Acta psychiat. scand. (1975) 52, 320-329 Institute of Community and Family Psychiatry (Director: H. Kravitz, M.D.),Jewish General Hospital, Montreal, Quebec, Canada
M A R I T A L S T A T U S A N D SCHIZOPHRENIA W. W. EATON The finding that married persons are more likely to be hospitalized schizophrenics is reviewed. Three interpretations of the finding are discussed: causation, selection, and differential utilization. A strategy to separate the three hypotheses is presented which uses data on rates of admission and duration of hospitalization and which concentrates on the widowed category. Data from the Maryland Psychiatric Case Register are used to test the hypotheses. Evidence of selection and differential utilization is found, but none in favor of the causation hypothesis. It is shown that selection operates less powerfully in rural areas. Key words: Schizophrenia
- marital status - register
- widowed
-
selection.
In 1946, Qmulf Qdegaard observed that two main hypotheses were fundamentally important in the interpretation of psychiatric epidemiological data. The two hypotheses provide contrasting interpretations of an association between a social characteristic and the occurrence of mental disorder. The causation hypothesis is that the social characteristic causes or protects against the disorder. The selection hypothesis is that the disorder influences the attainment of the particular social status. The two hypotheses are especially important if there is a question as to the relative importance of heredity and environment in the etiology of the disorder. The causation hypothesis is consonant with an environmental etiology, whereas selection suggests an inherited factor in etiology. Qdegaard interpreted his data on marital status in terms of the two hypotheses. Since then, they have provided the central interpretive focus to other studies on mental disorder and marital status (e. g., Adler (1953)), migration (e. g., Murphy (1965)), and social class (e. g., Dohrenwend & Dohrenwend (1969)). Qdegaard included a third hypothesis which is necessary whenever the epidemiologist interprets data including only treated disorders. If there exists an association between a social characteristic and the rate of disorder, it may be that the social characteristic influences entry into treatment and utilization of appropriate facilities. This differential utilization hypothesis has been formalized by Kramer (1969). In the absence of an intensive longitudinal study, evidence in favor of one or the other hypotheses must often be indirect, as in Qdegaard (1946). However,
321
natural situations sometimes occur which provide much stronger evidence, and they have been called “quasi-experiments” (Campbell & StanZey (1966)). For an application to the social class - mental disorder relationship, see Dohrenwend & Dohrenwend (1 969). This paper uses a quasi-experimental strategy to interpret data on marital status and schizophrenia. There is reason to suspect that having a spouse is protective against schizophrenia. Mamed persons are not as isolated as single persons, and social isolation may be an etiological factor (Faris (1934)). Mamed persons presumably have a stable sexual relationship, also thought to be important etiologically (Sullivan (1962)).
On the other hand, individuals who will eventually be diagnosed schizophrenic may have difficulty in finding a mate. In many cases, schizophrenia has an insidious onset, so that the premorbid personality may be a handicap. Marriage partners are usually carefully selected, and in western societies assortative mathg is based on a variety of characteristics. Recent studies by Rosen et al. (1971) and Turner et al. (1 970) give indirect evidence of selection. Finally, married persons with schizophrenic symptoms may be less likely to utilize treatment facilities. A spouse may care for the schizophrenic individual and mediate their relationship to the community at large (Sarnpson et al. (1962), ,
Hammer (1 963)).
All three hypotheses suggest that the rate of schizophrenia is higher among single persons than among married persons. Several studies have shown this to be the case. Table 1 shows ratios of rates of schizophrenia specific for categories of marital status for published studies. In all cases, the singlelmarried ratio is greater than 1.00. Distinguishing between categories of single allows separation of the hypotheses. In particular, the widowed category is of crucial importance. The never-married and the widowed are equivalent as far as causation and differential utilization are concerned because both lack a spouse. However, the widowed have endured the selection process, while the never-mamed have not. Thus, if rates for neverTable 1. Summary of studies of marital status and schizophrenia. Ratios of rates of schizophrenia: Singlelmarried
Single/married ratio Author and date
Male
Dayton 1936 gdegaard 1946 gdegaard 1953 Norris 1956
Thomas & Locke 1963 New York Ohio Malzberg 1964 Stein & Susser 1970
1
Female
1
Total 1.4
4.7 4.3 6.2
3.0 3.7 3.7
4.0 6.7
3.3 3.4
7.2
2.6
4.28
322 married are higher than rates for widowed, there is clear evidence of selection. It is appropriate to call the ratio of rates for never-married to widowed the selection ratio. This ratio provides information about mating patterns in the society which may be useful apart from the study of schizophrenia. The selection argument applies most strongly to never married persons, but also to divorced and separated persons, where schizophrenia may have caused the separation or divorce. However, the loss of one’s spouse through death is probably unrelated to schizophrenia. Widowed persons have endured the selection process to the same degree as mamed persons. Therefore, if widowed persons have higher rates than married persons, the causation argument and/or the differential utilization argument is supported; if widowed and married persons have equal rates there is no evidence for these two hypotheses. Data on chronicity allow separation of the causation and differential utilization interpretations. Widowed persons may have higher rates of first admission than mamed persons because of factors in etiology or utilization, but they should stop treatment at about the same time if causation alone is operating. If widowed persons have longer treatment durations than mamed persons, the factor of differential utilization must be operative.
