The Nutritional and Inflammatory Evaluation in Dialysis patients (NIED) study: Overview of the NIED study and the role of dietitians

The absolute majority of maintenance hemodialysis (MHD) patients die within 5 years of commencing dialysis treatment, mostly because of cardiovascular (CV) disease. The strongest and most common correlates of death in MHD patients are not conventional CV risk factors, but markers of protein-energy malnutrition and inflammation, together also known as malnutrition-inflammation complex syndrome (MICS). Paradoxically, classic risk factors such as obesity and hypercholesterolemia are associated with better survival in MHD patients. It has been hypothesized that this so-called reverse epidemiology is caused by the overwhelming prevalence and dominating effect of MICS in MHD patients. Hence, the key to improving survival and quality of life in MHD patients may be a better understanding of MICS and its interactions with CV disease and outcome. The Nutritional and Inflammatory Evaluation in Dialysis Patients (NIED) study is a longitudinal multicenter cohort study that aims to examine these hypotheses. At any given semiannual round, approximately 360 MHD patients from 8 DaVita dialysis facilities in the Los Angeles area are examined; 900 MHD patients will be cumulatively studied by the end of this 5-year prospective study (October 2001 to September 2006). Repeated measures of markers of nutritional status and inflammation are performed by 10 to 12 dialysis unit dietitians while patients attend their routine HD treatment in their dialysis facilities. All-cause and CV mortality, hospitalization, and quality of life are studied as outcome measures. The collaborating dietitians are the main evaluators and play crucial roles in all aspects of the study. This article reviews the design and infrastructure of the NIED study and reports preliminary findings of the first 12 to 30 months of the study.