The Psychological Outcomes following a nurse-led Preventative Psychological Intervention for critically ill patients trial is a cluster-randomised controlled trial of the clinical and cost-effectiveness of a complex nurse-led preventative psychological intervention compared with usual care in reducing patient-reported post-traumatic stress disorder symptom severity, and other reported psychological morbidities, at six months among Level 3 (intensive care) patients in adult general critical care units in England, Wales and Northern Ireland. This paper describes the proposed statistical and health economic analyses for the Psychological Outcomes following a nurse-led Preventative Psychological Intervention for critically ill patients trial. It is important to complete and publish this plan before inspecting and locking the trial data to ensure that post hoc and data-derived decisions are avoided. Trial registration: ISRCTN53448131