Department of Preventive Medicine, Faculty of Medicine and Section of Epidemiology, University Hospital, University of São Paulo, São Paulo, Brazil
Department of Psychiatry, Faculty of Medicine, and Section of Epidemiology, University Hospital, University of São Paulo, São Paulo, Brazil
Department of Psychiatry, Faculty of Medicine, University of São Paulo, São Paulo, Brazil
Department of Preventive Medicine, Faculty of Medicine and Section of Epidemiology, University Hospital, University of São Paulo, São Paulo, Brazil
Department of Psychological Medicine, Institute of Psychiatry, London, UK
Correspondence: Professor Dr Paulo R. Menezes, Department of Preventive Medicine, University of São Paulo Medical School, Av. Dr. Arnaldo 455, Sao Paulo–SP, Brazil, CEP 01246-903. Email: pmenezes{at}usp.br
Funding detailed in Acknowledgements.
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Aims To estimate the incidence of psychosis in São Paulo, a large metropolis of Brazil.
Method Prospective survey of first-episode psychosis among residents aged 18–64 years resident in a defined area of São Paulo, over a 30-month period (July 20 2002–December 2004). Assessments were carried out withthe SCID–I, and diagnoses given according to DSM–IV criteria. Population at risk was drawn from the 2000 Census data.
Results There were 367 first-episode cases identified (51% women), and almost 40% fulfilled criteria for schizophrenia or schizophreniform disorder. The incidence rate for any psychosis was 15.8/100 000 person-years at risk (95% CI 14.3–17.6). Incidence of non-affective psychoses was higher among younger males.
Conclusions Incidence of psychosisin São Paulo was lower than expected for a large metropolis.
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In Brazil, as in many low- and middle-income countries, marked demographic changes have taken place in recent decades, with population ageing and disorganised urbanisation (Cohen, 2003). These changes may have had an impact on the incidence of psychosis, since there has been an increase in the adult population at risk and in possible risk factors, such as migration, as well as higher exposure to viruses and to adverse life events. There is a lack of empirical data on the incidence of schizophrenia and affective psychoses in such settings. The present study aimed to estimate incidence rates of first-contact psychosis in São Paulo, the largest city in Brazil.
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Mental healthcare in São Paulo is provided mainly by the public sector, and a small proportion of the population receives mental healthcare from the private sector. Mental healthcare in the public sector is partially organised on a catchment-area basis. Emergency 24-h psychiatric services can be sought by anyone who needs immediate attention, regardless of where they live. Inpatient care is provided by some public psychiatric hospitals and by private hospitals that offer psychiatric beds to the public sector on a fee-for-service basis. There is a central registry service that controls all admissions to psychiatric in-patient care paid for by the public sector in the city, except for a few beds in some public general hospitals with psychiatric in-patient units. For individuals suffering from psychosis, mental healthcare centres offer out-patient appointments with psychiatrists, and may deliver typical antipsychotic medication. A small proportion of patients may have access to psychotherapy, occupational therapy, social support or day-hospital care. A few primary care centres that have mental health professionals may offer care to adults with psychotic disorders. Private mental healthcare includes both exclusively private care, where all expenses are paid for by the client, and care provided by healthcare plans, where clients can only use services specified by the healthcare plan company. About 40% of the population are covered by private healthcare plans, and seek healthcare in private clinics and hospitals. However, until recently such plans did not cover psychiatric care. Fully paid in-patient psychiatric care is available in a small number of clinics and private hospitals. There are hundreds of psychiatrists in the city who offer private consultations, with a wide range of fees.
The area defined for the study was composed of 21 administrative districts, in the central, western and northern regions of the city, with a total population of 1 382 861 inhabitants in the year 2000 (Prefeitura do Município de São Paulo, 2006). This area includes residential middle-class regions, deprived inner-city areas, working-class residential regions, and areas of favelas. Mental health services that offer care for the public sector in the area include five 24-h emergency services, six mental health centres, four in-patient units in public hospitals, and five primary care centres with mental health professionals. There are three teaching hospitals, two of them from public universities, located in the area of the study. These hospitals have large psychiatric services, and access to care in these services does not follow geographical catchment-area restrictions.
Case identification and ascertainment
All mental health services, public or private, from which individuals
living in the area defined might seek help for a psychotic episode, were
screened to identify all possible cases of first-contact psychosis. This
included the services listed above, plus the central registry service for
psychiatric inpatient admissions paid for by the public sector, all private
psychiatric hospitals and clinics in the city of São Paulo, and two
psychiatric services from private healthcare plans. Over 300 psychiatrists who
work privately, whose names and contacts were drawn from the Brazilian
Psychiatric Association list, were contacted by post and by phone and asked to
say whether they had seen first-contact patients who lived in the area defined
for the study during the period specified below. Medical records of each
service were browsed on a regular basis. Contact details of individuals with
any suggestion of a consultation or admission due to psychotic symptoms were
collected, because quite often it was not possible to establish whether it was
a first contact or not from the medical records. Confirmation of first-contact
had then to be made by phone or home visit.
