Schizophrenia Bulletin vol. 43 no. 6 pp.

1251–1261, 2017
doi:10.1093/schbul/sbx010
Advance Access publication May 17, 2017

Ethnic Minority Status, Age-at-Immigration and Psychosis Risk in Rural

Environments: Evidence From the SEPEA Study

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James B. Kirkbride*,1,2, Yasir Hameed3, Konstantinos Ioannidis2,4, Gayatri Ankireddypalli5,
Carolyn M. Crane4, Mukhtar Nasir3, Nikolett Kabacs4, Antonio Metastasio3, Oliver Jenkins3,
Ashkan Espandian4, Styliani Spyridi4, Danica Ralevic3, Suneetha Siddabattuni4, Ben Walden3,
Adewale Adeoye3, Jesus Perez2,4, and Peter B. Jones2,4
PsyLife Group, Division of Psychiatry, University College London, London, UK; 2Department of Psychiatry, University of Cambridge,
1

Cambridge, UK; 3Norfolk & Suffolk Foundation Trust, Norwich, UK; 4Cambridgeshire & Peterborough Foundation Trust and NIHR
Collaboration for Leadership in Applied Health Research and Care (CLAHRC) East of England, Cambridge, UK; 5North Essex
Partnership NHS Foundation Trust, Chelmsford, UK
*To whom correspondence should be addressed; Division of Psychiatry, University College London, 6th Floor Maple House, 149
Tottenham Court Road, London W1T 7NF, UK; tel: 44-(0)-20-7679-9297, e-mail: j.kirkbride@ucl.ac.uk

Objective: Several ethnic minority groups experience Key words:  epidemiology/ethnicity/migration/urbanicity/

elevated rates of first-episode psychosis (FEP), but most incidence/early intervention/social determinants
studies have been conducted in urban settings. We inves-
tigated whether incidence varied by ethnicity, generation
Introduction
status, and age-at-immigration in a diverse, mixed rural,
and urban setting. Method: We identified 687 people, Some migrants and their descendants experience
16–35  years, with an ICD-10 diagnosis of FEP, present- increased risk of schizophrenia and other psychotic
ing to Early Intervention Psychosis services in the East of disorders compared with the majority population in a
England over 2 million person-years. We used multilevel given setting.1,2 Precise risk correlates with visible minor-
Poisson regression to examine incidence variation by eth- ity status, meaning that black Caribbean and African
nicity, rural–urban setting, generation status, and age-at- migrants and their descendants in Europe and North
immigration, adjusting for several confounders including America experience greatest incidence.3–6 Rates are also
age, sex, socioeconomic status, population density, and 2–4 times higher in people of Pakistani and Bangladeshi
deprivation. Results: People of black African (incidence origin in the United Kingdom,7 and Moroccans in the
rate ratio: 4.06; 95% confidence interval [CI]: 2.63–6.25), Netherlands.8 Psychosis risk may also be raised among
black Caribbean (4.63; 95% CI: 2.38–8.98) and Pakistani white migrants, although research from Scandinavia sug-
(2.31; 95% CI: 1.35–3.94) origins were at greatest FEP gests “European” migrants may only have up to double
risk relative to the white British population, after multi- the risk of native-born groups.9,10 Nonetheless, the eth-
variable adjustment. Non-British white migrants were not nicity of these migrants was unknown; studies of white
at increased FEP risk (1.00; 95% CI: 0.77–1.32). These ethnic minorities in the United Kingdom suggest risk of
patterns were independently present in rural and urban set- first-episode psychosis (FEP) may be 50% higher than
tings. For first-generation migrants, migration during child- in the white British population.7,11 No epidemiological
hood conferred greatest risk of psychotic disorders (2.20; study has, however, been conducted since substantial
95% CI: 1.33–3.62). Conclusions: Elevated psychosis risk immigration from Eastern Europe following EU expan-
in several visible minority groups could not be explained by sion in 2004, while little is known about FEP risk in other
differences in postmigratory socioeconomic disadvantage. potentially marginalized groups, including minorities of
These patterns were observed across rural and urban areas Arabic origin.
of our catchment, suggesting that elevated psychosis risk Elucidation of the determinants of this variation in risk
for some ethnic minority groups is not a result of selection should be a mental health research priority, given that up
processes influencing rural–urban living. Timing of expo- to one-fifth of FEP worldwide may be preventable,12 if we
sure to migration during childhood, an important social and could remove the causes of excess risk experienced by black
neurodevelopmental window, may also elevate risk. and minority ethnic (BME) groups. Elevated risk is unlikely

© The Author 2017. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/),
which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
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J. B. Kirkbride et al

to be explained by selective migration13,14 or higher rates aged 16–35  years old, presenting to 6 early interven-
in countries of origin,15–18 arguing against solely genetic tion in psychosis (EIP) services with a suspected FEP
explanations of causation. Further, rates appear elevated in the East of England, over a 3.5-year period. Case
to similar extents among first- and later-generation BME ascertainment was from August 1, 2009 to January
groups,1 suggesting that exposure to psychosocial adversi- 31, 2013 in the catchment area of the Cambridgeshire
ties at all stages of the migration process (before, during, and Peterborough NHS Foundation Trust, and from
and after) contribute to underlying etiology. September 28, 2009 to March 28, 2013 in the Norfolk
To date, most epidemiological studies on FEP risk and Suffolk NHS Foundation Trust. The region had a
in different ethnic groups have been conducted in pre- population of 2.4 m people in 2011, and is varied in
dominantly urban settings or national databases; studies terms of ethnicity, socioeconomic deprivation, and

