Influence of diabetes mellitus on long-term clinical and economic outcomes after coronary artery bypass grafting

Background: China has the most patients with diabetes mellitus (DM) in the world and, annually, approximately 1 million Chinese become diabetic. We investigated both clinical and economic outcomes in a large Chinese cohort of diabetic patients undergoing coronary artery bypass graft surgery (CABG).

Methods: All 9,240 consecutive patients who underwent isolated, primary, elective CABG between January 1999 and December 2008 were included and analyzed for long-term major adverse cardiovascular and cerebrovascular events and economic outcomes up to 2 years after the procedure. The DM patients were divided into DM subgroups controlled by diet (n = 375), medication (n = 1,826) or insulin (n = 481).

Results: During the study period, the proportion of patients undergoing CABG who have DM increased from 20.1% to 31.8% in China. None of the DM subgroups was independently associated with in-hospital death, but DM was an independent predictor for long-term major adverse cardiovascular and cerebrovascular events (hazard ratio 1.29, 95% confidence interval: 1.14 to 1.46). Medically controlled DM and insulin-dependent DM, but not diet-controlled DM were independent predictors of long-term outcomes after CABG. Cost for initial hospitalization was higher for DM patients (76,782 Ren Min Bi [RMB] versus 65,521 RMB, respectively; p < 0.001). At 2 years after CABG, costs for DM patients were 11,261 RMB (approximately US $1,623) higher than for non-DM patients (p < 0.001).

Conclusions: CABG for patients with DM was significantly more expensive and was associated with worse long-term outcomes compared with non-DM patients. The rising incidence of DM, combined with the significant incremental costs represents significant clinical, economic, and social challenges for the Chinese healthcare system.