Measuring the impact of patient counseling in the outpatient pharmacy setting: the research design of the Kaiser permanente/USC patient consultation study

This article describes the research methods used to measure the impact of three alternative models of patient counseling in the outpatient pharmacy setting. The study was conducted in pharmacies operated by the Southern California region Kaiser Permanente Medical Care Program. Both random assignment and large-scale geographic area research designs were used. The presentation of the research design includes discussions of data collection and patient sampling methods; the measurement of patient outcomes, including measures of health care costs and utilization, patient functional status, and quality of life. Demographic data are presented for the study population, including an analysis of potential biased selection of patients electing to participate in random assignment. Data are also presented documenting potential selection bias across geographically determined treatment groups in the geographic area design arm. Finally, the article presents the analysis plan for the study and discusses study limitations.