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in rural populations have generally been too ethnically population density.22
homogeneous to investigate this issue. BME groups in
rural areas may differ from their urban counterparts in Case Ascertainment
important ways, including differential exposure to socio-
economic status (SES) and other aspects of social disad- EIP services were the sole referral point for any-
vantage, such as deprivation. Nonetheless, BME groups in one with suspected psychosis in the catchment area,
rural areas may also face increased exposure to other social and worked closely with a comprehensive range of
stressors, such as visible minority position or social isola- sources, including primary and secondary care pro-
tion, but how rural living affects psychosis incidence in viders, as well as tertiary services, schools, hostels,
BME groups has received little attention to date. It is also and self-referrals. FEP cases referred to other mental
unclear whether risk varies by generation status (first vs health services would normally be re-directed to EIP
later-generation BME groups) in more rural populations, services. We identified and followed all participants
or, more generally, whether timing of exposure to migra- accepted into EIP care until receipt of 3  years of
tion among first-generation groups also affects psychosis care, or discharge from services (for any reason), if
risk. To date only 3 peer-reviewed studies have investigated earlier. Inclusion criteria at first referral were:
this latter issue6,9,19; 2 found migration during childhood 1. 16–35  years old (17–35  years in Cambridgeshire and
conferred strongest psychosis risk,6,19 consistent with other Peterborough)
evidence that this may be a vulnerable window of exposure 2. Resident in the catchment area, including those of no
to psychosocial adversities affecting typical neurodevelop- fixed abode
ment.20,21 However, a third study, predominantly among 3. Absence of moderate or severe learning disabilities, or
European migrants to Denmark, did not.9 an organic basis to disorder
To investigate these issues, we used epidemiological data 4. No previous contact with health services for psychosis,
from a large, naturalistic cohort study in a rural setting in or previous treatment with anti-psychotic medication
the East of England,22 where 20% of the population at-risk for greater than 6 months
were from a BME background, half of whom were of non-
British white (mostly European) origins, following a decade
of EU expansion. We tested the following hypotheses: Diagnostic Outcomes
We initially included participants who received a clini-
1. Incidence would be elevated among most BME groups
cal diagnosis according to the tenth revision of the
compared with the white British population at-risk,
International Classification of Diseases (ICD-10) at
after adjustment for SES, population density and mul-
6 months and 3 years into their EIP care, or at discharge
tiple deprivation. The magnitude of excess risk would
from services, if sooner. These diagnoses were validated
broadly correlate with visible minority status
by an ethnically diverse panel of trained diagnosticians
2. Patterns of risk would be similar in both rural and
using the OPCRIT assessment,23 which uses a standard-
urban settings within the catchment area
ized, structured 90-item symptom checklist to ascertain
3. Rates would be elevated in first- and later-generation
valid and reliable research-based diagnoses from case note
groups to a similar extent
review.23,24 Participants without an OPCRIT-confirmed
4. For first generation migrants, rates would be most-
ICD-10 psychotic disorder (F10-33) at either time point
strongly associated with immigration in childhood and
were excluded. We classified participants according to
adolescence
their final OPCRIT-confirmed diagnosis as follows: all
clinically relevant psychotic disorders (F10–33), nonaf-
Methods fective psychoses (F20–29), schizophrenia (F20), and
affective psychoses (F30–33). We did not include sub-
Design and Setting stance-induced psychoses as a separate outcome in this
The Social Epidemiology of Psychoses in East Anglia article, given the small sample size, as previously reported
[SEPEA] study prospectively identified all people, (N = 30; 4.4%).22
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 Ethnicity and Psychosis in Rural Populations

Population At-Risk unadjusted incidence rate ratios (IRR) for FEP by 10-cat-
We estimated the population at-risk from the Office for egory ethnicity, with the white British population as the
National Statistics (ONS) 2011 Census of Great Britain, reference category, followed by incremental adjustment
conducted on April 1, 2011. We multiplied this by 3.5 for (1) age, sex and their interaction; (2) SES, and; (3)
to estimate person-years at-risk during case ascertain- population density and multiple deprivation. For this
ment. Data were stratified by: age, sex, SES, and ethnicity final adjustment, we used multilevel Poisson models with
(10-category), or by; age, sex, ethnicity (5-category), and random intercepts to account for hierarchical data (indi-
age-at-immigration/generation status, depending on the viduals within neighborhoods), excluding 28 participants
availability of stratified Census data for each analysis. of “No Fixed Abode,” who could not be geocoded to
a residential address at first referral. Second, we tested

