Baseline characteristics of an incident haemodialysis population in Spain: results from ANSWER—a multicentre, prospective, observational cohort study

Background. The ANSWER study aims to identify risk factors leading to increased cardiovascular morbidity and mortality in a Spanish incident haemodialysis population. This paper summarizes the baseline characteristics of this population. Methods. A prospective, observational, one-cohort study, including all consecutive incident haemodialysis patients from 147 Spanish nephrology services, was conducted. Patients were enrolled between October 2003 and September 2004. Sociodemographic, clinical, laboratory and health care characteristics were collected. Results. Baseline characteristics are described for 2341 incident haemodialysis patients [mean (SD) age 65.2 (14.5) years, 63% males]. The main cause of renal failure was diabetic nephropathy (26%). The majority of patients (57%) had a Karnofsky score of 80–100 and 27% were followed up by a nephrologist for ≤6 months. In total, 86% of the patients had hypertension, 43% had dyslipidaemia and 44% had a history of cardiovascular disease. Initial vascular access was obtained via a temporary catheter in 30% of patients, via a permanent catheter in 16% and via an arteriovenous fistula in 54%. Albumin levels were <3.5 g/dl in 43% of patients. Immediately prior to the onset of haemodialysis, the mean (SD) glomerular filtration rate (GFR) was 7.6 (2.8) ml/min/1.73 m(2), and only 6.7% of the patients were within the K/DOQI guidelines for all four bone mineral markers. In addition, a high proportion of patients had anaemia markers outside the EBPG guidelines (haemoglobin <11 g/dl, 59%, ferritin <100 or >500 ng/ml, 41% and saturated transferrin <20 or >40%, 50%) despite previous treatment with erythropoiesis-stimulating agents in 41% of cases. Conclusions. There is excessive use of temporary catheters and a high prevalence of uraemia-related cardiovascular risk factors among incident haemodialysis patients in Spain. The poor control of hypertension, anaemia, malnutrition and mineral metabolism and late referral to a nephrologist indicate the need for improving the therapeutic management of patients before the onset of haemodialysis.