Cardiac surgical risk models predict mortality preoperatively, whereas intensive care unit (ICU) models predict mortality postoperatively. Finding a large difference between the 2 (an acute risk change [ARC]) may reflect an alteration in the status of the patient related to the surgery. An adverse ARC was associated with morbidity and mortality in an Australian population. The aims of this study were to validate ARC in a UK population and to investigate the possible mechanisms behind ARC.

Design

This was a retrospective case–control study.

Setting

Single, high-volume cardiothoracic hospital.

Participants

Data from 4,842 cardiac surgical patients were collected between 2013 and 2015.

Interventions

None.

Measurements and main results

EuroSCORE was recalibrated to each preceding year’s data. ARC was defined as postoperative minus preoperative percentage mortality risk. Association among ARC, morbidity, and mortality was tested. Cases with large adverse ARC (greater than +15%) were compared with cases with large favorable ARC (less than –10%) with regard to intraoperative adverse events, unmeasured patient risk factors, and postoperative events. Adverse ARC was associated with hospital mortality, ICU stay, ICU readmission, renal support, prolonged intubation and return to the operating room (p < 0.001). Intraoperative adverse events occurred in 23 of 33 patients with adverse ARC; however, only 2 of 17 patients with favorable ARC reported adverse events (p < 0.001). Unmeasured risk factors were present in 48% of patients in the adverse ARC group.

Conclusion

ARC is a readily available and sensitive marker that correlates strongly with morbidity and mortality. The use of ARC in local and national quality monitoring could identify areas for improvement of the quality of cardiac surgical care.

Section snippets

Study Population

Data were obtained from a large, UK tertiary center between January 2013 and December 2015. Data from 2013 and 2014 were used for calibration. Data from 2015 were used for hypothesis testing. A database of cardiac surgery patients was obtained from the Intensive Care National Audit and Research Centre (ICNARC), a national database comprising demographic and clinical data from all patients admitted to the ICU. Included in the ICNARC is a new national risk for death calculation developed

Patient Population and Data Quality

A flowchart of patient numbers is shown in Fig 1, and demographic characteristics are shown in Table 2. The combined database had 4,842 patients available for analysis, of which 2,913 provided the data to calibrate the risk score and 1,929 operated in 2015 were analyzed for ARC. Of these 1,929 patients, high (greater than +15%) or low (less than –10%) ARC was identified in 50 patients. Seventeen cases showed favorable ARC and 33 adverse ARC. Both EuroSCORE and the ICNARC model were well

Discussion

ARC is measurable using the UK-validated risk scores, EuroSCORE and the ICNARC model, and can be monitored locally and continuously. It correlates strongly with morbidity markers. Large adverse ARC is associated both with a higher frequency of AEs as well as with unmeasured risk. There is variation in ARC among surgeons.

Because ARC can be measured after the first 24 hours in the ICU using readily available data, it could provide a more rapid identifier of changes in AE rates in the

Acknowledgments

The authors acknowledge the Intensive Care National Audit and Research Center and the Papworth Audit team for providing data for this study.

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