White European patients with schizophrenia are at greater risk for being treatment-resistant compared to other ethnicities, according to a new study.
Researchers measured treatment response in 497 patients diagnosed with schizophrenia spectrum disorders. Medication history was gathered from medical health records.
“The cause of this association could be mainly cultural,” said Vincenzo De Luca, M.D., Ph.D., and team from the University of Toronto in Ontario, Canada.
“Most studies involving access to care have shown significant ethnic differences in relation to social factors, which include employment, living situation, family support, or general practitioner involvement,” they said. “These factors affecting pathways to care have shown to be vital indicators of duration of untreated psychosis.”
Overall, 30 percent of the participants were found to be treatment-resistant according to American Psychiatric Association criteria.
A person is treatment-resistant when they have little or no symptomatic response to multiple (at least two) antipsychotic drug treatments within a sufficient time period (at least 6 weeks), and with an adequate dose of the drug within the therapeutic range.
When divided according to ethnicity, nearly 37 percent of white Europeans were resistant to treatment, compared with 19 percent of non-white Europeans.
In other words, being of white European ethnicity translates into a 1.78-fold increased risk for treatment resistance.
Neither gender nor a positive family history for psychiatric disorders were significantly associated with treatment resistance.
Those resistant to treatment had a much longer duration of illness than those who were not resistant, at 21 versus 15 years, and there was a significant link between a high number of hospitalizations and non-resistant status.
The researchers note that previous studies have shown that African-American patients with psychotic disorders are given higher doses of antipsychotic medications than white patients.
They are also more likely to be prescribed depot antipsychotics — which are injected and then released into the body over a number of weeks — and less likely to receive second-generation antipsychotics. This is despite no evidence of a difference in clinical severity or a need for higher therapeutic doses.
“There is a possibility that because African-American patients are prescribed higher doses and given depot medications they have a lower chance of developing resistance as compared to white Europeans,” the researchers said.
Source: Comprehensive Psychiatry