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whether the effect of ethnicity on psychosis risk differed
Exposure and Confounder Variables by rural–urban status, by testing for effect modification
Sociodemographic data including birthdate, sex, eth- between these variables via a likelihood ratio test (LRT).
nicity, birth country, date of immigration to the United Due to sample size considerations, we used 5-category
Kingdom, main or last occupation and postcode at ethnicity in these analyses. Third, we examined whether
initial referral were routinely collected at first contact. FEP rates varied by exposure to the index immigration
Participant ethnicity was self-ascribed to 1 of 18 cat- event among BME groups, by comparing incidence in
egories in the 2011 census, from which we created 10- first- and later-generation groups with the white British
and 5-category variables for analyses (Appendix 1), population. We tested whether patterns of psychosis risk
guided by previous research.7,11 Generation status, based by generation status also varied by 5-category ethnicity,
on birth country, was categorized as: white British via LRT as before. Finally, we investigated whether age-
(UK-born), white British (but born overseas), first-gen- at-immigration was associated with FEP incidence, rela-
eration BME groups (ie, foreign-born), and second- or tive to the white British population, after adjustment for
later-generation BME groups (ie, UK-born). For first- age and sex, and tested whether these patterns varied by
generation migrants, we categorized age-at-immigration ethnicity (5-category), as before. To investigate whether
as: migration during infancy (0–4 years old), childhood any observed age-at-immigration effects may have been
(5–12 years), adolescence (13–19 years), and adulthood due to time in the United Kingdom since migration, we
(20+ years). We obtained confounder data on age (16– followed the approach by Veling et  al19 to test whether
24, 25–29, 30–35), sex and a 6-category SES variable, age-at-immigration was associated with psychosis risk in
based on occupation, classified according to official younger (16–24  years) and older (25–35  years) partici-
national guidance (Appendix 1).25,26 We geocoded par- pants in a sensitivity analysis. If age-at-immigration was
ticipants to the small area neighborhood in which they a stronger determinant of psychosis risk than time-in-
lived at first referral, based on 530  “electoral wards” the-UK, any signal for elevated psychosis risk in a specific
in the catchment area (median total population: 3992; age-at-immigration category should have been present in
interquartile range: 2426–5935). We estimated popula- both our younger and older cohorts. Results for our main
tion density in people per square mile [ppsqm], based on outcome (all FEP) are presented in the main text and
2011 Census data22 to create a 4-category equal-interval tables. Given that 83.4% of the sample received a diag-
variable (48–4000; 4001–8000; 8001–12 000; over 12 000 nosis of nonaffective psychosis, results for nonaffective
ppsqm) to control for confounding. To inspect whether psychosis, schizophrenia (50.9%) and affective psychoses
variation in risk by BME status was present in rural (9.5%) are presented as supplemental material. Analyses
and urban areas, we used a binary version of this vari- were conducted using Stata (version 13).
able (less/more than 8000 ppsqm), which differentiated
rural areas (small market towns, villages, and agricul- Ethics
tural areas) from major towns and cities, as previously
shown.22 We also controlled for confounding by multiple Ethical approval was granted by Cambridgeshire III
deprivation, with neighborhoods classified into 4 equal- Local Research Ethics Committee (09/H0309/39).
interval groups, based on the proportion of house-
holds living in multiple deprivation in the 2011 Census Results
(7.8–18.0%; 18.1–28.0%; 28.1–38.0%; 38.1–47.1%) (see Baseline Characteristics
Appendix 1 for more details).
We identified 687 people with FEP during 2 million
person-years at-risk, of which 50.9% met diagnostic
Statistical Analyses criteria for schizophrenia (table  1). Detailed baseline
We first reported descriptive characteristics of the sam- characterization of the sample has been published,22
ple. Next, we conducted 4 sets of multivariable Poisson but briefly, two-thirds of FEP participants were men
analyses to test our hypotheses. First, we estimated (N = 459; 66.8%), with younger age groups and lower

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J. B. Kirkbride et al

Table 1.  Basic Sample Characteristics

Cases Person-Years at-Risk Crude Incidence

Variable (Test; P-Value)a

N (%) N (%) Rate (95% CI)

Diagnosis (ICD-10)
  Any FEP (F10–33) 687 (100.0) 2 021 663 (100.0) 34.0 (31.5–36.6)
  Schizophrenia (F20) 350 (50.9) 2 021 663 (100.0) 17.3 (15.6–19.2)
  Other nonaffective psychosis (F21–29) 223 (32.5) 2 021 663 (100.0) 11.1 (9.7–12.6)
  Bipolar disorder (F30–31) 65 (9.5) 2 021 663 (100.0) 3.2 (2.5–4.1)
  Psychotic depression (F32–33) 19 (2.8) 2 021 663 (100.0) 0.9 (0.6–1.5)

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  Substance-induced psychoses (F10–19) 30 (4.4) 2 021 663 (100.0) 1.5 (1.0–2.1)
Ethnicity (χ2-test: 13.0; P < .001)b
  White, British 514 (74.8) 1 623  285 (80.3) 31.7 (29.0–34.5)
  White, non-British 68 (9.9) 207 098 (10.2) 32.8 (25.9–41.6)
 Indian 2 (0.3) 27 911 (1.4) 7.2 (1.8–28.7)
 Pakistani 17 (2.5) 20 125 (1.0) 84.5 (52.5–135.9)
 Bangladeshi 6 (0.9) 8401 (0.4) 71.4 (32.1–159.0)
  Arabic ethnicities 4 (0.6) 4848 (0.2) 82.5 (31.0–219.8)
  Black, African 23 (3.3) 17 177 (0.8) 133.9 (89.0–201.5)
  Black, Caribbean 10 (1.5) 5966 (0.3) 167.6 (90.2–311.5)
  Mixed ethnicities 28 (4.1) 44 013 (2.1) 63.6 (43.9–92.1)
  Other ethnicities 15 (2.2) 62 851 (3.1) 23.9 (14.4–39.6)
Generation status (FE-test; P < .001)
  White, British (UK-born) 511 (74.4) 1 573 700 (77.8) 32.5 (29.8–35.4)
  White, British (born overseas) 3 (0.4) 49 331 (2.4) 6.1 (2.0–18.9)
  BME, later generation (UK-born) 67 (9.8) 73 586 (3.6) 91.0 (71.7–115.7)
  BME, first-generation (foreign-born) 106 (15.4) 325 046 (16.1) 33.8 (27.0–39.4)
Age-at-immigrationc (FE-test: P < .001)
  0–4 years (infancy) 4 (3.9) 9505 (2.9) 42.1 (15.8–112.1)
  5–12 years (childhood) 16 (15.5) 18 322 (5.6) 87.3 (53.5–142.5)
  13–19 years (adolescence) 31 (30.1) 70 364 (21.6) 44.1 (31.0–62.6)
  20+ years (adulthood) 52 (50.5) 226 854 (69.8) 22.9 (17.5–30.1)
Rural–urban statusd (χ2-test: 26.4; P < .001)
White British—rural 339 (51.4) 1 216 693 (60.2) 27.9 (25.0–31.0)
BME groups—rural 83 (12.6) 231 999 (11.5) 35.8 (28.9–44.4)
White British—urban 156 (23.7) 406 592 (20.1) 38.4 (32.8–44.9)
BME groups—urban 81 (12.3) 166 510 (8.2) 48.6 (39.1–60.5)

