An Elevated Ratio of Measured to Predicted Creatinine Production in Capd Patients is Not a Sensitive Predictor of Noncompliance with the Dialysis Prescription

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Abstract
Objective: To determine the effect a period of “intentional noncompliance” in stable continuous ambulatory peritoneal dialysis (CAPD) patients has on the ratio of measured to predicted creatinine generation. Design: Prospective study that compares baseline to noncompliant periods in individual CAPD patients. Patients: Nine chronic, stable CAPD patients. Study Design: At baseline, measured creatinine production and adequacy parameters (KT/V, creatinine clearance, lean body mass, and protein equivalent of nitrogen appearance) were calculated from 24-hour collections of dialysate and urine while patients were performing their routine dialysis prescriptions. After three days of intentional noncompliance (one less exchange/day) the patients repeated their 24-hour collections, again performing their routine number of exchanges. Measured creatinine production and adequacy parameters were again calculated. Predicted creatinine production for each patient was calculated from standard equations. All parameters at baseline were compared to corresponding parameters after intentional noncompliance. Results: In all patients, except one where there was no change, there was a statistically significant increase in not only the ratio of measured to predicted creatinine production but also all other parameters. Conclusion: As suspected by previous investigators, this study suggests that one cause of an elevated ratio of measured to predicted creatinine production may be a recent period of noncompliance with the patient's dialysis prescription. However, these data suggest that an isolated ratio of measured to predicted creatinine generation is not a sensitive predictor of noncompliance with the peritoneal dialysis prescription.