MATERIAL AND METHOD The source of data for this study is the Maryland Psychiatric Case Register. For 7 years (1961-1968), this register collected information on each admission from all the psychiatric facilities in Maryland. Records were l i k e d to create psychiatric careers for each individual, with information concerning all episodes in Maryland during this period. This study concerns Maryland residents admitted to any inpatient facility in Maryland and receiving a diagnosis (or diagnostic impression) of schizophrenia on both admission and discharge. Individuals with prior admission were eliminated. Thus, the rates presented are unduplicated rates of f i s t hospitalization for schizophrenia. Schizophrenics who had no inpatient experience were excluded. Although some researchers feel that virtually all schizophrenics are eventually hospitalized (Dunhum (1965)), other evidence indicates that about 15 % of those treated may be excluded (Miles & Gardner (1966)). These 15 % are probably equally distributed among the social classes (Gardner & Babigian (1966), Turner et al. (1969)). It is difficult to estimate the number of schizophrenics who do not get treatment. Although reliability of diagnosis for the mental disorders is notoriously low, the diagnosis of schizophrenia is more reliable than other diagnoses. For this type of situation (i. e., a variety of hospitals), the best guess is that reliability of diagnosis for schizophrenia is about 75 % (Babigian et al. (1965), Sandifer et al. (1964)). This register has been described in detail elsewhere (Bahn (1962, 1965a, b). The other major source of data is the U.S. census public use samples (1/100) of Maryland for 1960 and 1970, from which denominators were estimated. The joint occurrence of schizophrenia and widowhood is very rare. Therefore, large samples are required to provide stable rates for the widowed category.
323
Although some studies have provided rates specific for widows (see Table 3), none has also included data on duration of treatment. The Maryland Register catchment area is large enough to provide a good-sized population of schizophrenics (a total of 18,083), and data on chronicity are available through the automatic record linkage of the Register. Thus, these data are aptly suited to the task. RESULTS Table 2 presents estimated rates of first hospitalization specific for categories of marital status for the period January 1, 1965 to June 30, 1968. Since the age distribution of the never-married, married and widowed differ, these rates cannot be used as tests of the hypotheses presented above. They give a rough picture of the populations involved, however. The numerators are the 3% -year first admission groups, and the denominators are the estimated populations at the midpoint of that period. It is noteworthy that there are as many as 175 schizophrenics in the widowed category. Data quality improved in 1965, and the register terminated on June 30, 1968. Thus, the 3%-year period is as long as feasible in order to maximize the number of schizophrenics. Table 3 presents sex-specific age standardized rates for the three critical categories of marital status for this study and the four others that have included specific rates for the widowed. In a l l five studies, the never-married have substantially higher rates than the widowed in both sexes. Therefore, these data present clear evidence of selection. The data from Maryland suggest that the pre-schizophrenic personality is more of a handicap in finding a mate for men than for women. The selection ratio is larger for men than for women (2.22 for men compared to 1.36 for women) and further, the rate for married women is higher than that for married men (.44 compared to .22). indicating that women schizophrenics are more likely to find mates than men. These results for sex differences are only partially c o n f i i e d in Table 2. Marital status and schizophrenia in Maryland. Estimated rates of first hospitalization for schizophrenia, January I , 1965 -June 30, 1968
Frequencies Never married Married Widowed Separated Divorced
1188 273100 1673 1442600 175 77900 447 112900 257 58Ooo
3% -year rate 4.35 1.16 2.25 3.96 4.43
2.22
3.86
Ratio of selection Never manied/widowed
Ratio Widowed/married
I
2.14
1.36
1.28 .44 .94
Female
I
1.87
2.82
5.34 1.01 1.89
Male
I
1.16
3.11
4.95 1.37 1.59
Female
P)degaard** Norway 1935-1945
1
3.78
1.12
1.52 .37 1.36
Male
1
1.94
1.72
1.24 .37 .72
Female
I
3.54
1.91
.88 .13 .46
Male
1
2.09
1.64
.79 .23 .48
Female
Thomas & Locke**** Thomas & Locke*** Ohio New York 1950 1950
*Adults (20-64), age standardized in 5-year intervals by 1960 adult population of Maryland. **Adults (Single: 20-89; married and widowed: 30-69), “age standardized”. ***Adults (25-54), age standardized in 10-year intervals by 1950 population of New York. ****All ages, age standardized by 1961 population of Salford.
