In 2014, mainland China and India surpassed the UK in becoming New Zealand’s largest source of new migrants in a decade.1 The number of people who identify with at least one Asian ethnicity has risen 33% since 2006; current estimates are that 11.8% of New Zealand’s population is Asian. This makes Asians the fastest growing and third-largest ethnic group in New Zealand after European and Māori.2

There is consistent evidence that individuals from Asian cultures regardless of their age, gender and location have lower rates of mental health service utilisation than other ethnic groups.3–5 Data from local studies6,7 and the World Health Organization (WHO)8 suggest that Asian migrant communities are less likely to be diagnosed with a common mental disorder and may experience better mental wellbeing and lower rates of addiction than other ethnic communities. No systematic study of mental health service utilisation and psychiatric diagnoses of Asians in New Zealand mental health services have been conducted so far.

Methods

The Program for the Integration of Mental Health Data (PRIMHD) is a Ministry of Health single national mental health and addiction information collection of service activity and outcomes data for health consumers in New Zealand. The data is collected from district health boards (DHBs) and non-governmental organisations (NGOs) across New Zealand’s public mental health sector. PRIMHD records contain demographics, including gender, age and ethnicity. This study uses data from PRIMHD over a five-year period from 1 July 2008 to 30 June 2013.

The ethnic data divides patients into four major groups: European, Māori, Pacific and Asian. The Asian group is further sub-divided into four groups: Chinese, Indian, South East Asian and ‘Other Asians’. ‘Other Asians’ cover a wide geographical region including: Sri Lanka, Nepal, Bangladesh, Afghanistan, Pakistan, Japan and Korea.

Service utilisation is derived by counting the number of individual patients who presented at least once to public mental health services over the five-year period in the PRIMHD database. We then calculated the odds ratio of Asians having accessed mental health services with other ethnicities. The odds ratios were calculated using the number of people who accessed services as the numerator and the number of people who did not access services as the denominator. The denominator was derived from the 2013 census data. We have used Europeans as the reference group (OR=1).

The prevalence of the recorded mental disorders in the PRIMHD database is presented using the ICD-10 diagnostic grouping per 100 patients over the five-year period.

Tests of statistical significance were not used since this data is a census of the New Zealand population.

Results

There were a total of 320,896 referrals to specialist mental health services, but 91,022 were not seen by a mental health service during these five years. This study is based on the remaining 229,874 patients.

Demographics

The age range of service users from 2012 to 2013 is between 0–101. In general, most service users fall within the age group of 20–39. Europeans have the highest percentage of service users age 80 and above (7.81%) compared to other ethnic groups. Europeans and Asians share a similar age distribution with a slightly higher proportion of service users age 60 and above. Māori and Pacific peoples have lower proportion of service users aged 60 and above. The mode age is similar across all ethnic groups. Pacific peoples have a higher percentage of male service users (64.74%) compared to other ethnic groups. Otherwise, the proportion of male and female service users appear evenly distributed across European, Māori and Asian ethnic groups.

Table 1: Demographics including age and sex.

Service utilisation

Asians were much less likely to have accessed public mental health services over the five-year period when compared to other ethnic groups. The odds ratio compared to Europeans was 0.389 (95% CI=0.381–0.397). Māori have the highest rate of access with an odds ratio of 1.615 (95% CI=1.597–1.632) compared to Europeans. Pacific peoples have comparable service utilisation to Europeans with an odds ratio of 1.022 (95% CI=1.005–1.041).

Figure 1: Odds ratio of having accessed public mental health services over a five-year period among Māori, Pacific and Asian.

The reference group (odds ratio=1) is the European group.

All Asian sub-groups were less likely to present to mental health services compared to Europeans. South East Asians were least likely to access service (OR=0.192, 95% CI=0.188–0.216), followed by Chinese (OR=0.296, 95% CI=0.284–0.307), Indians (OR 0.424, 95% CI 0.41–0.439) and Other Asians who were most likely to utilise service among Asian sub-groups (OR 0.548, 95% CI 0.525–0.572).

Figure 2: Odds ratio of having accessed public mental health services over a five-year period among Chinese, Indian, South East Asian and Other Asian.

The reference group (odds ratio=1) is the European group.

Clinical diagnoses

In general, clinical diagnoses in mental health services were similar across ethnic groups. Differences were that Asians had lower rates of substance-related disorders when contrasted with other ethnic groups and lower rates of personality disorders except in contrast to Pacific peoples. Asian rates of adjustment disorders were also somewhat higher than other ethnic groups. Europeans had higher rates of mood disorders and anxiety disorders, but lower rates of schizophrenia/psychotic disorders.

