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ENVIRONMENTAL EPIDEMIOLOGY OF PSYCHOSES: Lessons from Nottingham. Jouko Miettunen Department of Public Health and Primary Care Institute of Public Health University of Cambridge. June 17th, 2003. PSYCHOTIC DISORDERS. chronic, severe, and disabling brain diseases
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ENVIRONMENTAL EPIDEMIOLOGY OF PSYCHOSES: Lessons from Nottingham Jouko Miettunen Department of Public Health and Primary Care Institute of Public Health University of Cambridge June 17th, 2003
PSYCHOTIC DISORDERS • chronic, severe, and disabling brain diseases • life-time prevalence approximately • 1% in schizophrenia • 1% other psychoses • more common in urban than in rural areas • more common in western countries
POSSIBLE ENVIRONMENTAL RISK FACTORS • related to urban birth or to upbringing • population density • stressful life-events • air pollution • social deprivation • temporal order can be the opposite • social drift? • more healthy people may move out from deprived areas?
Nottingham Health Authority Area • about 600,000 people in 105 electoral wards • districts of Nottingham, Ruschliffe, Broxtowe, Gedling and Ashfield • several previous studies (1969-1988) on schizophrenia and other psychoses • possible to estimate trends in incidence • relatively high social deprivation and incidence of schizophrenia
SAMPLES OF THE STUDY • SIN DATA • “Schizophrenia Incidence in Nottingham” • all incidence cases of psychoses in Nottingham Health Authority Area 1.6.1992 - 31.5.1994 • 167 cases (166 with known address) • ÆSOP DATA • “Aetiology and Ethnicity in Schizophrenia and Other Psychoses” • three-centre study (other centres are Bristol and South London) • all incidence cases of psychoses in Nottingham Health Authority Area 1.8.1997 - 31.7.1999 • 206 cases (202 with known address)
INDIVIDUAL VARIABLES DISTRIBUTIONS 1992-94 (N=167) 1997-99 (N=206) • Gender: males 98 (59%) 123 (60%) • Median age 28 y 30 y • Diagnoses • Narrow schizophrenia 56 67 • Broad schizophrenia 82 116 • Affective psychosis 85 90 • Ethnic groups • White 122 (73%) 159 (77%) • African-Caribbean 26 (16%) 26 (13%) • Other 19 (11%) 21 (10%)
POPULATION DATA • Census 1991 population of Nottingham • population at risk (16 to 64 years): 389,389 • after under-enumeration corrections: 399,439 • till 1992-94 population has increased approximately 2% and till 1997-99 approximately 6% from this estimate
ELECTORAL WARD LEVEL VARIABLES • Multiple Deprivation Index 2000 • Income • Employment • Housing • Health deprivation and disability • Education, skills and training • Geographical access to services • population density • proportion of ethnic minorities
HYPOTHESES OF THE STUDY • Incidence of psychoses is higher in more deprived areas (and/or in areas with higher population density) • Incidence of psychoses among ethnic minorities is relatively higher in areas with lower proportion of ethnic minorities • lack of social support?
CASES 1992-94 Deprivation: High to low
CASES 1997-99 Deprivation: High to low
300 272 250 222 I (high) 200 170 160 II 150 III 100 IV(low) 77 71 53 34 50 24 18 18 15 14 12 11 0 0 ALL white afro-c. others ANNUAL INCIDENCE OF ALL PSYCHOSES BY SOCIAL DEPRIVATION NOTTINGHAM 1992-1994
ANNUAL INCIDENCE OF ALL PSYCHOSES BY SOCIAL DEPRIVATION NOTTINGHAM 1997-1999 250 204 200 167 I (high) 136 150 128 II III 100 70 69 64 IV (low) 53 39 50 29 22 20 20 19 18 16 0 ALL white afro-c. others
PLAN FOR ANALYSES • Age-standardised rates (Nottingham as a standard) • Two studies separately and pooled • Results by • Sex • Ethnic group • Subdiagnoses • narrow schz, broad schz and affective psychosis • each of the six variables in the deprivation score • Poisson regression analyses
LIMITATIONS • Electoral ward as a unit? • Case-ascertainment? • Census population? • Social deprivation scores? • analyses can be repeated with other scores • Causality?
FUTURE WORK (1) • Smaller units than electoral wards • enumeration districts (no information on ethnicity) • using e.g. principal component analysis • Census 2001 variables are soon available • update all the analyses with new population data • update all the the analyses with new social deprivation variables • combinations of census 1991 and 2001 variables
FUTURE WORK (2) • Case-control study of ÆSOP • multilevel analyses with individual level variables e.g. social class • ÆSOP is a three-centre study • replicate the analyses in Bristol and South London
CONCLUSIONS • Preliminary findings: • incidence of schizophrenia is about 1.5 more common in the most deprived areas
CONCLUSIONS • Preliminary findings: • incidence of schizophrenia is about 1.5 more common in the most deprived areas • Much more work is needed in this thesis and also elsewhere to study social deprivation and incidence of psychoses • All your comments will be very helpful Thank You!