1.89 .22 .85
Male
Never married Married Widowed
I
Present Study* Maryland 1965-1968
I
2.28
3.15
1.01 .14 .32
Male
I
1.oo
2.61
.60 .23 .23
Female
Stein & Susser**** Salford, England 1961
Table 3. Comparison of rates from four studies. Estimated animal rates per 1,000 population f o r each sex, standardized by age
P
h,
u
325 the other four studies. In Norway and New York, the selection ratios are higher for women than for men, contrary to the Maryland result. In New York, married women have a slightly lower rate than males (.37 compared to .38), contrary to the Maryland result. In all five studies, the widowed have rates somewhere in between the married and the never-married. In all but one case (females in Salford), the widowed rate is substantially higher than the married rate, and therefore, there is clear evidence of causation and/ or differential utilization. Data on duration of hospitalization, which reflects on the differential utilization hypothesis, are available from earlier records of the Register. An earlier file must be used, even though the data are not of such uniformly high quality, because the Register terminated on June 30, 1968, allowing little or no follow-up period for the 1965-1968 cohort. Duration of stay and marital status were well-reported throughout the history of the Register, allowing the selection of the earliest cohorts (admitted during 1961-1962) for the analysis of length of stay. Widowed persons tend to be older than the married, and since age might affect length of stay, it is necessary to control for age as in the study of first hospitalization above. Therefore, length of stay for the widowed aged 40-64 will be compared to length of stay for the married aged 40-60 (comparisons below this age range are not feasible because the number of young widowed persons is small). For distributions of this type, the appropriate procedure is the KolmogorovCumulative
frequency
/ -
90-
4 91.8 “u
/
Married
80-
70-
} -+Maximum
deviation
60-
50-
40-
30-
20-
Duration
, inday 40
80
120
160
200
240
280
320
360
400
440
480 500
Fig. 1. Maryland Psychiatric Case Register data. Cumulative percent of first hospitalized schizophrenics released. 22 ACTA PSYCH, 5 2 5
Table 4. Marital status and residence. Estimated annual rates for first hospitalization for schizophrenia in Maryland per 1,000 adults, January 1 , 1965 - June 30, 1968. (Ape standardized bv 1960 adult population in Mawland)
I Central city Never married Married Widowed Separated Divorced Selection ratio
Met-urban
Rural
1.40 .3 1 .84 .92 1.21 1.64
.91
2.27 .48 1.12 1.50 1.53 2.02
.26 .75 .99 1.11 1.21
Smirnov two sample test (Siegel(l956)). This test makes no distributional assumptions and has nearly the same power-efficiency as the t-test. The cumulative percent discharged from the married and widowed cohort were calculated daily, the maximum absolute deviation being .152 at day 155 (see Fig. 1). The issue is whether the widowed have longer durations or not, justifying the one-tailed test. The chi-square is significant (x* = 6.83, 2 d.f., P < .05) indicating that the widowed stay in hospital longer. The median length of stay for widowed in this age range is 108 days, while for married of similar age it is 66 days. It should be noted that the selection ratio is important even aside from the study of schizophrenia because it reveals how chronic disabilities and attained statuses interact in society. The nature of the disability (in this case, schizophrenia) presumably changes relatively little, moving from society to society or from urban to rural areas. But the reaction to it may change markedly in different societies, and the selection ratio is one indicator of this reaction. Eaton (1974) has recently suggested that schizophrenia has less effect on an individual’s status attainment in rural than in urban areas. His finding suggests that the selection ratio should be greater in urban than in rural areas. Table 4 presents estimated annual age standardized rates of first hospitalization for schizophrenia specific for marital status for central city, metropolitan and small urban areas (“met-urban”), and rural areas. The selection ratio is computed also, and clearly it varies by residence. Selection against marriage for schizophrenics is greatest in the central city area (2.02) and lowest in the rural areas (1.21).
DISCUSSION The three arguments of selection, causation and differential utilization are presented above in simple forms, but there are several complications. There are many ways in which the status of the widowed does not fit precisely into one or the other argument. For instance, gdegaard (1946) noticed that widowhood formed a sort of natural experiment, but he felt that it could not provide strong evidence in favor of causation because the forces of selection operate after widowhood and influence chance of remarriage. As evidence in favor of this idea, he noted that rates for the male widowed were smaller than for the female widowed, indicating that males are more likely to remarry. The male-female difference
327 for widowed in these data is in the other direction (see Table 3). However, the argument is somewhat academic because these findings support the selection and differential utilization arguments, but there is no evidence of a causative factor. Bereavement could precipitate a schizophrenic episode (Birley & Brown (1970), Stein & Susser (1970)). The evidence indicates that a life crisis of this type has an influence of fairly short duration (about 3 weeks). Therefore, although the rates for widowed could be raised artifactually for this reason, the difference should not be too great. But again, if this were shown to be true, it would detract from the causation argument which is not supported here. Several other similar arguments can be presented which have some validity but which, if correct, would detract from the causation argument: Widowed might have higher rates because of the stresses of caring for children alone; widowed might have higher rates because schizophrenics marry those who are accident prone or physically unhealthy, and who die at a young age. But there are no strong arguments that show how a causative factor would be hidden in these data (i. e., an artifact that would lower rates for widowed). Many similar problems in the analysis of data on marital status and mental disorder are considered in an excellent analytical review by Bachrach (1975). The basic point of disagreement between this research and others does not concern selection or causation. In almost all the studies, there is clear evidence of selection and little proof of a causative factor (for a partial exception see C o v e (1972)). The disagreement concerns differential utilization, which gdegaard found no support for, and which was neglected by others. The evidence here supports differential utilization, but the question remains as to whether this argument can explain all of the differences in rates between married and widowed.
