Accelerated or out of control: the final months on dialysis

Mortality rates in dialysis patients are as high as 20% per year. Recent epidemiologic evidence indicates common patterns in biological and clinical indicators before death. Blood pressure, serum albumin levels, C-reactive protein, body weight, and other indicators change, at a population level, at an accelerated rate of change months before death. The escalation of inflammation (as indicated by a surge of C-reactive protein) appears to be a central event. The etiology of blood pressure decline before death is unclear. Although progressive heart failure is well documented in dialysis patients and a potential cause for blood pressure decline, adaptive functional changes need to be considered. In the general population, an inverse relationship between body weight and blood pressure is well described, and it is reasonable to hypothesize that the blood pressure decline before death is an adaptive response to a decline in body weight. Comparable trajectories of biological indicators before death are also documented in nonrenal illnesses, such as chronic obstructive pulmonary disease and certain malignancies. Descriptive analysis of clinical and laboratory variables clearly indicates an accelerated time course in most instances, pointing toward a loss of regulatory functions in a number of physiological subsystems. One can think of 2 reasons for that, (a) important control loops are damaged by the long-term effects of the disease, so that the system cannot react in a proper fashion to perturbations; and (b) the regulatory functions are still properly working, but are confronted with situations, which were of no relevance in the evolution of the system. More extensive research into qualitative and quantitative aspects of physiological control mechanisms is required to answer the question if the observed changes before death are indicative of failed control mechanisms and/or adaptive processes.