Brit. 3. Psjchiat. (1976), *29, @s8-@z

A Cross-National

Epidemiological

By J. P. LEFF, M. FISCHER

Study of Mania

and A. BERTELSEN

Summary. An epidemiological study of the fIrst admission rate for mania was carried out in London and Aarhus. The case registers in these two centres were used to conduct a retrospective study of case notes covering several years, and a screening procedurewas usedfortheprospective collection ofnew casesoverthe course of one year. The annual incidence of mania was found to be virtually identical in both centres. The retrospective study gave a figure of 26 per i oo,ooo population in both Aarhus and London. But the London sample was found to contain 45 per cent of immigrants in contrast to the Aarhus sample in which only a negligible proportion

were

born

outside

Denmark.

Male

West

Indians,

in particular,

were

over-represented in theLondon sample.

The International Pilot Study of Schizo phrenia (IPSS) is a transcultural psychiatric investigation of 1,202 patients in nine countries —¿Colombia, Czechoslovakia, Denmark, India, Nigeria, China (Taiwan), the Soviet Union, the United Kingdom and the United States. It was designed as a pilot study to lay scientific ground work for future international epidemiological studies of schizophrenia and other psychiatric disorders (WHO, 1973). We report here an epidemiological study of mania in two of the above countries, which grew out oftheIPSS. In reviewing the results of the initial examina tion phase of the IPSS, it was noted that the group of patients collected in Aarhus, Denmark, contained a relatively high proportion with a diagnosis of mania. Out of a total of 129 patients,

labelled mania in one centre, schizophrenia in another. Joint training in rating psychiatric symptomatology and a series of reliability exercises were an integral part of the IPSS. The psychiatrists involved achieved acceptable inter-rater reliability in assessingpsychiatric symptoms, but no attempt was made to stan dardize their diagnostic practice. Hence indi vidual differences in the diagnostic concept of mania could account for the above finding. However, the clinical data on all the patients in the IPSS were processed both using the CATEGO program (Wing et a!, 1974) and the DIAX computerized diagnostic program (Fischer, 1974), and the resulting diagnostic categories showed a similar distribution of manic patients. (b) The median age of the population could

20

also influence

hm@oDUc'r1oN

(i6

per

cent)

were

centre psychiatrists.

diagnosed

as manic

by the

A similarly high proportion

the raw figures

for incidence

of

manic-depressive psychoses. The median age (14 per cent) was found in the group from Agra, for the population of the catchment area was but in no othercentredid the proportionof considerably lower in the developingthan in manic patients exceed 7 per cent. The propor the developed centres, varying from i8 years tion in the London group was 5 per cent. (Cali) to 39 years (Prague). The risk period is There are several possible explanations for generally estimated as 15—65years, with a mean the relatively high proportion of manic patients age at onset of about 25 years. In the IPSS in the groups from Aarhus and Agra: both first admissions and readmissions were (a) A difference in diagnostic concepts, so included, so that a high median age of the that patients with similar symptoms might be population would result, other things being 425

J. P. LEFF, M. FISCHER AND A. BERTELSEN

429

similar, in a higher admission rate for mania. (c) A difference in availability of psychiatric

(b) the presence of at least three of the above symptoms in the absence of elated mood.

services

mania on admission.

and

influence psychiatric

in admission

policies

the results. The number wards

and hospitals

could

also

of beds in

(IPSS,

Vol

i,

(c) any patient

given

a hospital

diagnosis

of

Patients were excluded if there was an organic aetiology, mental retardation, abuse of drugs, or if there were language or hearing difficulties

