Background: Antipsychotic drug (APD) treatment has been associated with elevated risks of cardiovascular disease and premature death. This problem is yet to be effectively managed in many countries including New Zealand, where Maori face elevated rates of these disorders, even before the aggravating effects of medication are considered. We studied a sample of psychiatric patients to examine the role of ethnicity (Maori v. European) in the prevalence of APD-associated metabolic syndrome.
Method: A cross-sectional, convenience sample of Waikato adult mental health service users prescribed APDs was recruited during 2009-2013 and studied using anthropometry (height, weight, blood pressure, pulse, waist circumference), and fasting venous blood samples for glucose and lipids. Ethnicity was determined according to standards set by the NZ Government. Review of medical records enabled the estimation of total lifetime APD exposure, and the determination of medical treatments for hypertension, diabetes, and dyslipidaemia.
Results: Recruitment of subjects willing and able to consent was challenged by obstacles in a number of domains: institutional, cultural, and clinical. Nonetheless after 4 years we managed to recruit and consent 186 men and 103 women treated with APDs for at least 3 months. The ethnic distribution approximated that of patients treated for major mental illness in the Waikato, with 151 Europeans (53%), 121 Maori (32%) and 15 other (5%). The majority (92%) of 289 participants met at least 1/5 standard criteria for metabolic syndrome (NCEP ATP-III, see Appendix). Three or more criteria, thought to indicate clinical significance, were found in 75 Europeans (50% of that ethnicity) and 83 (69%) of Maori. Maori were at significantly elevated risk compared to Pakeha (Odds ratio 2.24 [95% CI: 1.38 – 3.70], p=0.0016, Fisher’s Exact Test). In terms of specific risk factors, hypertension was detected in 59/289 (20%) of participants, of whom only 6 (10%) were receiving medical treatment. Similarly, hyperglycaemia or frank diabetes was detected in 99/289 (34%), of whom 21 (21%) were treated. Likewise, dyslipidaemia was detected in 107/289, (37%), of whom 30 (28%) were treated.
Discussion: We found significantly elevated rates of multiple cardiovascular risk factors in APD-treated New Zealand adults, particularly among Maori. Baseline rates of these risk factors are also known to be higher in Maori, so it appears that both groups may be comparably affected by APD treatment; longitudinal data will be required to clarify this point. Most cases of elevated risk in all domains (blood pressure, diabetes, dyslipidaemia) were found to be untreated, indicating a major unmet need in this population. We encountered a number of barriers to effective monitoring of risk factors which also impair their effective management. These barriers will need to be addressed if this unmet need and associated mortality are to be effectively managed.
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