Interaction between parathyroid hormone and the Charlson comorbidity index on survival of incident haemodialysis patients

Background. Haemodialysis patients are ageing and have with a high rate of comorbidities. The impact of this novel clinical setting on intact parathyroid hormone (iPTH) is not well established. Methods. For this observational, prospective multicentre cohort study, incident haemodialysis patients were recruited in 40 Italian centres and followed up for a mean period of 18 ± 6.7 months. Clinical characteristics and biochemistry were recorded at baseline. Comorbid conditions were scored by the Charlson comorbidity index (CCI). Results. Data of 411 patients (mean age: 66.5 ± 14.8 years; 17.3% >80 years old) were recorded. The mean CCI was 4.17 ± 2.8. In patients with CCI >0, an inverse correlation was observed between CCI (excluding age) and iPTH (P = 0.00002). Independently of CCI, patients with iPTH < 150 pg/ml had 76% as high as the risk of all-cause mortality. After multivariable adjustment, the combination of the first tertile of iPTH with second and third tertiles of CCI was significantly associated with all-cause mortality (RR = 3.83, P = 0.02; RR = 3.79, P = 0.01, respectively). Conclusions. Incident haemodialysis patients suffer from a high rate of clinical complications. In these patients, low iPTH and high CCI are often associated and very likely responsible for an adverse outcome.