Time-dependent associations between total sodium removal and mortality in patients on peritoneal dialysis

PURPOSE

To determine if the time-dependent association between total sodium removal and mortality in patients on continuous ambulatory peritoneal dialysis (CAPD) is confounded by markers of diet and nutrition.

METHODS

The study enrolled 305 incident patients who started CAPD between July 2002 and February 2007. All patients were followed until death or censoring in February 2008. Demographics, blood pressure, and markers of volume and inflammation were collected at baseline. Biochemistry, fluid and solute removal, and diet and nutrition parameters were collected quarterly and thus calculated as time-averaged values.

RESULTS

Mean age of the study patients was 59.4 years, 42.3% were men, and 40.3% had diabetes. During the 31.4-month follow-up, 74 patients died. The time-averaged daily total sodium removal (TSR) in the overall cohort was 2.67 g (range: 2.02 g-3.47 g). Participants with a high time-averaged TSR tended to experience higher fluid, sodium, urea, and creatinine removal, mainly as a result of better residual renal function (RRF). They also had a higher nutrient intake and a higher lean body mass. Time-dependent TSR was an independent predictor of death, including when adjusted for age, Charlson index, time-dependent hemoglobin, RRF, and peritoneal transport rate (hazard ratio: 0.84; 95% confidence interval: 0.70 to 1.00; p=0.05), but the predictive effect disappeared in multivariate models after further individual adjustment for time-dependent total energy intake, total protein intake, serum albumin, and lean body mass. By contrast, the predictive effect did not disappear if the only adjustment was for time-dependent RRF.

CONCLUSIONS

The time-dependent association between TSR and mortality in patients on peritoneal dialysis can be largely explained by diet and nutrition parameters.

Peritoneal Dialysis in Anuric Patients: Old Problems and New Perspectives

Anuric patients are often excluded from peritoneal dialysis (PD) because of the fear that PD is inadequate to treat this higher-risk group of patients. However, advances in PD knowledge and technique allow better and adjusted treatments. There is now clinical evidence that anuric patients can be successfully treated with PD, while new solutions promise to mitigate some limitations of automated PD, such as sodium and fluid removal and preservation of membrane function.