Peritoneal Dialysis Patients with Critical Illness: Insurance May Be Hard to Come By

Despite significant advances in medical care and improved outcomes for patients in the intensive care unit (ICU), the mortality rate for such patients remains high, reflecting the severity of their illnesses. That fact is highlighted by a recent randomized controlled trial in ICU patients, which found an ICU mortality rate of 15.7% and an in-hospital mortality rate of 23.3% (1). Further, the longer-term outcome of patients who survive an ICU stay is also poor, with a 1-year mortality rate of 26% – 63% (2). Studies on outcomes in end-stage renal disease (ESRD) patients admitted to the ICU, particularly those on peritoneal dialysis (PD), are limited. A search of EMBASE and MEDLINE to identify articles addressing the prognosis of ESRD patients in an ICU setting—including a search of references from relevant articles—identified twenty publications describing cohorts ranging in size from 7 patients (3) to 3420 patients (4). Only two of the studies provided PD-specific data (5,6). Senthuran et al. (5) examined outcomes in chronic dialysis patients at a single center in Australia, identifying 70 ESRD patients admitted to their ICU or a high-dependency unit between 2001 and 2006. Of those 70 patients, 16 (23%) were on PD at the time of admission, and only 3 continued to receive PD during their admission. In-hospital mortality for all ESRD patients was 46%. This study was limited by its lack of a comparison group [that is, a non-ESRD or acute kidney injury (AKI) group] and the retrospective nature of the study. Impact of dialysis modality on survival was not described. Manhes and colleagues carried out a prospective observational study of a cohort of ESRD patients admitted to a single-center ICU (6). A nonsignificant increase in ICU mortality was seen in PD patients (7 of 16, 43.8%) compared with hemodialysis (HD) patients (19 of 57, 33.3%). The largest study in ESRD patients used a highquality database in the United Kingdom to examine outcomes in a cohort of 3420 dialysis patients admitted to the ICU between 1995 and 2004 (4). Mortality in the ICU was 26% and in-hospital mortality was 45.3% for those patients, compared with 20.8% and 31.2% respectively in the non-dialysis population. Unfortunately, despite the large size of the study, no information was provided about the proportion of patients on PD and on HD, or about any differences in outcome between PD and HD patients. The study by Khan and colleagues in this issue of Peritoneal Dialysis International informs the incidence and outcomes of PD patients admitted to the ICU with one of the largest studies concentrating on PD patients. Of 990 adult incident PD patients, 90 who were admitted to the ICU in the province of Manitoba in Canada were followed for up to 6 years. The study cohort was created by linking the Manitoba PD database to the Manitoba ICU database. The primary outcome in the study was death or technique failure (TF). Using a Cox proportional hazards model, 29 distinct predictor variables were examined for their association with the primary outcome, including demographics, comorbidities, and PD characteristics (transport status, renal and peritoneal clearance, and technique, among others) at the time of PD initiation. During the ICU admission, only 10% of patients died compared with 13.0% of HD patients, as described in a previous paper by the same group. Notably, in the latter manuscript, the authors described the PD mortality as 14.7% because of the inclusion of 5 additional patients that were excluded from the present study as a result of incomplete information (7). That same publication (7) revealed that, compared with PD patients and nonESRD patients respectively, patients on HD were more frequently admitted with cardiac arrest (11.3% vs 4.2% and 5.7%) and less frequently after elective surgery (6.5% vs 8.4% and 19.0%). Perhaps the most important finding of the study was the high rate of TF for PD patients. At 1 month, more than 25% of the patients still alive had been transferred to HD; that proportion gradually rose thereafter. The specific indications for modality change were not available, but certainly included peritonitis and intra-abdominal sepsis, as well as more subjective indications such as inadequate dialysis. One could speculate that the practice, based on conventional wisdom and some evidence (8) of using HD rather than PD for AKI in the ICU would have influenced physicians to transfer PD patients to HD in an effort to “maximize” medical therapy in the setting of critical illness. The reasons for ongoing TF after the ICU admission are also unclear, but the post-admission failures may simply reflect the basal rate of TF inherent