Literature Review of Polypharmacy and Older Drivers: Identifying Strategies to Study Drug Usage and Driving Functioning Among Older Drivers

Traffic Safety Administration, in the interest of information exchange. The opinions, findings, and conclusions expressed in this publication are those of the author(s) and not necessarily those of the Department of Transportation or the National Highway Traffic Safety Administration. The United States Government assumes no liability for its content or use thereof. If trade or manufacturers' names or products are mentioned, it is because they are considered essential to the object of the publication and should not be construed as an endorsement. The United States Government does not endorse products or manufacturers. This research product updates the state-of-the-knowledge regarding key factors that bear on NHTSA's ability to investigate the effects of multiple medications on safe driving among older people. First, the prevalence of medication use by older people in the population, the physiological/metabolic effects of specific drugs and drug classes, and the known effects on driving ability—principally for single substances—are reviewed. Next, the strengths and weakness of various methods that may be used to learn which prescription and over-the-counter drugs are being taken by older adults are described and contrasted; a consideration of which factors most strongly affect compliance with a medication regime, and which factors influence older people' willingness to participate in studies aimed at obtaining such information, complements this discussion. The remaining section in this review examines on-road, closed course, and simulation methods that have been applied in this arena, highlighting those that appear to hold the greatest promise for evaluating the effects of drugs on driving performance while also acknowledging shortcomings and limitations that have been reported in the literature. For the most part, this review concentrates on recent (since 2001) studies accessed through print and electronic media. A bibliography containing over 200 citations is included, plus an appendix identifying potentially inappropriate medications commonly prescribed for older, community-dwelling individuals. iv FOREWORD The goal of this project is to determine if there are practical means to obtain information about drug usage by older drivers under everyday, " real-world " conditions that are valid and reliable, and to measure the consequences of multiple drug use for safe driving. Further goals are to identify candidate methodologies for carrying out such studies that are both cost-effective and likely to be successful in obtaining a diverse and representative sample of older drivers. Project tasks are geared toward accomplishing these four main objectives: 1) A literature review that updates the findings in the …