Overall, the physical conditioning intervention was acceptable, safe, and effective in enhancing driving performance relative to controls. There was a least squares mean difference of 2.43 points at 3 months on a 72-point scale of driving performance, comparing intervention to control participants. The net effect was that the intervention group maintained their driving performance, while controls declined over the 3-month intervention period. This benefit was most noticeable among drivers with lower baseline driving scores. The exercise regimen was well tolerated with no injuries reported, and few complaints of pain.
The strengths of this study include its design, a randomized controlled trial of an exercise intervention with blinded intervention arm assignment and end point assessment. Also, participants were volunteers drawn from clinic sites and the community at large, but were not referred because of suspicion of driving difficulties. Two-thirds of participants were enrolled from clinical sites and are likely to be reflective of patients attending a doctor’s visit.
Several study features and findings suggest broad potential applicability. The intervention exercise regimen was designed to be safe, able to be performed in the home, and completed in 15 minutes or less and, thus, is applicable to an aging population with arthritis and other causes of physical impairment. Further analyses will determine if the protocol can be streamlined to enhance efficiency.
The trend toward fewer falls among intervention participants, while not statistically significant, is consistent with recent reports suggesting possible common risk factors for falls and crashes.32,38
If this association is confirmed in a cohort powered to detect a difference in falls, then the intervention’s potential benefits for driving performance and fall risk would make its clinical relevance and applicability even broader.
There were several limitations of the study. First, although 2.43 points is a meaningful difference from a driving evaluator’s perspective as established before the study, the clinical relevance of such a difference is unknown. Whether this difference translates to a difference in crash occurrence or driving patterns over time is uncertain. Data from a similar cohort of 552 drivers we have followed prospectively indicates that a one-point increase in the 72-point scale equates to a 3.3% decrease in crash occurrence over 2 years of follow-up. Extrapolating to the current findings, the overall 2.43 point treatment difference would equate to an 8% lower crash occurrence over 2 years among intervention participants, whereas the 4.81 point difference between groups in the lowest baseline tercile would translate to a 16% lower crash occurrence (data available on request). The trend toward fewer critical errors in the intervention group also suggests direct clinical relevance. Second, while the number of female and minority participants was relatively low, the proportion of drivers in these demographic groups is reflective of this geographic area based on earlier studies.
Current discussion regarding age and driving safety has centered on the question of who is at risk and whether anything can be done to improve or maintain driving performance. Given the importance of this determination and its implications, including limiting or stopping driving and potential negative effects on autonomy, mobility, out-of-home activity participation, and depressive symptoms, the issue has often been cast in a negative light, with reluctance on the part of drivers and clinicians to address it. A number of initiatives have been undertaken to facilitate and provide a framework for this discussion.39,40
This study demonstrated that it is possible to maintain or enhance driving performance among older drivers using a safe, well-tolerated physical conditioning program. The availability of such an intervention may change the content and tenor of clinician–patient discussions on this topic from a negative interaction regarding the need to limit or stop driving to a more positive one of possible interventions to prolong safe driving by maintaining or enhancing driving ability. Hopefully, this would increase the likelihood of this important issue being addressed.