The Dialysis Outcomes and Practice Patterns Study (DOPPS): An international hemodialysis study

The Dialysis Outcomes and Practice Patterns Study (DOPPS) is a prospective, longitudinal, observational study of hemodialysis patients and facilities in seven countries with large populations of dialysis patients: France, Germany, Italy, Japan, Spain, the United Kingdom, and the United States. This paper describes the study design, analytic methods, and preliminary findings of the DOPPS. The goal of the study is to determine which practice patterns are associated with the best patient outcomes, with adjustment for a wide range of patient case-mix characteristics. The primary outcomes of interest are mortality, hospitalization, quality of life, and vascular access events. The facility sample from the. seven countries consists of 327 hemodialysis centers in which 24,392 patients were treated when the study began. A random sample of 10,332 patients has been selected thus far for more detailed longitudinal data collection. Departing patients are replaced during the study using random selection. A study coordinator at each dialysis facility collects baseline and longitudinal patient data. Patients are asked to complete a questionnaire that addresses quality of life on a yearly basis. The medical director and nurse manager in each facility complete a practice pattern questionnaire. Preliminary data are presented concerning the sample facilities and the census of patients treated in each facility at the start of the study. Dialysis facilities vary widely in size and type (freestanding vs, institutionally-based) across countries. Variation is also seen in patient age, sex distribution, and diabetes mellitus as the attributed cause of endstage renal disease (ESRD). At this early phase, the DOPPS has proved to be technically feasible and has revealed basic differences in hemodialysis facilities and patients across the seven participating countries.