Note: FEP, first-episode psychosis; FE-test, Fisher’s Exact test; BME, black and minority ethnic group.
a
Test of whether the distribution of FEP participants is the same as the population at-risk, by each variable.
χ -test of white British vs all BME groups. A Fisher’s Exact test would not converge on 11 categories.
b 2
c
“BME, first-generation” group only, excluding 3 participants missing age-at-immigration data (N = 103).
d
Rural: 0–8000 people per square mile; Urban: 8001–22 000 people per square mile.

SES groups over-represented (table 1). One quarter of IQR: 2.6–9.5), although these patterns varied by ethnic
FEP participants (N  =  173; 25.2%) self-ascribed to a minority group (P = .03; supplementary figure 1).
BME group, compared with 19.7% of the population
at-risk (χ2 test: 13.0; P < .001). Of these, most FEP par- Incidence Rates by Ethnic Group
ticipants came from non-British white (9.9%), mixed Crude FEP incidence rates were raised across most eth-
(4.1%), black African (3.3%), or Pakistani (2.5%) nic minority groups relative to the white British popu-
backgrounds. Compared with the population at-risk, a lation (table  2); this pattern held for most diagnostic
greater proportion of FEP participants were of second- outcomes (supplementary figure  2). Progressive adjust-
or later-generation status, had migrated before 20 years ment for age, sex, their interaction, SES, and neighbor-
old and lived in urban areas (all P < .001, table  1). hood-level deprivation and population density did not
Median age-at-immigration in first-generation FEP substantially attenuate IRR estimates. Thus, after full
participants (N = 103) was 20.1 years old (interquartile adjustment (table 2), rates remained significantly elevated
range [IQR]: 15.6–23.7) and was negatively correlated among people of black African (IRR: 4.06; 95% confi-
(corr  =  −0.72; P < .001; see supplementary figure  1) dence interval [CI]: 2.63–6.25), black Caribbean (IRR:
with years in the United Kingdom (median: 4.9 years; 4.63; 95% CI: 2.38–8.98), Pakistani (IRR: 2.31; 95% CI:

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 Ethnicity and Psychosis in Rural Populations

Table 2.  First-Episode Psychosis Incidence Rate Ratios by Ethnic Group, After Multivariable Adjustment

Unadjusted Adjustment 1 Adjustment 2 Adjustment 3a

Ethnicity IRR (95% CI) IRR (95% CI) IRR (95% CI) IRR (95% CI)

Sample, N 687 687 687 659

White, British Ref Ref Ref Ref
White, non-British 1.00 (0.78–1.30) 1.21 (0.94–1.56) 1.11 (0.86–1.43) 1.00 (0.77–1.32)
Indian 0.23 (0.06–0.94) 0.27 (0.07–1.09) 0.28 (0.07–1.13) 0.29 (0.07–1.15)
Pakistani 2.77 (1.71–4.49) 2.93 (1.80–4.74) 2.67 (1.65–4.34) 2.31 (1.35–3.94)
Bangladeshi 2.34 (1.05–5.24) 2.34 (1.05–5.23) 2.19 (0.98–4.89) 2.03 (0.90–4.58)

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Arabic ethnicities 2.71 (1.01–7.25) 2.51 (0.94–6.71) 2.26 (0.84–6.05) 2.16 (0.80–5.84)
Black, African 4.20 (2.74–6.43) 4.62 (3.04–7.01) 4.21 (2.77–6.41) 4.06 (2.63–6.25)
Black, Caribbean 4.94 (2.56–9.55) 5.16 (2.76–9.66) 4.94 (2.64–9.24) 4.63 (2.38–8.98)
Mixed ethnicities 2.01 (1.37–2.94) 1.89 (1.29–2.77) 1.82 (1.24–2.66) 1.71 (1.15–2.54)
Other ethnicities 0.78 (0.47–1.31) 0.77 (0.46–1.29) 0.73 (0.43–1.22) 0.75 (0.45–1.26)

Note: IRR, incidence rate ratio; 95% CI, 95% confidence interval. Bold denotes P < .05. Adjustment 1: Adjusted for age group, sex, and
their interaction. Adjustment 2: Adjustment 1 + socioeconomic status + EIP setting. Adjustment 3: Adjustment 2 + population density +
multiple deprivation.
a
Twenty-eight participants of no fixed abode were excluded as they could not be assigned neighborhood-level exposures.