Table 4.') varied from 0@04 (Agra) to 2@9 (London) per thousand population,Aarhus sufficient toimpede interviewing. being at the lowerend with 1.0 per thousand Patients who satisfied the inclusion criteria population. The number of contacts with out were examined with the Present State Exami nation schedule (Wing et a!, 1974) and an patient services made up to some extent for the differences in available beds. additional schedule of manic items specially (d)Itispossible thatthescreening procedure prepared for this study*. Narrative summaries used in the IPSS was performed differently in of the psychiatrichistorywere alsoprepared. different centres. The retrospective case note study was based The first two of theseexplanations couldnot on the psychiatric case registers maintained at accountforthedifference betweenLondon and Aarhus State Hospital and the Maudsley Hospi Aarhus, and the issue was considered to be tal. The collection of data on in-patient ad worth investigating by conductingan epidernio missions is similar for both registers, but whereas diagnosisismade logical study of first admissions for mania in in Camberwell the register these two centres. The present study is an when the patientfirst contactsthe service, in evaluation of the annual incidence of mania. Aarhus the diagnosis is made on discharge or It includesmanic psychosesand thosebi-polar otherwise two months after admission. From the case registers were selected all first admissions to manic-depressives whose first admission happens tobe fora manic episode. hospitalfrom the respective catchment areas who were aged i8 to6o yearsand had a register METHOD diagnosis of mania, manic-depressi@re psychosis, or schizo-affective schizophrenia. An additional The study consisted of two parts, a prospective category of ‘¿reactive psychosis, exaltation' collection of manic in-patients and a retro spective study of case notes. The first part (298.1) was included in Aarhus and a category depression' was included in London. comprised a prospectivescreening of all of ‘¿severe psychiatric admissions from the defined catch For the Camberwell Register the diagnoses ment area in each centre (55o,ooo inhabitants are coded by the register psychiatrist from forms filled in by the psychiatrists responsible for the in Aarhus, i6o,ooo in London) to find patients between the ages of i8 and 6o admitted to patients' clinical care. For the purposes of the hospitalfor the firsttime who satisfied the register, depressive conditions are categorized criteria for a diagnosis of mania. These age as ‘¿psychoticdepression', either with or without limits were chosentoincludevirtually thewhole symptoms of mania, ‘¿severedepression' in the and ‘¿mild of the estimated risk period. The screening was absence of psychotic symptoms, carried out in both centres over the course of a depression'. The categoryof ‘¿severe depression' year. The selection criteria were: could include cases of bipolar affective illness. ‘¿Milddepression' includes the majority of (a) the presence of elated mood and at least one ofthefollowing symptoms: (i)grandiosity,neurotic depressions and was omitted from the register search. The diagnostic net was cast (2) excessive plans, (3) over-spending, giving away money, buying sprees, gambling,(ii) in quite wide to reduce the possibility of missing creased motor activity, (@) decreased need for any case of mania subsumed under another diagnosis. In Aarhus the cases were drawn sleep, (6) increased drive—food, sex, work, (7) distractibility, (8) flight of ideas. These from a 4-year period from i April 1969 to symptoms had to be present on admission or * Copies of the latter schedule are available from the withinthefirst week ofadmissionto hospital. authors on request.

A CROSS-NATIONAL

430 i April

1973;

in London

the period

was

EPIDEMIOLOGICAL

9 years

from the setting up of the Camberwell Register on i January 1965 to i January *974. The case notes were screened by means of the Syndrome Check List developed on the basis of the Present

STUDY

OF MANIA

The equivalentrate for Camberwell, with a populationof i6o,oooisi‘¿9 per 100,000. Retrospective screening of case notes After

excluding

patients

who were

found

to

have had previous admissions a total of 48 case additional manic items developed for this notes representing first admissions over a four study (see Table IV). Patients who developed year period were screenedin Aarhus. The manic symptoms at any time duringtheirfirst corresponding number forthenine-yearperiod admission were considered for inclusion in the covered in London was 172, including the study. A narrative history was compiled for manic patient who was missed during the each case thatsatisfied the inclusion criteria,prospective collection ofnew cases. and a number of items of demographic data Table I gives the relationship between were recorded. diagnoses made by the hospital doctors and by theresearchpsychiatrist. RESULTS In the London centre the new cases collected Prospective collection of new cases by prospective screening were too few for In both centresthe ongoing collection of separate analysis. As the catchment area has new cases by screening all first admissions took remained the same since the setting-up of the place between 1.12.72 and 1.12.73. In Aarhus register these two cases were added to the 36 the screening procedure was applied to Aarhus found from scrutiny of the case notes. The State Hospital, while in London the hospitals situation is different in the Aarhus centre, where screened were the Maudsley, Bethlem and the catchment area for the case note study was St Francis. In Aarhus a total of *6 patients smaller than that for the prospective study, so met the inclusion criteria, and of these 12 were that the cases collected prospectively and retro spectively are treated separately. diagnosed by the research psychiatrist as suffering from mania. In London two cases In the four-year period covered by the screen satisfied the inclusion criteria, and both were ing of case notes in Aarhus, 25 first admissions diagnosed by the research psychiatrist as mania. aged *8 to 6o with residence in Aarhus County In the Aarhus centre the catchment area is were diagnosedashavinga manic episodeby the served by three psychiatric departments in research psychiatrist. The corresponding figure State

Examination

general

hospitals

plus

in

a check

addition

to

list

the

of the

Aarhus

State Hospital. These departments may have admitted a few manics, so that the figure of 12 patients

in the screening

year is a minimum.

