We need to think about treatment journeys when evaluating complex interventions

by Dr Katrina Turner
Senior Lecturer
Centre for Academic Primary Care


Most clinical trials are pragmatic in nature and aim to assess the effectiveness of a new treatment against ‘treatment as usual’. When interpreting trial results, researchers tend to focus primarily on what treatment participants in different trial arms received. This may be difficult in the usual care arm, as this arm is often poorly defined, whereas the intervention arm is often clearly defined prior to the trial starting. In addition, this focus is very narrow. Treatment is a process and patients’ experiences of accessing and receiving care could also influence their treatment outcomes, and thus the trial’s results.

A paper recently published in Trials  highlights that differences do exist between the experiences of participants randomised to usual care and intervention arms. These differences relate not only to what treatment participants receive, but also how they access and engage with their allocated treatment, i.e. their treatment journeys. The paper is based on a secondary analysis and synthesis of data collected during three qualitative studies, all of which had been nested within large, NIHR HTA-funded primary care depression trials. In each trial, participants had been randomised to either an intervention (i.e. cognitive behavioural therapy, listening visits or facilitated physical activity) or to usual GP care for depression.

Varying treatment journeys

The findings showed that randomisation to an intervention arm had automatically led to changes and increases in care, and patients embarking upon a clear, pre-defined treatment pathway. Intervention participants were pleased with their treatment allocation, were contacted shortly after randomisation by the therapist responsible for their care, were able to secure appointments, and knew what treatment would be available to them having been allocated to the intervention. In contrast, allocation to usual care led to little or no changes in treatmentMost usual care participants were disappointed by their treatment allocation (viewing usual care as inferior to the intervention), were reluctant to consult their GP about their mental health, and described barriers to securing a treatment appointment. There were also differences between trial arms regarding continuity in terms of which practitioner participants saw; i.e. the intervention participants consulted the same practitioner during their time within the trial, while most usual care participants did not experience continuity of care.

Thinking ahead to future trials

To ensure successful recruitment and retention of trial participants, avoid ‘resentful demoralisation’ among usual care participants, and to evaluate interventions appropriately, more attention needs be given to how usual care is defined and presented to potential trial participants, and to how patients in the usual care arm access and receive care.

Usual care is often defined as unrestricted ‘treatment as usual’, but researchers can choose to restrict and define the usual care according to clinical guidelines, research evidence or patient and public involvement (PPI) feedback. Doing so may not only help researchers present usual care more clearly and more positively, but also guard against researchers who want to demonstrate an intervention effect ignoring, consciously or not, the standards and experiences of care associated with usual care.

To evaluate interventions more fairly, researchers may want to consider introducing trial processes to ensure they are comparing two treatments, i.e. intervention versus more structured GP care, and to limit the impact of contextual factors on treatment outcomes.  For example, where possible, researchers could request that both intervention and usual care participants are supported in securing an initial appointment and experience continuity of care in terms of the practitioner they see.

Further information

For more information, contact katrina.turner@bristol.ac.uk.

The National Institute for Health Research (NIHR): improving the health and wealth of the nation through research.

Established by the Department of Health, the NIHR:

  • funds high quality research to improve health
  • trains and supports health researchers
  • provides world-class research facilities
  • works with the life sciences industry and charities to benefit all
  • involves patients and the public at every step

For further information, visit the NIHR website www.nihr.ac.uk.

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