@rit. 3. Psychiat. (i977),
530, i6@6
Mortality in Patients with Schizophrenia, Mania, Depression and Surgical Conditions A Comparison with General Population Mortality By MING T. TSUANG Summary.
Mortality
data
and ROBERT
are presented
from
F. WOOLSON
a four-decade
follow-up
study
of 200 schizophrenic, 100 manic, 225 depressive patients, and i6o surgical controls (8o appendicectomy; 8o herniorrhaphy). Data for this analysis were available on 648 per cent) members of the study population. Using sex-age
@
standardized
mortality
population
was compared
served by the admitting
ratios
(SMR),
the mortality
experience
of the study
with that of the state of Iowa, the geographical
medical
facility for the study group.
Results
area
are presented
for a four-decade period beginning ‘¿935—44, and ending 1965—74.All three psychiatric groups had a significant increase in mortality risk. This was most pronounced in the first decade following admission, although schizophrenic patients, especially females, continued to show a significant excess of deaths throughout the entire four decades of the follow-up period. During no decade of the follow-up period did the mortality of the surgical controls differ significantly from that of the Iowa population.
Mortality in psychiatric populations has several times been shown to be higher than in comparable non-psychiatric populations (i, 3,6, 14);
however,
as
Kendell
(7)
points
out,
there
have been few studies reporting the mortality associated with specific psychiatric illnesses. The present paper reports increased mortality risk in schizophrenia and affective disorder. The data of this report were derived from our on-going research project, ‘¿Follow-upand family studies of schizophrenia, mania, and depression'
(i 7). The
results
of our study
seem
to indicate not only excess mortality generally but an increased risk of death associated with sex, specific diagnosis, and decade of follow-up period. SUBJECTS AND METHODS
During a two year period from early 1974 to the end of 1975, we have been conducting a combined 35-year follow-up and family study of
525
systematically
diagnosed
former
psychiatric
patients. The study subjects were selected by reviewing case records of patients consecutively admitted to the Department of Psychiatry, University Hospitals, Iowa City, during a ten year period from 1935 to 1944. Two hundred cases of schizophrenia
and 325 cases of primary
affective disorder (225 depression and zoo mania) were selected according to specified research criteria (i i). In order to have a base line for comparison
with the psychiatric
patients,
we selected a group of i6o control patients from the hospitals' Department of Surgery, all of whom were free from psychiatric symptoms. On preliminary examination, the Department's patient populations of appendicectomy and herniorrhaphy appeared to be appropriate to serve as non-psychiatric
controls.
A stratified
ran
dom sample of 8o cases of appendicectomy and 80 of herniorrhaphy was proportionally matched to the psychiatric group for the factors of time, ‘¿6a
MING T. TSUANG
AND ROBERT
period ofadmission, age, sex, and socio-economic status (as determined by pay status of the sub ject). In the final make-up of the index popu lation (525 cases + I6o controls), there were 45 per cent male and 55 per cent female subjects. The schizophrenia,
mean ages of admission were: 29 years; mania, 34; depression,
44; and controls, white. Follow.@ip
31. All study subjects were
information
on
these
cases
is
obtained through telephone and personal inter views with index cases and family members@ medical
records
at other
institutions@
and vital
statistics documents from health departments of the various states. In so far as possible, all study data are gathered
on standard
forms@which
are pre-coded for easy translation to computer cardL Each index patient for whom we obtain any current
follow-up
information
is immediately
given ratings on several variables which we consider relevant to outcome. These ratings represent either current status, or status at the time of death.
For this reason,
the basic item of
information about an index case is whether he or she is still alive. We have been able to make this determination for 95 per cent of the index population. We have recently begun analysing mortality status
as an outcome
variable
in its own right,
using age-sex standardized mortality ratios (SMR). A follow-up period from 1935 to 1974 was selected. This included the earliest possible year in which an index case could have died, and provided for a convenient division of the period into four separate decades of follow-up for which Iowa state population statistics could be obtained. Fbr those index cases whose mortality status was ascertained, as of 31 December 1974, an analysis was performed on the observed number of deaths in each cohort by comparison with the Iowa population and the Iowa mortality statistics. To compare the mortality experience o( the psychiatric sample with a relevant base popula tion, age-sex specific mortality rates were com puted for the state of Iowa for each of the last four census years; i.e. 1940, 1950, 1960, ar@d 1970.
