Concurrent validity of the Alcohol Purchase Task for measuring the reinforcing efficacy of alcohol: an updated systematic review and meta-analysis

Background and aims: An early meta-analysis testing the concurrent validity of the Alcohol Purchase Task (APT), a measure of alcohol''s relative reinforcing value, reported mixed associations, but predated a large number of studies. This systematic review and meta-analysis sought to: (1) estimate the relationships between trait-based alcohol demand indices from the APT and multiple alcohol indicators, (2) test several moderators and (3) analyze small study effects. Methods: A meta-analysis of 50 cross-sectional studies in four databases (n = 18 466, females = 43.32%). Sex, year of publication, number of APT prices and index transformations (logarithmic, square root or none) were considered as moderators. Small study effects were examined by using the Begg–Mazumdar, Egger''s and Duval & Tweedie''s trim-and-fill tests. Alcohol indicators were quantity of alcohol use, number of heavy drinking episodes, alcohol-related problems and hazardous drinking. APT indices were intensity (i.e. consumption at zero cost), elasticity (i.e. sensitivity to increases in costs), Omax (i.e. maximum expenditure), Pmax (i.e. price associated to Omax) and breakpoint (i.e. price at which consumption ceases). Results: All alcohol demand indices were significantly associated with all alcohol-related outcomes (r = 0.132–0.494), except Pmax, which was significantly associated with alcohol-related problems only (r = 0.064). The greatest associations were evinced between intensity in relation to alcohol use, hazardous drinking and heavy drinking and between Omax and alcohol use. All the tested moderators emerged as significant moderators. Evidence of small-study effects was limited. Conclusions: The Alcohol Purchase Task appears to have concurrent validity in alcohol research. Intensity and Omax are the most relevant indices to account for alcohol involvement