Functional impairment and risk of mortality in patients on chronic hemodialysis: results of the Lazio Dialysis Registry

Background: Functional impairment is associated with adverse outcomes in older people, as well as in patients on chronic hemodialysis. The aim of this study was to evaluate if functional impairment represents a risk factor for reduced survival in patients on chronic hemodialysis. Methods: All incident chronic hemodialysis patients of Lazio, a large region of central Italy, registered in the Dialysis and Transplant Lazio Region Registry (DTLRR) in the period 2008–2013 were considered eligible. Inclusion criteria were: age > 18 years, resident in Lazio, still doing dialysis after 90 days from incidence date, doing hemodialysis or hemodiafiltration treatment for > 9 h/week. Patients were stratified into three classes of functional activity: total autonomy, autonomy in some activities, and not self-sufficient. Functional activity was assessed for each patient by the referring physician for the DTLRR from the ~ 90 hemodialysis units of the Lazio region. Each patient was followed from date of first dialysis treatment to the end of the study (31/12/2015) or death or renal transplant, whichever occurred first. Cox proportional hazard models were performed to obtain mortality hazard ratios (HR), 95% confidence intervals (CI), for each class of functional activity adjusting for sex, age, country of birth, city of residence, body mass index (BMI), type of nephropathy, vascular access, previous nephrology counselling, weekly hours of hemodialysis, serum albumin, hemoglobin, and presence of comorbidities (e.g. vascular diseases, coronary disease, and diabetes). Results: A total of 3356 patients were studied. In the whole follow-up period, 1622 deaths occurred (48%). Functional impairment was associated with the risk of mortality: compared to ‘total autonomy’, the HR for ‘autonomy in some activities’ was 1.30 [95% CI: 1.14–1.49] and for ‘not self-sufficient’ 1.71 [1.47–1.99] (p for trend < 0.05). The number of evitable deaths attributable to reduced functional activity was 237. Conclusion: Functional impairment represents a risk factor for reduced survival in chronic hemodialysis patients. There is a need for early identification of patients who might benefit from interventions aimed at preventing, reversing or delaying the functional impairment.