How expensive are unlimited substance abuse benefits under managed care?

Substance abuse (SA) care has been excluded from recent federal and state l egislation mandating equal benefits for mental health and medical care ("pa rity"), largely because of cost concerns. This article studies how many pat ients are affected by SA coverage limits and the likely implications of lim its on insurance payments, using 1996-97 claims from 25 managed care plans with unlimited SA benefits. Changing even stringent limits on annual SA ben efits has a small absolute effect on overall insurance costs under managed care, evert though a large percentage of SA patients are affected. Removing an annual limit of $10,000 per year on SA care is estimated to increase in surance payments by about 6 cents per member per year, removing a limit of $1,000 increases payments by about $3.40. As long as care is comprehensivel y managed, "parity" for SA in employer-sponsored health plans is nor very c ostly.