Original article: cardiovascular
The society of thoracic surgeons: 30-day operative mortality and morbidity risk models

Presented at the Thirty-eighth Annual Meeting of The Society of Thoracic Surgeons, Fort Lauderdale, FL, Jan 28–30, 2002.
https://doi.org/10.1016/S0003-4975(03)00179-6Get rights and content

Abstract

Background

Although 30day risk-adjusted operative mortality (ROM) has been used for quality assessment, it is not sufficient to describe the outcomes after coronary artery bypass grafting (CABG) surgery. Risk-adjusted major morbidity may differentially impact quality of care (as complications occur more frequently than death) and enhance a surgical team’s ability to assess their quality. This study identified the preoperative risk factors associated with several complications and a composite outcome (the presence of any major morbidity or 30-day operative mortality or both).

Methods

For CABG procedures, the 1997 to 1999 Society of Thoracic Surgeons (STS) National Adult Cardiac Surgery Database was used to develop ROM and risk-adjusted morbidity (ROMB) models. Risk factors were selected using standard STS univariate screening and multivariate logistic regression approaches. Risk model performance was assessed. Across STS participating sites, the association of observed-to-expected (O/E) ratios for ROM and ROMB was evaluated.

Results

The 30-day operative death and major complication rates for STS CABG procedures were 3.05% and 13.40%, respectively (503,478 CABG procedures), including stroke (1.63%), renal failure (3.53%), reoperation (5.17%), prolonged ventilation (5.96%), and sternal infection (0.63%). Risk models were developed (c-indexes for stroke [0.72], renal failure [0.76], reoperation [0.64], prolonged ventilation [0.75], sternal infection [0.66], and the composite endpoint [0.71]). Only a slight correlation was found, however, between ROMB and ROM indicators.

Conclusions

Used in combination, ROMB and ROM may provide the surgical team with additional information to evaluate the quality of their care as well as valuable insights to allow them to focus on areas for improvement.

Section snippets

Study population

Since its inception, the STS National Cardiac Database has grown to 1.5 million records by 1999. For data obtained during the study period from 1997 to 1999, there were 497 participating member sites (representing approximately 589 unique hospitals) submitting data (668,386 total records). Of these records, 505,645 records indicated that a CABG-only procedure was performed.

From the set of records with CABG-only procedural designation, records with missing age (or out-of-range age) or missing

Risk profile for study population

For the STS CABG patient population studied (total STS CABG-only patient records = 503,478), the average age was 64.9 years (median, 66.0) with a standard deviation of 10.7 years. This generally male CABG population (29.1% female) was predominantly noted to have three-vessel disease (69.9%). There were 6.6% that required an emergent or salvage procedure and 31.1% that required an urgent procedure. Preoperatively, there was a relatively high level of other comorbidities including peripheral

Comment

Ultimately, the aim of performing a cardiac surgical procedure is to get the patient through their hospital experience both alive and well with a substantial improvement in functional and overall health. Historically, risk-adjusted 30-day operative mortality rates have been a predominant focus of STS national quality improvement reporting. These STS 30-day risk models were developed with the goal of providing surgical teams clinically relevant risk-adjusted mortality and morbidity reports to

Acknowledgements

Doctor Shroyer’s participation in this project was supported in part by funding from the Department of Veterans Affairs’ Health Services Research and Development Office (Grant IHY 99214–1, Dr Shroyer Principal Investigator), the VA Office of Patient Care Services, and the VA Office of Quality and Performance, VA Headquarters, Washington, DC. The authors wish to thank all of the participants of the STS National Database Committee for their support to make this risk-adjusted mortality/morbidity

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