Mortality and causes of death in first admitted schizophrenic patients PB Mortensen and K Juel The British Journal of Psychiatry 1993 163: 183-189 Access the most recent version at doi:10.1192/bjp.163.2.183
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British Journal of Psychiatry (1993), 163, 183—189
Mortality and Causes of Death in First Admitted Schizophrenic Patients PREBEN BO MORTENSEN and KNUD JUEL
Although many studies have shown an increased mortality in schizophrenic patients, the literature provides little information about mortality from specific causes in relation to age, gender, and duration of illness. This study examined mortality and causes of death in a total national sample of 9156 first admitted schizophrenic patients. Suicide accounted for 50% of deaths in men and 35% of deaths in women. Suicide risk was particularly increased during the first year of follow-up. Death from natural causes, with the exception of cancer and cerebrovasculardiseases,was increased.Suicide risk during the first year of follow-up increased by 56%, with a 50% reduction on psychiatric in-patient facilities. The study confirms that mortality in schizophrenia is still markedly elevated, and the finding of an increasing suicide risk may be an indicator
of some adverse effects
of deinstitutionalisation.
An increased mortality in schizophrenic patients has been shown repeatedly. This extensive literature has been reviewed by Simpson (1988) and Allebeck (1989), and the literature regarding suicide in schizophrenic
The present study of mortality in a total national sample of first admitted patients diagnosed as schizophrenic aims at describing the general pattern
patients has been reviewed by Caidwell & Gottesman
gender, and duration
(1990). However, although schizophrenia is not an uncommon disorder, the incidence of first admissions
The study evaluates if any changes in mortality, or in the pattern of causes of death, among schizophrenic patients have accompanied the 50% reduction of psychiatric in-patient beds that has
for schizophrenia is low enough to make it difficult
of mortality and causes of death, in relation to age, of illness.
to obtain population-based samples of first admitted schizophrenic patients large enough to make mortality studies possible. Furthermore, a number of methodological pro blems exist in mortality studies. These include difficulties in establishing a sufficient sample size, incomplete follow-up of study cohorts, including failure to establish the cause of death, inclusion of newly diagnosed schizophrenic patients together with chronic in-patients, failure to include deaths outside
We studied all 9156 people, 5658 men and 3498 women, who were first admitted to a Danish psychiatric hospital ordepartment between 1April1970and31December1987, and who at the first or a later admission received a diagnosis of schizophrenia (ICD-8, 295; World Health Organization,
treatment settings, and so on. Because of these difficulties, most recent studies
1967). The aim of the design was to include a sample representing the incident cases of schizophrenia, as opposed
concerning mortality in schizophrenia report only summary rates of increased mortality, such as standardised mortality ratios; more information, for
to prevalent cases. It was decided, however, not to base
example mortality from specific causes in relation to basic variables such as age, gender, and duration of illness, is necessary if the findings from different
taken place in Denmark
during the last decades.
Method
inclusion
into the study
solely
on the diagnosis
from
the
first admission because only approximately half of those patients who eventually are diagnosed as schizophrenic receive this diagnosis at their first psychiatric admission
(Munk-JØrgensen, 1987). The patients wereallidentified throughtheDanish
studies are to be compared, because standardised
Psychiatric Case Register. This nationwide register has been
mortality ratios are not necessarily comparable (Wood eta!, 1985; Breslow & Day, 1987). Furthermore, such
in operation on a computerised basis since 1969, covering all Danish psychiatric in-patient facilities since 1 April 1970 (Dupont, 1983). This study did not examine the validity
information is a necessary starting point when trying to identify groups at high risk in order to target possible interventions. Another important issue is the possible changes in mortality rates that may have accompanied deinstitutionalisation.
