Utilization of orthopaedic services in a capitated population.

BACKGROUND The utilization rate for orthopaedic services (office visits and surgery) is not well known. The purpose of this study was to determine the utilization rates for orthopaedic office visits and surgical procedures in a large population of captured lives. METHODS The study population comprised an average of 134,902 persons per month who were enrolled under a capitated insurance plan between January 1999 and December 1999. This plan was serviced by an independent physician association of sixty-two orthopaedic surgeons who were responsible for all orthopaedic care. Data were collected prospectively and stored in a centralized database. All analyses were conducted with use of monthly averages. Poisson regression was used to compare utilization rates and to calculate odds ratios in order to determine whether the utilization rates varied by age and gender. RESULTS The highest proportions of office visits were due to fractures (21%), osteoarthritis (4%), meniscal tears (4%), and low-back pain or sciatica (4%). Knee arthroscopy (30%), foot and ankle procedures (10%), and spine procedures (9%) accounted for the highest proportions of surgical procedures. The overall utilization rates were 6.96 office visits and 1.99 surgical procedures per 1000 covered lives per month. Across all age groups, males and females did not differ with respect to the utilization rate for office visits (p = 0.42) or surgery (p = 0.09). Increased age was significantly related to increased utilization rates for office visits (p < or =0.0002) and surgery (p < or = 0.002). CONCLUSIONS These data may be used to determine the size of a capitated population that an orthopaedic practice can accommodate, to determine the number of orthopaedic providers that is needed to provide services for a capitated population, and to estimate the expenses associated with providing orthopaedic services for a capitated population in an orthopaedic practice.