STS publicly reports risk-adjusted participant group outcomes and composite quality ratings for the following surgical procedures:
| CABG | Isolated Coronary Artery Bypass Graft |
| AVR | Isolated Aortic Valve Replacement |
| AVR+CABG | Combined AVR and CABG |
| MVRR | Isolated Mitral Valve Repair/Replacement |
| MVRR+CABG | Combined Mitral Valve Repair/Replacement and CABG |
Risk Adjustment
Risk adjustment allows STS database participants to compare their performance to other groups, such as the overall STS cohort, other participants, or by region or state. A participant’s case mix refers to the types of patients being treated, including their age, health conditions, how serious their heart problems are, and other factors. By accounting for and controlling patient risk factors present before surgery, risk adjustment “levels the playing field” as best as possible. Specifically, some hospitals care for more ill patients, and those patients are at greater risk of dying due to their underlying conditions, not necessarily because of the care they receive. Risk adjustment accounts for these risk factors. Unadjusted event rates are not used for these comparisons because they may be affected by variation in patient case mix and disease severity across participants.
Using risk adjustment provides a more accurate reflection of a participant’s performance relative to a reference cohort with similar patient characteristics. Direct comparisons between the risk-adjusted mortality rates of two individual participants are generally inadvisable unless their patient populations are relatively similar.
Composite quality ratings, patient populations, and reporting periods
| Isolated Coronary Artery Bypass Graft (CABG) | |
| Overview | The STS CABG composite includes four domains: 1) absence of operative mortality; 2) absence of major morbidity; 3) use of Internal Mammary Artery (IMA); 4) use of all evidence-based perioperative medications. All domains are risk adjusted. Participants receive scores and star ratings for each of the four domains, plus overall composite results. In addition to receiving a numeric score, participants are assigned rating categories designated by one, two, or three stars. |
| Patient population | Adult patients aged 18 years or older who underwent isolated CABG surgery at an STS participating hospital. Patients were excluded if they had missing data on age or if they were younger than 18 years old. |
| Reporting period | Three years (36 months) |
| Isolated Aortic Valve (AVR) Aortic Valve Replacement + CABG (AVR+CABG) Isolated Mitral Valve Repair/Replacement (MVRR) Isolated Mitral Valve Repair/Replacement + CABG (MVRR+CABG) | |
| Overview | STS AVR, AVR+CABG, MVRR, and MVRR+CABG composite scores, respectively, represent two domains: 1) absence of operative mortality; and 2) absence of major morbidity. Both domains are risk adjusted. Participants receive scores and star ratings for each of the two domains, plus overall composite results. In addition to receiving a numeric score, participants are assigned rating categories designated by one, two, or three stars. |
| Patient population | Adult patients aged 18 years or older who underwent isolated AVR, AVR+CABG, MVRR, or MVRR+CABG surgery at an STS participating hospital. Note: MVRR populations include all previously defined isolated mitral valve repairs and replacements and also allow concomitant surgical atrial fibrillation correction procedures, tricuspid valve repairs, and surgical ASD repairs. Patients were excluded if they had missing data on age or if they were younger than 18 years old. |
| Reporting period | Three years (36 months) |
Star Ratings and Credible Intervals
STS ACSD participant scores are shown as both a number and a vertical black line within a dark blue graph. To demonstrate how a participant compares to the STS average, the STS average score is shown as a vertical red line within a light blue graph that represents the lowest-to-highest range across all North American STS ACSD participants.
Following the participant’s score, numbers in parentheses – (##, ##) – represent the range within which the participant’s score was likely to fall. This is known as a credible interval. Determined using a statistical formula, each participant has a different range based on the their unique mix of patients and number of surgical procedures in each category.
Participants receive star ratings based on their scores and how they compare to the STS average:
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| If the participant's score and range are lower than the STS average score, the participant receives 1 star. |
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| If the STS average score falls within the participant's range, the participant receives 2 stars. |
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| If the participant's score and range are higher than the STS average score, the participant receives 3 stars. |
