A pilot study to test multiple medication usage and driving functioning

Abstract

John Siegler was the NHTSA Task Order Manager on this project. AbstractThe use of medications and multiple medications becomes more prevalent with increasing age. This pilot study explored the relationship between polypharmacy and driving functioning through separate but related research activities. A patient-level administrative claims database containing prescription information as well as E-codes identifying the incidence of motor vehicle injuries was mined, yielding combinations of drugs that became inclusion criteria in a following field study of driver performance among 44 older adults (range: 57 to 89; mean: 79). Driving performance evaluations by an OT/CDRS, a brake response time measure, and functional screening measures were conducted for the study sample, whose drug profiles were documented through a "brown bag" review by a licensed pharmacist. The relationship between medication usage and each of these outcome measures was examined in descriptive data summaries and regression analyses. The driving evaluations were carried out in a dual-brake vehicle also equipped with speed sensor (OBD-2), GPS logger, and two miniature video cameras (driver's face and forward road views) plus digital recorder. A subsample allowed the same instrumentation package to be installed in their private cars for a week of independent driving; this supported an analysis of within-subject variability in driving behavior during a formal driving evaluation versus independent driving.Additional project activities included a current (to October 2007) review of the literature on the prevalence of prescription medications and effects on driving of specific drugs/drug classes. The feasibility of conducting future studies using large, administrative claims databases was critically examined, with an overview of candidates and evaluation of their suitability for NHTSA research. This report concludes with a discussion of project findings and recommendations for future research. Key WordsDrugs, medications, driver impairing, driver function, safety, performance, database analysis, instrumented vehicle, video analysis, behavioral analysis. Distribution StatementThis report is free of charge from the NHTSA Web site at www.nhtsa. EXECUTIVE SUMMARYThe number of older licensed drivers in the United States is growing at a rate faster than the overall population. As people age, they are more likely to take one or more potentially driver-impairing (PDI) medications. TransAnalytics, LLC, completed a pilot study to gain a better understanding of the safety impact on older drivers of taking multiple PDI medications, providing an update on the prevalence of prescription medications in the older population, and the effects on driving of specific drugs/drug classes. Research activities included a literature review; a data mining exercise; the prioritization of other databases for future data mining; and a field study including on-road evaluations of older drivers who take multiple PDI medications by an occupational therapist, and associated instrum...