TEST-RETEST RELIABILITY OF STANDARD DEVIATION OF LANE POSITIONAS ASSESSED ON A PC-BASED DRIVING SIMULATOR

摘要

Driving is an everyday activity that is commonly affected by neurologic disorders and medicaltreatments. A frequently used metric for assessing driving ability is the standard deviation of laneposition (SDLP), or the amount that subjects "swerve" within their driving lane. Thismeasurement has been used with individuals under the influence of alcohol, illicit drugs, andprescribed medications in both on-road and simulator studies. Although good test-retestreliability is critical if one is to measure change in individuals over time, there is surprisinglylimited data regarding the test-retest reliability of SDLP.Objective. To examine the test-retest reliability of SDLP in subjects tested at (1) a 3-month retestinterval (a time frame common to clinical trials), and (2) a year or longer retest interval (a timeperiod over which one might track changes in neurologic patients.Methods. Group 1 completed retesting an average of 84 (s.d. = 8.1) days after their initialsimulator assessment. Both HIV negative (HIV-; n = 16) and positive (HIV+; n = 13) subjectswere included to explore short-term reliability in control and mildly ill patient groups. All HIV+subjects were medically asymptomatic, and unlikely to experience HIV-related changes over thisinterval. Two HIV+ subjects were neuropsychologically (NP) impaired.Group 2 (n = 31), a different cohort, was retested an average of 19.8 (8.3) months after baseline.All subjects completed NP evaluations at baseline and follow-up, with NP status rated on a scaleof 1 (above average) to 9 (severe impairment) by a clinician blinded to simulator performance.Twelve subjects (39%) were NP impaired. In order to examine reliability in a stable neurologiccohort, all subjects were selected because they remained at the same level of NP functioning atfollow-up.SDLP was assessed in both groups using an interactive PC-based driving simulator that consistedof a monitor, steering wheel, and brake/accelerator pedals. Participants were required to maintainlane position while holding a constant speed (55 mph) and responding to divided attention tasksin the corner of the monitor. Group 2 completed an existing, standardized scenario (TOPS),while Group 1 completed a newly developed driving scenario. Both simulations lastedapproximately 7 minutes.Results. Combined reliability for Group 1 was .74. Test-retest reliability was .68 for the HIV-and .83 for the HIV+ subjects. For Group 2, SDLP was significantly correlated with NPfunctioning at baseline (r = .5, p = .005) and follow-up (r = .48, p = .006), with impaired subjects