Systematic review on the prevalence of lack of capacity in medical and psychiatric settings
OVERVIEW
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Editor – I read with interest the systematic review on the prevalence of lack of decision-making capacity (DMC) in medical and psychiatric settings (Clin Med 2015;15:337–43).1
DMC for treatment (DMC-T) is an important consideration for clinicians working in all clinical settings. The authors set out to synthesise the evidence in this area. However, I have concerns over their methods.
The authors treat DMC as a generic ability, rather than one that is by definition specific to the decision in hand as per the Mental Capacity Act 2005, as they have included studies assessing DMC for research (DMC-R) along with those assessing DMC-T in their meta-analysis. Decisions around treatment versus participation in research on treatment involve different considerations. Research decisions can be particularly complex due to the need to appreciate that the primary purpose of the research is not to guide individual care (the ‘therapeutic misconception’)2 among other non-treatment related issues. DMC-T is not synonymous with DMC-R and should be analysed and presented separately.
Studies on DMC are highly nuanced by the specific population studied and the specific decision for which DMC is being assessed. They are particularly vulnerable to selection bias given that clinical factors that may impact on recruitment into a research study (ie severity of illness) can be expected to affect DMC. This includes the potential ‘catch 22’ of research participants being required to have DMC-R in order to consent to a study on DMC.3 The authors perform a sub-analysis to take into account clinical setting (inpatients/outpatients); however, they also need to consider these factors among others, such as diagnosis, separately.
Their meta-analyses included all studies non-discriminately ignoring the heterogeneity and inherent biases within, rather than being grouped by the factors above and crucially the specific decision for which DMC is being assessed.
Therefore I do not understand what their summary data and analysis represents other than a reflection of the complexity and heterogeneity of studies in this field.
- © 2016 Royal College of Physicians
References
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- Lepping P
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- Kimmelman J.
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- Saks ER
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