Peritonitis among CAPD Patients: Host, Agent and/or Environment?

At the Omaha Veteran's Administration Medical Center, Omaha, Nebraska, USA the authors used the classic epidemiological model based on the interaction between host, agent and environment, and a historical-prospective design to study the risk factors for peritonitis among all continuous ambulatory peritoneal dialysis (CAPD) patients. Data were abstracted from the medical records of the patients and from questionnaires completed by the nurses who had cared for the entire population since the inception of CAPD at this hospital. Using the Cox proportional hazard regression model, they analyzed variables considered to be associated with the host, agent and environment. This survival analysis demonstrated that, when other host, agent and environmental factors are controlled, age (younger patients), low patient motivation and minimal social support are significant risk factors for peritonitis. The literature suggests that the study of and the attempts to control peritonitis among continuous ambulatory peritoneal dialysis (CAPD) patients has not considered the host, agent and environment as a unit, but rather have centered on one element at a time. Most investigators focus upon the host as the contributing factor (1–4) and view the infectious agent as ubiquitous (5, 6). Others consider as primary the social and/or psychological environment of the host (7–9). None have undertaken an investigation which has studied all three aspects of the infectious disease model so that risk can be estimated while controlling for confounding factors.