A critical evaluation of QIDS-SR-16 using data from a trial of psilocybin therapy versus escitalopram treatment for depression

A reanalysis of data from a trial comparing psilocybin therapy (PT) to escitalopram (ET) for major depressive disorder found that 14 of 16 outcome measures favored PT, but the QIDS-SR-16 did not. The QIDS-SR-16 showed higher variance, imprecision from compound items and sum-scoring, vague response options, and lack of focus on a core depression factor. When the trial data were examined at item, facet, and factor levels, results suggested PT was superior in reducing depressed mood, anhedonia, a core depression factor, and specific symptoms like sexual dysfunction. This raises concerns about relying on individual scales that miss depression's multidimensional structure.

Study at a glance

Abstract

Background: In a recent clinical trial examining the comparative efficacy of psilocybin therapy (PT) versus escitalopram treatment (ET) for major depressive disorder, 14 of 16 major efficacy outcome measures yielded results that favored PT, but the Quick Inventory of Depressive Symptomatology, Self-Report, 16 items (QIDS-SR 16 ) did not. Aims: The present study aims to (1) rationally and psychometrically account for discrepant results between outcome measures and (2) to overcome psychometric problems particular to individual measures by re-examining between-condition differences in depressive response using all outcome measures at item-, facet-, and factor-levels of analysis. Method: Four depression measures were compared on the basis of their validity for examining differences in depressive response between PT and ET conditions. Results/Outcomes: Possible reasons for discrepant findings on the QIDS-SR 16 include its higher variance, imprecision due to compound items and whole-scale and unidimensional sum-scoring, vagueness in the phrasing of scoring options for items, and its lack of focus on a core depression factor. Reanalyzing the trial data at item-, facet-, and factor-levels yielded results suggestive of PT’s superior efficacy in reducing depressed mood, anhedonia, and a core depression factor, along with specific symptoms such as sexual dysfunction. Conclusion/Interpretation: Our results raise concerns about the adequacy of the QIDS-SR 16 for measuring depression, as well as the practice of relying on individual scales that tend not to capture the multidimensional structure or core of depression. Using an alternative approach that captures depression more granularly and comprehensively yielded specific insight into areas where PT therapy may be particularly useful to patients and clinicians.