Led by Krista Huybrechts, Ph.D., an instructor in medicine in the Division of Pharmacoepidemiology and Pharmacoeconomics at the hospital, the team of researchers performed a population-based cohort study with linked data from Medicaid, Medicare, the Minimum Data Set, the National Death Index, and a national assessment of nursing-home quality. The participants were 75,445 new users of antipsychotic drugs (haloperidol, aripiprazole, olanzapine, quetiapine, risperidone, and ziprasidone; other antipsychotics were excluded because they were used by too few patients). All participants were aged 65 or older, eligible for Medicaid, and living in a nursing home during 2001 to 2005.