Mid-year
abstracted
populations
for
for the four respective
the
state
were
census years
163
F. WOOLSON
(18—21). Mortality data, in terms of numbers
of
deaths during the year, were taken from 1940, ‘¿950, 1960, and 1970 respectively (22—25).The resulting age-specific mortality rates were used to construct the expected mortality pattern of each diagnostic group; this expected pattern, so constructed, was then contrasted to the observed mortality experience in the group. More precisely, we proceeded as follows for each diagnostic group: (a) Observed number of deaths by age (in b-year intervals 0-9, 10—19,etc) and sex were tallied
by decade of follow-up (I@-44,
1945—54,
1955—64, I965—74)@
(b) Age-sex specific mortality rates (age in io..year •¿ intervals) were computed
for 1940, 1950, 1960
and 1970 as described above. (c) The total person-years exposed to the risk of, death was computed for each diagnostic group by decade of follow-up, age (in 10-year inter vals) and sex. (d) For each decade and age-sex category, the age-sex specific mortality rate computed in step (b) was multiplied by the person-years at risk in step (c). This is the expected number of deaths for individuals in this age-sex group during the particular follow-up decade. It is assumed
that the Iowa age-sex specific mortality
rates apply throughout the follow-up decade. (e) For each decade of follow-up, the expected number of deaths was summed across all ages for each sex and each diagnostic group. This
is the age-adjusted expected number of deaths. (f) The observed number of deaths was summed across all ages in the same manner as described in step (e). The age-standardized mortality ratio (i.e. observed number of deaths in step (f) divided by expected number of deaths in step (e)) was computed for each sex and decade of follow-up. The single degree of freedom chi-square statistic was calculated to determine whether the age.. standardized mortality ratio (SMR) deviated significantly from one. A P value of less than •¿o5
was considered statistically significant. As described above, our statistical analysis is a hybrid of an analysis used in conventional longitudinal studies (i.e. the person-years of risk from a life table analysis) and one used in typical cross-sectional studies (i.e. indirect adjustment of rates). This method requires very few assumptions, principally that the Iowa
164
MORTALITY
IN PATIENTS
WITH SCHIZOPHRENIA,
death rates remain stable within each follow-up decade, and utilizes all of the available mortality statistics for the state. The mortality of 95 per cent (648/685) of the index population was available for the present analysis.
The
remaining
37 cases were
elimin
ated from the mortality analysis. Of the 648 cases, 346 had died during the designated follow up
period
(1935-1974);
302
were
known
MANIA, DEPRESSION,
assumptions
SURGICAL
of two possible
CONDITIONS
extremes;
namely,
the date of death was assumed to be the year of admission, and alternatively, the closing year of the study.
Neither
assumption
produced
substantially different from below which were obtained allocation.
results
those presented by proportional
RESULTS
to
have survived the entire period. For 35 of the known deceased no precise date of death could
It can be seen from the table that increased mortality risk was found in schizophrenia,
be ascertained,
mania,
although
the fact of death
was
certain. These cases were proportionally al located a date of death using a conditional probability distribution based upon the age-sex specific mortality rates for the state of Iowa during this period. The data were likewise analysed
with
these
cases allocated
under
the
and depression,
and that
no significant
excess mortality was found among the surgical controls. Analysis of the data according to decade and sex shows significant
excess mortality
in the first
decade (i@-@) for both sexes in all psychiatric sub-groups except male manics. Although the
TAiiz.x I
Observednumberof deaths (a), expectednumberQfbat/is (b) and standardizedmortalit, ratio (c) CohortSexn1935—441945—541955-641965—74Schizophrenia
i.@F939@OO
N =
58o b2@I3 2@65 ii@8i c 4.69**9@OO 3.4o**5@OO o@86I7@0O
192Maio@oo
1.80*ManiaM345@0O
I@26N
5.34
2@73 3.30**4.()()
3.07 I@301I@0O
2@I5
420
2@33200
o@@87.()()
0@9I10@00
2@24
3@42
5@46
3.57**4@0O
I@I76@oo
11013'oo
8.@a
2.06*I5@0O
7.69
7@93
= 91F578@co 1.80*Depression
i.@zF12!I4@OO
8@35 1.80*14'OO
I4@O6 1002I@OO
2O@8O
724
I6@97
10124@OO
N = 216M95I5@OO 8@ii j@#jM58000
6.62Controloooi@6ii86I•21N =
1.73*I6@OO
13.41 I@I928@OO
21'13
I@55400
2@497@0O
3.778'co
2@87
4@'4
7.0!
