Determinants of lengths of outpatient visits in a prepaid group practice setting.

In this paper we have examined the amount of time that physicians (MDs) and physician's assistants (PAs) expended on office visits. The purpose was to determine the extent to which a series of patient-related and system-related characteristics explain variations in that time. Using regression analyses, we found most of the explained variation generally to be due to system-related characteristics. Whether the provider was an MD or PA made little difference in the length of time spent with patients. The principal determinant of provider time for unscheduled and scheduled 15-minute visits was the patient-load (number of patients per minute); for scheduled 30-minute visits, the number of associated morbidities was relatively more important than patient-load. Discriminant analysis was used to identify factors that could distinguish PA visits that require an MD input from those that do not. The data were collected from three months of observation in the department of medicine of a prepaid group practice.