[Factors associated with health related quality of life in patients undergoing renal replacement therapy]

The aim of this study was to investigate the sociodemographic and clinical variables which influence health-relate quality of life (HRQOL) of patients on renal replacement therapy (RRT). A cross-sectional study was carried out with a sample including all patients on hemodialysis (n = 170) and transplant patients (n = 210) of our region. The HRQOL assessment instruments used in this study were: the Spanish versions of the sickness impact profile (SIP) and the SF-36 health survey (SF-36). Sociodemographic and clinical data (including age at start of RRT, age at the interview, gender, hospital, socioeconomic level, educational level, living conditions, inclusion in transplant waiting list, renal disease diagnosis, time in any RRT, hemoglobin, hematocrit, serum urea, creatinine, proteins and albumin, hospital admissions and length of hospital stay during last year), a comorbidity index and the Karnofsky performance scale score step. To investigate which studied variables had independent influence over the HRQOL measures, logistic regression method was employed in the case of the SF-36, and multiple regression, in the case of the SIP. A model was adjusted step by step in each RRT method (hemodialysis and transplantation) for each dimension of the PCE (physical dimension, psychosocial dimension and total score), and for each component summary score of the SF-36 (physical and mental component summary). In patients on hemodialysis, variables associated with better HRQOL were: higher age, female gender, higher educational level, and better functional status; and variables associated with worse HRQOL were: higher number of hospital admissions, and higher comorbidity index. In transplant patients, variables associated with better HRQOL were: higher age and higher functional status; and variables associated with worse HRQOL were: longer time on dialysis before transplant, longer time with functioning transplant, and higher comorbidity index. Despite the independent influence on the HRQOL demonstrated for some of the studied variables, it seems that HRQOL assessment instruments scores may mainly depend on other non-studied variables, and it may be that these instruments evaluate other aspects of the patients which have not been taken into account until now.