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AHRQ--Agency for Healthcare Research and Quality: Advancing Excellence in Health Care
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DEcIDE Research: Improving Patient Safety and Pharmacovigilance: Methods Using Observational Data and Cohort Studies

The use of prescription drugs has grown dramatically with the advent of increased insurance coverage and greater numbers of products available. Consequently, prescription drug expenditures grew from $5.5 billion in 1970 to $179.2 billion in 2003. Growth in the number of elderly having access to drug coverage will likely increase utilization in this population.

Pharmaceuticals, like all health care interventions, offer benefits to patients but also pose risks. Clinical trials, which provide basic information on the efficacy and safety of drugs, often do not provide insight into adverse drug events (ADEs) that occur in low frequencies. Observational studies, voluntary systems for reporting adverse events, and post-marketing surveillance studies are strategies for detecting serious but rare adverse events that were undiscovered during premarketing clinical trials.

The EHC Program commissioned the RTI International DEcIDE Center to study ways to improve methods for using claims data to examine patient safety and pharmacovigilance issues. The Center developed a data analytic framework and methods for pharmacoepidemiologic research on ADEs using population-based claims and administrative data sources. They tested their framework and methods by performing pilot analyses using drugs for dementia, including Alzheimer’s disease, as the illustrative case. Because Medicare prescription drug claims are not yet available, the Center used pharmacy and medical claims and death records from the State of Utah Medicaid program.

The Center developed a database that allowed the characterization of drug exposure and evaluation of the association between drug exposure and three types of adverse drug effects (death, expected events, and idiosyncratic events).

The Center concluded that researchers could easily apply their framework for working with observational data, particularly pharmacoepidemiologic databases. Data from Medicaid, employer, insurer, and (eventually) Medicare claims can be used to examine specific drug classes and individual drugs for known and unknown ADEs. You can view a copy of the full report, "Improving Patient Safety and Pharmacovigilance: Methods Using Observational Data and Cohort Studies."