Performance of the J-CTO score versus other risk scores for predicting procedural difficulty in coronary chronic total occlusion interventions

BACKGROUND: Although the Japanese chronic total occlusion (J-CTO) score is widely used to assess the complexity of revascularization for CTO lesions, ambiguous and conflicting results are reported in validation studies. Therefore, we aimed to quantitatively evaluate the effectiveness of the J-CTO score and explore the heterogeneity of its comparison with other CTO scores. METHODS: PubMed, Embase, the Cochrane Library, and ClinicalTrials.gov databases were systematically searched from January 1st, 2011 to December 23rd, 2021. Studies that examined the accuracy of the J-CTO score were eligible. Where feasible, estimates of discrimination and calibration were pooled with a random-effects model. The Prediction model Risk Of Bias ASsessment Tool (PROBAST) was used for risk-of-bias assessment. This study was reported according to PRISMA guidelines and prospectively registered with PROSPERO (CRD42019126161). RESULTS: Of 28 included studies (N = 34,944 lesions), 24 were eligible for meta-analysis. The J-CTO score demonstrated significant discrimination for 30-min wire crossing (summary C-statistic 0.76; 95% CI 0.68–0.84) and technical success (0.68; 95% CI 0.61–0.74) despite significant heterogeneity. Only 19 (33%) of the 58 pairwise comparisons with 14 competing scores that were based on discrimination reported a statistical result. The J-CTO score performed worse (relative difference of C-statistics >5%) in eight out of 33 independent comparisons but better in another 13. Methodological shortcomings resulted from only one study evaluating model calibration appropriately. CONCLUSION: The discrimination power of the J-CTO score was useful for time-efficient wire crossing and moderate for angiographic success. Head-to-head comparisons of CTO scores would benefit from standardized reporting and appropriate statistical methods. KEY MESSAGES: The J-CTO score has useful discrimination in predicting 30-min wire crossing while performing moderately for technical success. After excluding optimism bias, there is insufficient independent evidence supporting the superiority of newly introduced models over the J-CTO score. Standardized methodology and assessment are needed to achieve a better understanding of CTO scores, especially for their calibration.