Implementation of a fluid balance control strategy in critically ill patients: POINCARE-2 trial process evaluation

Background: POINCARE-2 trial aimed to assess the effectiveness of a strategy designed to tackle fluid overload through daily weighing and subsequent administration of treatments in critically ill patients. Even in highly standardized care settings, such as intensive care units, effectiveness of such a complex intervention depends on its actual efficacy but also on the extent of its implementation. Using a process evaluation, we aimed to provide understanding of the implementation, context, and mechanisms of change of POINCARE-2 strategy during the trial, to gain insight on its effectiveness and inform the decision regarding the dissemination of the intervention.

Methods: We conducted a mixed-method process evaluation following the Medical Research Council guideline. Both quantitative data derived from the trial, and qualitative data from semi-structured interviews with professionals were used to explain implementation, mechanisms of change of the POINCARE-2 strategy, as well as contextual factors potentially influencing implementation of the strategy.

Results: Score of actual exposure to the strategy ranged from 29.1 to 68.2% during the control period, and from 61.9 to 92.3% during the intervention period, suggesting both potential contamination and suboptimal fidelity to the strategy. Lack of appropriate weighing devices, lack of human resources dedicated to research, pre-trial rooted prescription habits, and anticipated knowledge of the strategy have been identified as the main barriers to optimal implementation of the strategy in the trial context.

Conclusions: Both contamination and suboptimal fidelity to POINCARE-2 strategy raised concerns about a potential bias towards the null of intention-to-treat (ITT) analyses. However, optimal fidelity seemed reachable. Consequently, a clinical strategy should not be rejected solely on the basis of the negativity of ITT analyses' results. Our findings showed that, even in highly standardized care conditions, the implementation of clinical strategies may be hindered by numerous contextual factors, which demonstrates the critical importance of assessing the viability of an intervention, prior to any evaluation of its effectiveness.

Trial registration: Number NCT02765009.