Objective: To determine whether the protective effects of seat belt use on acute injury are followed by corresponding reductions in outpatient health care utilization.
Design: Retrospective cohort analysis.
Setting: Northern California Region Kaiser Health Plan hospitals and medical offices.
Patients: All Kaiser Foundation Health Plan members injured in motor vehicle crashes in Santa Clara County during one year (total number of patients = 246).
Measurements and main results: 54% of the study participants had been wearing seat belts at the time of injury, and 46% had not been. The belted patients had fewer head injuries (30% vs 50%, p < 0.05), better mean Injury Severity Scale scores (4.3 vs 7.4, p < 0.05), and smaller mean hospital charges ($8,580 vs $16,209, p < 0.05). However, the effects of injury did not end upon discharge from the trauma center; the patients averaged about eight outpatient visits during the subsequent year, a rate almost double their prior use. In contrast to inpatient measures of utilization, the patients who had been wearing seat belts at the time of injury had more outpatient visits during the year after injury than had their unbelted counterparts (9.0 vs 7.1, p < 0.05). This discrepancy was not explained by differences in amounts of utilization during the year before injury, which were similar in the two groups (4.4 vs 4.8, p = NS). Overall, general internists provided the most follow-up care and accounted for the largest discrepancy in utilization between the belted and unbelted patients.
Conclusions: Seat belt use does not result in lower utilization of follow-up outpatient services in the year following injury. However, the beneficial effects on acute care utilization more than offset the marginal effects on subsequent medical services utilization.