This issue has not been studied
specifically for schizophrenia in an epidemiologically defined population.
of the diagnosis
of schizophrenia
recorded
in the Danish
Psychiatric Case Register, but in a study of 53 schizophrenic patients from one catchment area selected along the same lines as in this study (Munk-JØrgensen & Mortensen, 1989),
45 of the 53 patients met DSM—IIIcriteria (American Psychiatric Association, 1980)for schizophrenia; a further three patients met these criteria except for that of age at onset which was above 45 years (and thus fulfilled DSM—III—R
183
184
MORTENSEN & JUEL
criteria; American Psychiatric Association, 1987), and four could not be classified according to DSM—IIIbecause of
lack of sufficient information in the case records. There are no private psychiatric in-patient facilities in Denmark,
Table 1 Person-years1 distributed by age at admission
yearsMenWomen15—191378.2559.520-247140.42875.625-2911030.34544.730-3410294.846 Age bands:
and the study population thus represents a total national sample of all patients first admitted to psychiatric wards who were diagnosed as schizophrenic. Mortality and causes of death were ascertained using two different procedures. Firstly, information about whether the patient was alive on the closing date of the study was provided by linkage to the Danish Central Person Registry (CPR) using the patient's unique person identifier (CPR number). In this manner the date of death for a total of 1100 patients was established. Through linkage with the Register of Causes of Death at the Danish Institute for Clinical Epidemiology, the cause of death was established for 1081 of these patients. For the remaining 19 patients information regarding the cause of death could not be found in the register.
The cause of death was therefore establishedin 98.3% of 1100casesin this study, the findingsof this study being unbiased by incomplete follow-up. When calculating the expected number of deaths in the study population the age-, gender-, and cause-specific rates for the general Danish
1. Cumulative total of time spent by patients in each age band, between admission (for schizophrenia)and census date.
populationfrom the Registerof Causesof Deathwereused
Results
as a reference. Standardised
mortality
ratios (SMRs) are reported
(rate
of deaths in study population: rate of deaths in the Danish general population). When calculating these, the expected number of deaths was calculated separately for the periods 1970—74,1975—80,and 1981—88 in order to correct
for any secular
trends
in mortality
rates in the
general population. The expectednumber of deaths were calculated by the person-years method (Breslow & Day, 1987), using the computer program OVLP6 developed by Juul (1984) and the computer package EPILOG(EPIL0G PLUS,
1989).
Mortality was significantlyincreased in schizophrenicpatients (Table 2). In men the overall SMR was 4.68 and in women it was 2.34. As in the general population, absolute mortality rates were higher in men than in women, whereas relative risk (i.e. age-specific SMR) was generally higher in women, particularly in the younger groups. Relative risk decreased with increasing age, but was significantly increased in all age groups, except for men 85 years or older and women
80 years or older. The cause-specificSMRs are summarised in Table 3. Suicidesaccountedfor morethan 50% of the deathsin men
All patients were entered into the study on the date of their first admission for schizophrenia and were all censored
and approximately
on 25 March 1988,to seeif theywerestillaliveon this day. The 95% confidence limits were calculated assuming the observed number of deaths to be Poisson distributed (Breslow& Day, 1987).The person-yearsdistribution by age is shown in Table 1.
20 timesmore frequent thaninthegeneral population. Also,
35% of the deaths in women.
Deaths
from suicide in both men and women were approximately
The calculation of the ‘¿avoidable mortality', as an
other violent causes of death were increased in both sexes. Fatal accidentsweremore than four times more frequent in both schizophrenic men and women than in the general population, and schizophrenic men were victims of homicide almost ten times more frequently than expected.
indicatorof the qualityof the medicalcaresuppliedto these patients, was based on deaths from the causes in the age
diseasesand diseasesof the respiratory systemwassignifi
Among the natural causes of death, mortality from heart
groups proposed by Rutstein et a! (1976). The difference between the admission cohorts was determined by comparing the suicide rates for the first year
cantly increased both in schizophrenic men and women. Furthermore, mortality from diseases of the digestivesystem
(1984) using the program MANKO(Juul, 1984). The autopsy rate in the study population was 33.8% v. the autopsy rate in the general population of 35% in the average year of death in the study population.