1.35–3.94), and mixed ethnic backgrounds (IRR: 1.71; Incidence Rates by Generation Status
95% CI: 1.15–2.54). There was no evidence that risk Second- and later-generation (ie, UK-born) BME groups
by ethnic group differed for men and women (LRT for were at increased FEP risk relative to the UK-born white
interaction χ2 on 9 df: 13.4, P = .15). These patterns were British population, after adjustment for age and sex
similar for nonaffective psychoses and schizophrenia (figure  1 and supplementary table  3; IRR: 2.59; 95%
separately (supplementary table  1). For schizophrenia, CI: 2.01–3.34). While there was no overall evidence of
we observed substantially elevated rates across several increased rates in first-generation migrants (IRR: 1.16,
ethnic groups after control for confounders, including 95% CI: 0.94–1.43), this pattern varied by ethnicity (LRT-
Bangladeshi (IRR: 2.85; 95% CI: 1.06–7.67) and Arabic χ2 on 3 df: 9.2, P = .03; figure 1, supplementary table 3).
groups (IRR: 3.14; 95% CI: 1.00–9.85), albeit in a small Thus, rates were elevated to a similar extent for first- and
sample of the latter group (N-4). People of Pakistani, later-generation black and Pakistani and Bangladeshi
black Caribbean, and mixed ethnic backgrounds were groups (figure  1, supplementary table  3), after adjust-
also at substantially elevated rates of affective psychoses ment for age and sex, compared with the UK-born white
(supplementary table  1) after adjustment. We found no British population. By contrast, while first generation
evidence to suggest people of non-British white (IRR: non-British white migrants were not elevated (IRR: 1.09;
1.00; 95% CI: 0.77–1.32) or Indian (IRR: 0.29; 95% CI: 95% CI: 0.83–1.42), we observed excess rates in the small
0.07–1.15) ethnicities were at elevated FEP risk overall proportion of later-generation (ie, UK-born) non-British
(table 2). white migrants (IRR: 3.36; 95% CI: 1.67–6.75).

Incidence Rates by Ethnic Group and Incidence Rates by Age-at-Immigration

Rural–Urban Status Three (2.8%) first-generation FEP participants with
There was no evidence that FEP risk by ethnicity differed missing data on immigration date were excluded from
between rural and urban populations (LRT P value for these analyses. For remaining participants (N  =  103),
interaction: χ2 on 9 df: 13.4, P  =  .32). Thus, rates were those who immigrated to the United Kingdom in child-
raised for black, Pakistani, and Bangladeshi groups in hood (5–12  years old) experienced elevated rates of
both rural and urban regions, after adjustment for age, psychotic disorders compared with the UK-born white
sex, SES, and neighborhood-level deprivation (table  3). British population (IRR: 2.20; 95% CI: 1.33–3.62;
There was no evidence that rates were raised for non-Brit- figure 2), but there was no evidence that immigration at
ish white or other ethnic groups in rural or urban regions. other ages was associated with FEP risk (supplementary
These patterns were similar for nonaffective psychoses table  4). Excess risk associated with childhood immi-
and schizophrenia (supplementary table  2). Although gration was observed independently for first generation
the sample of affective psychoses was small, there was black (IRR: 6.02; 95% CI: 2.69–13.47) and non-British
evidence some ethnic minority groups (Pakistani and white groups (IRR: 2.21; 95% CI: 1.05–4.68), with a
Bangladeshi, non-British white and “other” ethnicities) trend in this direction for Pakistani and Bangladeshi
in rural areas had elevated risk (supplementary table 2). migrants (IRR: 3.36; 95% CI: 0.84–13.49; P  =  .09;

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J. B. Kirkbride et al

Table 3.  Rural–Urban Patterns in First-Episode Psychosis Incidence Rate Ratios by Ethnic Group

Rurala Urbana

Broad ethnicity N % aIRR (95% CI) N % aIRR (95% CI)

White, British 339 80.3 Ref 156 65.8 Ref

White, non-British 33 7.8 1.03 (0.71–1.48) 30 12.7 1.01 (0.68–1.50)
Black ethnicities 12 2.8 3.19 (1.79–5.70) 19 8.0 5.18 (3.20–8.37)
Pakistani and Bangladeshi 28 6.6 3.08 (1.62–5.85) 19 8.0 2.01 (1.10–3.66)
Other ethnicities 10 2.4 1.29 (0.88–1.91) 13 5.5 0.84 (0.52–1.37)
LRT P value for interaction .32

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Note: aIRR, adjusted incidence rate ratio for age group, sex, their interaction, SES, and neighborhood-level multiple deprivation. Bold
denotes P ≤ .05.
a
Based on a dichotomous cut-off of 8000 people per square mile, corresponding to the distinction between rural areas and major towns
and cities in the catchment area.