In the London centre the Camberwell Register was used to search for any cases missed during the screening year because of their admission to hospitals not screened. One patient with mania was discovered who had been admitted to St Olave's Hospital. Thus a total of 3 patients who satisfied the criteria for mania were admit ted for the first time from a Camberwell address during the screening year. It is noteworthy that all these patients were born outside the United Kingdom. The population in the catchment area of the Aarhus centreduring the screeningyear was

for the nine-year period pective and retrospective

in London is 38. The proportion

Aarhus sample and 55 per cent in the London sample.

The rates for mania in the two samples,

including age and sex-specific figures are given in Table II. Since

only

patients

who

were

admitted

to

hospital for the first time with symptoms of mania or who developed mania during their first

admission

were

considered

in

this

study,

patients presenting with depression and deve loping mania on a subsequent occasion would

be missed. In order to estimate the magnitude of this error, patients admitted for the first time in both centres with a diagnosis of depressive

550,000, giving an annual rateforfirstadmissions

psychosis

was selected

total population.

of males in the

two samples was very similar, 6o per cent in the

for mania

of 2@2 per i oo,ooo

covered by the pros screening procedures

were followed

up. In Aarhus

of 30 patients

admitted

a sample

for the

J.P. LEFF,M. FISCHERAND A. BERTELSEN

43'

TABus I Diagnosis according to hospital and to researchp.gvchiatrist Aarhus sample:

Retrospective

collection

of cases over four years

(no patient

with

schizo-affective

psychosis)

psychiatristManic-depressive Diagnoses by research

Mama

psych.TotalManic-depressive, Hospital diagnoses

448London .. ..

or hysterical

abuse

24

3

3

5

I

3

I I

336

6

7

3 I

25

sample: Retrospective

6

Severe

Mania

by research Schizo-

deDc-

4

and prospective yearsDiagnoses collection of cases over nine

psychiatristManic-depressive

psych.TotalManic-depressive, Hospital diagnoses circular

Reactive

noid psych.

..

and

psych. and drug

pression

.. ..

..

Dc-

Organic

circular

mania and circular Manic-depressive, unspecified 8Total Reactivepsych., exaltation..

and

Schizophrenia and para-

affective

pression

psych.

Schizophrenia

and paranoid

pression

psych,

Organic psych.

Reactive or

and

hyste-

de

drug

rical

pression

Mild

abuse

mania andcircular

..

28

5

Manic-depressive, de pression .. .. Severe depression .. 26Total Schizo-affective psych...

2 2 4

43 4 4

36

56

..

..

3

9

II 14 3

3 6

10 2 8

2 i51

28

12

29

5

first time during the period i April 1969 to i April 1970 with a diagnosis of manic

depressive, depression, made both by the hospital and the research psychiatrist. The register was checked for any later admissions during the follow-up period, which ranged from four to five years.

In London

the case notes

were examined

of all patients admitted

first

Camberwell

time

from

with

depressive psychosis between I January

1973.

The

follow-up

period

3

I

I I 3

67 28

3172

mania from first admissions only seems from the present study to be rather small. However, Pens

(1968)

reported

that

of

i 3I

bipolar

manic-depressive patients only 45 (@ per cent) were manic at the onset of the illness. Winokur et al (1969), reported on a consecutive series of 6z admissions for mania. This material consisted

for the

a diagnosis

iJanuary

2

of

1965 to ranged

TABLE

II

Annual first admission ratesfor mania per 100,000 population

from one to nine years. In both centres the age

limits of i8 to 6o years were applied. In Aarhus, of 30 cases of depressive psychosis followed up only 2 (@per cent) were readmitted with a manic episode. In London the corre

TotalMaleFemaleTotalAarhus

sponding

London..

figures were 2 (i@per cent) out of 45.

