3 CONSECUTIVE DAY COLLECTION OF DIALYSATE AND URINE TO IDENTIFY NONCOMPLIANCE IN CAPD PATIENTS

Background. Compliance with dialysis prescription is an important dete rminant of adequacy of CAPD. Several reports have suggested that non-c ompliance may be detected by a high creatinine excretion ratio (CrEx r atio = measured creatinine excretion in a 24-h collection of urine and dialysate/predicted creatinine excretion) and that it occurs in a sub stantial proportion of patients. However the validity of this screenin g method to identify non-compliant patients has been questioned, mostl y because of the interindividual variation of creatinine excretion in a CAPD population. Methods. Whenever possible we performed a 3-day col lection of dialysate and urine in all patients on our CAPD programme, and calculated the daily CrEx ratio. Non-compliance was defined as a p rogressive and greater than 7.5% decrease of the CrEx ratio associated with a more than 7.5% decrease of serum creatinine during the test. R esults. Among 19 patients only one (5%) fullfilled both criteria for n on-compliance and the subsequent interview revealed that he was truly non-compliant. The other patient admitting non-compliance had a signif icant decrease of CrEx ratio but showed only a slight decrease of seru m creatinine. Conclusions. Our preliminary results suggest that this 3 -day collection test, unlike previous procedures, identifies non-compl iance with a good specificity. However, it may not be sensitive enough to detect a low level of non-compliance and has the disadvantage of b eing quite cumbersome. It may require further refinements to be clinic ally useful.