Development and Validation of Questionnaires on Professional Drivers' Knowledge and Attitudes About Various Medications' Influence on Driving Ability.

Introduction: Professional drivers' knowledge about driving-impairing medications is not satisfactory. The aim of this study was to develop and test the reliability and validity of the questionnaires designed to measure the knowledge and attitude of professional drivers about the influence of various medications on driving ability.

Methods: The questionnaires for assessing professional driver's knowledge (performance-based) and attitudes about influence of various medications on driving abilities were developed by creating the item pool, testing reliability and validity, and factor analysis. The study was conducted as a multicenter, cross-sectional study in Serbia and Bosnia and Herzegovina. The study population consisted of professional drivers, who filled out both questionnaires in three time intervals.

Results: Both questionnaires showed great internal consistency and temporal stability. Cronbach's Alpha for the first questionnaire was 0.984 and for the second it was 0.944. The Kaiser-Meyer-Olkin test for the first questionnaire confirmed sampling adequacy with its value of 0.964 and for the second questionnaire it was 0.933. Exploratory factor analysis of the questionnaire showed that three factors were revealed after rotation for the first questionnaire and they explained 78.0% of variance. Both questionnaires showed high degree of correlation between scores after the first and repeated administration, Spearman's rho coefficient of correlation for was 0.962 and 0.980.

Conclusion: Based on the results of this study, we believe that both questionnaires are useful tools for testing professional drivers' knowledge and attitudes about the influence of medications on driving ability.