Validation of James Whetstone's Measure of Amaxophobia

Background: Whetstone’s Vehicle Anxiety Questionnaire is a 31 item measure of driving anxiety (amaxophobia) as common in survivors of motor vehicle accidents (MVAs).

Method: Scores on Whetstone’s questionnaire were available for 53 survivors of car accidents (mean age 40.2 years, SD=13.6, 15 men, 38 women). Their scores on the Driving Anxiety Questionnaire and on Steiner’s Automobile Anxiety Inventory were also available, as well as scores on measures of PTSD (PCL-5), and on scales of post-concussive and whiplash symptoms, pain, insomnia, depression, and anxiety. Whetstone’s scores were also available for 24 normal persons (mean age 51.7 years, SD=17.5, 14 men, 10 women) who were never injured in a serious car accident.

Results and Discussion: With respect to criterion validity, Whetstone’s scores were significantly higher (r=.88) in the patients than in the controls. The highest Whetstone score of the controls was 19 and the lowest of the patients was 23: there was no overlap between the two groups.

With respect to convergent validity, high correlations were found of Whetstone questionnaire to the Driving Anxiety Questionnaire (r=.83) and to the PCL-5 measure of PTSD symptoms (r=.78). Whetstone scores were found to be also highly correlated with the post-concussion syndrome (r=.63) and moderately with whiplash symptoms (r=.46), post-MVA insomnia (r=.56), ratings of post-MVA pain (rs ranging from .43 to .51), and ratings of depression (r=.40) and of generalized anxiety (r=.43). Significant correlation was also found of Whetstone to Steiner’s Automobile Anxiety Inventory (r=.45).

Conclusion: The results indicate an excellent criterion validity and convergent validity of Whetstone’s Vehicle Anxiety Questionnaire as a clinical assessment tool for amaxophobia.

Keywords: phobia of driving, amaxophobia, PTSD, post-concussion syndrome, whiplash syndrome.