New tool explores why people with pain turn to cannabis

Although pain-related outcome expectancies are hypothesized to contribute to elevated rates of cannabis use among individuals with pain, research has been hindered by the absence of a psychometrically validated measure of expectancies regarding the effects of cannabis on pain. The goals of this study were to develop a Cannabis Pain Expectancies Scale (CPES; Study 1) and assess its psychometric properties (Study 2). An initial pool of 58 items was drafted; 32 items were retained after evaluation by a panel of subject-matter experts. Study 1: Items were administered to 277 cannabis users with chronic pain via online survey. Item properties were examined, and exploratory factor analysis (EFA) was used to evaluate factor structure. Study 2: The CPES developed in Study 1 was administered to a separate sample of 314 cannabis users with chronic pain to confirm the factor structure and evaluate reliability and validity. Study 1: EFA of proposed CPES items indicated a two-factor structure comprising 14 items. Study 2: Confirmatory factor analysis indicated that a parsimonious one-factor model provided comparable fit and was retained for the final scale. The CPES demonstrated excellent internal consistency, reliability, and evidence of convergent validity via positive covariation with measures of cannabis use and chronic pain. This study provides initial support for the factor structure, reliability, and validity of a new measure of expectancies regarding the effects of cannabis on pain. Future research is needed to corroborate these findings and evaluate the predictive utility of CPES scores in relation to pain and cannabis use trajectories. PERSPECTIVE: The article presents the psychometric properties of a novel measure of cannabis-related pain expectancies, the Cannabis Pain Expectancies Scale (CPES). The CPES may inform prevention and treatment efforts by identifying pain-related expectancies associated with continued or escalating cannabis use.