Are Males
More
Likely
William
Objective: is equivalent
G.
lacono,
Ph.D.,
in a large established
and
Morton
Beiser,
diagnostic among
systems.
males
than
than 300 interview
Results: among
The
females.
were identified, 1 75 of whom diagnoses according to five
of schizophrenia
though
M.D.
of 2”i years. A comprehensive community settings where psy-
potential subjects and were assigned
incidence Even
Schizophrenia?
the incidence of schizophrenia made to identify every first-epi-
Canadian city over a period that included hospital and
chotic persons might appear. More underwent a structured psychiatric different
to Develop
This study was undertaken to determine whether for males and females. Method: An attempt was
sode case of psychosis referral network was
higher
Females
Than
was
two
the use ofdifferent
to three
diagnostic
times systems
yielded slightly different risk rates, the elevated risk for males remained consistent. There were no differences between the sexes in the incidence of affective psychosis. In comparison with schizophrenia, the incidence rates for mood disorders with psychotic features were sometimes lower and sometimes higher, depending on the diagnostic system used. Conclusions: The findings, tional (Am
coupled
with
belief
that
reports the
J Psychiatry
in the past
incidence
1992;
1 0 years
ofschizophrenia
nowledge about the sex distribution of psychosis among adults is important for several reasons. Because males and females differ in biology, rate of maturation, social status, and duration and types of experiences encountered, differences in the proportion of males and females afflicted with a disorder can suggest etiological clues (1). Moreover, males are more likely than females to develop psychoses in childhood. Whether this pattern continues with increasing age, thus suggesting that males are more vulnerable to severe psychopathology even in adulthood, is also of great interest. Although authorities have long agreed that the prevalence and incidence of schizophrenia are the same for both sexes (2, 3), surveys in the past 10 years have provided inconsistent results. While studies in Asia (4), Europe (5-8), and North America (9, 10) have suggested an excess of schizophrenia among males, the NaReceived April 16, 1991; revision received Sept. 18, 1991; accepted Dec. 26, 1991. From the Department of Psychology, University of Minnesota, and the Department of Psychiatry, University of British Columbia, Vancouver, Canada. Address reprint requests to Dr. lacono, Department of Psychology, University of Minnesota, 75 East River Road, Minneapolis, MN 55455. Supported by grants from NIMH, the Canada Health and Welfare National Research Directorate Program, the British Columbia Health Care Research Foundation, and the Medical Research Council of Canada. The authors thank J.A.E. Fleming, M.D., T.-Y. Lin, M.D., and M. Moreau, Ph.D., for assistance with clinical data collection and diagand
Copyright
I 070
David
Erickson,
M.A.,
© I 992 American
for
help
Psychiatric
other
is the
investigators,
same
for
challenge
the
two
the conven-
sexes.
149:1070-1074)
K
nosis
from
with
data
Association.
analysis.
tional Institute of Mental Health (NIMH)-sponsored Epidemiological Catchment Area (ECA) survey suggested that among noninstitutionalized populations, rates of schizophrenia are higher among women than among men (11). The World Health Organization (WHO) study of the incidence of schizophrenia (12) demonstrated no consistent pattern of male-female differences across sites. Studies of mood disorder have been more consistent in suggesting that men and women have an equal risk of developing bipolar disorder but that women have higher rates of major depressive disorder (13). However, studies of major depressive disorden have not differentiated between the relatively small percentage of individuals who have affective disorder with psychotic features and those who have affective disorder in general. This report examines sex ratios in a broadly based sample of persons suffering a first episode of psychosis. First-episode subjects are particularly well suited for the study of sex differences. Studies that examine chronic patients risk confounding estimates of the sex distribution with sex differences in the course of psychotic illness, which is known to be more severe in schizophrenic men (14).
To avoid institutionalized
were
recruited
potential
bias
patients
from
associated from
multiple
with
a single
sources
reliance
setting,
both
on
subjects
within
and
outside the traditional mental health care system. The project goal was to come as close as possible to obtaining a sample of all residents in a major Canadian coastal city who were experiencing psychotic symptoms
Am
]
Psychiatry
1 49:8,
August
1992
WILLIAM
for the first time in their lives. Since diagnostic criteria might influence estimates of relative risk, we compared male and female incidence rates (based on the number of new cases identified each year) using different diagnostic systems. To our knowledge the present study is the first to explore sex distributions in a large, community-based, diagnostically heterogeneous sample of first-episode psychotic patients.
