Postdischarge utilization of medical services by high-risk infants: experience in a large managed care organization.

BACKGROUND Infants discharged from intensive care nurseries are a high-risk infant (HRI) population known to have increased utilization of medical services. Most studies tracking HRIs have been based on data obtained from individual chart review or direct patient contact. Given the high cost of such studies, it is desirable to develop less costly methods to track such infants. OBJECTIVES Our goals were: (1) to identify an HRI cohort at two neonatal intensive care units; (2) to identify a control group of infants not meeting HRI criteria; and (3) to measure outpatient and inpatient utilization in both controls using computerized files in a managed care organization. METHODS Using California Children's Services criteria as our starting point, we established an HRI definition. From a 1-year birth cohort of 7579 infants at two facilities, we identified 250 infants meeting the HRI definition at two neonatal intensive care units during 1990. We then matched the HRIs with a cohort of 896 randomly selected control newborns (those not meeting the HRI definition). Using organizational computer files and state of California death certificate tapes, we followed these infants until February 28, 1992. We measured the number of hospitalizations, total number of hospital days, and total number of outpatient visits and expressed these outcomes as rates per person-year. We also measured postdischarge mortality. RESULTS The rate of hospitalization in the HRI group was 6.07 times (95% confidence interval [CI], 4.74-7.77) that in the control group. The utilization of hospital days by the HRI population (hospital days per 1000 person-months) was 13.24 times higher (95% CI, 11.00-16.04). The outpatient visit rate was 1.40 times higher (95% CI, 1.36-1.45) in the HRI population. CONCLUSION Our findings in a large managed care organization corroborate previous studies showing that hospitalization rates are significantly higher among HRIs. In our study population, outpatient utilization was significantly higher as well. Our study also demonstrates the feasibility of using computerized files to study outcomes in selected pediatric populations. These methods can be used for epidemiologic studies, interventional trials, and planning for resource allocation.