The error involvedin computing ratesfor

Al1 age groupsiS-6o

..3'I

3'I2@O

2'32@6

[email protected]

years

4.7

A CROSS-NATIONAL EPIDEMIOLOGICAL STUDY OF MANIA

432

of both bipolar manic-depressive unipolar mania. per cent) were

admission.

psychoses and

Of the 53 readmissions 29 (58 diagnosed mania at their first

If we estimate

that in Winokur's

TABus III Characteristics

of non-UK

Country

patients in London sample

at

at

of arrival first in originSexAge in UKAge admissionDifference yearsAustraliaF27292,,F1935i6CaribbeanM2526i,,M21298,,M233815,,M294 the proportionof bipolarmanic-depressives whose first episode is manic is therefore similar material

about

to what Penis

one third are unipolar

manics,

found. Both of these studies have

a considerably longer follow-up period than the average five years of the present study. Social and clinical characteristics of samples As there are major difficulties in comparing social classes across countries, the social class distribution of each sample was compared with the social class distribution of its respective general population. No significant differences emerged from these comparisons. The average

@

age of the Aarhus sample was 34'5 years and of theLondon sample32.4 years. It was noted that a high proportion of the London sample came from overseas. In fact only 21 per cent) of the 38 were born in the United Kingdom. This gives an annual first admissionrateof i•¿8 per boo,ooofornative born subjects. The immigrants came from a variety of places, as shown in Table III, the largestsinglegroup originating in the Carib bean. Five of the six West Indian patients were men.

There

were

no Asian

patients

in this

sample, reflecting the small size of the Asian population in Camberwell. It can be seen from Table III that there is considerable variation in the length of time between the immigrant's arrival in the United Kingdom and the first admission to hospital with mania. One of the Nigerian immigrants was admitted

within

a few days

of his arrival

in London. His relatives reported that he had arrived without warning and brought no luggage with him. It is very likely that his flight to London was part of the manic episode. This could not be said of any of the other immigrants in the London sample. The proportionofimmigrantsin thissample is several times the proportion in the Camber well population. The annual first admission rate

It would be of great interest

to determine

the

exact rates for the sub-groups of each nationality, however there are considerable problems affect

ing both the numerators and the denominators. A major problem in calculating thedenomina tors is that the available

census figures are not

broken down into all the national groups required. Furthermore,numeratorsformost of the national groups are too small for the calcula tion of reliable rates. Only the male West Indians form a large enough group to justify the determination

of their annual first admission

rate for mania. A further problem with the denominator, which is illustrated by the West Indian group, is that the proportion of the total population made up by immigrants from a particular country

changes

over

time.

A full

census

was

carried out in 1961, a 10 per cent census in 1966, and another

full census in 1971. The proportion

of the Camberwell population made up by West Indian immigrants changed over that period

as follows:

2@5 per cent, 4,7

per cent,

4@9 per cent. These changes reflect the general pattern of immigration from the West Indies, which was greatly influenced by the Common for mania for the immigrants, calculated from the 1971 censusdata,is 6.g/Ioo,ooo, thatis wealthImmigrationAct of 1962.The influxof nearlyfourtimesthefigureforthenative-born.West Indians reached its peak in 1964 and

J.P. LEFF,M. FISCHERAND A. BERTELSEN

@

433

dropped sharply after 1965, because very few were derived from the Camberwell Register for work voucherswere issuedto them. Thus over the years 1965 to 1974 inclusive. The diagnoses the period of this study, from 1965 to 1974, used were those coded on the register. The ratio of schizophrenia to mania was 4@7: i for the the proportion of West Indians in the Cam berwell population hardly increased at all and UK-born and 4@6: for the non-UK-born. little error can be involved in taking the 1971 Hence there is no evidence for a diagnostic census figure as representative of the whole bias of the kind postulated, and some other explanation has to be found for the excess of period. However, there is yet another problem with male West Indian manics. This is considered the

denominator.

An

immigrant

population

tends to be skewed towards the middle range of age groups, because the very young and the elderly are usually left behind. In confirmation of this, the male West Indian manics were all between

the ages of 25 and

49. A population

with an age distribution of thiskind willhave an apparently high rate of conditions such as mania

which

present

mainly

in middle

life.

further in the Discussion. In order to determine

whether

there

any differences in basic demographic non-UK

patients

were

treated

were

data, the

as a homo

geneous group and were compared with the native-born. The average ages of the UK and non-UK samples,33 and 32 yearsrespectively, the propoition

of males,

48 and 65 per cent

respectively, and the social class distributions did not differ significantly.

