Mental Health and Substance Abuse Prescription Drug Spending Trends in Medicaid and Privately Insured Populations

We describe the different factors accounting for high increases in mental health and substance abuse prescription drug spending during the late 1990's in publicly and privately insured populations. Prescription drug claims data were used from four states' Medicaid populations (one million enrollees per year), and a national pharmacy benefits manager (1.4 million individuals per year). Trends in drug spending growth were decomposed to distinguish the contributions of growth in utilization (users per enrollee, and claims per user), and cost per claim. Results: Drug spending increased 30 percent per year in the late 1990's for public and private populations. The mix of MHSA medications differed considerably between public and private sectors. In the public sector, three-fourths of drug spending growth was due to an increase in the cost of a prescription, with most of the remaining growth (20%) due to more covered individuals using MHSA medications and more prescriptions per user; atypical antipsychotics were the drug class that contributed most to spending growth, at 44%. In the private sector, spending growth was driven by increased cost of a prescription (41%), increased prescriptions per user (27%), and increased number of users (23%); newer antidepressants contributing most to spending growth. Between 1996 and 2000, more costly prescriptions, more users, and more prescription per user were the primary contributors to growth in MHSA drug spending. The increasing cost per prescription reflects the introduction of newer medications which are purported to have fewer side effects than their older counterparts.