METHOD Subjects were recruited in Vancouver, B.C., Canada, from a metropolitan catchment area of approximately 480,000 persons. The referral network included all psychiatnic hospitals and psychiatric services of general hospitals, university and college counseling services, community mental health centers, psychiatrists in private practice, private counseling services, employment and immigration counseling services, and a random sample of one-sixth of all general practitioners in Vancouver. About 1 8% of the referrals were from other
than
inpatient
hospital
services,
including
9%
from
G. IACONO
AND
MORTON
BEISER
terview (the Present State Examination) (15). Information from the psychiatric interview, reviews of clinical charts, and interviews with family members and friends
was brought staff,
to case conferences
including
at least
two
attended
by the project
experienced
diagnosticians;
this process resulted in a “best estimate” diagnosis for each subject. We used five different diagnostic systems, which
(16) var-
ied in the breadth of their definition of schizophrenia, to classify participants: DSM-III, ICD-9, the Research Diagnostic Criteria (RDC) (17), the Feighner et al. critenia (1 8), and the 12-point flexible system of Carpenter et al. (19). With the exception of ICD-9, each of these systems has an explicit set of criteria for making diagnoses. To adapt the fairly loose ICD-9 psychotic disor-
den categories cians
criteria the
for research
used
a checklist
derived
ICD-9
from
purposes, of
the project
symptoms
the clinical
and
clini-
diagnostic
constructs
described
in
manual.
To ensure
that
subjects
received
the
most
accurate
diagnoses possible, all symptoms and diagnostic cnitena associated with the psychotic disorders described in each diagnostic system were reviewed for each patient
community mental health centers, 7% from private practice clinicians and community agencies, and 2% from hospital outpatient services. Over a period of 2 years beginning in 1982, we identified a total of 318 potential subjects for our study. Of these, 3 1 terminated contact with their referral source or disappeared before
to determine whether each symptom was present or absent. Then the diagnostic algorithms specified for each system (or the descriptive guidelines presented in ICD-9) were strictly followed to arrive at a diagnosis. Only subjects who satisfied the criteria for an active
we could contact viewed. Although
were
entered
into
ages,
sex,
them, and 94 refused these 125 nonparticipants
our
and
study,
the
we were
diagnoses
able
to be interwere not
to ascertain
assigned
by the
episode
all of whom were sode of psychosis, in the study.
To cast as wide
of psychosis.
Thus,
experiencing gave informed
their first lifetime epiconsent to participate
a referral
175 individuals,
net as possible,
we supplied
our referral agencies with a broad definition of potential cases, including persons 1 ) who were currently psychotic (i.e., experiencing hallucinations or delusions, displaying grossly disorganized behavior, showing marked thought and speech disorder, or having two of the following symptoms: marked loss of drive, social withdrawal, severe excitement, overwhelming anxiety or fear, and gross self-neglect) and 2) who had not been treated before the present episode with antipsychotic, antimanic, or antidepressant drugs. Other inclusion and exclusion criteria required 1 ) that the subjects had lived in the Vancouver metropolitan area for at least 6 months, 2) that they were between 15 and 54 years of
age,
and
illness, disorder, clinical cluding cruited
Am
]
3) that
they
did not
have
an organic
cerebral
severe mental retardation, a chronic physical or chemical dependence. A psychiatrist psychologist examined all potential subjects, doubtful and borderline cases, initially for the study using a structured psychiatric
Psychiatry
1 49:8,
August
1992
disorder
retained
in at
least
one
diagnostic
system
for study.
their
referral
sources. An additional 1 8 subjects agreed to participate but were dropped when they were found not to be psychotic or to be ineligible because they had experienced
a previous
psychotic
or inrein-
RESULTS To determine whether an excess of patients of either sex was present in a category or group, we used chisquare tests to compare observed frequencies against the a priori expectation that the sexes would be equally represented. Among the I 75 participants, who ranged in age from 16 to SO years (mean=2S.0 years, SD=7.8, for males; mean=25.7 years, SD=8.9, for females), 68% (N=1 1 9) were male, a proportion that deviated significandy from the expected rate of 50% (goodness-of-fit X222.68 ticipants system
df=1, p