The Cannabis Problems Questionnaire: Factor structure, reliability, and validity

Aim: To develop a multi-dimensional valid and reliable measure of cannabis-related problems. Method: The Cannabis Problems Questionnaire (CPQ) was developed from the Alcohol Problems Questionnaire to measure cannabis treatment outcome. The CPQ was administered on two occasions 1 week apart to a stratified sample of adults who had used cannabis at least once in the previous 3 months. Exploratory factor analyses were conducted and the relationship between items of the CPQ and measures of daily use and dependence assessed. The reliability of the CPQ was also assessed using a test-retest and inter-rater reliability methodology. Results: Exploratory factor analyses revealed a three factor solution best described the data accounting for 57% of the variance in the larger item set. The CPQ is highly reliable with test-retest tetrachoric correlations of between 0.92 and 1.00 and inter-rater reliability correlations between 0.74 and 1.00. The total CPQ score classified DSM-IV cannabis dependence with 84% specificity and sensitivity and daily cannabis use with 83% specificity and 55% sensitivity. Conclusions: The 22-item CPQ is a valid, reliable and sensitive measure of cannabis-related problems for use with clinical and research populations of current cannabis users.