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. 2019 Feb 28;20(1):151.
doi: 10.1186/s13063-019-3206-x.

Statistical design and analysis in trials of proportionate interventions: a systematic review

Jane Candlish  1 , M Dawn Teare  2 , Judith Cohen  2   3 , Tracey Bywater  4
Affiliations

Statistical design and analysis in trials of proportionate interventions: a systematic review

Jane Candlish et al. Trials. .

Abstract

Background: In proportionate or adaptive interventions, the dose or intensity can be adjusted based on individual need at predefined decision stages during the delivery of the intervention. The development of such interventions may require an evaluation of the effectiveness of the individual stages in addition to the whole intervention. However, evaluating individual stages of an intervention has various challenges, particularly the statistical design and analysis. This review aimed to identify the use of trials of proportionate interventions and how they are being designed and analysed in current practice.

Methods: We searched MEDLINE, Web of Science and PsycINFO for articles published between 2010 and 2015 inclusive. We considered trials of proportionate interventions in all fields of research. For each trial, its aims, design and analysis were extracted. The data synthesis was conducted using summary statistics and a narrative format.

Results: Our review identified 44 proportionate intervention trials, comprising 28 trial results, 13 protocols and three secondary analyses. These were mostly described as stepped care (n=37) and mainly focussed on mental health research (n=30). The other studies were aimed at finding an optimal adaptive treatment strategy (n=7) in a variety of therapeutic areas. Further terminology used included adaptive intervention, staged intervention, sequentially multiple assignment trial or a two-phase design. The median number of decision stages in the interventions was two and only one study explicitly evaluated the effect of the individual stages.

Conclusions: Trials of proportionate staged interventions are being used predominantly within the mental health field. However, few studies consider the different stages of the interventions, either at the design or the analysis phase, and how they may interact with one another. There is a need for further guidance on the design, analyses and reporting across trials of proportionate interventions.

Trial registration: Prospero, CRD42016033781. Registered on 2 February 2016.

Keywords: Adaptive intervention; Adaptive treatment strategy; Complex intervention; Proportionate intervention; Proportionate universalism; Sequential multiple assignment randomised trial; Stepped care; Systematic review; Trial.

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Not applicable.

Competing interests

The authors declare that they have no competing interests.

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Figures

Fig. 1
Fig. 1
MEDLINE search strategy
Fig. 2
Fig. 2
PRISMA study flow diagram. Number of records identified, included and excluded during the literature search
Fig. 3
Fig. 3
Example of a stepped-care trial with three steps and the option to rejoin treatment if relapse occurs. R randomise
Fig. 4
Fig. 4
SMART design with second randomisation dependent upon an intermediate outcome response status. SMART Sequential Multiple Assignment Randomised Trial, R randomise, B/B+, C/C+ and D represent different treatments, with for example, B+ being the more intense version of B
See this image and copyright information in PMC

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