Quality of Life Over Time in Dialysis: The Netherlands Cooperative Study on the Adequacy of Dialysis, by Merkus MP, Jager KJ, Dekker FW, de Haan RJ, Boeschoten EW, Krediet RT, for the NECOSAD Study Group. Kidney Int 56:720–728, 1999

Patient survival among patients with end-stage renal disease (ESRD) has improved over recent years, with advances in renal replacement therapies, improvement in the nutritional status, and adequacy of dialysis. As patients live longer, greater attention has been focused on the quality of life on dialysis. The Institute of Medicine has recently recommended including in survival analysis some standard validated measure of the patient’s assessment of his/her health status (1). Historically the study of factors that are associated with clinical outcomes such as mortality and hospitalization has been limited to laboratory values, demographic characteristics, diagnostic categories, and dialysis parameters. However, comorbidity and health status may also be important predictors of clinical outcomes. Traditional clinical measures do not detect changes such as pain, energy, and distress. An ideal tool to detect comorbidity and heath status should be easy to administer, reliable, validated, and multidimensional. Different instruments have been used to measure quality of life (QOL) in patients with ESRD such as the KDQOL (Kidney Disease Quality of Life–Short Form), modified Karnofsky scale, Hemodialysis and Kidney Transplant Questionnaire, and SF-36 (Short Form-36). The SF-36 was constructed for use in the Medical Outcomes Study (MOS). A major goal of the MOS was to advance the state of the art of methods used for routine monitoring of patient outcomes in medical practice and clinical research. The SF-36 is a 36-question generic instrument without questions specific to ESRD or chronic renal failure (CRF). It can be completed in about 10 min and has been validated in dialysis patients (2). The questions address the patient’s ability to perform vigorous activity and the activities of daily life, and to participate in social, family, and occupational activity. The patient is asked to describe his/her mood, current and past health, and to judge his/her energy and susceptibility to illness. There are eight scales describing domains of physical function, social function, physical and emotional role function, mental health, bodily pain, vitality, and general health perception. The scales are scored on a scale of 0–100, with a higher number indicating a more favorable state. The component summary scores combine the physical and mental components of the eight scales into a physical (PCS) and mental (MCS) component summary score (3). Several studies have shown that the level of comorbidity and health status are strong predictors of subsequent mortality among incident and prevalent dialysis patients. In a study of 249 incident hemodialysis patients, McClellan et al. (4) demonstrated that a patient’s assessment of his/her ability to give social support to friends and family correlates positively with survival. DeOreo (3) found that the predictive power of self-reported health status as assessed by the SF-36 is comparable to laboratory, dialysis adequacy, and nutritional adequacy measurements in the prediction of mortality and hospitalization. Among 360 patients with a mean calculated creatinine clearance of 25 ml/min, Harris et al. (5) reported that the mean Sickness Impact Profile (SIP) score was higher than that found in patients on dialysis. Lower educational level and income, prior diagnosis of coronary artery disease and stroke, and lower serum albumin were independently associated with higher SIP scores (greater disability) (5). Studies have also compared the quality of life among different modalities of renal replacement therapy. In a study of 859 patients, Evans et al. (6) found that 79.1% of transplant recipients were able to function at nearly normal levels, as compared with between 47.5% and 59.1% patients treated with dialysis. In cross-sectional study of 33 matched pairs of chronic continuous ambulatory peritoneal dialysis (CAPD) and hemodialysis patients, Walcott and Nissenson (7) concluded that CAPD patients had a better quality of life as evidenced by higher Karnofsky scores. There are, however, few longitudinal studies examining the quality of life in ESRD. The current study by Merkus et al. explores the relationship between dialysis modality and the physical and mental QOL during the first 18 months of renal replacement therapy. It is a prospective study of patients who were participating in the Netherlands Cooperative Study on the Adequacy of Dialysis, phase I (NECOSAD-1). QOL was assessed at baseline, 6, 12, and 18 months after the initiation of dialysis with the SF-36 questionnaire. The authors divided the 228 patients into five groups: (a) patients who started and stayed on hemodialysis (HD) throughout ( n 4 84); (b) patients who started and stayed on peritoneal dialysis (PD) throughout ( n 4 55); (c) patients who switched their dialysis modality ( n 4 26); (d) patients who received a transplant ( 4 35); and (e) Address correspondence to: Brian J. G. Pereira, MD, DM, Division of Nephrology, New England Medical Center, Box 391, 750 Washington St., Boston, MA 02111. E-mail: bpereira@lifespan.org. Seminars in Dialysis—Vol 13, No 1 (January–February) 2000 pp. 54–55