Physical functioning and mortality in very old patients on dialysis.

BACKGROUND:Old patients with end-stage kidney disease (ESKD) represent an increasing segment of the ESKD population maintained on chronic dialysis treatment. Quality of life (QoL) is notoriously poor in ESKD but relationship between QoL and mortality has not been investigated in the old dialysis population. The objective of this study is to investigate the relationship between QoL and mortality in the old dialysis population. METHODS:Quality of Life was measured by the Rand- QoL Short Form 36 questionnaires in a multicentre, perspective cohort study including 253 very old patients (age ≥ 75 years) on chronic dialysis. Prognostic power of QoL was assessed applying C-statistics. RESULTS:In multivariate statistical models including a series of demographic and clinical variable physical function and general health maintained an independent relationship with survival (P ≤ 0.01). In analyses testing the prognostic value of these two SF36 components physical functioning was the component adding the highest explanatory power to standard demographic and clinical risk factors (+5.7%). Furthermore, the same parameter increased by 4.5% the discriminant power by the Harrell's C Index, improved risk reclassification by the 20% (P = 0.003) and model calibration by the 83%. CONCLUSIONS:In the very old dialysis population the physical function component of the SF36 is the QoL component holding the highest predictive power for mortality among the eight components of this instrument. As the discrimination power and risk reclassification ability by physical functioning is of degree relevant for clinical practice, such a measure has potential for refining prognosis and informing exercise programs in this population.