I9@35
@•¿3327@OO
149F9!I@O0
I•15*P
530, i6@6
Mortality in Patients with Schizophrenia, Mania, Depression and Surgical Conditions A Comparison with General Population Mortality By MING T. TSUANG Summary.
Mortality
data
and ROBERT
are presented
from
F. WOOLSON
a four-decade
follow-up
study
of 200 schizophrenic, 100 manic, 225 depressive patients, and i6o surgical controls (8o appendicectomy; 8o herniorrhaphy). Data for this analysis were available on 648 per cent) members of the study population. Using sex-age
@
standardized
mortality
population
was compared
served by the admitting
ratios
(SMR),
the mortality
experience
of the study
with that of the state of Iowa, the geographical
medical
facility for the study group.
Results
area
are presented
for a four-decade period beginning ‘¿935—44, and ending 1965—74.All three psychiatric groups had a significant increase in mortality risk. This was most pronounced in the first decade following admission, although schizophrenic patients, especially females, continued to show a significant excess of deaths throughout the entire four decades of the follow-up period. During no decade of the follow-up period did the mortality of the surgical controls differ significantly from that of the Iowa population.
Mortality in psychiatric populations has several times been shown to be higher than in comparable non-psychiatric populations (i, 3,6, 14);
however,
as
Kendell
(7)
points
out,
there
have been few studies reporting the mortality associated with specific psychiatric illnesses. The present paper reports increased mortality risk in schizophrenia and affective disorder. The data of this report were derived from our on-going research project, ‘¿Follow-upand family studies of schizophrenia, mania, and depression'
(i 7). The
results
of our study
seem
to indicate not only excess mortality generally but an increased risk of death associated with sex, specific diagnosis, and decade of follow-up period. SUBJECTS AND METHODS
During a two year period from early 1974 to the end of 1975, we have been conducting a combined 35-year follow-up and family study of
525
systematically
diagnosed
former
psychiatric
patients. The study subjects were selected by reviewing case records of patients consecutively admitted to the Department of Psychiatry, University Hospitals, Iowa City, during a ten year period from 1935 to 1944. Two hundred cases of schizophrenia
and 325 cases of primary
affective disorder (225 depression and zoo mania) were selected according to specified research criteria (i i). In order to have a base line for comparison
with the psychiatric
patients,
we selected a group of i6o control patients from the hospitals' Department of Surgery, all of whom were free from psychiatric symptoms. On preliminary examination, the Department's patient populations of appendicectomy and herniorrhaphy appeared to be appropriate to serve as non-psychiatric
controls.
A stratified
ran
dom sample of 8o cases of appendicectomy and 80 of herniorrhaphy was proportionally matched to the psychiatric group for the factors of time, ‘¿6a
MING T. TSUANG
AND ROBERT
period ofadmission, age, sex, and socio-economic status (as determined by pay status of the sub ject). In the final make-up of the index popu lation (525 cases + I6o controls), there were 45 per cent male and 55 per cent female subjects. The schizophrenia,
mean ages of admission were: 29 years; mania, 34; depression,
44; and controls, white. Follow.@ip
31. All study subjects were
information
on
these
cases
is
obtained through telephone and personal inter views with index cases and family members@ medical
records
at other
institutions@
and vital
statistics documents from health departments of the various states. In so far as possible, all study data are gathered
on standard
forms@which
are pre-coded for easy translation to computer cardL Each index patient for whom we obtain any current
follow-up
information
is immediately
given ratings on several variables which we consider relevant to outcome. These ratings represent either current status, or status at the time of death.
For this reason,
the basic item of
information about an index case is whether he or she is still alive. We have been able to make this determination for 95 per cent of the index population. We have recently begun analysing mortality status
as an outcome
variable
in its own right,
using age-sex standardized mortality ratios (SMR). A follow-up period from 1935 to 1974 was selected. This included the earliest possible year in which an index case could have died, and provided for a convenient division of the period into four separate decades of follow-up for which Iowa state population statistics could be obtained. Fbr those index cases whose mortality status was ascertained, as of 31 December 1974, an analysis was performed on the observed number of deaths in each cohort by comparison with the Iowa population and the Iowa mortality statistics. To compare the mortality experience o( the psychiatric sample with a relevant base popula tion, age-sex specific mortality rates were com puted for the state of Iowa for each of the last four census years; i.e. 1940, 1950, 1960, ar@d 1970.
