Summary:

Selective outcome reporting can result in overestimation of treatment effects, research waste, and reduced openness and transparency. 
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\ This review aimed to examine selective outcome reporting in trials of behavioural health interventions and determine potential outcome reporting bias. 
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\ A review of nine health psychology and behavioural medicine journals was conducted to identify randomised controlled trials of behavioural health interventions published since 2019. 
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\ Discrepancies in outcome reporting were observed in 90% of the 29 trials with corresponding registrations/protocols. 
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\ Discrepancies included 72% of trials omitting prespecified outcomes; 55% of trials introduced new outcomes. 
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\ Thirty-eight percent of trials omitted prespecified and introduced new outcomes. Three trials (10%) downgraded primary outcomes in registrations/protocols to secondary outcomes in final reports; downgraded outcomes were not statistically significant in two trials. 
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\ Five trials (17%) upgraded secondary outcomes to primary outcomes; upgraded outcomes were statistically significant in all trials. 
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\ In final reports, three trials (7%) omitted outcomes from the methods section; three trials (7%) introduced new outcomes in results that were not in the methods. 
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\ These findings indicate that selective outcome reporting is a problem in behavioural health intervention trials. 
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\ Journal- and trialist-level approaches are needed to minimise selective outcome reporting in health psychology and behavioural medicine.

My Comment: We need better ethics and more rigorous methodology.