Development and Validation of Risk Models for Outcomes of Isolated Coronary Artery Bypass Grafting ― A Nationwide Analysis in Japan ―

Q: What is the clinical evidence from this study?

Study design: Observational. Population: Isolated coronary artery bypass grafting (n=70180). Intervention: JapanSCORE III risk model vs. JapanSCORE II. Primary outcome: 30-day operative mortality (AUC 0.84, 95% CI 0.82-0.86, p=<0.001).

Q: What does this research mean for the field?

JapanSCORE III is a newly developed and validated risk model that provides updated preoperative risk assessment for isolated coronary artery bypass grafting to reflect contemporary practice in Japan. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Sachiko Hayashi; Hiraku Kumamaru; Shiori Nishimura; Aya Saito; Hideyuki Shimizu; Noboru Motomura

doi:10.1253/circj.cj-26-0160

September 1, 2026Circulation JournalOpen Access

Development and Validation of Risk Models for Outcomes of Isolated Coronary Artery Bypass Grafting ― A Nationwide Analysis in Japan ―

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Key result

The updated JapanSCORE III risk model for isolated CABG demonstrated good discrimination for 30-day operative mortality with an AUC of 0.84, significantly outperforming the previous JapanSCORE II.

Why the study?

Reliable preoperative risk assessment is essential in cardiac surgery, requiring an updated risk model for isolated CABG from the JCVSD-A to reflect contemporary practice.

Does the updated JapanSCORE III model accurately predict operative mortality and postoperative complications in patients undergoing isolated CABG in Japan?

Key Points

To develop and validate JapanSCORE III, an updated risk prediction model for operative mortality and postoperative complications following isolated coronary artery bypass grafting (CABG).
Analyzed nationwide data from the Japan Cardiovascular Surgery Database – Adult section (JCVSD-A) collected between 2018 and 2023, comprising 70,180 patients who underwent isolated CABG surgery.
Used LASSO logistic regression to optimize variable selection from candidate predictors across operative mortality and multiple postoperative complications.
Across the cohort of 70,180 patients, operative mortality was 2.7% (n=1,926), major morbidity was 9.3% (n=6,545), stroke occurred in 1.8% (n=1,247), and renal failure occurred in 2.3% (1,409/61,780).
The proposed JapanSCORE III model demonstrated superior discrimination compared with JapanSCORE II for operative mortality (AUC 0.84, 95% CI 0.82–0.86 vs. AUC 0.81, 95% CI 0.78–0.83; P<0.001) and stroke (AUC 0.69, 95% CI 0.65–0.73 vs. AUC 0.62, 95% CI 0.58–0.66; P<0.001).
Model calibration slope was 1.10 (95% CI 1.00–1.19) for operative mortality in JapanSCORE III compared to 0.91 (95% CI 0.82–1.00) for JapanSCORE II, while achieving acceptable agreement across most secondary complications.

Study Design

Type

Observational (n=70,180)

Multicenter

Yes

Structured PICO

Does the updated JapanSCORE III model accurately predict operative mortality and postoperative complications in patients undergoing isolated CABG in Japan?

P

Population

70,180 adults (mean age 69.3 years, 20% female) undergoing isolated coronary artery bypass grafting in Japan between 2018 and 2023, used to develop and validate the JapanSCORE III preoperative risk model.

E

Exposure

Development and validation of the JapanSCORE III risk prediction model using LASSO logistic regression

C

Comparator

JapanSCORE II (for comparison of model performance)

O

Outcome

30-day operative mortality (defined as death within 30 days after operation or before hospital discharge)hard clinical

Main Result

Effect estimate: AUC 0.84 (95% CI 0.82-0.86)

p-value: p=<0.001

The updated JapanSCORE III risk model provides accurate, contemporary preoperative risk stratification for operative mortality and complications in Japanese patients undergoing isolated CABG.

Limitations

Registry data may lack granularity or have missing data for certain clinical factors like detailed anatomical parameters and frailty.
No external validation was performed outside the Japanese population.
The model focuses only on periprocedural outcomes, not long-term clinical outcomes.
Potential variability in measurement or recording of predictors like ascending aortic calcification across institutions.
High PCI-to-CABG ratio in Japan may introduce potential selection bias
Direct comparison with other widely used risk models (EuroSCORE II, STS risk score) was not feasible due to differences in outcome and variable definitions

Implication

JapanSCORE III may refine CABG risk stratification in Japan; extends prior models yet leaves open external validation before adoption.

Abstract

Background: Reliable preoperative risk assessment is essential in cardiac surgery. In Japan, coronary artery bypass grafting (CABG) risk models have been developed from the Japan Cardiovascular Surgery Database – Adult section (JCVSD-A), with JapanSCORE I and II released previously. To reflect contemporary practice, we developed and validated JapanSCORE III, an updated risk model for isolated CABG, using JCVSD-A.

Discussion

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Cite This Study

Hayashi et al. (2026) conducted an observational in Isolated coronary artery bypass grafting (n=70,180). JapanSCORE III risk model vs. JapanSCORE II was evaluated on 30-day operative mortality (AUC 0.84, 95% CI 0.82-0.86, p=<0.001). The updated JapanSCORE III risk model for isolated CABG demonstrated good discrimination for 30-day operative mortality with an AUC of 0.84, significantly outperforming the previous JapanSCORE II.

synapsesocial.com/papers/6a993586636c6408cfa7dc70 https://doi.org/10.1253/circj.cj-26-0160

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Development and Validation of Risk Models for Outcomes of Isolated Coronary Artery Bypass Grafting ― A Nationwide Analysis in Japan ―

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Development and Validation of Risk Models for Outcomes of Isolated Coronary Artery Bypass Grafting ― A Nationwide Analysis in Japan ―

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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