Does managed care affect the supply and use of ICU services?

This paper analyzes use of hospital intensive care units (ICUs) by adult pa tients who are under age 65 and not covered by Medicaid; it allows for vari ation in indicators of the patient's condition, severity of illness, type o f admission, emergency status, and degree of constraint on the total hospit al ICU supply. We use data for Massachusetts and Florida in 1992. In neithe r state is there a significant difference in ICU admission rates between ma naged care patients and other privately insured patients. In Massachusetts, we find that the length of stay in the ICU is somewhat less for managed ca re and uninsured patients than for other privately insured patients. In bot h states, a hospital's ratio of total annual supply of ICU services to expe cted demand has a strong effect. In Massachusetts, the differences across p ayer groups in length of stay disappear for hospitals where the total ICU s upply is relatively constrained.