CONCLUSIONS
Four major conclusions can be drawn on the basis of these data. First, there is strong evidence that selection operates and is partially responsible for the overrepresentation of the never-married in the schizophrenic population. Secondly, there is also evidence that differential utilization helps to produce that overall finding. Thirdly, there is no evidence that marriage is protective against schizophrenia. Finally, selection operates more powerfully in urban than in rural areas. ACKNOWLEDGMENTS This research was supported by NIMH grant MH25691. I would like to thank Irving Goldberg and Morton Kramer of the NIMH Biometry Branch for making available to me (unidentified) files of the Maryland Psychiatric Case Register. I would like to thank Luc Goudreault for his assistance in analyzing the data. REFERENCES Adler, L. (1953): The relationship of marital status to incidence and recovery from mental disease. SOC. Forces 32, 185-194. Babigian, H . M., E. A . Gardner, H . C.Miles & J . Romano (1965): Diagnostic consistency and change in a follow-up study of 1215 patients. h e r . J. Psychiat. 121, 895991.
328 Bochrach, L. (1975): Marital status and mental disorders: An analytical review. Government Printing Office, Washington, D. C. Bahn, A. K . (1962): Psychiatric Case Register Conference, 1962. Public Health Reports 77, 1071-1076. Bahn, A. K . (1965a): An outline for community mental health research. Comm. ment. Hlth J. 1 , 23-28. Bahn, A. K . (1965b): Experience and philosophy With regard to case registers in health and welfare. Comm. ment. Hlth. J. 1 , 245-250. Birley, J . L. T., & G . W . Brown (1970): Crises and life changes preceding the onset or relapse of acute schizophrenia: Clinical aspects. Brit. I. Psychiat. 116, 327-333. Campbell, D . T.. & J . C . Stanley (1966): Experimental and quasi-experimental designs for research. Rand McNally, Chicago. Dayton, N . A. (1936): Marriage and mental disease. New Engl. J. Med. 215, 153-155. Dohrenwend. B. P., & B. S. Dohrenwend (1969): Social status and psychological disorder: A causal inquiry. John Wiley & Sons, New York. Dunham, H . W . (1965): Community and schizophrenia: An epidemiological analysis. Wayne State University Press, Detroit. Eaton, W . W . (1974): Residence, social class, and schizophrenia, J. Hlth soc. Behav. 15, 289-299. Faris, R . E . L. (1934): Cultural isolation and the schizophrenic personality. Amer. J. Sociol. 40, 155-164. Gardner, E. A., & H . M . Babigian (1966): A longitudinal comparison of psychiatric service to selected socioeconomic areas of Monroe County, New York. h e r . J. Orthopsychiat. 36, 818-828. Gove, W . (1972): The relationship between sex roles, marital roles, and mental illness. Soc. Forces 51, 34-44. Hammer, M . (1963): Influences of small social networks as factors on mental hospital admission, Hum. Organ. 22, 243-251. Kramer, M . (1969): Applications of mental health statistics. WHO, Geneva. Miles, H. C., & E. A . Gardner (1966): A psychiatric case register. Arch. gen. Psychiat. 14, 571-580. Malzberg, B. (1964): Marital status and the incidence of mental disease. Int. J. soc. Psychiat. 10, 245-249. Murphy, H . B. M . (1965): Migration and the major mental disorders. In Kantor, M . B. (ed.): Mobility and mental health. Charles C. Thomas, Springfield, Illinois, pp. 5-29. Norris, V. (1956): A statistical study of the influence of marriage in the hospital care of the mentally sick. J. ment. Sci. 102, 467-486. Odeguard, 8. (1946): Marriage and mental disease: A study in social psychopathology. J. ment. Sci. 92, 35-59. Odeguard, 0. (1953): New data on marriage and mental disease: Incidence of psychoses in widowed and divorced. J. ment. Sci. 9,778-785. Rosen, B., D . Klein & R . Gittleman-Klein (1971): The prediction of rehospitalization: The relationship between age of first psychiatric treatment contact, marital status and premorbid asocial adjustment. J. nerv. ment. Dis. 152, 17-22. Sampson, H.. S. L. Messinger & R . D . Towne (1962): Family processes and becoming a mental patient. Amer. J. Sociol. 68, 88-96. Sandifer, M.. G . C. Pettus & D . Quade (1964): A study of psychiatric diagnosis. J. nerv. ment. Dis. 139, 350-356. Siegel, S. (1956): Non-parametric methods for the behavioral sciences. McGraw-Hill, New York. Stein. Z.,& M . W . Susser (1970): Bereavement as a precipitating event in mental illness. In Hare, E. H., & J . K . Wing (eds.): Psychiatric epidemiology, an international symposium. Oxford University Press, London. Sullivan, H . S. (1962): Schizophrenia as a human process. W. W. Norton & CO., New York.