Eligible individuals were all adults aged 18–64 years, resident in the defined geographical area of São Paulo for at least 6 months, who had a first contact with any mental health service due to a psychotic episode between 1 July 2002 and 31 December 2004. Participants had to meet DSM–IV criteria (American Psychiatric Association, 1994) for psychotic disorder (295.10–295.90; 297.1; 298.8; 298.9; 296.0; 296.4; 296.24).
DSM–IV diagnoses were obtained for those who agreed to be interviewed, using the Structured Clinical Interview for the DSM–IV Axis I Disorders (SCID–I; Spitzer et al, 1992). For those who refused a direct assessment or for those who could not be directly contacted for other reasons, DSM–IV diagnoses were made based on information gathered from case notes and informants, wherever possible. Assessments were carried out as close as possible to the identification of each case in the mental health service. Interviews with participants took place at participants homes, and were carried out by mental health professionals trained in the use of the standardised assessments. Training of interviewers included sessions for discussion of all standardised assessment schedules used in the study, and interview of patients with psychosis by each interviewer, watched by all remaining interviewers and coordinators of the study, followed by discussion. There was constant supervision of interviewers during the study, with discussion of difficulties and doubts in any of the schedules of the study protocol. Written informed consent was obtained from all participants.
A leakage study was also carried out, in order to identify cases missed throughout the study period, and included surveillance of cases who had a first contact during the period of the study but were only found at a later date by the research team and review of casenotes of services not routinely visited by the research team.
Analysis
The total number of person-years at risk was calculated using the number of
resident individuals aged 18–64 years living in the area defined for the
study (926 081), according to data from the 2000 Census of the Brazilian
population, multiplied by 2.5, to give the population at risk over the
30-month period of inclusion of cases. Overall, non-standardised incidence
rates were estimated for first-contact psychosis (all diagnostic categories
above), non-affective psychoses (DSM–IV codes 295.10–295.90;
297.1; 298.8; 298.9) and affective psychoses (DSM–IV codes 296.0; 296.4;
296.24). Respective binomial exact 95% confidence intervals were calculated.
Age- and gender-specific incidence rates were also estimated, with 95%
confidence intervals.
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The mean age at first contact for any psychosis was 32.9 years (95%CI 31.7–34.1), and the median age was 30.0 years (Table 1). The average age at first contact for men was younger than for women, and the distribution of age at first contact was more positively skewed for men than for women. Similar patterns of skewness were observed for both non-affective and affective psychoses. Men showed mean and median ages at first contact for non-affective psychoses 4–5 years younger than for affective psychoses, whereas for women there were almost no differences between non-affective and affective psychoses.
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View this table: [in a new window] | Table 1 Mean and median ages at first contact for any psychosis, non-affective and affective psychoses by gender |
The unadjusted rate for first-contact psychosis was 15.8 per 100 000 person-years at risk (Table 2). Rates for non-affective and affective psychoses were 10.1 per 100 000 and 5.8 per 100 000, respectively. First-contact psychosis rates declined with increasing age; this was mostly due to rates of non-affective psychoses among the male population, which showed the highest rates in younger age groups followed by a sharp decline in older age groups (Figs. 1 and 2).
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View this table: [in a new window] | Table 2 Population at risk, number of cases (n) and incidence rates of first-contact psychosis, non-affective psychosis and affective psychosis by age group and total population |
![]() View larger version (13K): [in a new window] [as a PowerPoint slide] |
Fig. 1 Incidence rates of non-affective (a) and affective (b) psychoses by age
group among women.
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![]() View larger version (13K): [in a new window] [as a PowerPoint slide] |
Fig. 2 Incidence rates of non-affective (a) and affective (b) psychoses by age
group among men.