significantlyincreased (SMR=2.19, 95% confidence interval 1.20—3.68).Mortality from cancer was slightly reduced in schizophrenic men and equal to that of the general
was significantly increased in the men. Cerebrovascular of follow-up. The relative risk was corrected for age and mortality did not differ from the general population rates. In men, but not in women, ‘¿avoidable mortality' was genderdifferencesby stratificationas describedby Breslow
After indirect standardisation for age, however, the autopsy rate among the schizophrenicpatients was 17.9% in suicides v. the expected 16.5% (NS), and in all other causes of death it was 47.5% v. expected 40.8%
(P5 years 90.2 (36.3-185.8) 49.7 (26.4-84.9) years
82.5
(35.6-162.5)
16.3
50-59 (95% confidence
54.2
(0.0-38.7)2-3 year 319.8 (200.4-484.2)
SMR
confidence
(49.4-100.8)
(45.1-95.3) (35.8-74.8)
40-49 (95%
confidence
(0.2-52.4)4-5 years 88.6 (66.5-115.6) 28.9 (19.1-42.1) (0.0-35.4)>5 years 66.8 (0.5—16.0)Women1 years 52.7
71.8
SMR
(8.9—27.4)
(27.0-96.9)
21.7
(2.6-78.3)
SMR
117.3
(2.6-24.6) 16.4
(3.4-48.1)
9.4
21.3 8.8
(9.7-40.5) (5.1-14.1)
0.0 5.7
(0.0-21.6) (1.6—14.7)
0.0 4.4
29.8
(8.1-76.4)
30.7
(8.4-78.6)
0.0
(0.1-23.0) (5.0-46.9)
5.3 5.5
(0.9-13.1)
2.9
40.1 (19.3-73.8) 4.1 13.1 (2.7-38.2) 18.3 6.4
(2.1-14.9)
4.5
(0.3—10.4)
MORTALITY, CAUSESOF DEATH, AND SCHIZOPHRENIA
187
Table 6 Relative suicide risk (RR) during first year of follow-up Admission cohortRRTotal (95% confidence interval)RRMen (95% confidenceinterval)RRWomen interval)1970-741-1-1—1975-801.19(0.75-1.89)0.91(0.54-1.54)2.81(0.95-830)1981-871.56(1.01-2.41)1.35(0.83-2.19)2.72(0.94-7.89) (95% confidence
of a higher mortality, in comparison with other to be increased (Tsuang et a!, 1980; Eastwood et a!, studies, due to the high mortality during the early 1982; Black et a!, 1985; Martin et a!, 1985). Neuro course of schizophrenia. leptic treatment has been mentioned as a possible This may explain why the SMRs for all causes of source of this increase (Hoffister & Kosek, 1965; death (4.68 in men and 2.34 in women) are 50—l00°lo Saugstad & Odegárd, 1985) but no firm empirical higher than in most other studies. Table 2, however, evidence, linking increased cardiovascular morbidity shows that the relative risks (RRs) of death (SMR or mortality to treatment with neuroleptics, has been estimates) are highly dependent on the age distribution reported (Craig & Lin, 1981; Risch eta!, 1981). The of the study population, demonstrating that it is not higher incidence of alcoholism in schizophrenic possible to determine differences in mortality from patients reported in the literature (Craig & Kovasznay, comparison of SMRs from different studies. 1988) and the increased frequency of heavy smoking As in other studies, suicide was the most important among psychiatric patients (Masterson & O'Shea, cause of excess mortality, and suicide risk was higher 1984; Hughes et a!, 1986) are probably important than reported previously in the literature (Caldwell parts of the explanation for this finding. In a Danish & Gottesman, 1990). Part of the reason for this sample of first admitted psychiatric patients, 72.8°lo comparatively high risk is probably the inclusion of of men and 7201oof women reported to be smokers deaths early during the course of schizophrenia. In (Mors & SØrensen, personal communication). The some studies based on mixed populations of first corresponding figures for the general Danish popu admitted and readmitted patients (e.g. Saugstad & lation in 1987 are 49.6°lo(men) and 41.5°lo(women). Odegârd,1979, 1985), chronic patients (Giel et a!, The proportion of heavy smokers (more than 15 1978; Black & Winokur, 1988; Mortensen & Juel, cigarettes per day) was 53.1°loand 43.9% in male 1990), or patients discharged after their first schizo and female psychiatric patients respectively. The phrenic admission (Allebeck eta!, 1986), some of the proportion of heavy smokers in the general Danish early suicides are not included. population was 21.6% in men and 15.2% in women Fatal accidents also contributed substantially to (Nielsen eta!, 1988).This may also be the explanation the excess mortality. An increase of accidental deaths for the increased mortality from respiratory diseases, in schizophrenic patients has been found in many a finding that is similar to the results of many other studies (e.g. Tsuang & Woolson, 1978; Black other studies (e.g. Wood et a!, 1985; Allebeck & et a!, 1985; Allebeck et a!, 1986). Wistedt, 1986). An increase of deaths from homicide has been Cancer mortality was not increased significantly reported in the schizophrenic population by Hillard in any age group, despite a comparatively high eta! (1985), and Martinet a! (1985) reported a similar autopsy rate, and there was a trend towards a lower increase in a mixed sample of psychiatric out cancer mortality among the older patients. This patients. Homicide is an uncommon cause of death resembles the findings of Zilber et a! (1989). The in Denmark, and the almost tenfold increase in comparatively high autopsy rate indicates that this homicide risk in schizophrenic men contributes little result is probably not due to an increase of to the total excess mortality in this group. undiagnosed cancer. Neuroleptic drugs may have Of the natural causes of death, cardiovascular contributed tothiscomparatively low cancermortality diseases and respiratory diseases, including pneu (Jones, 1985; Mortensen, 1987, 1989).
