What are the predictors and patterns of antipsychotic drug use in people with dementia?

Problem

Antipsychotic Drugs (APDs) are sometimes used to treat behavioural and psychological symptoms of dementia, despite warnings to restrict their use due to associations with serious harm. To better interpret these risks, it would be helpful to know more about the patterns of APD use or factors that influence APD initiation and persistence. We therefore aimed to describe these in relation to history of psychosis.

Approach

We used the Clinical Practice Research Datalink to delineate a prevalent dementia cohort between 01/01/1998-12/31/2017 without prior APD prescription. We estimated the association of previous mental health diagnoses, treatments, demographics and care home residence status with APD initiation, in relation to history of psychosis, using logistic regression models. In stage 2, we restricted the cohort to new-users of APD and began follow-up on this date. We used summary statistics to describe patterns of APD use. Using cox-proportional hazards models, we estimated the persistence of individual APDs and any APD in relation to history of psychosis.

Findings

Of 104,170 individuals with prevalent dementia, 21,814 (20.9%) were new-users of APDs. Ninety percent of these did not have a record of psychosis. Prior diagnosis of depression or anxiety was associated with APD prescription. Prior prescription of antidepressants, benzodiazepines or z-drugs in the previous 12 months increased the likelihood of APD use whereas opioids or anti-dementia drugs reduced it. Referral to specialist psychiatric or geriatric care was associated with APD use in those with (OR 2.67, 95%CI2.41-2.96) and without (OR 2.01, 95%CI1.93-2.08) history of psychosis. People who were in care home residence were less likely to be prescribed APDs than those who were not (psychosis: OR 0.79, 95%CI 0.70-0.89; no psychosis: OR 0.84, 95%CI 0.81-0.87). In stage 2, the most commonly prescribed APDs were risperidone (20.6%), quetiapine (18.2%) and haloperidol (15.0%). Compared to risperidone, those initiated with quetiapine (OR 0.73, 95%CI0.69-0.77) were less likely to have a single exposure period without reintroduction. The converse was true for haloperidol (OR 1.55 95%CI 1.47-1.63). People with a history of psychosis were less likely to have a single continuous exposure to APDs without reintroduction, than those without (OR 0.81, 95%CI 0.77-0.86). For individuals who were re-exposed to APDs, on average, two months elapsed until the first reintroduction, but there was large variation (55 days, IQR 18-190 days).

Consequences

We have identified certain factors that predict APD initiation and persistence. By providing a clear understanding of drug utilisation and predictors of drug initiation and discontinuation, we will help target future interventional studies to minimise potentially inappropriate APD use in people with dementia in community settings.