Mid-year
abstracted
populations
for
for the four respective
the
state
were
census years
163
F. WOOLSON
(18—21). Mortality data, in terms of numbers
of
deaths during the year, were taken from 1940, ‘¿950, 1960, and 1970 respectively (22—25).The resulting age-specific mortality rates were used to construct the expected mortality pattern of each diagnostic group; this expected pattern, so constructed, was then contrasted to the observed mortality experience in the group. More precisely, we proceeded as follows for each diagnostic group: (a) Observed number of deaths by age (in b-year intervals 0-9, 10—19,etc) and sex were tallied
by decade of follow-up (I@-44,
1945—54,
1955—64, I965—74)@
(b) Age-sex specific mortality rates (age in io..year •¿ intervals) were computed
for 1940, 1950, 1960
and 1970 as described above. (c) The total person-years exposed to the risk of, death was computed for each diagnostic group by decade of follow-up, age (in 10-year inter vals) and sex. (d) For each decade and age-sex category, the age-sex specific mortality rate computed in step (b) was multiplied by the person-years at risk in step (c). This is the expected number of deaths for individuals in this age-sex group during the particular follow-up decade. It is assumed
that the Iowa age-sex specific mortality
rates apply throughout the follow-up decade. (e) For each decade of follow-up, the expected number of deaths was summed across all ages for each sex and each diagnostic group. This
is the age-adjusted expected number of deaths. (f) The observed number of deaths was summed across all ages in the same manner as described in step (e). The age-standardized mortality ratio (i.e. observed number of deaths in step (f) divided by expected number of deaths in step (e)) was computed for each sex and decade of follow-up. The single degree of freedom chi-square statistic was calculated to determine whether the age.. standardized mortality ratio (SMR) deviated significantly from one. A P value of less than •¿o5
was considered statistically significant. As described above, our statistical analysis is a hybrid of an analysis used in conventional longitudinal studies (i.e. the person-years of risk from a life table analysis) and one used in typical cross-sectional studies (i.e. indirect adjustment of rates). This method requires very few assumptions, principally that the Iowa
164
MORTALITY
IN PATIENTS
WITH SCHIZOPHRENIA,
death rates remain stable within each follow-up decade, and utilizes all of the available mortality statistics for the state. The mortality of 95 per cent (648/685) of the index population was available for the present analysis.
The
remaining
37 cases were
elimin
ated from the mortality analysis. Of the 648 cases, 346 had died during the designated follow up
period
(1935-1974);
302
were
known
MANIA, DEPRESSION,
assumptions
SURGICAL
of two possible
CONDITIONS
extremes;
namely,
the date of death was assumed to be the year of admission, and alternatively, the closing year of the study.
Neither
assumption
produced
substantially different from below which were obtained allocation.
results
those presented by proportional
RESULTS
to
have survived the entire period. For 35 of the known deceased no precise date of death could
It can be seen from the table that increased mortality risk was found in schizophrenia,
be ascertained,
mania,
although
the fact of death
was
certain. These cases were proportionally al located a date of death using a conditional probability distribution based upon the age-sex specific mortality rates for the state of Iowa during this period. The data were likewise analysed
with
these
cases allocated
under
the
and depression,
and that
no significant
excess mortality was found among the surgical controls. Analysis of the data according to decade and sex shows significant
excess mortality
in the first
decade (i@-@) for both sexes in all psychiatric sub-groups except male manics. Although the
TAiiz.x I
Observednumberof deaths (a), expectednumberQfbat/is (b) and standardizedmortalit, ratio (c) CohortSexn1935—441945—541955-641965—74Schizophrenia
i.@F939@OO
N =
58o b2@I3 2@65 ii@8i c 4.69**9@OO 3.4o**5@OO o@86I7@0O
192Maio@oo
1.80*ManiaM345@0O
I@26N
5.34
2@73 3.30**4.()()
3.07 I@301I@0O
2@I5
420
2@33200
o@@87.()()
0@9I10@00
2@24
3@42
5@46
3.57**4@0O
I@I76@oo
11013'oo
8.@a
2.06*I5@0O
7.69
7@93
= 91F578@co 1.80*Depression
i.@zF12!I4@OO
8@35 1.80*14'OO
I4@O6 1002I@OO
2O@8O
724
I6@97
10124@OO
N = 216M95I5@OO 8@ii j@#jM58000
6.62Controloooi@6ii86I•21N =
1.73*I6@OO
13.41 I@I928@OO
21'13
I@55400
2@497@0O
3.778'co
2@87
4@'4
7.0!
I9@35
@•¿3327@OO
149F9!I@O0
I•15*P
