What is a complex intervention?

The UK Medical Research Council (MRC) defines complex interventions as those with several interacting components.1 In addition, interventions can be thought of as complex if they are dependent on the behaviours of those delivering and receiving the intervention, there are a range of possible outcomes, or there is a need to tailor the intervention to different contexts and settings.1

In palliative and end of life care (EoLC) settings, helping people make sense of their lives is as important as managing disease symptoms. Dignity therapy (DT) is a validated psychotherapeutic intervention designed to bring about a sense of meaning and purpose for individuals at the end of life.2 DT addresses psychosocial and existential distress by encouraging patients through focused interviews to discuss valued memories, accomplishments, roles, life lessons and hopes for significant others. Interviews are recorded, transcribed, edited and transcripts returned to the patient, who can add to the document. The format of the documents, typically labelled a ‘generativity document’ or ‘written legacy’, is evolving, for example, picture books, including cherished photos alongside briefer key commentaries. Many patients share these documents with significant others, providing opportunity for meaningful conversations that can assist with the bereavement processes. DT can be thought of as a complex intervention because: (1) DT is dependent on the skills of professionals delivering the intervention and the receptiveness of those receiving the intervention; (2) there are a range of outcomes measures that can evaluate the effectiveness of DT such as the Dignity Impact scale3 (a new measure specifically developed as an outcome measure for DT, measuring influences on the spiritual domain of well-being including meaning making, preparation for death and life completion tasks), The Palliative Performance Scale4 (assesses psychological, existential and spiritual distress), anxiety/depression scales5 and the patient dignity inventory6 (a measure of dignity-related distress); (3) DT needs to be tailored to different service settings and patient illness trajectories.

What are the key stages in developing a complex intervention?

Although MRC guidance on complex intervention1 has been in existence since 2000, methodological development is continuing to progress at a rapid pace. Although multicomponent interventions will be necessary to support patients and their families in an increasingly complex healthcare environment, the reporting of complex interventions has been criticised for not always including all ‘ingredients’ of the intervention.7 For intervention development to be successful, rigorous, structured and methodologically appropriate processes must be followed.8 Involvement of stakeholders throughout the development process is central to producing an intervention that is fit for purpose that meets both health professional and patient needs, and ensures implementation is well-adopted.9 Furthermore, the MRC guidelines on complex intervention development emphasise that interventions must be theory-driven in order to understand how they work and in order to achieve the best outcomes.1 A poorly conceptualised phenomenon results in interventions that are rarely well developed.10

The Methods Of Researching End of life Care (MORECare)11 statement builds on the MRC guidance in relation to best practice and solutions to developing and evaluating complex interventions within EoLC. It is important to combine MRC guidance with guidance that supports best practice in terms of research design/population needs.11 Table 1 provides a brief summary of the stages that guide the development of complex interventions based on a widely adopted framework developed by O’Cathain and colleagues, combined with components of the MORECare statement that are particularly pertinent to EoLC interventions, such as DT.8 11 In addition to effective planning and meaningful stakeholder engagement, the development of a complex intervention includes synthesising the evidence, understanding how the intervention would changes behaviours by drawing on existing theory, and patient-focused research to identify its components.

In relation to DT, the intervention evolved from the Dignity Conserving Model of Care (DCMC).12 The DCMC, the theoretical/conceptual framework underpinning DT was developed from detailed qualitative work. Participants comprised a range of stakeholders including patients and their families, who were invited to explore what constitutes dignity and how it can be achieved or maintained through experiences, cares and interactions. The model contains several themes and related subthemes that informed the schedule of questions and tenor of DT.2 Table 2 provides a brief summary of each theme/component of the DCMC12 13 and highlights how each theme has influenced DT. Following its initial development, the effectiveness of DT has been studied in feasibility and randomised control trial studies to evaluate its value for different patient populations and their families.14 To date, DT is proving to be a supportive psychotherapeutic intervention for middle-aged and older adults.14 However, further studies are required to develop DT as a complex intervention to support the needs of younger life-limited populations.15 16

In summary, we offer some key considerations to successful complex intervention development in healthcare, with additional considerations for EoLC studies, highlighting through the example of DT as a complex intervention. Research evidence, using mixed methods approaches and theory, inform the content, structure and delivery of complex interventions to increase the likelihood of them being effective. Collaboration with stakeholders through all stages of development, testing and implementation can enhance the perceived value, efficacy and effectiveness of complex interventions.