Seven-year mortality in heart failure patients with undiagnosed diabetes: an observational study

Cardiovascular Diabetology Seven-year mortality in heart failure patients with undiagnosed diabetes: an observational study Juana A Flores-Le Roux 0 1 2 Josep Comin 1 Juan Pedro-Botet 1 David Benaiges 1 Jaume Puig-de Dou 1 Juan J Chillarn 1 Alberto Goday 1 Jordi Bruguera 1 Juan F Cano-Perez 1 0 Department of Endocrinology, Hospital del Mar, Departament de Medicina, Universitat Autonoma de Barcelona , Spain 1 Department of Endocrinology, Hospital del Mar , Paseo Maritimo, 25-29 E-08003 Barcelona , Spain 2 Department of Endocrinology, Hospital del Mar, Departament de Medicina, Universitat Autonoma de Barcelona , Spain Background: Patients with type 2 diabetes mellitus and heart failure have adverse clinical outcomes, but the characteristics and prognosis of those with undiagnosed diabetes in this setting has not been established. Methods: In total, 400 patients admitted consecutively with acute heart failure were grouped in three glycaemic categories: no diabetes, clinical diabetes (previously reported or with hypoglycaemic treatment) and undiagnosed diabetes. The latter was defined by the presence of at least two measurements of fasting plasma glycaemia 7 mmol/L before or after the acute episode. Group differences were tested by proportional hazards models in allcause and cardiovascular mortality during a 7-year follow-up. Results: There were 188 (47%) patients without diabetes, 149 (37%) with clinical diabetes and 63 (16%) with undiagnosed diabetes. Patients with undiagnosed diabetes had a lower prevalence of hypertension, dyslipidaemia, peripheral vascular disease and previous myocardial infarction than those with clinical diabetes and similar to that of those without diabetes. The adjusted hazards ratios for 7-year total and cardiovascular mortality compared with the group of subjects without diabetes were 1.69 (95% CI: 1.17-2.46) and 2.45 (95% CI: 1.58-3.81) for those with undiagnosed diabetes, and 1.48 (95% CI: 1.10-1.99) and 2.01 (95% CI: 1.40-2.89) for those with clinical diabetes. Conclusions: Undiagnosed diabetes is common in patients requiring hospitalization for acute heart failure. Patients with undiagnosed diabetes, despite having a lower cardiovascular risk profile than those with clinical diabetes, show a similar increased mortality. acute heart failure; diabetes; cardiovascular mortality; undiagnosed diabetes - Introduction Type 2 diabetes has an estimated prevalence of 20-40% in heart failure patients, being an independent risk factor not only for the development of heart failure [1-6] but also for increased morbidity and mortality [7-13]. On the other hand, several studies have highlighted the frequent underdiagnosis of diabetes in the general population and in high cardiovascular risk patients [14-17]. The few reports on the prevalence of undiagnosed diabetes in patients with stable chronic heart failure suggest it could affect 10% of patients [18,19]. Most of the studies that have quantified the adverse outcomes of patients with diabetes and heart failure have been limited to patients with a known diagnosis of diabetes. Previous reports have outlined the prognostic importance of undiagnosed diabetes in patients with different cardiovascular diseases [16,20-22]. In patients with established coronary artery disease, undiagnosed diabetes has been proven to be a highly significant and independent predictor of cardiovascular and all-cause mortality [21,22]. Patients with heart failure requiring hospital admission for an acute episode represent a high-risk population for adverse outcomes [23-26]. In this group of patients, mortality is higher than in those with chronic stable heart failure and, thus, identification of patients with an increased risk within this group who could benefit from more aggressive therapeutic interventions could help improve their poor outcomes. However, the risk associated with undiagnosed diabetes in patients with acute heart failure has not been described. Thus, the aim of the present study on patients hospitalized for acute heart failure was to determine the prevalence and characteristics of patients with undiagnosed diabetes and its impact on all-cause and cardiovascular mortality during a 7-year follow-up in comparison with patients with and without clinical diabetes. Patients and Methods Patients and baseline measurements An observational study of a retrospective cohort of all patients admitted to the cardiology department of Hospital del Mar (Barcelona, Spain) with the diagnosis of acute heart failure was carried out between January 1st, 2000 to December 31st, 2002. All patients with acute heart failure as one of the two first discharge diagnoses were included. Discharge records were reviewed and the following data was gathered: demographic and clinical characteristics, cardiovascular risk factors, previous diabetes treatment, cause of heart failure, left ventricular ejection fraction measured by echocardiography, chronic renal failure, peripheral vascular disease, previous myocardial infarction or stroke, plasma biochemical parameters at the time of admission [glycemia, creatinine, hemoglobin and glycosylated hemoglobin (HbA1c)] and drug therapy at discharge. Before the year 2002 HbA1c was only determined in patients with a clinical diagnosis of diabetes at admission. From January 2002 onwards, HbA1c was systematically measured in all subjects admitted with acute heart failure. Thus, data on HbA1c for individuals without clinical diabetes was available in only 35% of the cases. Investigators obtained data from medical and laboratory records and did not participate in patient treatment and management. To identify undiagnosed diabetes, we had access to clinical diagnosis, laboratory data and pharmaceutical treatment registered in all primary health care centres in the province of Barcelona and in the autonomous community of Catalonia. Laboratory data for blood samples drawn in acute situations are specified as emergency laboratory, as these blood samples are processed in a different laboratory, and thus these samples were excluded for diabetes diagnosis. For blood samples drawn in primary health care centres at routine checkup visits, patients are given specific instructions regarding fasting a minimum of 8 hours, as per protocol. In patients presenting hyperglycaemia during admission, but no prior glucose values in the range of diabetes, we also reviewed the laboratory data of the year after discharge to rule out recent-onset diabetes. Diabetes was diagnosed according to 1997 American Diabetes Association criteria [27], and patients were classified in three categories: 1) clinical diabetes mellitus, when the diagnosis was specified in medical reports or patients were being treated for diabetes (dietary advice, oral drugs or insulin); 2) undiagnosed diabetes mellitus, without clinical diabetes but with two or more outpatient fasting plasma glucose concentrations 7 mmol/L; and 3) no diabetes mellitus, who did not (...truncated)