The evidence base for interventions for child mental health and neurodevelopment is weak and the current capacity for rigorous evaluation limited. We describe some of the challenges that make this field particularly difficult and expensive for evaluation studies.
We describe and review the use of novel study designs and analysis methodology for their potential to improve this situation.
While several novel designs appeared ill-suited to our field, systematic review found others that offered potential but had yet to be widely adopted, some not at all.
While funding is inevitably a constraint, we argue that improvements in the evidence base of both current and new treatments will only be achieved by the adoption of a number of these new technologies and study designs, the consistent application of rigorous constructive but demanding standards, and the engagement of the public, patients, clinical and research services to build a design, recruitment, and analysis infrastructure.

Background: Stressful events during a pandemic are a major cause of serious health problems, such as burnout, depression and posttraumatic stress disorder (PTSD) among health care workers (HCWs). During three years, HCWs, on the frontline to fight the COVID-19 pandemic, have been at an increased risk of high levels of stress, anxiety, depression, burnout and PTSD. Regarding potential psychological interventions, Eye Movement Desensitization & Reprocessing (EMDR) is a structured, strongly recommended therapy based on its well-known efficacy in reducing PTSD symptoms and anxiety.Objectives: This study, designed as a trial within a cohort (TwiC), aims to 1) estimate the prevalence of depression, burnout and PTSD in a sample of HCWs after experiencing the COVID-19 emergency (cohort part) and 2) assess the efficacy and acceptability of \'EMDR + usual care\' for HCWs from the cohort who report significant psychological symptoms (trial part).Methods: The study, designed as a TwiC, consists of a prospective cohort study (n = 3000) with an embedded, pragmatic, randomized open-label superiority trial with two groups (n = 900). Participants included in the trial part are HCWs recruited for the cohort with significant symptoms on at least one psychological dimension (depression, burnout, PTSD) at baseline, 3 months or 6 months, determined by using the Patient Health Questionnaire (PHQ-9), Professional Quality of Life (ProQOL) scale, and PTSD Checklist for the DSM-5 (PCL-5). The intervention consists of 12 separate EMDR sessions with a certified therapist. The control group receives usual care. The trial has three primary outcomes: changes in depression, burnout and PTSD scores from randomization to 6 months. All participants are followed up for 12 months.Conclusions: This study provides empirical evidence about the impact of the COVID-19 pandemic and the mental health burden it places on HCWs and assesses the effectiveness of EMDR as a psychological intervention.Trial registration NCT04570202.
Health care workers are at increased risk of stress, anxiety, depression, burnout and PTSD following the COVID-19 pandemic.In this study, the effectiveness of EMDR in reducing depression, burnout and PTSD in health care workers exposed to COVID-19 is investigated.In this study, an original ‘trial within a cohort’ (TwiC) design that consists of a cohort study with an embedded pragmatic randomized trial is used.The study is fully web-based, including online screening, consent and assessments.