The specific objective of the project is to establish an initial measure set that will encompass surveillance for process measures such as misuse, over- and under-use of prescription medications based on dispensing claims in outpatient, inpatient, nursing home, and transitional settings such as rehabilitation centers. The process measures will be developed using an evidence-based approach, i.e., by scanning the literature for published papers that have addressed these issues. We will consult with advisors to determine the integrity of the initial measure set selected and determine which indicators will be the focus of the validation phase. We will assess the validity of the measure set using state Medicaid data. The tasks for this project will be described in more detail below. The investigators will conduct a brief but focused literature scan to identify publications that have dealt with the conceptualization of medication safety using administrative databases as well as studies of specific misuse and underuse of medications. Our literature search will focus on Medical Subject Headings and text word searches as appropriate. A preliminary search identified over 600 articles using drug utilization review and health maintenance organization, insurance claim review, or health maintenance organization. Once we have assembled the literature, have identified examples of process measures (misuse, overuse, and underuse of medications) and have developed an initial measure set, we will share this information with collaborators and outside project advisors. We will seek constructive criticism on our conceptualization of the measures and the possible usage situations to evaluate based on the typical structure of Medicare, Medicaid, SCHIP, and managed care administrative claims data. We will test the process measures using data from state Medicaid claims files. We will select a particular clinical situation for evaluation as informed by the literature scan and the suggestions of our collaborators and advisors. Investigators will begin with evidence-based clinical guidelines for the treatment of patients with the clinical issue being studied by reviewing websites and journals from the appropriate clinical society, in addition to the National Guideline Clearinghouse and other relevant sources. Based on the literature, we will develop algorithms for identifying usage patterns and their appropriateness for the condition under study along with highly prevalent co-morbidities. We will conduct sensitivity analyses to refine the algorithms and will characterize the patients in each use pattern after sensitivity analyses, by age and sex. Our final report will include a description of the literature scan and the evidence tables; processes for developing the algorithm(s); will discuss any problems encountered; and will provide an assessment of the algorithms’ overall robustness.