How many patients are required to provide a high level of reliability in the Japanese version of the CARE Measure? A secondary analysis

BACKGROUND: Empathy is widely regarded as being key to effective consultation in general practice. The Consultation and Relational Empathy (CARE) Measure is a widely used and well-validated patient-rated measure in English. A Japanese version of the CARE Measure has undergone preliminary validation, but its ability to differentiate between individual doctors has not been established. The current study sought to investigate the reliability of the Japanese version of the CARE Measure in terms of discrimination between doctors. METHODS: We conducted secondary analysis of a dataset involving 252 patients assessed by nine attending General Practitioners. The intra-cluster correlation coefficient was evaluated as an index of the reliability of the Japanese version of the CARE Measure for discriminating between doctors. With a criterion of intra-cluster correlation coefficient = 0.8, we conducted a decision (D) study using generalizability theory to determine the required number of patients for reliable CARE Measure estimates. RESULTS: The ability of the CARE Measure to discriminate between doctors increased with the number of patients assessed per doctor. A sample size of 38 or more patients provided an average intra-cluster correlation coefficient of 0.8. CONCLUSIONS: The Japanese CARE Measure appears to reliably discriminate between doctors with a feasible number of patient-ratings per doctor. Further studies involving larger numbers of doctors with a multicenter analysis are required to confirm the results of the current study, which was conducted at a single institution.