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Age at first contact also followed patterns observed previously (van Os et al, 2000; Boydell et al, 2001; Svedberg et al, 2001; Scully et al, 2002; Welham et al, 2004; Kirkbride et al, 2006). More than 60% of the cases had their first contact before the age 35, confirming that psychosis is more frequent in young adults, but a proportion of cases can occur at older ages. Men had younger mean and median ages at first contact than women for both affective and non-affective psychoses, a finding also consistent with results from some recent studies carried out in high-income countries (Svedberg et al, 2001; Scully et al, 2002; Kirkbride et al, 2006). However, comparison of mean or median age at first contact between studies is not straightforward, since there is variation in the age range criterion used in each study. Some studies have used the age range 15–45 or 15–54 years, which will influence their samples towards younger age means, whereas those that have wider age ranges, particularly for the upper limit, will tend to find older sample means. Comparison of age- and gender-specific incidence rates is less subject to such methodological issues. However, few studies yielded age- and sex-specific incidence rates for both affective and non-affective psychoses, making comparison of results limited. Age- and gender-specific rates from the present study are lower than those found in the UK (Kirkbride et al, 2006), but rates in that study were influenced upwards by the uncommonly high rates found in South London. A recent study carried out in Queensland, Australia (Welham et al, 2004) also estimated age- and gender-specific incidence rates for affective and non-affective psychoses, and results from both studies are remarkably similar.
Limitations and implications
The incidence rate of first-contact psychosis may have been underestimated.
It is possible that a small proportion of first-contact psychosis cases were
not identified due to missing files, lack of any notes that could allow
checking for possible diagnosis or address, or because they were not living at
the address provided. Use of private psychiatric services not covered by the
present study, and non-inclusion of psychoses due to intoxication or
withdrawal of psychoactive substances may also have contributed to the low
rates. However, these cases only accounted for small proportion of the total
number of cases of psychosis in two recent studies
(Scully et al, 2002;
Kirkbride et al,
2006). It is unlikely that the low incidence rates might be due to
non-detection of cases owing to premature death or to moves to other areas of
the city. The main cause of premature death among individuals with psychosis
is suicide (Craig et al,
2006). However, suicide rates in São Paulo are much lower
than those observed in high-income countries
(Mello-Santos et al,
2005). Moving house because of psychotic breakdown is also
unlikely, since around 80–90% of those with psychosis in São
Paulo live with their relatives and most rely entirely on their families to
survive (Menezes & Mann,
1993). Therefore, even if our rates may be slightly
underestimated, we nevertheless believe that we have identified the vast
majority of cases. Non-systematic errors regarding diagnosis may have
happened, but are not likely to explain the patterns observed. The areas
covered by the study were heterogeneous regarding socio-economic status of the
population, but there are large parts of the city with higher proportions of
more deprived areas. This means that if the incidence of psychosis varies
within city areas, and if this variation is associated with neighbourhood
socio-economic levels, the present rates may be also slightly underestimating
the overall rates for the metropolis.
We did not examine the possible association between incidence of psychosis and ethnicity. One of the marked characteristics of the Brazilian population is its ethnic admixture. According to the Brazilian Census, which uses self-reported skin colour or ethnicity, in the State of São Paulo 71% of the population classify themselves as white, 4% as black, and 23% as mixed (Instituto Brasileiro de Geografia e Estatística, 2006). Genetic studies also have shown that in Brazil, ethnic phenotypes do not allow adequate classification of ethnic ancestry, because of the high levels of admixture (Parra et al, 2003). Therefore, the Brazilian population is not adequate to explore comparisons of incidence of psychosis by ethnic group. However, modern genotyping techniques are allowing more precise measurement of the amount of different genetic ethnic ancestries in individuals, and these techniques could be used to examine possible associations between degree of admixture and risk of psychosis, using a case–control design.
The studies on the outcome of schizophrenia coordinated by the WHO showed a better prognosis among those with psychosis living in lower- and middle-income societies (Jablensky et al, 1992). If the relatively low incidence rates observed in the present study are followed by a high proportion of recovery, then a low prevalence of psychosis would also be expected, and that might have an impact on planning and provision of mental health services. However, more recently the notion of a better outcome of psychosis in lower- and middle-income countries has been disputed, based on some methodological limitations of the WHO studies, the lack of evidence for specific sociocultural factors that might contribute to a better prognosis of psychosis, new data showing a gloomier picture for the prognosis of psychosis in some lower- and middle-income societies, and on important economic and demographic changes that are taking place in many lower- and middle-income countries (Patel et al, 2006). Indeed, São Paulo follows more closely the patterns of living conditions and social demands found in industrialised societies, and therefore the prognosis of psychosis may not be a favourable one. Follow-up of the present first-contact cohort will help to answer this issue.
Recent studies are helping to show how the observed variation in incidence rates between different ethnic or social groups may be at least partly explained by heterogeneous distribution of psychosocial risk factors (Wicks et al, 2005; Morgan et al, 2006). Similar investigations in different settings (large and smaller urban centres, rural areas) from lower- and middle-income countries must be carried out in order to contribute to a better understanding of the determinants of the incidence of these disorders.
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