Systematic review on the prevalence of lack of capacity in medical and psychiatric settings.

Recent court cases in England and Wales have refocused attention on patients' decision-making capacity to consent. Little is known about the prevalence of incapacity across specialities but decision-making capacity is likely to be overestimated by clinicians. The aim of this systematic review is to estimate the prevalence of incapacity to consent to treatment or admission in different medical and psychiatric settings, and compare the two.