monia, were significantly increased in both men and women. The finding of an increased cardiovascular mortality is in accord with the findings of Herrman eta! (1983), Brook (1985), Allebeck & Wistedt (1986), and Saugstad & Odegãrd (1979, 1985), whereas
other studies have not found cardiovascular mortality
For ‘¿avoidable mortality', the data suggested that medical care, at least in the male patients,
was less
effective than in the general population. This replicates the findings in a cohort of chronic schizophrenic in-patients (Mortensen & Juel, 1990) and corresponds well with the known difficulties in
188
MORTENSEN
diagnosing physical illness in schizophrenic patients and other psychiatric patients (Adler & Griffith, 1991).
Most studies find that young men, especially during the early course of schizophrenia, comprise the group at the highest risk (Caldwell & Gottesman,
& JUEL
psychiatric in-patient facilities. The finding is dis turbing and could be an indicator of adverse effects of the deinstitutionalisation that has taken place in Denmark, as in many other countries last decades.
during the
1990; Roy, 1986). This was in part confirmed by the
study. However, a second peak in both absolute and relative suicide risk occurred in men aged 70 years or more, but not in the corresponding age group in women. One might speculate that they represent patients who have been living with their disease for several years without seeking treatment, where external factors, for example physical illness or the death of relatives who
have taken care of them, aggravate the schizophrenic symptoms and necessitate a psychiatric admission. This significant excess risk was only evident during the first year after the diagnosis of schizophrenia and was based on a limited number of suicides in the older men (ten suicides in men aged 60 or over). In most studies, however, young schizophrenic patients have been found to have the highest absolute as well as relative rates of suicide, and if the finding of a second peak of suicide risk in older men can be replicated, this could indicate the existence of a group of schizophrenic patients at high risk of suicide which is currently receiving little attention when discussing suicide prevention in schizophrenia. A strong relation between suicide risk and duration of follow-up was found here as in many other studies (e.g. Pokorny, 1960; Temoche eta!, 1964; Roy, 1982;
Conclusion This study confirms that mortality in schizophrenia
is still markedly elevated. The increase is both a result of a highly increased risk for suicide and other unnatural causes of death, as well as mortality from heart disease and respiratory diseases. Excessive tobacco smoking may contribute to this risk increase.
In this context it is notable that cancer mortality is equal to, or in men even marginally lower, than that of the general population. The finding of an increasing suicide risk may be an indicator of some adverse effects of deinstitution alisation. Acknowledgements The authors wish to thank Dr Peter Allebeck, Dr Annalise Dupont, and Professor Erik Stromgren for their helpful comments, and the staff of The Institute of Psychiatric Demography for their help
duringthe courseof the study.The studywassupportedby a grant from Sygekassernes Helsefond (Hi 1/280.88), and Danish Medical Research Council (grant no. 12—9871-1).
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•¿Preben Bo Mortensen, MD,Senior Registrar, Department of Psychiatric Demography, Institute of Basic Psychiatric Research,Psychiatric Hospita! in Aarhus, DK-8240 Risskov, Denmark; Knud Juel, CandStat, Statistician, Danish Institute for C!inical Epidemio!ogy, Copenhagen,Denmark Correspondence