Fig. 1.  Incidence rate ratios for first-episode psychosis (FEP) by generation status and broad ethnic group. Overall there was evidence
that FEP risk by generation status varied by ethnic group (LRT-χ2 P-value for interaction between ethnicity and generation status on
3 degrees of freedom: χ2 = 9.2; P = .03). Thus, compared with the UK-born white British group, rates were raised to a similar extent for
first- and later-generation black and Pakistani and Bangladeshi groups, with no statistically significant differences in risk by generation
(supplementary table 3). For non-British white and other ethnic groups, excess rates were confined to later-generation groups. Foreign-
born white British groups and first generation “other” ethnic groups were at significantly reduced psychosis risk compared with the
UK-born white British group. All incidence rate ratios are adjusted for age and sex. The white British (UK-born) reference population is
shown in green, with the white British (born overseas) shown in red. BME: black and minority ethnic. Data corresponding to this figure
are presented in supplementary table 3.

figure  2). Black (IRR: 2.62; 95% CI: 1.24–5.55) and table  4), suggesting age-at-immigration operated inde-
Pakistani and Bangladeshi (IRR: 2.87; 95% CI: 1.18– pendently of time-in-the-UK.
6.94) migrants who immigrated to the United Kingdom
in adulthood (20+ years) also remained at increased psy-
Discussion
chosis risk (figure 2). Lower rates in adult migrants from
“other” ethnic backgrounds (IRR: 0.31; 95% CI: 0.11– Our findings demonstrate that the incidence of all major
0.82) were also observed, but difficult to interpret given psychotic disorders were raised in several ethnic minor-
within-group heterogeneity. There was no evidence that ity groups after controlling for important confounders,
these patterns differed between our younger and older including SES, neighborhood-level population density,
cohorts (LRT-χ2 on 4 df: 6.0; P = 0.20; supplementary and multiple deprivation (Hypothesis 1). Arising within

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Fig. 2.  Incidence of all clinically relevant psychotic disorders by age-at-immigration, major ethnic group, and generation status.
Incidence rate ratios (IRR) by age-at-immigration show a peak with childhood migration (5–12 years old) for all black and minority
ethnic (BME) groups overall (IRR: 2.20; 95% CI: 1.33–3.62). There was no evidence that this effect differed by 5-category ethnicity (LRT
χ2 on 16 df: 23.1; P = .11). This finding was independently replicated in first-generation black (IRR: 6.02; 95% CI: 2.69–13.47) and non-
British white (IRR: 2.21; 95% CI: 1.05–4.68) immigrants, with a trend in this direction for Pakistani and Bangladeshi (IRR: 3.36; 95%
CI: 0.84–13.49; †P = .09). IRRs appeared to decrease in relation to later age-at-immigration. Only first-generation black (IRR: 2.62; 95%
CI: 1.24–5.55) and Pakistani and Bangladeshi migrants (IRR: 2.87; 95% CI: 1.18–6.94) who moved to the United Kingdom in adulthood
were at significantly increased psychosis risk compared with the white British population. People from the “other ethnicities” group who
migrated aged 20 years or older were at significantly decreased risk of psychosis compared with the UK-born white British group (IRR:
0.31; 95% CI: 0.11–0.82). IRR for second- and later-generation UK-born groups are shown for comparison. There were insufficient first-
episode psychosis participants of foreign-born white British descent (n = 3) to analyze results by age-at-immigration. All IRRs adjusted
for age group and sex. 95% confidence intervals omitted for presentational purposes. *P < .05. †P = .09.

a large, diverse, and representative population at-risk, by ethnicity. EIP services were the sole referral point for
elevated risks were largest and most consistent for people any suspected psychosis presenting to multiple sources,
of black Caribbean, black African, and Pakistani ori- actively engaged in outreach to minimize under ascertain-
gin. We extend previous knowledge by demonstrating ment, and operated across rural and urban settings within
that patterns of risk among BME groups were broadly our catchment area. Further, both our overall estimates of
similar for people living in rural or urban environments incepted incidence,22 and those by ethnicity here, are in line
(Hypothesis 2). Rates were equivocally raised for first- and with previous rates from more urban populations,1,3,27 sug-
later-generation black Caribbean and African, Pakistani, gesting differential under-ascertainment in BME groups,
and Bangladeshi groups (Hypothesis 3), though for non- which would have made our results conservative, was
British white minorities, elevated rates were restricted to unlikely. We also believe that over-ascertainment of ethnic
UK-born, later generations. Finally, for first-generation minority cases was an unlikely explanation of the excess
migrants—exposed to the index migration event—excess incidence rates observed in our study. We cannot exclude
risk was consistently most-pronounced in those migrat- the possibility that patterns of psychiatric help-seeking by
ing during childhood, partially supporting Hypothesis 4. generation status may have differed,28 but little empirical
work on how this ultimately may affect case ascertainment
has been conducted to date. We used a 2-stage diagnostic
Methodological Considerations procedure established well-validated, research-based FEP
Incidence rates were based on incepted cases presenting to diagnoses; clinical diagnoses obtained in stage one were
NHS mental health services in our catchment area, which provided by an ethnically diverse group of clinicians, rati-
may have differed slightly to the true incidence in the popu- fied in stage 2 by independent (ie, different) diagnosticians
lation. Nevertheless, we do not believe our methodology using OPCRIT.
led to substantial under-ascertainment of FEP cases in We controlled for several important confound-
our catchment, either nondifferentially, or differentially ers in our main analyses, including age, sex, SES, and
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neighborhood-level deprivation and population density. that—on average—variation in psychosis risk would be
We could not control for confounders omitted from the less apparent in more rural populations; in contrast, we
Census, including paternal age, parental SES, substance observed substantially elevated risk of several psychotic
use, or family history of mental illness. Control for par- outcomes in BME groups living in rural areas, indepen-
ticipant rather than parental SES will have led to conser- dent of SES and area-level deprivation. This implies that
vative IRR estimates in ethnic minority groups, given the other social exposures, including putative roles for ethnic
possibility of downward social drift for some FEP partic- density,35 social isolation,35 discrimination,36 and stress
ipants. This was the largest epidemiological study of FEP experienced by BME groups operate across the entire
conducted in the United Kingdom since the multi-center rural–urban gradient of environmental susceptibility.
ÆSOP study,27 and our diverse study setting had a higher We found no evidence, overall, that non-British white

