Decision-making capacity for research in schizophrenia

Student thesis: Doctoral ThesisDoctor of Philosophy


This thesis is a story of a journey into understanding the phenomenon of decision-making capacity for research (DMC-R) in inpatients with schizophrenia and seeing if there are possibilities to enhance it.

It starts with the legal background to the concept of decision-making capacity, the regulation for research participations, and the research already done in the area. It finds a variety of conceptual questions, such as the nature of the DMC-R test itself, the role of insight in DMC-R, and whether the ‘therapeutic misconception’ really is as central as some have made it out to be.

It tells of my study setting out to measure DMC-R in inpatients in schizophrenia and the associated symptoms with a direct comparison with decision-making capacity for treatment (DMC-T). Half had DMC-R (51%, 95%CI 40-62%) and a third had DMC-T (31%, 95%CI 21-43%), this difference was statistically significant, p<0.01. Thought disorder was most associated with lacking DMC-R (OR 5.72, 95%CI 2.01-16.31, p=0.001) whereas lack of insight was most associated with lacking DMC-T (OR 26.34, 95%CI 3.60-192.66, p=0.001).
Knowing that previous studies doing similar have methodological issues with selection bias it reports the nature of participants and crucially non-participants in the study. It finds that women were far less likely to be recruited than men into the study (OR, 2.36, 95%CI 1.46-3.82, p<0.001) and explores reasons for this.

It investigates whether the central measure that I use in the study, the clinician’s expert ‘judgement standard’ of DMC-R is reliable by using an expert-panel evaluation of a range of actors in the research consent world, finding that group reliability is fair (pairwise kappa=0.68 (‘substantial’) between my assessments and that of the panel decision).

To explore how research works in practice and the suitability and any means to enhance DMC-R it has a qualitative sub-study exploring the views of clinicians, patients, and carers. It finds that within the process of research consent there are a series of tensions, with clinicians torn between their duty of care and respect for the ‘wishes and feelings’ of the patient. Patients on the other hand simply want to have the power to make the choice, and are more focussed on experiential reasons for participation in research, than the clinicians who prioritise altruism and academic endeavour. Depending on one’s role in the process of research consent one is either assessing or asserting decision-making authority.

It unites all these strands of research to develop a new conceptual model of DMC-R, the ‘salience model’. This model incorporates my evidence that DMC is not just time and decision specific, but also person specific; the weight given to individual factors within the decision will vary by the individual. It makes policy recommendations for enhancing DMC-R and supporting research in the future.
Date of Award1 May 2018
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorGareth Owen (Supervisor), Tania Gergel (Supervisor) & Matthew Hotopf (Supervisor)

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