Brazilian multicentric study of psychiatric morbidity. Methodological features and prevalence estimates N Almeida-Filho, J Mari J de, E Coutinho, JF Franca, J Fernandes, SB Andreoli and ED Busnello The British Journal of Psychiatry 1997 171: 524-529 Access the most recent version at doi:10.1192/bjp.171.6.524
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Brazilian multicentric study of psychiatric morbidity Methodologicalfeaturesand prevalenceestimates NAOMAR ALMEIDA-FILHO,JAIRDEJESUSMARl, EVANDROCOUTINHO, JOSIMARFARIASFRANcA, JEFFERSON FERNANDES, SERGIO BAXTER ANDREOLI and ELLIS D'ARRIGO BUSNELLO
Background
Psychiatric morbidity
studies in developing countries have used diagnostic procedures of low reliability, without a clinical definition of caseness, producing descriptive data with limited application for mental health planning.
Method
A two-stagecross-sectional
design (with a sample size of 6476) was conducted to estimate the prevalence of DSM —¿ IIIpsychiatric diagnoses in three metropolitan areas of Brazil (Brasilia, SãoPaulo and Porto Alegre).
All subjectswere screenedfor the presenceof psychopathologywith a 44-item instrument (the QMPA) and a subsample was selected for a psychiatric interview.
Results Age-adjustedprevalence ofcasespotentially in needofcare ranged from l9% (SãoPaulo) to 34% (Brasilia and Porto Alegre). Anxiety disorders comprised the highest prevalences (upto 8%). Alcoholism yielded the most consistent prevalence levels, around 8% in all sites. Depression showed great variation between areas: from lessthan
3% (São Pauloand Brasilia)to 10% (Porto Alegre).
Conclusions Overallprevalences were highin comparisonwith previous studiesconducted in Brazil.A female excessofnon-psychotic disorders (anxiety, phobias. somatisation and depression) and a male excess for alcoholism were consistently found.
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Epidemiological surveys of psychiatric morbidity carried out in Latin America (Tarnopolsky et a!, 1977; Gonzalez et a!, 1978; Gallegos & Miguez, 1984; Penayo et a!, 1992) have produced descriptive data with limited use for the planning of mental health programmes. Such studies have been usually based on community samples and direct application of screening question naires, sometimes followed by a diagnostic assessment of potential cases. In Brazil, exemplary of this methodological pattern is the series of population studies of psychiatric morbidity conducted in the State of Bahia during the past decade (Santana, 1982; Almeida-Filho et a!, 1983, 1989). However, a new generation of psychiatric morbidity studies, based on standardised diagnostic instruments and improved classification systems, have in many ways followed the guidelines estab lished by the Epidemiological Catchment Area (ECA) surveys conducted in the USA (Robins & Regier, 1991). This paper reports some of the methodological features and prevalence findings of the Brazilian Multicentric Study of Psychiatric Morbidity, which was conducted in three metropolitan areas of different regions of Brazil (Brasilia, São Paulo and Porto
Alegre), with a study design and classifica tion system compatible with contemporary psychiatric epidemiological research, en hancing the comparability of research findings.
METHOD The research sites were chosen as being representative of different geo-cultural re gions of Brazil. SãoPaulo is the biggest metropolis in South America, with more than 16 million inhabitants. It is located in the south-east, the most industrialised and urbanised region of the country, and its peripheral, impoverished areas receive migrants from all over the country. Brasilia,
currently the national capital city, with almost 1.2 million people, is located in the central west region. The city is formed by a core sector, named Plano Piloto, which concentrates bureaucratic and administrat lye services and apartment buildings of public employees, surrounded by satellite towns populated by low-income people who work as helpers and servants in the city centre. Porto Aiegre is the capital city of the State of Rio Grande do Sul, located in the southern section of Brazil, whose economy is largely agro-industrial. With about 2 million inhabitants, this metropolis is populated mainly by descendants of European immigrants. A two-stage cross sectional design was applied to a represent ative sample of adults (aged more than 14 years) in the three research sites. A pilot study was conducted in Brasilia to test the feasibility of the methodology.
Sampling design The study used a cluster sampling strategy, based on the stratification of all census units within metropolitan limits. This strat egy was successfully employed in Brasilia and Porto Alegre, but in SãoPaulo, because of its population size, the stratification was performed in three of the 48 districts that comprise the metropolitan area. Census units were randomly selected and, with the help of updated surface maps, cluster blocks and housing units were identified and also randomly selected for inclusion in the study. Sample size calculations were based on modules of 900 individuals, within a 2% precision interval for preva lence estimates of up to two strata (to allow male—female comparisons). The baseline sample size was 1800 subjects. Considering expected losses and refusals of 10%, the number of eligible interviewees for the first screening phase was established as 2000 subjects for each research site. For the second phase of diagnostic confirmation, a subsample (n=300) was drawn for each base sample, including 30% of screened probable cases and 10% of probable non cases. The final sample sizes were the following: Brasilia, 741 housing units, 2345 sample, 285 subsample; SãoPaulo; 600 housing units, 1742 sample, 236 subsample; Porto Alegre, 903 housing units, 2384 sample, 3 15 subsample; total: 1244 housing units, 6470 sample, 836 subsample.
