Impact of diabetes among revascularized patients in Japan and the U.S

Approximately 25% of patients who undergo percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG) have diabetes, and the diagnosis of diabetes roughly doubles the mortality risk associated with coronary artery disease. However, the impact of diabetes may differ according to ethnicity. Our objective was to examine the impact of diabetes on long-term survival among U.S. and Japanese patients who underwent PCI or CABG.

For the current analysis, we included 8,871 patients from a Japanese multicenter registry (Coronary Revascularization Demonstrating Outcome database in Kyoto; median follow-up 3.5 years; interquartile range [IQR] 2.6-4.3) and 7,229 patients from a U.S. multipractice registry (Texas Heart Institute Research Database; median follow-up 5.2 years; IQR 3.8-6.5).

Diabetes was more prevalent among Japanese than U.S. patients (39.2 vs. 31.0%; P < 0.001). However, after revascularization, long-term all-cause mortality was lower in diabetic Japanese patients than in diabetic U.S. patients (85.4 vs. 82.2%; log-rank test P = 0.009), whereas it was similar in nondiabetic Japanese and U.S. patients (89.1 vs. 89.5%; P = 0.50). The national difference in crude mortality was also significant among insulin-using patients with diabetes (80.8 vs. 74.9%; P = 0.023). When long-term mortality was adjusted for known predictors, U.S. location was associated with greater long-term mortality risk than Japanese location among nondiabetic patients (hazard ratio 1.58 [95% CI 1.32-1.88]; P < 0.001) and, especially, diabetic patients (1.88 [1.54-2.30]; P < 0.001).

Although diabetes was less prevalent in U.S. patients than in Japanese patients, U.S. patients had higher overall long-term mortality risk. This difference was more pronounced in diabetic patients.