What determines the clinical outcomes of patients with end stage renal failure on long-term peritoneal dialysis

Abstract

The prevalence of end stage renal disease (ESRD) is increasing even with an improvement in management of diabetes, hypertension and glomerulonephritis in the past decades. This phenomenon is plausibly due to a high prevalence of diabetic mellitus (DM) and increased aging in the general population. Nowadays, more than forty percent of ESRD patients on dialysis have DM as the primary disease. For patients with ESRD, peritoneal dialysis (PD), haemodialysis and RTx are the choices of replacement therapy. Although transplantation is the most desirable modality, the waiting time may take decades because of shortage of organ donors.

In Hong Kong, about 80% of ESRD patients receive PD as the dialysis treatment. The peritoneum acts as a dialysis membrane for both solute clearance and fluid removal. Inevitably, PD treatment carries some adverse effects on patient survival and various reasons may account for the associated morbidity and treatment failure. PD related peritonitis and failure of fluid removal due to ultrafiltration (UF) failure are the most common causes for discontinuation of PD treatment. Both peritonitis and UF failure impair solutes exchange and cause inadequate dialysis.

The aims of this thesis are to study the risk factors for 1) reduced patient survival, 2) developing peritonitis, and 3) having UF failure during PD treatment. Any improvement in management of these adverse factors will definitely prolong the longevity of PD treatment and patient survival.

Our prospective multi-centre study of patients on long-term PD has shown that patients had 2- and 4-year survival rates at 94.0% and 74.8%, respectively. The risk factors for reduced patient survival included high body mass index (BMI), low urine volume and cardiovascular disease (CVD). In another study, we found that patients with chronic inflammation after peritonitis associated with a high mortality. This happened even if the patients were in remission of the peritonitis. One possible reason was patients had lost their lean body mass and the nutritional markers was decreased significantly when they developed peritonitis.

We also studied the predisposing factors for peritonitis and UF failure. Impairment of cognitive function and hand function were found to be associated with risk of touch contamination and peritonitis when they performed PD exchange. A full assessment of mental and hand function before training patients to self-perform PD exchange may reduce the incidence of peritonitis. Patients may develop UF failure after long-term PD treatment due to morphological changes of the peritoneal membrane (PM). Patients with DM and higher glucose exposure in the first year of PD treatment were found to have a risk for UF failure. For patients developed acute UF failure, apart from fluid compliance, retroperitoneal leakage was found to be the cause for this problem.

In conclusion, the findings of the studies in this thesis help to identify the risk factors for mortality and complications of PD treatment. It is conceivable that patient survival and longevity of PD treatment may improve if these risks factors can be corrected or avoided.