Introduction: Vaping is a growing public health concern. Interventions that address vaping must build upon rigorous research that uses psychometrically sound instruments to measure vaping-associated outcome expectancies. The primary aim was to appraise the reporting of psychometric properties of instruments used to measure vaping outcome expectancies. Secondary aims were to distinguish the different types of outcome expectancies assessed across the measures, the conceptual underpinnings, and the evidence explaining e-cigarette use etiology.
Methods: This systematic review was guided by an adapted version of the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guideline and Risk of Bias Checklist. Five electronic databases were searched for peer-reviewed studies, dissertations, and theses that psychometrically evaluated instruments that measure vaping outcome expectancies. Studies that met the inclusion criteria were appraised based on their reporting of nine psychometric properties outlined in the COSMIN checklist.
Results: The review included 11 studies that described eight instruments and reported on two to five of nine pre-determined psychometric properties. Structural validity, construct validity, and internal consistency were the most commonly reported properties. No studies reported test-retest, intra-rater, or inter-rater reliability, measurement error or responsiveness. Content validity and measurement invariance were only reported by two and four studies, respectively. The most commonly included subscales in the instruments were affect regulation, positive sensory experience, and negative health consequences. Many of the outcome expectancy subscales were associated with e-cigarette behaviors.
Conclusions: There is limited reporting of psychometric testing of instruments that measure vaping outcome expectancies; however, utilization of the COSMIN guideline could enhance the quality of such reporting.
Implications: Appraising the reporting of psychometric properties of instruments that measure vaping outcome expectancies is a first step to ensuring valid and reliable instruments are used to support rigorous research and build evidence-based knowledge. Future research should focus on testing for responsiveness, measurement error, and reliability, and on quality appraisal of the instruments. Studying vaping outcome expectancies may improve understanding of factors that influence and deter vaping. This may contribute to the development of effective interventions aimed at vaping cessation and prevention.
Keywords: outcome expectancies; psychometric properties; reliability; validity; vaping.
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