Managing Dual Diagnosis Patients and the Importance of Assessing Capacity: Data from London Inpatient Services

Objective: Substance use in patients with mental disorders is often associated with worse outcomes, increased risks, and impaired decision-making. Therefore, the evaluation of mental capacity in patients with coexisting mental illness and substance use disorder (dual diagnosis) is necessary to improve clinical outcomes and mitigate risks to self and others. Design: A retrospective inspection of electronic records for patients admitted between March 2017 and August 2020 in two London inpatient facilities was conducted. Capacity was assessed using the principles set out in the Mental Capacity Act 2005. Results: A capacity assessment was recorded in 34.9% of admissions. Only 6.2% of admissions whose primary diagnosis was mental and behavioral changes due to the use of substances had a recorded mental capacity assessment. Capacity to understand the negative impact of substances was assessed in 2.1% of total admissions. Conclusions: This study indicates very low rates of mental capacity assessment across acute psychiatric admissions, with very few relating to capacity to understand the risks associated with using substances. Further research on the capacity of patients with dual diagnosis is needed. This may help to manage certain risks in this patient population.