A secondary study revealed that the presence of diabetes mellitus in patients with chronic heart failure leads to a higher risk of early death.
The existence of chronic heart failure (CHF) and diabetes mellitus (DM) as comorbidities increase patient risk of early death significantly, per a study from the Italian Group for the Study of Survival in Cardiac Impairment-Heart Failure (GISSI-HF).
Marco Dauriz, MD, PhD, of the Division of Endocrinology, Diabetes and Metabolism, at the University of Verona in Italy, and his fellow researchers led a 7-year long trial originally set out to test the efficacy of rosuvastatin (Crestor/AstraZeneca) and n-3 polyunsaturated fatty acids (PUFAs) in outpatients with CHF, producing valuable data on 6,975 patients with HF of any cause.
Dauriz and colleagues performed a secondary analysis of the collected GISSI-HF data on 6,935 participants (99.5% of the original study participants) with "available data on previous history of DM as well as fasting plasma glucose or hemoglobin A1c measurements at the study entry."
The group performed multiple comparisons between different patient groups — those with DM, those who were determined to be pre-DM, and non-DM – in non-adjusted and adjusted models factoring in variables such as age, sex, BMI, heart rate, hypertension, and others.
The goal of the study was to determine what role DM and pre-DM might have in connection with all-cause death or cardiovascular hospitalization. The group also tested whether poorer glycemic control at baseline carried a higher risk of adverse clinical outcomes by looking at data of patients with hemoglobin A1c (HbA1c) measurements.
The study data showed that 41% of the CHF study cohort also had DM. 69.2% of those patients with DM had been previously diagnosed, but 30.8% (878 total patients) had not been diagnosed despite having HbA1c levels and/or fasting glucose levels in diabetic range. The study data also showed that among 4,011 patients who died, the instance of all-cause death for patients who also had DM was significantly higher.
Dauriz and colleagues stated that "patients with DM had remarkably higher (P<0.0001) cumulative incidence rates of all cause death (n=984; 34.5%) compared with patients with pre-DM (n+465; 23.1%) or those without DM (n=509; 24.6%)." The same pattern held true for cardiovascular hospitalization, with 1,481 (51.9%) of patients with DM being hospitalized for cardiovascular events, versus 887 (44.1%) of pre-DM patients, and 934 (45.1%) of non-DM patients.
The combined end point of all-cause death or cardiovascular hospitalization for patients with DM was 63.6%, significantly higher than the numbers for pre-DM (52.9%) or non-DM (54.7%).
Overall, the data determined that "patients with DM had a ≈1.5-fold increased risk of all-cause death and a 1.3-fold increased risk for the composite of all-cause death or cardiovascular hospitalization compared to patients without DM," independent of any other risk factors. Dauriz and colleagues also pointed out that hazard ratios for patients with HbA1c greater than 7.5% were 1.14 (95% CI, 1.10-1.29) for combined all-cause death or cardiovascular hospitalization, and 1.21 (95% CI, 1.02-1.43) for all-cause death alone.
The secondary analysis of GISSI-HF data findings indicates that pre-DM and DM are common comorbidities among CHF patients and that the presence of DM (diagnosed or previously undiagnosed) and poor glycemic control in patients with DM are independently associated with a higher risk of all-cause death or cardiovascular hospitalization.
The findings are at odds with several previously published clinical trials which report that "independent prognostic impact of DM, on survival outcomes in patients with advanced HF might be confined only to those with ischemic cardiomyopathy," but confirm the findings of studies that have determined a more general link between DM and "poor long-term clinical outcomes in patients with CHF.
Dauriz and colleagues stated that the GISSI-HF data study provides "clear evidence on the prognostic role of DM" and poor glycemic control on the risk of long-term survival outcomes in a large cohort of CHF patients, highlighting the prognostic value of DM and "the need for therapies that improve survival outcomes in patients with coexistent CHF and DM."
The study was originally published in the Journal of the American Heart Association.