Logistic, ethical, and political dimensions of stepped wedge trials: critical review and case studies

Abstract

BackgroundThree arguments are usually invoked in favour of stepped wedge cluster randomised controlled trials: the logistic convenience of implementing an intervention in phases, the ethical benefit of providing the intervention to all clusters, and the potential to enhance the social acceptability of cluster randomised controlled trials. Are these alleged benefits real? We explored the logistic, ethical, and political dimensions of stepped wedge trials using case studies of six recent evaluations.MethodsWe identified completed or ongoing stepped wedge evaluations using two systematic reviews. We then purposively selected six with a focus on public health in high, middle, and low-income settings. We interviewed their authors about the logistic, ethical, and social issues faced by their teams. Two authors reviewed interview transcripts, identified emerging issues through qualitative thematic analysis, reflected upon them in the context of the literature, and invited all participants to co-author the manuscript.ResultsOur analysis raises three main points. First, the phased implementation of interventions can alleviate problems linked to simultaneous roll-out, but also brings new challenges. Issues to consider include the feasibility of organising intervention activities according to a randomised sequence, estimating time lags in implementation and effects, and accommodating policy changes during the trial period. Second, stepped wedge trials, like parallel cluster trials, require equipoise: without it, randomising participants to a control condition, even for a short time, remains problematic. In stepped wedge trials, equipoise is likely to lie in the degree of effect, effectiveness in a specific operational milieu, and the balance of benefit and harm, including the social value of better evaluation. Third, the strongest arguments for a stepped wedge design are logistic and political rather than ethical. The design is advantageous when simultaneous roll-out is impractical and when it increases the acceptability of using counterfactuals.ConclusionsThe logistic convenience of phased implementation is context-dependent, and may be vitiated by the additional requirements of phasing. The potential for stepped wedge trials to enhance the social acceptability of cluster randomised trials is real, but their ethical legitimacy still rests on demonstrating equipoise and its configuration for each research question and setting.

Stepped wedge cluster randomized controlled trial designs: a review of reporting quality and design features

“…Numerous papers have discussed when the design is more efficient, or preferential on alternate grounds, such as ethical or logistical grounds, to the parallel group CRCT [10, 18–27], whilst there have also been recommendations on how to analyze and report trials employing the SW-CRCT design [28]. Overviews of some of the benefits and limitations of SW-CRCTs can be found in the studies of de Hoop et al [29], Hargreaves et al [30], and Prost et al [31]. …”

Deciphering assumptions about stepped wedge designs: the case of Ebola vaccine research

“…Our list of points to consider is preliminary, and we hope that in the future general ethical recommendations, such as the Ottawa statement, and an extension of the Consolidated Standards of Reporting Trials statement for reporting SW studies will be developed 23 42–44. Of note, we were considering the case of vaccine trials for Ebola when no vaccine was available, thus we did not question the justification for a randomised controlled trial in this setting; equipoise and justification for randomisation in SW studies have been discussed elsewhere 26 41Points to consider in the ethical and scientific analysis of a stepped wedge (SW) design

Justification and rationale for the choice of a stepped wedge design:

Is the research question clear?

…”

“…Recent qualitative data report challenges in the conduct of cluster SW studies 26. For instance, phased implementation is not necessarily easy, and roll-out requires significant coordination.…”

“…Challenges also arise if there is change in the way the intervention is administered on the basis of experience due to a learning curve or intervention fatigue. Prost et al 26 note that “phased implementation pose challenges that need to be appraised on a case-by case basis, and it is not entirely clear that SW trials win in terms of logistic convenience”.…”

“…To our knowledge, no methods to implement interim analysis in a stepped wedge design have yet been studied. Therefore, case-specific simulation studies and analysis of the advantages and disadvantages of the SW design may be necessary to appropriately evaluate the trade-offs in the choice between designs 24 26 27 37. Overall, extra effort and methodological support are necessary to guarantee that a stepped wedge trial is appropriately designed, implemented and analysed in order to have reliable and useful conclusions.…”