Measurement of Continuous Ambulatory Peritoneal Dialysis Prescription Adherence Using a Novel Approach

Abstract

Objective The purpose of the study was to test a novel approach to monitoring the adherence of continuous ambulatory peritoneal dialysis (CAPD) patients to their dialysis prescription. Design A descriptive observational study was done in which exchange behaviors were monitored over a 2-week period of time. Setting Patients were recruited from an outpatient dialysis center. Participants A convenience sample of patients undergoing CAPD at Piedmont Dialysis Center in Winston–Salem, North Carolina was recruited for the study. Of 31 CAPD patients, 20 (64.5%) agreed to participate. Measures Adherence of CAPD patients to their dialysis prescription was monitored using daily logs and an electronic monitoring device (the Medication Event Monitoring System, or MEMS; APREX, Menlo Park, California, U.S.A.). Patients recorded in their logs their exchange activities during the 2-week observation period. Concurrently, patients were instructed to deposit the pull tab from their dialysate bag into a MEMS bottle immediately after performing each exchange. The MEMS bottle was closed with a cap containing a computer chip that recorded the date and time each time the bottle was opened. Results One individual's MEMS device malfunctioned and thus the data presented in this report are based upon the remaining 19 patients. A significant discrepancy was found between log data and MEMS data, with MEMS data indicating a greater number and percentage of missed exchanges. MEMS data indicated that some patients concentrated their exchange activities during the day, with shortened dwell times between exchanges. Three indices were developed for this study: a measure of the average time spent in noncompliance, and indices of consistency in the timing of exchanges within and between days. Patients who were defined as consistent had lower scores on the noncompliance index compared to patients defined as inconsistent ( p = 0.015). Conclusions This study describes a methodology that may be useful in assessing adherence to the peritoneal dialysis regimen. Of particular significance is the ability to assess the timing of exchanges over the course of a day. Clinical implications are limited due to issues of data reliability and validity, the short-term nature of the study, the small sample, and the fact that clinical outcomes were not considered in this methodology study. Additional research is needed to further develop this data-collection approach.