Superiority, equivalence or non-inferiority?

AbstractOne of the most important critical decision to be taken when designing a randomized controlled trial (RCT) in clinical psychopharmacology is the choice of the comparator. This choice is crucial because it affects many issues related to both internal and external validity. The aim of a RCT may be to establish efficacy in absolute terms, against an inert treatment (usually a placebo), or to establish efficacy with respect to another treatment (also known ascomparator), a trial may be designed to demonstrate that the new drug is superior to the control intervention or, by contrast, that the new drug is similar to the control intervention in terms of, say, symptoms' reduction. Three kinds of RCTs may be designed: Superiority trials, Equivalence studies, Non-inferiority studies.

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Preventing depression in final year secondary students: School-based randomized controlled trial

10.26686/wgtn.12331265.v1 ◽

2020 ◽

Author(s):

Y Perry ◽

A Werner-Seidler ◽

A Calear ◽

A Mackinnon ◽

C King ◽

...

Keyword(s):

Randomized Controlled Trial ◽

Depressive Symptoms ◽

Secondary Students ◽

Controlled Trial ◽

School Level ◽

Control Group ◽

Depression Symptoms ◽

Randomized Controlled ◽

Control Intervention ◽

The Impact

Background: Depression often emerges for the first time during adolescence. There is accumulating evidence that universal depression prevention programs may have the capacity to reduce the impact of depression when delivered in the school environment. Objective: This trial investigated the effectiveness of SPARX-R, a gamified online cognitive behavior therapy intervention for the prevention of depression relative to an attention-matched control intervention delivered to students prior to facing a significant stressor-final secondary school exams. It was hypothesized that delivering a prevention intervention in advance of a stressor would reduce depressive symptoms relative to the control group. Methods: A cluster randomized controlled trial was conducted in 10 government schools in Sydney, Australia. Participants were 540 final year secondary students (mean 16.7 [SD 0.51] years), and clusters at the school level were randomly allocated to SPARX-R or the control intervention. Interventions were delivered weekly in 7 modules, each taking approximately 20 to 30 minutes to complete. The primary outcome was symptoms of depression as measured by the Major Depression Inventory. Intention-to-treat analyses were performed. Results: Compared to controls, participants in the SPARX-R condition (n=242) showed significantly reduced depression symptoms relative to the control (n=298) at post-intervention (Cohen d=0.29) and 6 months post-baseline (d=0.21) but not at 18 months post-baseline (d=0.33). Conclusions: This is the first trial to demonstrate a preventive effect on depressive symptoms prior to a significant and universal stressor in adolescents. It demonstrates that an online intervention delivered in advance of a stressful experience can reduce the impact of such an event on the potential development or exacerbation of depression.

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