Table 2: Prevalence of commonly diagnosed mental disorders measured in number of diagnoses per 100 people over a five-year period.

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Diagnoses across Asian sub-groups were also similar. Chinese and ‘Other Asians’ had higher rates of eating disorders. Chinese had higher rates of delirium and dementia and lower rates of substance-related disorders.

Table 3: Prevalence of commonly diagnosed mental disorders measured in number of diagnoses per 100 people over a five-year period.

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* SEA = South East Asians; ** OA = Other Asians.

Comorbidity

We also studied the total number of diagnoses in different ethnic groups. Asian and Pacific ethnic groups were less likely to have two or more diagnoses. Rates for two or more diagnoses were as follows: European (21.42%), Māori (19.65%), Pacific (9.43%) and Asian (12.9%) (Details available on request).

Discussion

These data are a census of Asian patterns of mental health service use since there are no significant private facilities available in New Zealand. The results clearly show Asians are much less likely to use mental health services compared with other ethnic groups. The odds ratio of Asians using services was 0.39 compared to Europeans. South East Asians are the least likely to utilise services (OR=0.20) among the Asian sub-groups. This low level of mental health service utilisation was consistent with other international studies.8 The reasons for the low service use are less clear.

One explanation is cultural factors. Many Asians have a different cultural explanatory model of mental illness, which does not necessarily conform to a traditional Western concept. For some there is intense shame and stigma associated with being mentally ill.9 Asians may be more likely to seek help outside traditional mental health services. For example, a study by Dolly et al reported that 35% of Asian-Americans with a lifetime mental disorder seek help with religious/spiritual advisors, which was a similar rate to seeking help from a psychiatrist.10

However, our data did not support a model of delayed help seeking when mentally ill due to language and cultural barriers. If this were so then we would expect to see higher rates of severe mental illness among Asians who present to mental health services. Our data did not support this hypothesis. Asians have the highest rates of adjustment disorders of any ethnic group, which is generally considered the most benign mental disorder. While Asian rates of psychotic disorders are higher than European and Pacific groups, they are lower than Māori and are still only present in around one-tenth of patients. In addition, Asians have relatively low rates of comorbidity, which may be seen as a proxy measure of severity.

An alternative hypothesis for the low use of mental health services is that Asians have better mental health than other ethnicities. This might reflect the high standards screened for in Asian immigrants or protective factors related to their family and community functioning. There is evidence from other countries that migrant communities begin to suffer higher rates of mental disorders as they acculturate to their host population.11 There is some weak evidence that mental illness appears to be more common in second and third generation migrants than in overseas born migrants in New Zealand.12 Overall, the relationship between migration and mental illness is inconsistent. A meta-analysis reported that migration was an important risk factor for development of schizophrenia13 but other studies have reported a lower risk of other psychiatric disorders such as alcohol and drug misuse, major depression, dysthymia, mania and anxiety disorders in immigrant populations.14,15

The study has limitations. First, the study relies on clinical diagnoses, which are not standardised. Second, it is possible clinicians may have cultural bias when diagnosing mental disorders in different ethnic groups. Third, we are unable to determine the country of birth in our study sample and therefore unable to evaluate factors such as immigration status or length of stay in New Zealand. Fourth, the ‘Other Asians’ group is poorly defined with individuals from vastly different countries with contrasting beliefs, languages and cultures. Fifth, data collected by PRIMHD is sometimes incomplete due to the inconsistent data collection process. For example, PRIMHD mainly captures data from mental health and addiction services but data on psychogeriatric services are incomplete. The age of patients are also determined by date of birth, which makes it less reliable especially for older patients. Clinical diagnoses are not always reported in PRIMHD. Therefore, rates of clinical diagnoses do not reflect absolute rates but comparative rates among ethnic groups. Sixth, Kumar et al16 have argued against a study of service utilisation due to different help seeking pathways in Asians and other language and cultural barriers. However, we believe data which universally represents the mental health needs of diverse groups of Asians in New Zealand is difficult to attain. Therefore, this study serves as a starting point despite its limitations.

Conclusion

Asian New Zealanders are now a significant proportion of New Zealand society. There has been virtually no study of their mental health needs. Asian populations will need to be oversampled in future studies to compensate for the lack of reliable community samples. Asians are less likely to use mental health services, but when using them do not appear to be significantly more unwell than other ethnic groups. It is likely that Asian demand for mental health services will increase both due to an increase in number of New Zealand Asians and the possibility that their rates of mental disorder will increase as they acculturate to New Zealand.

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