329 Thomas, D . S., & B. 2. Locke (1963): Marital status, education and occupational differentials in mental disease. Millbank Mem. Fund Quart. 41, 145-160. Turner, R . J., L . Dopkeen & G . Labreche (1970): Marital status and schizophrenia: A study of incidence and outcome. J. abnorm. Psychol. 76, 110-1 16. Turner, R . J., J . Raymond, 3. Zaba L J . Diamond (1969): Field survey methods in psychiatry: The effects of sampling strategy upon findings in research on schizophrenia. J. Hlth soc. Behav. 10, 289-297. Received July 15, 1975
William W . Eaton, Ph.D. Institute of Community and Family Psychiatry Jewish General Hospital 4333 Cote Ste. Catherine Road Montreal, Quebec Canada
M A R I T A L S T A T U S A N D SCHIZOPHRENIA W. W. EATON The finding that married persons are more likely to be hospitalized schizophrenics is reviewed. Three interpretations of the finding are discussed: causation, selection, and differential utilization. A strategy to separate the three hypotheses is presented which uses data on rates of admission and duration of hospitalization and which concentrates on the widowed category. Data from the Maryland Psychiatric Case Register are used to test the hypotheses. Evidence of selection and differential utilization is found, but none in favor of the causation hypothesis. It is shown that selection operates less powerfully in rural areas. Key words: Schizophrenia
- marital status - register
- widowed
-
selection.
In 1946, Qmulf Qdegaard observed that two main hypotheses were fundamentally important in the interpretation of psychiatric epidemiological data. The two hypotheses provide contrasting interpretations of an association between a social characteristic and the occurrence of mental disorder. The causation hypothesis is that the social characteristic causes or protects against the disorder. The selection hypothesis is that the disorder influences the attainment of the particular social status. The two hypotheses are especially important if there is a question as to the relative importance of heredity and environment in the etiology of the disorder. The causation hypothesis is consonant with an environmental etiology, whereas selection suggests an inherited factor in etiology. Qdegaard interpreted his data on marital status in terms of the two hypotheses. Since then, they have provided the central interpretive focus to other studies on mental disorder and marital status (e. g., Adler (1953)), migration (e. g., Murphy (1965)), and social class (e. g., Dohrenwend & Dohrenwend (1969)). Qdegaard included a third hypothesis which is necessary whenever the epidemiologist interprets data including only treated disorders. If there exists an association between a social characteristic and the rate of disorder, it may be that the social characteristic influences entry into treatment and utilization of appropriate facilities. This differential utilization hypothesis has been formalized by Kramer (1969). In the absence of an intensive longitudinal study, evidence in favor of one or the other hypotheses must often be indirect, as in Qdegaard (1946). However,
321
natural situations sometimes occur which provide much stronger evidence, and they have been called “quasi-experiments” (Campbell & StanZey (1966)). For an application to the social class - mental disorder relationship, see Dohrenwend & Dohrenwend (1 969). This paper uses a quasi-experimental strategy to interpret data on marital status and schizophrenia. There is reason to suspect that having a spouse is protective against schizophrenia. Mamed persons are not as isolated as single persons, and social isolation may be an etiological factor (Faris (1934)). Mamed persons presumably have a stable sexual relationship, also thought to be important etiologically (Sullivan (1962)).
On the other hand, individuals who will eventually be diagnosed schizophrenic may have difficulty in finding a mate. In many cases, schizophrenia has an insidious onset, so that the premorbid personality may be a handicap. Marriage partners are usually carefully selected, and in western societies assortative mathg is based on a variety of characteristics. Recent studies by Rosen et al. (1971) and Turner et al. (1 970) give indirect evidence of selection. Finally, married persons with schizophrenic symptoms may be less likely to utilize treatment facilities. A spouse may care for the schizophrenic individual and mediate their relationship to the community at large (Sarnpson et al. (1962), ,
Hammer (1 963)).
All three hypotheses suggest that the rate of schizophrenia is higher among single persons than among married persons. Several studies have shown this to be the case. Table 1 shows ratios of rates of schizophrenia specific for categories of marital status for published studies. In all cases, the singlelmarried ratio is greater than 1.00. Distinguishing between categories of single allows separation of the hypotheses. In particular, the widowed category is of crucial importance. The never-married and the widowed are equivalent as far as causation and differential utilization are concerned because both lack a spouse. However, the widowed have endured the selection process, while the never-mamed have not. Thus, if rates for neverTable 1. Summary of studies of marital status and schizophrenia. Ratios of rates of schizophrenia: Singlelmarried
Single/married ratio Author and date
Male
Dayton 1936 gdegaard 1946 gdegaard 1953 Norris 1956
Thomas & Locke 1963 New York Ohio Malzberg 1964 Stein & Susser 1970
1
Female
1
Total 1.4
4.7 4.3 6.2
3.0 3.7 3.7
4.0 6.7
3.3 3.4
7.2
2.6
4.28
322 married are higher than rates for widowed, there is clear evidence of selection. It is appropriate to call the ratio of rates for never-married to widowed the selection ratio. This ratio provides information about mating patterns in the society which may be useful apart from the study of schizophrenia. The selection argument applies most strongly to never married persons, but also to divorced and separated persons, where schizophrenia may have caused the separation or divorce. However, the loss of one’s spouse through death is probably unrelated to schizophrenia. Widowed persons have endured the selection process to the same degree as mamed persons. Therefore, if widowed persons have higher rates than married persons, the causation argument and/or the differential utilization argument is supported; if widowed and married persons have equal rates there is no evidence for these two hypotheses. Data on chronicity allow separation of the causation and differential utilization interpretations. Widowed persons may have higher rates of first admission than mamed persons because of factors in etiology or utilization, but they should stop treatment at about the same time if causation alone is operating. If widowed persons have longer treatment durations than mamed persons, the factor of differential utilization must be operative.
