The design of randomized clinical trials in dialysis patients

The prevalence of end-stage renal disease (ESRD) has increased dramatically during the past two decades, resulting in over 230,000 dialysis patients in the United States alone by 1998 (1). The need for therapeutic advances in dialysis therapy is underscored by the high rates of morbidity and mortality in this population. Fortunately, the progress of observational research for patients receiving dialysis therapy has been extensive, including the development and widespread utilization of national databases for ESRD. Observational studies have provided much information regarding the associations among numerous variables in dialysis populations, and have in many instances led to changes in clinical practice. However, the possibility of bias is difficult to rule out in observational studies of dialysis patients just as it is in other areas of biomedical research, and in most cases randomized clinical trials are required to definitively establish the effects of treatments on patient outcome.