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Abstract

Objective: This paper identifies rates of common mental disorders among Maori and non-Maori consulting a general practitioner (GP), and explores the association between ethnicity and social and material deprivation.

Method: Survey of GPs and their patients. Participants were randomly selected GPs (n = 70), and their patients (n = 3414, of whom a subset of 786 form the basis of this paper). The main comparison is between self-identified ethnicity, mental disorder assessed by the Composite International Diagnostic Interview, and social and material deprivation measured by NZDep2001 (an area based measure), and an individualized index of deprivation.

Results: Rates of mental disorder among Maori general practice attenders were higher than among non-Maori. Overall, Maori women attenders were twice as likely as non-Maori women attenders to have a diagnosable mental disorder. The rates of anxiety, depressive and substance use disorders were all higher for Maori than for others attending GPs. Treatment for psychological problems was offered by the GP at similar rates to both Maori and non-Maori. Although there were differences between Maori and non-Maori in terms of social and material deprivation, higher rates of mental disorder among Maori attending GPs compared to non-Maori cannot be accounted for by these differences alone.

Conclusions: These findings support the view that whilst social and material deprivation may play a role in the high rates of mental disorders among Maori general practice attenders, there are additional ethnicity-specific factors involved. Interventions to address Maori mental health (whether by reducing risk factors for mental disorder, by promoting disclosure, early recognition and intervention, or by ensuring access to acceptable and effective treatments) may need to explicitly take those factors into account.

Keywords

ethnic groups mental disorders primary care social and material deprivation

Over the last 20 years clear evidence has emerged of poorer health among Maori compared with non-Maori New Zealanders [1]. Mortality rates for Maori males are significantly higher than for non-Maori, for each social class and for the total population [2]. This may reflect several interrelated factors [3], including poorer social and economic status; discrimination [4]; higher rates of behaviour-related risk factors such as smoking and diet; and less frequent access to, or poorer effectiveness of, health services [5].

Maori are said to have poorer mental health than non-Maori [6], [7]. The only general population study of mental disorders in New Zealand failed to provide evidence of this, as the number of Maori participants in the Christchurch-based study was too low [8].

Patterns of mental health service use by Maori differ from those of non-Maori, but not consistently. While national data indicates that both groups have similar rates of first admission [9], a recent Otago study found a four-fold increased rate of first admission to their services for Maori [10]. Part, but not all, of this increase may reflect an increased rate of readmission for psychotic disorders among Maori [9] as half of the Otago Maori, but only 24% of the non-Maori, had been previously admitted elsewhere [10]. Among the Otago subjects Maori experienced more social disadvantage but no greater rates of family psychiatric illness [10].

Social deprivation is associated with poorer health [11], and higher rates of psychiatric hospitalization, especially for severe and enduring mental illnesses (such as schizophrenia and bipolar disorder) [12–15] both in New Zealand and elsewhere. This study examines the extent to which high rates of common mental disorders among Maori using primary care health services are accounted for by social and material deprivation.

Methods

This paper uses data from the MaGPIe study, which is described in detail elsewhere [16].

Setting and sampling

Participants were 70 randomly selected General Practitioners in the lower North Island of New Zealand. General Practice in New Zealand is a partially state-subsidized health system, that is predominantly funded by fee-for-services, financed by a combination of patient payments, tax funding and less frequently, insurance.

Fifty consecutively attending eligible adult patients were recruited from each general practitioner's practice. Stratified sampling identified a primary sample of 1151 patients, of whom 788 were interviewed.

Measures

The measures of mental disorder used were based on the World Health Organization's Collaborative Study of Psychological Problems in General Health Care [17].

Social and material deprivation was assessed in two ways. The first method used the 2001 census Deprivation Index (NZDep). NZDep is a census-based index of deprivation based on the geographical area of residence. NZDep consists of nine age and gender standardized variables that identify a standardized proportion of people with a lack of a defined material or social resource who reside in a small census-based geographical area [18].

An individualized study-specific index of social and material deprivation was also created using similar constructs as NZDep2001, using the general methodology developed for such indicators [19], but using available deprivation data for each participant in the study. Participants were scored 1 for each of the following: if they were unemployed, had no educational qualifications, held a Community Services Card, had no car, or had no telephone. The count of these attributes was then used as the individualized social and material deprivation index.

Ethnicity was determined by self-identification using the Statistics New Zealand question used in the 1996 census [20]. Maori were defined as any participants identifying themselves as Ma ori, solely or in combination with any other ethnic group.