Data collection —¿ first phase In the first phase of the fieldwork, the following instruments were applied: (a) a family chart, covering demographic and solo-economic information (including mi grational and occupational history); (b) the QMPA (Questionário de Morbidade Psi quiátrica de Adultos), a 44-item screening instrument developed by Santana (1982) for the detection of psychiatric morbidity in epidemiological studies adequate for the Brazilian urban environment. Different validation tests have showed adequate
sensitivity (89—93%)and specificity (72—
@
98%), and low misclassification rates (6— 12%) for the instrument; a reliability study of the supporting diagnoses found a kappa of +0.88 (Santana, 1982). The research team for this first phase was composed of a total of S1 interviewers (16 in BrasIlia, 15 in SãoPaulo and 20 in Porto Alegre). They were either medical students or had a university degree in a health profession (nursing, psychology), and received a 72-hour training pro gramme, basically through techniques of role-playing, and had several reliability tests throughout the fieldwork. They were also trained in the field, in order to get acquainted with each research setting, by practising questionnaire application to fam ilies not included in the sample. Each interviewer was in charge of approximately 60 families.They were instructedto do the first visits at meal times, weekends and in the evenings, up to three times before con sidering that unit missing. The screening questionnaire was answered by each family member older than 14 years. The survey received major coverage by local media, in order to reduce the refusal rate to a mm imum. Field supervisors monitored closely the data collection, revisiting participating families at random to ensure the quality control of the fieldwork. The duration of the first phase of fieldwork varied from two (Brasilia, SãoPaulo) to three months (Porto Alegre).
Data collection —¿ second phase In the second stage, a subsample of individuals considered as probable cases (QMPA scores above 7) had diagnostic interviews with a team of psychiatrists specially trained for this type of investi gation. These diagnostic interviews took an average of 35 minutes, and included the application of the Brazilian version of the DSM—III Symptom Checklist, translated
and adapted by Miranda et a! (1987). The survey employed a total of 25 psychiatrists and clinical psychologists (six in Brasilia, eight in SãoPaulo and 11 in Porto Alegre), trained in the use of the checklist through a 46-hour intensive programme developed by the Escola Paulista de Medicina, including clinical supervision and a reliability check of the interviewers. A subsample of the possible non-cases was also interviewed by the second-phase team, in order to mini mise false positives. Neither interviewers nor respondents had previous information on scores or on screening status. Results of the diagnostic interview were also regis tered in terms of the diagnostician's degree of confidence in the presence of psycho pathology, duration and severity of symp toms. The interval between the first-phase interview and the diagnostic examination varied from one to four weeks. Due to out migration and irregular working schedules, it was
impossible
to locate
42 subjects
(15
in Brasilia, 16 in SãoPaulo, 11 in Porto Alegre) assigned for second-phase inter viewing.
of the screening instrument, taking as a gold standard the DSM-.III Symptom Checklist. Sensitivity, specificity, negative and positive predictive values were calcu lated for each study site and within every stratum of gender and age. These correc tions were done according to the following formula: Pe=Ps (VP+)+Pn (1—VP—) where Pc is the prevalence estimate, Ps is equivalent to the proportion of QMPA
positives In the sample, Pn is the proportion of QMPA negatives, VP+ and VP— are, respectively, the positive and the negative predictive values of the screening instru ment. Prevalence estimates according to diag nostic categories were calculated consider ing the contribution of each diagnostic group in the subsample of confirmed cases, multiplied by the overall prevalence or need-for-treatment age-adjusted rates, ac cording to the following formula: PDC=Pe (FdTfc)
Data analysis The indicators of psychiatric morbidity considered in the present research were: (a) lifetime prevalence, based on summing up all cases of any psychiatric symptoma tology at any point in a lifetime, as detected by the QMPA and adjusted by the second phase results; (b) one-year potential need for-treatment (PNT), defined as the pre valence of cases that occurred within the past 12 months, which potentially needed professional assistance as assessed by the second phase diagnostician on the basis of both the clinical examination and the self report of interviewees. In order to help prevalence comparison between study sites and with other research, the extensive list of DSM—IIIdiagnoses was condensed into a smaller number of groups (10 categories), according to their frequence and similarity, following ICD—10 hierarchical criteria. Some DSM—IIIdiagnostic categories, such as cognitive impairment, anorexia nervosa and bulimia, antisocial personality, drug abuse and addiction, psychosexual dysfunc tion, and tobacco use disorder, were excluded from the data analysis because the screening methodology seemed made quate for their identification in the com munity. Prevalence estimates were calculated adjusting for the differential performance
where PDC is the prevalence by diagnostic category, Pc is equivalent to a prevalence estimate (calculated as above), Fd is the frequency of cases in that diagnostic cate
gory, and Tc corresponds to the total of cases confirmed in the second phase of the study. Lifetime prevalence and PNT estimates were adjusted using the indirect method, taking the age and gender distribution of the Brasilia pilot study as a standard population. Sampling standard errors of the prevalence estimates were calculated in accordance to Fleiss's (198 1) criteria. Man tel—Haenszel tests were performed to assess the statistical significance of intra area gender comparisons (Kleinbaum et a!, 1982). Inference-based confidence intervals are not indicated for inter-area compar isons because the prevalences were esti mated from samples of different reference populations.
