Discussion
anxiety, traumatic, PTSD, insomnia, depression, trauma
ADVERSE EVENTS, EVENTS, SECONDARY
This paper reports the frequentist analyses of both the primary and secondary outcomes in the final study population of a two-arm, parallel-group randomised controlled trial of a remotely-administered digital intervention seeking to reduce the number of intrusive memories of trauma experienced by ICU staff who worked during the COVID-19 pandemic. One arm received immediate access to the intervention, while the comparator arm received delayed access to the active treatment (crossover). Sequential Bayesian analyses were used to optimise the intervention as reported elsewhere [The primary outcome was impact on the number of intrusive memories. Staff who had immediate access to the imagery-competing task had approximately one-tenth the number of intrusive memories during week 4 compared to staff who received usual care over the 4-week interval. In addition, ICU staff in the immediate intervention arm had on average a 78% reduction in their number of intrusions in week 4 compared to their baseline, with 36% experiencing zero intrusive memories. Importantly, this finding was further replicated by the comparator arm participants who had delayed access to the trial intervention (crossover design) who had on average a 73% reduction in the number of intrusions in week 8 compared to week 4, with 38% experiencing zero intrusive memories. Moreover, the intrusive memories were found to be less distressing [These results indicate a robust effect despite a number of factors. First, staff generally expressed only modest expectations of the intervention having an effect (as measured by credibility/expectancy ratings) and critically this did not differ between groups. Second, participants were informed that they would receive the intervention at some point in the next 4 weeks but not when, and, therefore, were not aware of the delayed crossover design which maintained blinding. Finally, the two arms showed a similar level of ongoing work-related trauma during each phase of the study (>40%). This indicates the possibility that individuals may benefit from the intervention despite ongoing trauma exposure. In addition, the sensitivity analyses indicated robustness of the treatment effect across different statistical scenarios. This included eliminating outlier effects and the use of a per protocol population that excluded those with protocol deviations.For the secondary outcomes, we found that participants in the intervention arm who had immediate access to the intervention showed significant reductions in clinical symptoms of PTSD, insomnia and anxiety, as well as increased work functioning and wellbeing at week 4, compared to the those in the comparator arm who had delayed access to the trial intervention. Furthermore, these effects were sustained at week 8 within the immediate arm, and significant reductions in symptoms of depression and sickness absence rates were also observed at this time point compared to baseline. Importantly, the comparator (delayed) arm participants showed the same pattern of changes after crossover, demonstrating replication of the beneficial effects of the intervention on PTSD, insomnia and anxiety symptoms, as well as work functioning and wellbeing. All adverse events were unrelated to the study, no other harms were reported, and no withdrawals due to harms occurred, suggesting the intervention approach was safe.The finding that a reduction in the number of intrusive memories was also accompanied by an improvement in clinical symptoms related to PTSD and anxiety supports the possibility that changing a single symptom – intrusions - may have a causal influence on other symptoms. Network models of PTSD symptoms suggest intrusion symptoms are centrally-linked and may emerge within connected networks over time [Questionnaire feedback from staff indicated the intervention was acceptable and easy to use, suggesting that the approach might help overcome some of the challenges that ICU and other healthcare staff can face in accessing mental health support. This includes stigma and low willingness to disclose mental health problems [Our findings that the two arms showed a similar and high level of ongoing work-related trauma during each phase of the study indicates how this intervention may be of potential use in the context of continued traumatic exposure. At baseline, participants reported having experienced a very high number of traumatic events during the pandemic, which may reflect how working on an intensive care ward during the pandemic has been an unprecedented time for healthcare staff. Further work is needed to benchmark work-related trauma exposure during the pandemic and also pre-pandemic [In addition, our finding of positive effects of the intervention on work functioning (improved engagement and less burnout), general functioning and quality of life may be important for ICU staff who are continuously exposed to traumatic clinical events, while taking critical decisions for patient care. For example, whilst working with a dying patient, a nurse may suddenly have a vivid intrusive memory of the face of a previous dying patient, which disrupts concentration and brings difficult emotions at a critical time. Reducing the number of intrusive memories, or complete removal of this symptom as seen by over a third of participants in this trial, may therefore be of direct benefit to the individual and their work.The limitations of this trial include a relatively short follow-up (4 weeks for the primary outcome), and no assessment of the number of intrusive memories at 8-week or longer-term follow-up in the immediate arm. There is a need to determine whether there is persistence of the treatment effect beyond the first month, for both primary and secondary outcomes such as work functioning and quality of life. Longer-term follow up (such as at 3 and 6 months) might allow us to better assess change on measures that are unlikely to show change after only one month, such as sickness absence. We used a usual care control in the delayed arm (where participants accessed any treatments they would otherwise receive) given the novel use of this intervention. Having established positive effects, future trials would benefit from an additional active control comparator with an alternative cognitive task delivered using the same digital platform. Under pandemic conditions, for this first optimisation study we did not wish to withhold a treatment that potentially improves intrusive memories (based on previous studies) and hence a delayed intervention group was used rather than a traditional control group. We have tested our digital intervention as a standalone approach, but future studies could investigate combination approaches with other mental health treatments [Investigation of brain mechanisms of the current intervention is beyond the scope of the current RCT and should be the focus of further work [To apply this idea to established intrusive memories of older trauma, the procedure has been informed by research on memory updating and so-called memory reconsolidation [In conclusion, we found that a brief, digital imagery-competing task intervention reduced the number of intrusive memories, and improved clinical symptoms, work functioning and wellbeing after 4 weeks, for ICU staff exposed to work-related traumatic events experienced during the COVID-19 pandemic. The intervention was acceptable for ICU staff with ongoing trauma exposure. Findings support progression to an efficacy trial comparing the guided intervention with an active control, using a longer follow-up. This remotely-delivered, brief, flexible, low-intensity intervention offers one potential solution to address the impact of work-related trauma on the mental health and functioning of healthcare workers, with potential for future scalability.