MATERIAL AND METHOD The source of data for this study is the Maryland Psychiatric Case Register. For 7 years (1961-1968), this register collected information on each admission from all the psychiatric facilities in Maryland. Records were l i k e d to create psychiatric careers for each individual, with information concerning all episodes in Maryland during this period. This study concerns Maryland residents admitted to any inpatient facility in Maryland and receiving a diagnosis (or diagnostic impression) of schizophrenia on both admission and discharge. Individuals with prior admission were eliminated. Thus, the rates presented are unduplicated rates of f i s t hospitalization for schizophrenia. Schizophrenics who had no inpatient experience were excluded. Although some researchers feel that virtually all schizophrenics are eventually hospitalized (Dunhum (1965)), other evidence indicates that about 15 % of those treated may be excluded (Miles & Gardner (1966)). These 15 % are probably equally distributed among the social classes (Gardner & Babigian (1966), Turner et al. (1969)). It is difficult to estimate the number of schizophrenics who do not get treatment. Although reliability of diagnosis for the mental disorders is notoriously low, the diagnosis of schizophrenia is more reliable than other diagnoses. For this type of situation (i. e., a variety of hospitals), the best guess is that reliability of diagnosis for schizophrenia is about 75 % (Babigian et al. (1965), Sandifer et al. (1964)). This register has been described in detail elsewhere (Bahn (1962, 1965a, b). The other major source of data is the U.S. census public use samples (1/100) of Maryland for 1960 and 1970, from which denominators were estimated. The joint occurrence of schizophrenia and widowhood is very rare. Therefore, large samples are required to provide stable rates for the widowed category.
323
Although some studies have provided rates specific for widows (see Table 3), none has also included data on duration of treatment. The Maryland Register catchment area is large enough to provide a good-sized population of schizophrenics (a total of 18,083), and data on chronicity are available through the automatic record linkage of the Register. Thus, these data are aptly suited to the task. RESULTS Table 2 presents estimated rates of first hospitalization specific for categories of marital status for the period January 1, 1965 to June 30, 1968. Since the age distribution of the never-married, married and widowed differ, these rates cannot be used as tests of the hypotheses presented above. They give a rough picture of the populations involved, however. The numerators are the 3% -year first admission groups, and the denominators are the estimated populations at the midpoint of that period. It is noteworthy that there are as many as 175 schizophrenics in the widowed category. Data quality improved in 1965, and the register terminated on June 30, 1968. Thus, the 3%-year period is as long as feasible in order to maximize the number of schizophrenics. Table 3 presents sex-specific age standardized rates for the three critical categories of marital status for this study and the four others that have included specific rates for the widowed. In a l l five studies, the never-married have substantially higher rates than the widowed in both sexes. Therefore, these data present clear evidence of selection. The data from Maryland suggest that the pre-schizophrenic personality is more of a handicap in finding a mate for men than for women. The selection ratio is larger for men than for women (2.22 for men compared to 1.36 for women) and further, the rate for married women is higher than that for married men (.44 compared to .22). indicating that women schizophrenics are more likely to find mates than men. These results for sex differences are only partially c o n f i i e d in Table 2. Marital status and schizophrenia in Maryland. Estimated rates of first hospitalization for schizophrenia, January I , 1965 -June 30, 1968
Frequencies Never married Married Widowed Separated Divorced
1188 273100 1673 1442600 175 77900 447 112900 257 58Ooo
3% -year rate 4.35 1.16 2.25 3.96 4.43
2.22
3.86
Ratio of selection Never manied/widowed
Ratio Widowed/married
I
2.14
1.36
1.28 .44 .94
Female
I
1.87
2.82
5.34 1.01 1.89
Male
I
1.16
3.11
4.95 1.37 1.59
Female
P)degaard** Norway 1935-1945
1
3.78
1.12
1.52 .37 1.36
Male
1
1.94
1.72
1.24 .37 .72
Female
I
3.54
1.91
.88 .13 .46
Male
1
2.09
1.64
.79 .23 .48
Female
Thomas & Locke**** Thomas & Locke*** Ohio New York 1950 1950
*Adults (20-64), age standardized in 5-year intervals by 1960 adult population of Maryland. **Adults (Single: 20-89; married and widowed: 30-69), “age standardized”. ***Adults (25-54), age standardized in 10-year intervals by 1950 population of New York. ****All ages, age standardized by 1961 population of Salford.
