OBJECTIVE: To compare communication in triadic (three-person) and dyadic 
(two-person) older patient medical interviews and to determine the influence of 
the presence of a third person on the physician-older patient relationship.
DESIGN: Matched sample of dyadic and triadic audiotaped outpatient medical 
visits. Audiotapes were coded with the Multi-dimensional Interaction Analysis 
(MDIA) system.
SETTING: Hospital-based medical primary care group practice in a major urban 
teaching institution.
PARTICIPANTS: Patients 60 years and older who were making their first visit to 
study physicians. In a sample of 96 audiotaped initial medical visits, 15 
encounters involved three persons. These 15 cases were matched with 15 dyadic 
interviews for gender and race of the patient and for gender and race of the 
physician.
MAIN OUTCOME MEASURES: Content, interactional processes, and specific language 
and communication behaviors of older patients, physicians, and third persons in 
the medical encounter, as measured by the MDIA system.
RESULTS: The specific content and the quality of interactional processes of 
physicians were not affected by the presence of a third person. However, older 
patients raised fewer topics in all content areas (medical, personal habits, 
psychosocial, and physician-patient relationship) in triads than in dyads. 
Overall, patients were less responsive (ie, the quality of their questioning, 
informing, and supportiveness was poorer) on patient-raised topics in triads 
than in dyads. Patients were rated as less assertive and expressive, and there 
was less joint decision-making and shared laughter in triads than in dyads. 
Patients were frequently excluded from conversations in visits in which a third 
person was present.
CONCLUSIONS: The presence of a third person in the medical encounter changes the 
interactional dynamics of older patient medical interviews and may influence the 
development of a trusting and effective physician-older patient relationship.