Procedures

Ethics approval

This study was approved by the Wellington and Manawatu-Whanganui Ethics Committees.

Recruitment of general practitioners

General practitioners were selected randomly from 299 eligible GPs in two health districts in New Zealand (see [16] for detail).

Recruitment of patients/index consultation

Patients were eligible for screening if they were 18 years old or over, read English well enough to understand and complete the 12 item General Health Questionnaire (GHQ) screening instrument [21], and were about to consult with the general practitioner for their own health concerns.

GHQ score was used to select the primary sample for detailed interviews. The doctor completed an Encounter Form that included an assessment of psychological health for every patient aged 18 or over who was seen that day. For those patients selected and consenting, the general practitioner completed a more detailed Patient Management Questionnaire on the patient's condition/s and treatment/ s implemented.

The patient interview

The patient interview consisted mainly of the Composite International Diagnostic Interview (CIDI) [22], computerized using the World Health Organization's ISHELL software. Patients were interviewed, usually in their own homes, within days of the index consultation.

Data scoring and statistical methods

CIDI v2.1 data were scored using algorithms to produce DSM-IV diagnoses. Statistical analyses were carried out using Statistical Analysis Software (SAS) version 8.2. Data were weighted to adjust for differences in probability of being sampled using the method of Kish [23]. Weighted prevalence estimates were derived using the SAS procedure SURVEYMEANS, which also adjusted confidence intervals for the effects of clustering within general practitioner. Relative Risks were estimated from a generalized regression, accounting for both weighting and clustering [24], using the statistical programme STATA.

Results

Ninety per cent of eligible randomly selected GPs participated, and 70 per cent of eligible patients completed interviews. Of participants, 10.3% were Maori, the same percentage as those identifying as Maori in the 2001 census in this region (derived from regional tables for 2001 Census at http://www.statistics.govt.nz/). Table 1 shows Maori were significantly under-represented in the highest NZDep2001 category (Group 1) (z = 6.2, p < 0.001) and significantly over-represented in the lowest category (Group 9–10) (z = 2.95, p = 0.03). There was a similar trend to findings for the individualized deprivation index (z = 1.80, p = 0.072).

Table 1.

Demographic characteristics of general practice attenders by ethnicity

	Overall n = 786		Maori n = 81		Non-Maori n = 705
	%^†	CI^‡	%^†	CI^‡	%^†	CI^‡
Marital status
Living with a partner	59.1	52.8–65.3	59.4	42.7–76.2	59.0	52.6–65.5
Not living with a partner	40.9	34.7–47.2	40.6	23.8–57.3	41.0	34.5–47.4
Educational qualifications
No qualification	42.4	36.3–48.4	54.9	36.0–73.8	41.0	34.7–47.4
School qualification only	57.6	51.6–63.7	45.1	26.2–64.0	59.0	52.6–65.3
Number of children
No children	35.8 ^§	28.8–42.7	34.1 ^¶	14.9–53.2	35.9	28.3–43.5
One or two children	33.5 ^§	28.1–38.9	37.6 ^¶	21.8–53.4	41.0	34.7–47.4
Three or more children	30.8 ^§	23.6–38.0	28.3 ^¶	13.4–43.2	31.0	23.6–38.5
Employment status
Paid employment/self-employed	51.2	44.3–58.0	50.1	32.2–68.0	51.3	43.9–58.6
Home-maker or voluntary unpaid	12.6	8.7–16.4	18.3	3.3–33.4	12.0	8.0–16.0
Student	4.7	0.0–9.5	8.1	0.0–20.2	4.4	0.2–8.5
Unemployed for health reasons	6.8	4.2–9.4	12.3	0.2–24.4	6.2	3.8–8.7
Unemployed	3.0	1.1–5.0	8.3	0.0–18.3	2.5	0.7–4.3
Retired or other	21.4	16.0–26.9	[2.8]	0.0–6.2	23.4	17.4–29.4
Indices of deprivation NZDep2001 (address-based)
Group 1	21.7 ^† ^†	15.2–28.3	[1.5] ^‡ ^‡	0.0–3.2	23.8 ^§ ^§	16.8–30.8
Group 2–3	22.7 ^† ^†	17.3–28.1	20.2 ^‡ ^‡	4.0–36.4	23.0 ^§ ^§	17.3–28.6
Group 4–6	24.0 ^† ^†	18.4–29.7	17.1 ^‡ ^‡	4.2–30.1	24.7 ^§ ^§	18.7–30.8
Group 7–8	20.1 ^† ^†	14.3–25.8	27.9 ^‡ ^‡	12.5–43.3	19.3 ^§ ^§	13.2–25.3
Group 9–10	11.5 ^† ^†	7.2–15.8	33.3 ^‡ ^‡	17.8–48.8	9.2 ^§ ^§	5.1–13.3
Individualized index of deprivation
Score 0	47.4	41.5–53.3	44.8	25.3–64.3	47.7	41.6–53.8
Score 1	29.0	23.8–34.1	25.0	12.0–37.9	29.4	23.9–34.9
Score 2	17.7	13.3–22.0	13.2	4.2–22.2	18.1	13.4–22.8
Score 3 or more	5.9	3.5–8.4	17.0	3.6–30.4	4.8	3.1–6.4