RESULTS As shown in Table 1, overall lifetime prevalences of psychiatric symptoms, stan dardised by age, were unexpectedly high in the three areas surveyed: the metropolitan region of Brasilia showed the highest life time prevalences, around 51% ( ±3.4%), followed by Porto Alegre, with 43%
525
Table I
Age.adjustedlifetimeprevalence(LTP)andone-yearpotentialneed.fortreatment (PNT) estimates
states came second place: 17% in Brasilia and 8% in SãoPaulo. The nosological profile of the Porto Alegre sample was quite distinct: phobic disorders were the most Brasilia SãoPaulo PortoAlegre prevalent (14%), followed by depressive and anxiety states. Alcohol abuse/depen LTP PNT LTP PNT LTP PNT dence was also well-ranked among the Anxietydisorders17.612.110.66.99.65.4Phobicstates16.7I diagnostic categories considered, occupying .67.65.014.17.1Somato-dissociativedisorders8.15.82.81.94.82.8Obsessive—compulsivedisorders0.70.5——2.1.2Adjustmentdisorders2.01.30.60.4.6.0Depressivestates2.81.5.9. the fourth place in Porto Alegre (lifetime prevalence 9%), sharing the third position with somato-dissociative disorders in Bra silia and the second place with phobic states in SãoPaulo (lifetime prevalence around 8%). The overall prevalence of learning disability was consistent at around 3% in all areas studied. The group of abuse/dependence8.04.77.64.39.28.7Learningdisability3.0.92.61.63.4.8Allcases'50.534.131.019.042.533.7 psychotic disturbances reached prevalences of less than 1% for Brasilia and SãoPaulo, but more than 2% in Porto Alegre. Table 1 also shows PNT prevalences by I. The'aII cases'estimates do not correspond to the sum ofprevalences by diagnosisbecauseofthe occurrence of comorbidity. diagnostic groups. In Brasilia, approxi mately 12% of the population potentially needed mental health care because of than males, while for Brasilia and SãoPaulo (±3.5%), and São Paulo, around 30% anxiety disturbances and/or phobic states; they were not significantly different. Among ( ±3.6%). Age-adjusted prevalences of somato-dissociative disorders ranked sec PNT ranged from 19% ( ±3.5%) for São males, Porto Alegre showed the highest ond with approximately 6%, followed by PNT prevalence (34%; ±5.3%), followed Paulo to 34% (±3.2%) for Brasilia and alcoholism (almost S%). In SãoPaulo a by Brasilia (27%; ±2.5%) and SãoPaulo Porto Alegre. similar profile was observed, with anxiety (19%; ±4.7%). For females, Brasilia had The stratification by gender revealed disorders and phobic states ranking first the most elevated PNT prevalence (41%; diverse morbidity profiles for each site, as and second-place (7 and 5%, respectively), ±3.2%), approximately 25% bigger than seen in Tables 2 and 3. Among males, in Porto Alegre and more than twice the São and alcoholism in third (PNT=4%). For lifetime prevalence in Brasilia was 47% both cities, the PNT for psychotic disorders Paulo estimates. There was a clear excess of (±4.5%), higher than for São Paulo (33%; in general did not reach the 1% prevalence PNT prevalence among females in Brasilia, ±4.3%) and Porto Alegre (34%; ±5.4%). level. Findings from Porto Alegre indicated while PNT estimates by gender in SãoPaulo Among females, the highest prevalence was a distinct pattern: the most salient pathol and Porto Alegre seemed equivalent. still found in Brasilia (54%; ±4.3%), ogy was alcoholism (PNT=9%), followed Lifetime prevalence estimates by DSM slightly higher than in Porto Alegre (50%; by phobic and depressive states (around ±4.0%)but almosttwice asmuchasin São III diagnoses are presented in Table 1. 7%), and anxiety and somato-dissociative Anxiety disorders ranked first in Brasilia Paulo (29%; ). Only in Porto Alegre did disorders, respectively, with 5% and 3%. (18%) and in SãoPaulo (11%). Phobic females have overall prevalences higher
of DSM—III diagnoses in three metropolitanareasof Brazilin 1991
Table2 Age-adjusted lifetimeprevalence estimates ofDSM—lll diagnoses bygenderinthreemetropolitan areasofBrazilin1991
BrasiliaSãoPauloPortoAlegreMaleFemaleRatioMaleFemaleRatioMaleFemaleRatioAnxietydisorders3.621.6l.59@7.33.9l.90**5.24.02.69**Phobicstates10.822.72.I0**4910.42.12**7720.52.66@Somato-d
I. The'all cases'estimates do not correspond to the sum of prevalencesby diagnosisbecauseofthe occurrence of comorbidity. NSat P>0.05: ,0.05>P>0.005; es, P