1.89 .22 .85
Male
Never married Married Widowed
I
Present Study* Maryland 1965-1968
I
2.28
3.15
1.01 .14 .32
Male
I
1.oo
2.61
.60 .23 .23
Female
Stein & Susser**** Salford, England 1961
Table 3. Comparison of rates from four studies. Estimated animal rates per 1,000 population f o r each sex, standardized by age
P
h,
u
325 the other four studies. In Norway and New York, the selection ratios are higher for women than for men, contrary to the Maryland result. In New York, married women have a slightly lower rate than males (.37 compared to .38), contrary to the Maryland result. In all five studies, the widowed have rates somewhere in between the married and the never-married. In all but one case (females in Salford), the widowed rate is substantially higher than the married rate, and therefore, there is clear evidence of causation and/ or differential utilization. Data on duration of hospitalization, which reflects on the differential utilization hypothesis, are available from earlier records of the Register. An earlier file must be used, even though the data are not of such uniformly high quality, because the Register terminated on June 30, 1968, allowing little or no follow-up period for the 1965-1968 cohort. Duration of stay and marital status were well-reported throughout the history of the Register, allowing the selection of the earliest cohorts (admitted during 1961-1962) for the analysis of length of stay. Widowed persons tend to be older than the married, and since age might affect length of stay, it is necessary to control for age as in the study of first hospitalization above. Therefore, length of stay for the widowed aged 40-64 will be compared to length of stay for the married aged 40-60 (comparisons below this age range are not feasible because the number of young widowed persons is small). For distributions of this type, the appropriate procedure is the KolmogorovCumulative
frequency
/ -
90-
4 91.8 “u
/
Married
80-
70-
} -+Maximum
deviation
60-
50-
40-
30-
20-
Duration
, inday 40
80
120
160
200
240
280
320
360
400
440
480 500
Fig. 1. Maryland Psychiatric Case Register data. Cumulative percent of first hospitalized schizophrenics released. 22 ACTA PSYCH, 5 2 5
Table 4. Marital status and residence. Estimated annual rates for first hospitalization for schizophrenia in Maryland per 1,000 adults, January 1 , 1965 - June 30, 1968. (Ape standardized bv 1960 adult population in Mawland)
I Central city Never married Married Widowed Separated Divorced Selection ratio
Met-urban
Rural
1.40 .3 1 .84 .92 1.21 1.64
.91
2.27 .48 1.12 1.50 1.53 2.02
.26 .75 .99 1.11 1.21
Smirnov two sample test (Siegel(l956)). This test makes no distributional assumptions and has nearly the same power-efficiency as the t-test. The cumulative percent discharged from the married and widowed cohort were calculated daily, the maximum absolute deviation being .152 at day 155 (see Fig. 1). The issue is whether the widowed have longer durations or not, justifying the one-tailed test. The chi-square is significant (x* = 6.83, 2 d.f., P < .05) indicating that the widowed stay in hospital longer. The median length of stay for widowed in this age range is 108 days, while for married of similar age it is 66 days. It should be noted that the selection ratio is important even aside from the study of schizophrenia because it reveals how chronic disabilities and attained statuses interact in society. The nature of the disability (in this case, schizophrenia) presumably changes relatively little, moving from society to society or from urban to rural areas. But the reaction to it may change markedly in different societies, and the selection ratio is one indicator of this reaction. Eaton (1974) has recently suggested that schizophrenia has less effect on an individual’s status attainment in rural than in urban areas. His finding suggests that the selection ratio should be greater in urban than in rural areas. Table 4 presents estimated annual age standardized rates of first hospitalization for schizophrenia specific for marital status for central city, metropolitan and small urban areas (“met-urban”), and rural areas. The selection ratio is computed also, and clearly it varies by residence. Selection against marriage for schizophrenics is greatest in the central city area (2.02) and lowest in the rural areas (1.21).
DISCUSSION The three arguments of selection, causation and differential utilization are presented above in simple forms, but there are several complications. There are many ways in which the status of the widowed does not fit precisely into one or the other argument. For instance, gdegaard (1946) noticed that widowhood formed a sort of natural experiment, but he felt that it could not provide strong evidence in favor of causation because the forces of selection operate after widowhood and influence chance of remarriage. As evidence in favor of this idea, he noted that rates for the male widowed were smaller than for the female widowed, indicating that males are more likely to remarry. The male-female difference
327 for widowed in these data is in the other direction (see Table 3). However, the argument is somewhat academic because these findings support the selection and differential utilization arguments, but there is no evidence of a causative factor. Bereavement could precipitate a schizophrenic episode (Birley & Brown (1970), Stein & Susser (1970)). The evidence indicates that a life crisis of this type has an influence of fairly short duration (about 3 weeks). Therefore, although the rates for widowed could be raised artifactually for this reason, the difference should not be too great. But again, if this were shown to be true, it would detract from the causation argument which is not supported here. Several other similar arguments can be presented which have some validity but which, if correct, would detract from the causation argument: Widowed might have higher rates because of the stresses of caring for children alone; widowed might have higher rates because schizophrenics marry those who are accident prone or physically unhealthy, and who die at a young age. But there are no strong arguments that show how a causative factor would be hidden in these data (i. e., an artifact that would lower rates for widowed). Many similar problems in the analysis of data on marital status and mental disorder are considered in an excellent analytical review by Bachrach (1975). The basic point of disagreement between this research and others does not concern selection or causation. In almost all the studies, there is clear evidence of selection and little proof of a causative factor (for a partial exception see C o v e (1972)). The disagreement concerns differential utilization, which gdegaard found no support for, and which was neglected by others. The evidence here supports differential utilization, but the question remains as to whether this argument can explain all of the differences in rates between married and widowed.
