Nonmedical influences on medical decision making: an experimental technique using videotapes, factorial design, and survey sampling

To study nonmedical influences on the doctor-patient interaction. A technique using simulated patients and "real" doctors is described. A random sample of physicians, stratified on such characteristics as demographics, specialty, or experience, and selected from commercial and professional listings. A medical appointment is depicted on videotape by professional actors. The patient's presenting complaint (e.g., chest pain) allows a range of valid interpretation. Several alternative versions are taped, featuring the same script with patient-actors of different age, sex, race, or other characteristics. Fractional factorial design is used to select a balanced subset of patient characteristics, reducing costs without biasing the outcome. Each physician is shown one version of the videotape appointment and is asked to describe how he or she would diagnose or treat such a patient. Two studies using this technique have been completed to date, one involving chest pain and dyspnea and the other involving breast cancer. The factorial design provided sufficient power, despite limited sample size, to demonstrate with statistical significance various influences of the experimental and stratification variables, including the patient's gender and age and the physician's experience. Persistent recruitment produced a high response rate, minimizing selection bias and enhancing validity. These techniques permit us to determine, with a degree of control unattainable in observational studies, whether medical decisions as described by actual physicians and drawn from a demographic or professional group of interest, are influenced by a prescribed set of nonmedical factors.