Prognostic role of brain natriuretic peptide (BNP) levels in patients with type 2 diabetes mellitus

Abstract

We hypothesized that BNP levels can predict cardiac mortality in diabetic patients. Design: 482 diabetic patients (majority males with NIDDM) from VAMC San Diego, were divided into two groups: a) patients referred by the physician for echocardiogram on the basis of clinical suspicion of cardiac dysfunction (Referred (R), n=180) b) patients randomly selected from the diabetic clinic in which there was no suspicion of cardiac dysfunction, (Not-Referred (N-R), n=302). These groups were followed, and all documented cardiac events and all-cause mortality in relation to initial BNP levels were examined. Results: There were 71 (14.7%) deaths during the follow-up period: 52/180 (29%) in Referred and 19/302 (6%) in Not-Referred group. In Referred group 30/52 (58%) died of cardiac cause, 10/52 (19%) non-cardiac, 2/52 (4%) renal and 10/52 (19%) due to unknown cause. Similarly 6/19 (32%) died of cardiac causes in the Not-Referred group. Median BNP level of the patients in both Referred and Not-referred groups, who died of: 1) cardiac causes were 537 and 87 pg/ml, 2) Non-cardiac causes were 80 and 53 pg/ml, 3) unknown cause of death were 343 and 38 pg/ml respectively. ROC values for mortality in Referred and Non-Referred groups in relation to BNP, revealed the AUC to be 0.720 and 0.691 respectively (p<0.01 in both). Among HDL, LDL, triglycerides, HgA1c, only the ROC for triglycerides significantly predicted mortality in diabetic patients. The specificity and negative-predictive values were higher in the Not-Referred versus Referred group across the range of BNP cut-points. The most accurate cut-point was a BNP of 120 pg/ml in both the Not-Referred (87%) and Referred group (61%). Cox Regression (multivariable) showed BNP as the most significant predictor of the all cause mortality in Referred group. The Kaplan-Meier's Survival curves showed the marked decrease in survival in patient group with BNP>120pg/ml. Conclusion: BNP appears to be a reliable predictor of future cardiac and all cause mortality in diabetic patients.