Percentages in [] should be interpreted with caution due small n in this cell; ^†estimated for the population by weighting the sample according to probability of selection; ^‡confidence interval adjusted for clustering within general practitioners; ^§n = 785 due to missing data; ^¶n = 80 due to missing data; ^† ^†n = 734 due to missing data; ^‡ ^‡n = 76 due to missing data; ^§ ^§n = 658 due to missing data.

Table 2 shows higher rates of disorder among Maori than non-Maori general practice attenders, particularly for Maori women, who were twice as likely as non-Ma ori women to have a diagnosable mental disorder. This was not specific to any of the common mental disorders, with Maori at greater risk of all three conditions: anxiety, depressive and substance use disorders. This increased risk was not fully accounted for by social and material deprivation as assessed by either the census-based geographical area index NZDep2001, or by the individualized index of social and material deprivation (Table 3).

Table 2.

Twelve month prevalence of CIDI-DSM-IV mental disorder among general practice attenders by gender and ethnicity

Type of mental disorder in last 12 months	Overall n = 786		All non-Maori n = 705		All Maori n = 81		Non-Maori men n = 249		Maori men n = 28		Non-Maori women n = 456		Maori women n = 53
	%^†	95% CI^‡	%^†	95% CI^‡	%^†	95% CI^‡	%^†	95% CI^‡	%^†	95% CI^‡	%^†	95% CI^‡	%^†	95% CI^‡
Any depressive disorder	18.4	14.2–22.5	15.4	11.9–19.0	46.4	28.8–64.0	10.1	6.0–14.3	21.3	2.3–40.3	18.8	13.6–23.9	55.2	33.0–77.4
Any anxiety disorder	20.1	15.4–24.8	17.6	13.1–22.0	43.8	27.2–60.4	10.8	5.9–15.8	17.2	0.5–34.0	21.8	16.5–27.2	53.0	31.3–74.8
Any substance disorder	11.4	7.8–15.0	9.4	6.0–12.8	29.8	15.2–44.3	15.1	7.6–22.6	30.5	5.8–55.2	5.9	2.7–9.0	29.5	8.2–50.8
Any CIDI-DSM-IV disorder	35.5	29.5–41.5	32.5	26.3–38.7	64.4	48.2–80.5	29.2	20.5–37.8	40.9	10.6–71.1	34.6	27.1–42.0	72.6	55.7–89.4

^†Percentage within disorder group estimated for the population of general practice patients with each disorder by weighting the sample according to probability of selection; ^‡confidence intervals are adjusted for clustering within general practitioners.

Table 3.

Mental disorder and social and material deprivation amongst Maori and non-Maori New Zealanders attending their general practitioner

Type of mental disorder in last 12 months	Ethnicity/gender	n	Unadjusted RR		RR adjusted for NZDep2001^‡		RR adjusted for individualized index of social deprivation
			RR	95% CI^†	RR	95% CI^†	RR	95% CI^†
Any depressive disorder	Maori male	28	1.13	0.45–2.88	1.04	0.42–2.53	0.98	0.38–2.50
	Maori female	53	2.94	1.87–4.62	2.61	1.73–3.95	2.89	1.89–4.43
	Non-Ma ori male	249	0.54	0.33–0.88	0.44	0.27–0.74	0.59	0.36–0.97
	Non-Ma ori female (reference)	456	1	–	1	–	1	–
Any anxiety disorder	Maori male	28	0.79	0.29–2.16	0.66	0.25–1.73	0.68	0.24–1.95
	Maori female	53	2.43	1.55–3.81	2.06	1.30–3.26	2.43	1.60–3.70
	Non-Ma ori male	249	0.50	0.32–0.77	0.48	0.30–0.77	0.52	0.33–0.81
	Non-Ma ori female (reference)	456	1	–	1	–	1	–
Any substance use disorder	Maori male	28	5.20	1.99–13.58	3.83	1.38–10.62	5.93	2.60–13.50
	Maori female	53	5.03	2.21–11.45	4.24	1.81–9.91	5.55	2.59–11.90
	Non-Ma ori male	249	2.57	1.24–5.31	2.51	1.21–5.20	2.66	1.29–5.46
	Non-Ma ori female (reference)	456	1	–	1	–	1	–
Any mental disorder	Maori male	28	1.18	0.61–1.17	1.05	0.49–2.26	1.07	0.46–2.45
	Maori female	53	2.10	1.54–2.86	2.05	1.56–2.71	2.02	1.47–2.78
	Non-Ma ori male	249	0.84	0.61–1.17	0.82	0.58–1.16	0.86	0.62–1.20
	Non-Ma ori female (reference)	456	1	–	1	–	1	–

