A University of Otago (Christchurch campus) study published in the latest New Zealand Medical Journal found that one in 36 Kiwis were prescribed antipsychotic medication in 2015 – up majorly in under a decade.

European women aged 65 and over were the highest users with 5.04 per cent of that demographic using them compared to 2.81% of the population. The demographic with the next highest use were Māori men between 25 and 44 (4.77 per cent.)

These findings make for “interesting, but slightly concerning” news , says study author Professor Roger Mulder, mainly because the study demonstrates that all age and gender groups, in all parts of the country, have increased usage of the drugs, – up 50 per cent in less than a decade.

“The Ministry of Health tracks all prescriptions dispensed so we have a very accurate picture of use. What we can’t say from this study is categorically why people are using these medications and at what doses. This is an area that would be useful to explore further. There is no evidence rates of psychosis increasing so rate increases appear to be related to other issues”, said Mulder.

One possible explanation for the discrepancy between rates of reported psychosis and prescription rates of drugs designed to treat the condition is that New Zealanders are using the drugs ‘off label’: using and prescribing the drugs for something other than their intended primary purpose, as a sleep aid for example, or as an anti-anxiety drug.

Professor Mulder says the study shows the prevalence and distribution of use of the medication appears to be somewhat arbitrary. “This arbitrariness in prescribing rates across areas and ethnicity is concerning. Antipsychotics have significant adverse effects, and data on long term safety and effectiveness is lacking,’’ he says.

There are two types of antipsychotics – traditional (those developed in the 1960s) and atypical antipsychotics (the next-generation medication developed in the 1990s and with different side-effects), Professor Mulder says. The biggest increase in usage rates were for atypical antipsychotics, particularly quetiapine and olanzapine, which accounted for 82% of these medications prescribed.

Other findings included:

  • The number of New Zealanders being prescribed antipsychotic medication has risen to one in 36 New Zealand adults, or 2.81% of the population in 2015. In comparison, antidepressants are used by approximately one in 13 New Zealand adults.
  • The rate of prescribing for Māori is increasing faster than other ethnic groups: 60% in Māori, compared with 52% for Europeans, for example.
  • Asian people are far less likely to be prescribed antipsychotics than otherethnicities (0.86% in 2015, compared with 3.1% of Europeans).
  • Māori and Pacific males and females were prescribed clozapine, one of the most ‘potent’ of these medications, at rates disproportionately higher than others. For example, Māori were 2.7 times more likely to be prescribed clozapine than other ethnic groups.

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