CONCLUSIONS
Four major conclusions can be drawn on the basis of these data. First, there is strong evidence that selection operates and is partially responsible for the overrepresentation of the never-married in the schizophrenic population. Secondly, there is also evidence that differential utilization helps to produce that overall finding. Thirdly, there is no evidence that marriage is protective against schizophrenia. Finally, selection operates more powerfully in urban than in rural areas. ACKNOWLEDGMENTS This research was supported by NIMH grant MH25691. I would like to thank Irving Goldberg and Morton Kramer of the NIMH Biometry Branch for making available to me (unidentified) files of the Maryland Psychiatric Case Register. I would like to thank Luc Goudreault for his assistance in analyzing the data. REFERENCES Adler, L. (1953): The relationship of marital status to incidence and recovery from mental disease. SOC. Forces 32, 185-194. Babigian, H . M., E. A . Gardner, H . C.Miles & J . Romano (1965): Diagnostic consistency and change in a follow-up study of 1215 patients. h e r . J. Psychiat. 121, 895991.
328 Bochrach, L. (1975): Marital status and mental disorders: An analytical review. Government Printing Office, Washington, D. C. Bahn, A. K . (1962): Psychiatric Case Register Conference, 1962. Public Health Reports 77, 1071-1076. Bahn, A. K . (1965a): An outline for community mental health research. Comm. ment. Hlth J. 1 , 23-28. Bahn, A. K . (1965b): Experience and philosophy With regard to case registers in health and welfare. Comm. ment. Hlth. J. 1 , 245-250. Birley, J . L. T., & G . W . Brown (1970): Crises and life changes preceding the onset or relapse of acute schizophrenia: Clinical aspects. Brit. I. Psychiat. 116, 327-333. Campbell, D . T.. & J . C . Stanley (1966): Experimental and quasi-experimental designs for research. Rand McNally, Chicago. Dayton, N . A. (1936): Marriage and mental disease. New Engl. J. Med. 215, 153-155. Dohrenwend. B. P., & B. S. Dohrenwend (1969): Social status and psychological disorder: A causal inquiry. John Wiley & Sons, New York. Dunham, H . W . (1965): Community and schizophrenia: An epidemiological analysis. Wayne State University Press, Detroit. Eaton, W . W . (1974): Residence, social class, and schizophrenia, J. Hlth soc. Behav. 15, 289-299. Faris, R . E . L. (1934): Cultural isolation and the schizophrenic personality. Amer. J. Sociol. 40, 155-164. Gardner, E. A., & H . M . Babigian (1966): A longitudinal comparison of psychiatric service to selected socioeconomic areas of Monroe County, New York. h e r . J. Orthopsychiat. 36, 818-828. Gove, W . (1972): The relationship between sex roles, marital roles, and mental illness. Soc. Forces 51, 34-44. Hammer, M . (1963): Influences of small social networks as factors on mental hospital admission, Hum. Organ. 22, 243-251. Kramer, M . (1969): Applications of mental health statistics. WHO, Geneva. Miles, H. C., & E. A . Gardner (1966): A psychiatric case register. Arch. gen. Psychiat. 14, 571-580. Malzberg, B. (1964): Marital status and the incidence of mental disease. Int. J. soc. Psychiat. 10, 245-249. Murphy, H . B. M . (1965): Migration and the major mental disorders. In Kantor, M . B. (ed.): Mobility and mental health. Charles C. Thomas, Springfield, Illinois, pp. 5-29. Norris, V. (1956): A statistical study of the influence of marriage in the hospital care of the mentally sick. J. ment. Sci. 102, 467-486. Odeguard, 8. (1946): Marriage and mental disease: A study in social psychopathology. J. ment. Sci. 92, 35-59. Odeguard, 0. (1953): New data on marriage and mental disease: Incidence of psychoses in widowed and divorced. J. ment. Sci. 9,778-785. Rosen, B., D . Klein & R . Gittleman-Klein (1971): The prediction of rehospitalization: The relationship between age of first psychiatric treatment contact, marital status and premorbid asocial adjustment. J. nerv. ment. Dis. 152, 17-22. Sampson, H.. S. L. Messinger & R . D . Towne (1962): Family processes and becoming a mental patient. Amer. J. Sociol. 68, 88-96. Sandifer, M.. G . C. Pettus & D . Quade (1964): A study of psychiatric diagnosis. J. nerv. ment. Dis. 139, 350-356. Siegel, S. (1956): Non-parametric methods for the behavioral sciences. McGraw-Hill, New York. Stein. Z.,& M . W . Susser (1970): Bereavement as a precipitating event in mental illness. In Hare, E. H., & J . K . Wing (eds.): Psychiatric epidemiology, an international symposium. Oxford University Press, London. Sullivan, H . S. (1962): Schizophrenia as a human process. W. W. Norton & CO., New York.
329 Thomas, D . S., & B. 2. Locke (1963): Marital status, education and occupational differentials in mental disease. Millbank Mem. Fund Quart. 41, 145-160. Turner, R . J., L . Dopkeen & G . Labreche (1970): Marital status and schizophrenia: A study of incidence and outcome. J. abnorm. Psychol. 76, 110-1 16. Turner, R . J., J . Raymond, 3. Zaba L J . Diamond (1969): Field survey methods in psychiatry: The effects of sampling strategy upon findings in research on schizophrenia. J. Hlth soc. Behav. 10, 289-297. Received July 15, 1975
William W . Eaton, Ph.D. Institute of Community and Family Psychiatry Jewish General Hospital 4333 Cote Ste. Catherine Road Montreal, Quebec Canada