This source of bias becomes evident when we The proportion of immigrants in the Aarhus considerthe proportionof 25—49-year-olds in sample was very small, only two of the retro the populations being compared. They form 26 per cent of the native-born Camberwell spective sample being born abroad, in Finland males, which is somewhat lower than the and Norway. The Aarhus sample is therefore treated as homogeneous in this respect, and in national figure (32 per cent). This is because Table IV is compared with the UK and non of a continuing process of depopulation of Camberwell, with a selective outmigration of UK patients from London in terms of clinical data relating to mania, using the Symptom the middle range of age groups. By contrast, Check List for Manic Items. 25—49-year-olds make up 62 per cent of the There is evidently a very close correspondence West Indian male population of Camberwell. A comparisonof ratesformania calculated on between the clinical features of the Aarhus patients and the native-born London patients. the basis of the total populations of males would On the other hand the London immigrants result in a spuriously higher figure for the West Indians. This source of bias can be elimi include a significantly higher proportion with delusions of special abilities, grandiose identity, nated by calculating age-specific rates. When this is done the annual first admission rate for and a special mission than either of the other two groups. In fact all but one of the London mania for native-born Camberwell males be tween the ages of 25 and @g,is found to be immigrants held at least one of the delusions on the Check List, a significantly higher proportion 3.7/100,000. The corresponding rate for West than either of the two other groups. Indian males is 23.9/100,000, that is more than six times

the

native-born

rate.

Usefulness of Symptom Check List A difference of this order cannot be explained It is worth considering whether the additional by errorsin the numerator and denominator, but itcould resultfrom a diagnostic biason Symptom Check List for Manic Items was of the part of native-bornpsychiatrists, who any value for diagnostic purposes. To determine this the data from the Syndrome Check List, might be more likely to diagnose mania than developed from the Present State Examination, schizophrenia in psychotic immigrants. This possibility was checked by determining the which were available for 36 London cases were processed by the Catego program (Wing et al, ratio of the diagnoses of schizophrenia and 1974). Twenty-eight of the London cases were mania among UK-born and non-UK-born assigned to Catego class MN +, four to class first admissions from Camberwell. These data 3A

A CROSS-NATIONAL EPIDEMIOLOGICALSTUDY OF MANIA

434

T@z IV Comparison of Aarhus sample and UK and non-UK patients in London sample using the S@mptomCheck List for

Manic ItenLs sampleUKpatientsNon-UK

sample

retrospective Manic itemsAarhus patientsSignificance(25)(21)(‘7)i. (@@%)NS2. Elated mood .. Overspending .. (@i@%)NS3. Increased sexual activity

....25

Overtalkativeness (82%)NSg.Flightofideas

..

....22

..

..

Increased sociability (0%)NS12. Feeling healthier .. (0%)NS13.

....6

efficient

(24%) ‘¿3 (77%) 4 (24%)NS

(24%) 21

..

.... ..6 ....I ....3

....

more

(28%)9(i@%)4

..

io. NSu.Excessive plans .. Feeling

(ioo%)20(@@%)i6

....7

4.Increased motoractivity .. 5. Singing or dancing NS6. Decreasedsleep .. (i@%)NS7. Distractibility .. (24%)NS8.

onlyLondon

5 7

(84%)

(8i%) (@%)4 3(@%)

17

(20%)7 (68%)15(71%)8

(12%)3(x@%)4 (88%)i8(86%)14 (6o%)

(29%) 6(52%) (29%)5

8 (32%)ii

..15

,

....2

(8%)3(i@%)0

..

(8%)

(12%) ‘¿@ (@%)NS

of special abilities.. ..2 5(@4,%) (24%)2 4 (i6%)3 0'OIi6. Delusions of grandiose identity..(@%)5(24%)9 Delusions of wealth ....i (12%)NSI (@%),(@%)2 O•OIi8. 7. Delusions of a special mission..3 (12%)3(@@i,%)8 Any delusion .. ....i@ (56%)12(@@%)x6

HM +, two to class MN?, and two to class DPMN. The first three classes correspond to an lCD coding of mania. Thus the Catego classi fication was congruent with the research diagnosis

in 34 out

of 36 cases.

List,

the absence of first-rank symptoms of schizo phrenia. In the retrospective sample from Aarhus, of the 25 cases the Diax program categorized 15

Syndrome somewhat

as manic, 6 as mixed manic-depressive psychosis and 4 as hypomanic. Thus there was no dis agreement between the Diax program and the psychiatrist's

diagnosis.

The

two cases

in the London sample assigned to Catego class DPMN pose a genuine dilemma for the clini cian, who is faced with a choice between the diagnoses of mania and paranoid psychosis. An excessof eithermanic or delusional symp toms willtipthediagnosis one way or theother both

for the clinician

and for the Catego

pro

p