Abstract
Objective:
To develop a clinical rating scale of treatment compliance for use in chronic hemodialysis patients and to test its reliability and validity.
Method:
Forty-eight of 65 patients undergoing hemodialysis treatment at the Ottawa General Hospital during June 1994 met criteria for inclusion and completed the study. Patients underwent a 10–15-minute interview, with 1 of 2 independent clinical interviewers, regarding diet, fluid intake, prescribed medication usage, smoking, alcohol or drug use, and hemodialysis treatment attendance. Following each interview, a predesigned 3-point rating scale evaluating compliance in each of 6 domains (yielding an 18-point total score) to the treatment regimen was completed. Compliance ratings on 10 patients assessed independently by both interviewers were used to establish scale reliability. Criterion validity was assessed by correlating compliance scale scores with 3 biological measures (weight gain [kg], K+ [mmol/l], and PO4 [mmol/l]).
Results:
Reliability between clinical interviewers using the overall compliance scale score (Intraclass correlation coefficient = 0.825) as well as component subscales was high (kappa values, 0.33–1.00). Biological measures of compliance correlated well with each other but poorly with clinical ratings (range 0.01–0.16). Biological measures identified compliance as being poorer than that found with the clinical interview scale.
Conclusions:
The Compliance Rating Scale (CRS) was shown to be reliable but was not well-validated against selected biological measures. Discrepancies between these 2 methods of assessing compliance may be due to differing underlying compliance constructs or patient or interviewer biases. The CRS has value as a patient education tool in that it can be used to instruct patients regarding the benefits of adhering to the treatment regimen.