RR, relative risk; ^†confidence intervals adjusted for clustering and weighting using STATA; ^‡total n = 734 as 52 had incomplete data on NZDep2001 variables; the reference category was chosen was the largest category numerically, and the four ethnicity/gender categories were created because of the interaction of the two component models used to generate the relative risks.

Treatment for psychological problems was offered by the GP at similar rates to both Maori and non-Maori (31.4%, 95% CI = 14.9–47.9 vs. 28.7%, 95% CI = 22.2–35.2). Among those offered treatment, Maori were more likely than non-Maori to have been identified by the GP as having clinically significant symptoms or an explicit diagnosis (84.7%, 95% CI = 69.3–100.0 vs. 76.8%, 95% CI = 66.1–87.4%), and Maori were less likely than non-Maori to have been identified as having subclinical or no symptoms (15.3%, 95% CI 0.0–30.7, vs. 23.2%, 95% CI = 12.6–33.9).

Discussion

This study of the patients of randomly selected general practitioners is likely to closely represent the experience of typical general practices in New Zealand. The study is limited because of the low, although proportionate, number of Maori recruited. The diagnostic interview lacks of explicit validation for use with Maori, although it has been used in many different cultures [17], [22], [25], [26]. The rates of attending general practice in New Zealand do not differ between Maori and non-Maori [27]. However, those attending general practice, particularly in a fee paying setting, do not necessarily reflect the prevalence of illness in a community, and this study cannot address whether Maori are more likely to experience mental illness or whether they are more likely to seek help for it.

This study suggests that rates of mental disorder among Maori general practice attenders are higher than for non-Maori. Overall, Maori women attenders were twice as likely as non-Maori women to have a diagnosable mental disorder. The rates of anxiety, depressive and substance use disorders were all higher for Maori than for others attending GPs. These differences are congruent with higher rates of illness among Maori compared to non-Maori in other domains of health [1].

Although rates of mental disorder were higher among Maori, treatment for psychological problems was offered by the GP at similar rates to both Maori and non-Maori. Among those offered treatment there was a trend towards Maori having somewhat greater severity of symptoms than non-Maori, suggesting that there may be ethnic differences in patient disclosure of symptoms to the GP, or that the GPs threshold for offering treatment may be slightly higher for Maori than for non-Maori.

The higher rates of disorder among Maori general practice attenders compared to non-Maori cannot be accounted for solely by differences in social and material deprivation.

Currently there is considerable debate in New Zealand about the need for services, remedial interventions or other initiatives that specifically target Maori. These findings support the view that whilst social and material deprivation may play a role in the high rates of mental disorders among Maori general practice attenders, there are additional ethnicity-specific factors involved. Interventions to address Maori mental health (whether by reducing risk factors for mental disorder, by promoting disclosure, early recognition and intervention, or by ensuring access to acceptable and effective treatments) may need to explicitly take those factors into account.

Footnotes

Acknowledgements

We are grateful to Mason Durie and Joanne Baxter for reviewing a draft of this paper. We would like to thank the participating general practitioners and other practice staff, the patients who participated, and our research staff. The Health Research Council of New Zealand funded the project (grant 99/065), with supplementary funds also contributed by the Alcohol Advisory Council (ALAC).

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Mental Disorders Among M a ori Attending Their General Practitioner

Abstract

Keywords

Methods

Setting and sampling

Measures

Procedures

Ethics approval

Recruitment of general practitioners

Recruitment of patients/index consultation

The patient interview

Data scoring and statistical methods

Results

Discussion

Footnotes

Acknowledgements

References