Quality of life at the initiation of maintenance dialysis treatment - a comparison between the SF-36 and the KDQ questionnaires

Objective: To evaluate the construct validity of the Medical Outcomes Study Questionnaire 36-Item Short Form Health Survey (SF-36) and to assess the quality of life of patients with end-stage renal disease (ESRD) at the initiation of maintenance dialysis treatment. Methods: Cross-sectional study. Setting: Eight ambulatory dialysis units in Sao Paulo city, Brazil. Study participants: Eighty ESRD patients at the initiation of chronic dialysis program and consecutively accepted for treatment in selected units in 1998. Main outcome measures: Quality of life as measured by the dimensions of the SF-36 questionnaire. The 'Kidney Disease Questionnaire' was used in a subgroup of patients to evaluate the validity of the SF-36. Results: Median (range) scores of the SF-36 dimensions (ranging from 0 to 100, higher scores representing better quality of life) were: Physical Function 70 (0-100), Role Limitations due to Physical Problems 25 (0-100), Bodily Pain 62 (0-100), General Health 57 (5-100), Vitality 55 (10-100), Social Function 63 (0-100), Role Limitations due to Emotional Problems 34 (0-100) and Mental Health 68 (0-100). SF-36 dimensions correlated significantly with those of the 'Kidney Disease Questionnaire' (correlation coefficients ranging from 0.23 to 0.68). Conclusions: The SF-36 was shown to have construct validity when used in patients with ESRD in Brazil. The quality of life of ESRD patients is impaired at the initiation of dialysis treatment and this was clearly evidenced in the Role Limitations due to Physical Function and Emotional Function items. Greater attention should be given to interventions that could improve the quality of life parameters at the initiation of dialysis treatment.