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proportion of BME groups (19.7% vs 17.6%), although groups were at elevated risk of FEP, including first-gen-
the ethnic composition of these samples differed substan- eration migrants. This is an important null finding, given
tially, with 52.0% of the BME population in our study the large number of white migrants, particularly from
of non-British white ethnicity (vs 9.9% in ÆSOP27). This Eastern Europe, who have arrived in the United Kingdom
resulted in fewer BME cases in our study overall, given since EU expansion in 2004. Nonetheless, we did observe
the incidence in non-British white minorities, leading to some variation in risk within this group, including raised
broader confidence intervals when estimating FEP risk rates among non-British white minorities born in the
for some specific ethnic groups. We cannot exclude type II United Kingdom. Although our sample was small, this
error as an explanation for some null findings, although group included a high proportion of people (3 of 8;
the absence of substantially elevated risk in our largest 37.5%) who self-ascribed as “white Gypsy or traveler” in
BME group—non-British white migrants—should be the 2011 census. While several explanations for this excess
robust. Furthermore, while FEP incidence appeared to may exist, including under-enumeration of these commu-
peak for first-generation participants who immigrated nities in censuses, such groups may also be subject to high
in childhood, we could not determine whether this dif- degrees of marginalization and discrimination; interest-
fered significantly from risk at other ages of immigration. ingly, our data replicate a similar finding in inner London
Nonetheless, there was some replicability of this finding, among UK-born, non-British white minorities.37 We
observed in black, Pakistani and Bangladeshi and non- also reported a trend toward higher schizophrenia rates
British white migrants independently. among people of Arabic origin, never previously studied
The 2011 UK Census provided valid ethnicity catego- in the United Kingdom. While this requires replication
ries29 and included measures to minimize, estimate, and in a larger sample, the 2001–2011 intercensal period wit-
adjust for nonresponse,30 making substantial under-esti- nessed increased discrimination toward this diverse eth-
mation of our denominator population unlikely. The cen- nic group,38 coinciding with the emergence of elevated
sus included information on age-at-immigration for the schizophrenia risk in this group; from limited epidemio-
first time, for which we obtained especially commissioned logical evidence in Arabic countries, rates do not appear
denominator data, additionally stratified by age, sex, and to be raised prior to migration.39
ethnicity. For this reason, our age-at-immigration catego- With regard to age-at-immigration and psychosis, 2
ries were chosen a priori, as they had to pass stringent studies9,40 (one, an un-reviewed letter40), found no asso-
ONS disclosure benchmarks; therefore this data could ciation in Denmark, but most migrants were from neigh-
not be additionally stratified by SES. boring Scandinavian countries. In 2 more ethnically
diverse studies, younger ages-at-migration predicted later
psychosis risk among migrants,6,19 peaking with infant
Meaning of the Findings migration in one study19 and later childhood migration in
Consistent with the previous literature,1,3,7 people of black another,6 partially consistent with our findings. We also
African, black Caribbean, and Pakistani origin were 3–5 hypothesized that migration during adolescence would
times more likely to be diagnosed with a psychotic disor- increase psychosis risk, but found only limited evidence
der than the white British population. These risks were (ie, among older participants in our cohort, supplemen-
raised to a similar extent in rural and urban parts of tary table 4). One possibility here is that younger partici-
our study region. Previous studies in rural settings have pants in our cohort who migrated in adolescence might
generally lacked sufficient ethnic diversity to investigate not, on average, have passed through a sufficient latency
this issue.31,32 Our study overcomes this limitation. This period to develop psychotic symptoms, suggesting that
is important because the selection processes which influ- both age-at-immigration and time lived in the “host”
ence whether people live in more rural or urban areas may country may jointly influence psychosis risk.
mean that the distribution of social, genetic, and envi- If early life migration does increase psychosis risk, it
ronmental determinants of psychosis risk are stratified in is worth considering the possible underlying mechanisms
the population. If this were the case, as suggested by pro- through which this may emerge. Sociocognitive models,
ponents of the social drift hypothesis,33,34 it would imply eg, emphasize early childhood as an important window
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 Ethnicity and Psychosis in Rural Populations

for developing Theory of Mind (the ability to attribute Service (Stowmarket, NSFT). We are also grateful to
mental states to the self and others), acquiring complex staff at the NIHR Clinical Research Network: Eastern
language skills, and establishing social ties with non- (formerly the Mental Health Research Network) for the
kin peers.41,42 Migration during this period may disrupt invaluable support provided to the study, and the dedi-
typical neurodevelopment, particularly when the migra- cated help of all assistant psychologists and Clinical
tion event is stressful or invokes substantial changes to Studies Officers who contributed to data collection.
language, peer group maintenance (eg, by changing We are grateful to Drs Eva Aguilar (CPFT), Poornima
schools43) or sociocultural adaptation. Sociocognitive Chandrappa (NSFT), Louise Colledge (CPFT), Ben
impairments,44,45 social withdrawal,46–48 and social stress49 Davies (CRN: Eastern), Jeanine Gambin (CPFT),
in childhood have been associated with later psychosis Martina Gariga (CPFT), Maria Gonzalez (CPFT),

