Table 2.
Automobile Crashes of Older Drivers, Clustered on the Individual, with Robust Standard Errors, Adjusted for Fear of Adult Changes in Thought (ACT) Visit
| Factor | IRR (95% CI) | P-Value |
|---|---|---|
| CASI-IRT scorea | 1.26 (1.07–1.48) | <.01 |
| Medication classes | .92 | |
| Benzodiazepine | 0.82 (0.51–1.30) | |
| Opioids | 1.03 (0.78–1.34) | |
| Sedatives | 1.07 (0.57–1.99) | |
| Anti-psychotics | 0.83 (0.26–2.75) | |
| Depression | 1.26 (1.03–1.53) | .02 |
| Performance-based physical function | 1.01 (0.98–1.05) | .36 |
| RxRiskb quartile (reference 1 (1,119–2,132)) | .10 | |
| 2 (2,132–3,146) | 1.47 (0.98–2.20) | |
| 3 (3,146–4,543) | 1.60 (1.06–2.40) | |
| 4 (4,543–52,970) | 1.69 (1.10–2.58) | |
| Age | 0.99 (0.96–1.02) | .50 |
| Education, years (reference <13) | .14 | |
| 13–15 | 1.27 (0.95–1.71) | |
| ≥16 | 1.37 (1.00–1.88) | |
| Female | 0.88 (0.68–1.13) | .32 |
| Race (reference white) | .50 | |
| Black | 1.11 (0.62–1.94) | |
| Asian | 1.47 (0.89–2.43) | |
| Other | 0.98 (0.51–1.70) | |
| Vision problems | 1.08 (0.85–1.37) | .45 |
| Hearing problems | 0.89 (0.73–1.12) | .37 |
All presented variables were included in the model.
This analysis assumed that the length of time between study visits (the exposure period) was similar across panels. ACT study protocol involves assessment every 2 years. More details can be found in the Statistical Analysis section and in Supplementary Methods I. We performed sensitivity analyses in which we used log-transformed offsets for follow-up time. This approach accounted for variation in length of follow-up intervals between participants. Using this approach, there was no significant change in study findings. Every unit reduction in Cognitive Abilities Screening Instrument scored using item response theory (CASI-IRT) score was associated with greater risk of a crash (incidence rate ratio (IRR) = 1.27, 95% confidence interval (CI) 5 1.08–1.51).
CASI-IRT results have been flipped; each 1-unit lower CASI-IRT score is associated with a 26% higher crash rate.
This expansion of the Chronic Disease Score is a chronic comorbidity score that algorithmically combines age, sex, insurance-based prescription drug coverage, and chronic conditions measured using pharmacy data.49 For example, cardiac disease is associated with a weight of 2,914.48, and being a man aged 75 and older is associated with a weight of 2,842.19.49 The overall score was quartiled and modeled as categorical indicators.