Among people prescribed antipsychotics on the NHS for a diagnosis of severe mental illness, people from ethnic minority backgrounds and those from deprived areas in the UK are prescribed higher doses, according to an analysis led by UCL researchers.
The researchers say their findings, published in The British Journal of Psychiatry and supported by Wellcome, do not confirm why some groups are prescribed higher doses, but raise concerns that certain groups may be given higher than necessary doses with associated risks of side effects.
Similar findings have previously been found in the US, but this is the first study to identify these disparities in the UK.
Antipsychotics can have potential side effects, such as weight gain or drowsiness. The most prescribed antipsychotic, olanzapine, is one of the antipsychotics most significantly associated with weight gain. Olanzapine has been used for a long time, so many prescribers are familiar with it.
The research team reviewed data from 309,378 people who were first diagnosed with a severe mental illness in the UK between 2000-2017, 212,618 (68.7%) of whom were prescribed an antipsychotic between 2000-2019. They found that antipsychotic prescribing prevalence increased from 2000 to 2016, before declining slightly by 2019.
The researchers found that Black patients tended to be prescribed the highest doses of antipsychotics, while White patients were prescribed the lowest doses. People from deprived areas were also prescribed higher doses on average.
Black patients are also more likely to be prescribed long-acting injectables, which are sometimes used for people who are too unwell to consent to treatment.
Lead author, PhD candidate Alvin Richards-Belle (UCL Psychiatry) said: "There's no intrinsic reason why being from an ethnic minority or a deprived area would require a higher dose. It's possible that some groups of people are often being prescribed higher than necessary doses."
The researchers say that different pathways into accessing mental health services may partly explain the differences.
Richards-Belle said: "Further research is needed to understand what is causing the disparities we have identified, whether there may be unconscious bias or structural racism involved, or else differences in severity when people present to primary care services.
"Antipsychotic medications can improve the quality of life of people who take them, and are associated with a significantly lower long-term mortality rate, so these prescriptions can be very beneficial, but prescribing the correct dosage is important."