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onset, while migration during childhood and early adoles- Clare Knight (CPFT), Santvana Pandey (NSFT) and
cence has also been associated with social withdrawal and Swathi Theegala (CPFT), Rebecca Webster (CPFT),
perceived social support in adulthood.50 Corollary data Antonio Zambrana (CPF) for their assistance with
from social neuroscience suggests that among healthy OPCRIT completion. The authors have declared that
volunteers, second-generation BME participants exhibit there are no conflicts of interest in relation to the sub-
elevated neural responses to social stress compared with ject of this study.
native-born participants,51 although this requires repli-
cation in first-generation immigrants. Further research
on the potential psychosocial stressors associated with Appendix 1
migration during sensitive neurodevelopmental windows
Detailed Methodology on Exposure Variables
should elucidate clues to the elevated psychosis risk in
some migrant groups. If true, interventions which pro- We recorded detailed sociodemographic data on all people
mote social support and resilience during important peri- accepted for inclusion in EIP services consistent with the
ods of sociocultural and neurodevelopmental transitions classification systems available for our denominator pop-
in childhood may ameliorate such serious mental health ulation, estimated from the 2011 Census. For ethnicity, we
outcomes later in life.52 initially asked people to self-ascribe to one of 18 Census
categories, from which we created 10- and 5-category eth-
Supplementary Material nicity variables for analytical purposes. The 10-category
ethnicity variable included: white British, non-British
Supplementary data are found at Schizophrenia Bulletin white ethnicities (white Irish, white traveller or gypsy,
online. other white ethnicities), black African, black Caribbean,
mixed ethnicities (mixed white and black Caribbean,
Funding mixed white and black African, mixed white and Asian,
other mixed ethnicity), Indian, Pakistani, Bangladeshi,
This work was supported by a Sir Henry Wellcome Arabic ethnicity and all other ethnicities (Chinese, other
Research Fellowship from the Wellcome Trust (WT085540 Asian, other black ethnicities, other). The five-category
to J.B.K.), a Sir Henry Dale Fellowship jointly funded by ethnicity included: white British, non-British white, black
the Wellcome Trust and the Royal Society (101272/Z/13/Z ethnicities (black African, black Caribbean, other black
to J.B.K.) and by the National Institute of Health Research ethnicities), Pakistani and Bangladeshi, and all other eth-
(RP-PG-0606-1335 to J.P.). Prof Peter Jones directs the nic groups (Indian, Chinese, other Asian, Arabic, mixed
NIHR Collaboration for Leadership in Applied Health ethnicities, other ethnicities). Detailed data on country of
Research and Care (CLAHRC) East of England. birth and, if relevant, month and year of immigration to
the UK were also ascertained from all participants at first
contact with an EIP professional. Data on self-ascribed
Acknowledgments
ethnicity and country of birth was obtained from all
We thank the Cambridgeshire & Peterborough (CPFT) clients. Age-at-migration could not be ascertained for 3
and Norfolk & Suffolk Foundation Trusts (NSFT) for participants.
sponsoring this research. We are indebted to all service We categorized participant SES according to National
users and staff at the 6 EIP services where the SEPEA Statistics Socio-Economic Classification,25,26 based on
study took place: CAMEO North (Peterborough, occupation at first referral, 7 as: professional and mana-
CPFT), CAMEO South (Cambridge, CPFT), the gerial, intermediate occupations, self-employed, lower
West Norfolk Early Intervention Service (Kings Lynn, supervisory and technical occupations, semi-routine and
NSFT), the Central Norfolk Early Intervention Team routine occupations, and those in long-run unemploy-
(Norwich, NSFT), the Great Yarmouth & Waveney ment, never worked or students.
Early Intervention Service (Great Yarmouth, NSFT) We defined multiple deprivation according to 4 domains
and the former Suffolk Early Intervention Psychosis of deprivation used in the 2011 Census : unemployment
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J. B. Kirkbride et al

(any working-age adult classified as long-term sick or disorders among prospective emigrants. Psychol Med.
unemployed), education (households without any adult 2015;45:727–734.
with age 16 national qualifications (5 or more GCSEs) 15. Mahy GE, Mallett R, Leff J, Bhugra D. First-contact inci-
dence rate of schizophrenia on Barbados. Br J Psychiatry.
or without a full time student), health (any household 1999;175:28–33.
member with bad or very bad self-rated health or a long- 16. Bhugra D, Hilwig M, Hossein B, et al. First-contact incidence
term limiting health problem) and the living environment rates of schizophrenia in Trinidad and one-year follow-up. Br
(household overcrowding, no central heating, or more J Psychiatry. 1996;169:587–592.
than one family sharing a single dwelling). For each neigh- 17. Hickling FW, Rodgers-Johnson P. The incidence of
bourhood, we estimated the proportion of households first contact schizophrenia in Jamaica. Br J Psychiatry.
who were classified as deprived on at least 2 of these 4 1995;167:193–196.

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domains, and categorized this into 4 equal interval bands, 18. Hanoeman M, Selten JP, Kahn RS. Incidence of schizophre-
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as described in the main article.
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and future risk of psychotic disorders among immigrants in
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