Vol. 21, No. 6 Printed in Great Britain
International Journal of Epidemiology © International Eptdemiotogical Association 1992
Migraine and Tension-Type Headache in a General Population: Psychosocial Factors BIRTHE KROGH RASMUSSEN Rasmussen B K (The Glostrup Population Studies, Department of Internal Medicine C, Elevboligen 7. sal, Glostaip Hospital, DK-2600 Glostrup, Denmark). Migraine and tension-type headache in a general population: psychosocial factors. International Journal of Epidemiology 1992; 21: 1138-1143. In a cross-sectional study of headache disorders in a representative general population, the prevalence of migraine and tension-type headache was assessed in relation to various psychosocial factors. The random sample comprised 1000 25-64 year old men and women of whom 740 attended the investigation. The headache disorders were classified on the basis of a clinical interview, a physical and a neurological examination using the operational diagnostic criteria of the International Headache Society. None of the sociodemographic variables: marital status, cohabitation, educational level, occupational category or employment status were significantly associated with migraine or tension-type headache. In the univariate analyses tension-type headache was significantly associated with a high Neuroticism score on the Eysenck Personality Questionnaire whereas migraine was not. Variables on work conditions and psychosocial factors significantly associated with the headache disorders in univariate analyses were subjected to multivariate analysis. Migraine was significantly associated with exposure to chemicals and fumes at work in women and poor selfappraisal of health in men. In the univariate analyses tension-type headache was significantly related to a series of psychosocial variables. In the multivariate analyses it remained associated with a current feeling of fatigue in both sexes, time-pressure at work in women and exposure to fumes in men.
factors. Multivariate analyses were used to trace the jointly significant variables among the many individually informative ones.
Epidemiological studies on the relationship between headache and psychosocial factors are numerous but the findings are not consistent. Estimates of associations based on clinic patients are uncertain, since these comprise less than half of the overall headache sufferers' and selection bias may thus be considerable. Some studies focus on social variables and others on psychological problems. Only a few studies have analysed both these factors simultaneously in a nonselected population.2 In a representative general population the presence of migraine and tension-type headache was ascertained by a structured diagnostic headache interview as well as a neurological and a physical examination of all subjects. The operational diagnostic criteria of the International Headache Society3 (IHS) were used to diagnose the headaches. The aim of this paper is to analyse possible associations between migraine or tension-type headache and various psychosocial
MATERIALS AND METHOD Population A random sample of 1000, 25-64 year old people was drawn from the National Central Person Registry. The subjects lived in the western part of Copenhagen County. The sample was reduced to 975 as 25 subjects could not be contacted (dead, emigrated etc.) All subjects were invited to a free general health examination and 76% (387 men, 353 women) participated. The examination took place between January and July 1989 at the Glostrup Population Studies Center. A detailed description of the general study design, the representativeness of the population, and characteristics of the non-participants has been published previously.4 The project was approved by the ethical committee for Copenhagen County and by the Inspection of Registry.
The Glostrup Population Studies, Department of Internal Medicine C, Glostrup Hospital, University of Copenhagen and Department of Neurology, Gentofte Hospital, University of Copenhagen, Denmark. Reprint requests: Dr Birthe Krogh Rasmussen, The Glostrup Population Studies, Department of Internal Medicine C, Elevboligen 7. sal, Glostrup Hospital, DK-2600 Glostrup, Denmark.
Questionnaire Accompanying the invitation, a detailed questionnaire to be completed at home was enclosed. At the health 1138
MIGRAINE AND TENSION-TYPE HEADACHE, PSYCHOSOCIAL FACTORS
examination, the questionnaire was checked, and unanswered questions were repeated verbatim to obtain an answer. From this questionnaire nine variables related to marital status, cohabitation, residence in various regions of the country, employment status, occupational grouping, and education were included in the study. Occupation and education were recorded according to the International Standard Industrial Classification3 (ISIQ with modifications made by the Danish Statistical Department. Furthermore, the analyses included 16 variables on working conditions (e.g. job satisfaction, night duty, work speed, monotony), three variables on social network, five variables on current problems (e.g. personal, familial, financial) and a variable of self-appraisal of health. In all, 34 items were included. Personality Eysenck's Personality Questionnaire6 (EPQ)(N- and L-scale, 44 items) was given to each participant on the day of examination. The N-scale includes 23 items and is a measure of the personality trait of neuroticism. The scale includes items about a general tendency to worry about one's health. The 'Lie' scale includes 21 items and is a measure of dissimulation. Because the N-scale is constructed by questions the key answer to which is 'yes', it is also a measure of the tendency to answer 'yes' whatever the content of the question. Thus, it is important to compare the results from this scale with the L-scale in order to correct for the effect of dissimulation. Headache Interview, Examination and Diagnoses On the day of examination a clinical structured headache interview, a general physical and a neurological examination were performed for all participants. The interview included an extensive description of the headache history including the headache frequency, duration, location, character of pain, intensity, accompanying symptoms etc. The exact wording and details of the replies to individual questions about various features of migraine and tension-type headache have been published previously.4 Based on this information all headache disorders were classified according to the operational diagnostic criteria of the IHS.3 In this paper the migraine group encompasses all subjects with migraine during the previous year (oneyear prevalence). The migraine group also included subjects with coexisting tension-type headache. A pure migraine group was not used since the numbers for analyses would be too small. Thus 83% of the migraineurs also had tension-type headache/ and
1139
therefore the use of a pure migraine group may lead to non-representative results (diagnostic purity bias7). The tension-type headache group included subjects with tension-type headache for more than 14 days in the previous year and who had never had migraine. STATISTICAL METHODS Data for each sex were analysed separately. In the univariate analyses the x2 test was used for nominal variables and a logistic regression analysis for continuous variables; 5% was chosen as the level of statistical significance. To account for any associations between the independent variables, a multiple logistic regression analysis was performed by means of the BMDP (Biomedical Computer Program) estimating the association between each variable and migraine/tension-type headache adjusting for the influence of the other variables. The logistic coefficient (log coeff) and standard error were estimated. The odds ratio (OR) was calculated by exp (log coeff) and 95% confidence limits (CL) were used. Variables on working conditions were analysed only for those participants who were gainfully employed at the time of examination. When these variables were included in the multivariate analyses, the analyses were restricted to participants gainfully employed. The multivariate analyses were done both with and without inclusion of the occupational variables. RESULTS The age-adjusted one-year prevalence of migraine was 10% (n = 77); among men 6% (n = 23) and among women 15% (n = 54). The age-adjusted prevalence of tension-type headache for more than 14 days in the previous year was 22% (n = 167); among men 17% (n = 65) and among women 28% (n = 102). No significant associations between age and the dependent variables used in the present study were found. Sociodemographic Factors No significant relationships were found between migraine or tension-type headache and marital status, employment status, category of industry or education. There was a non-significant trend in the direction of higher migraine prevalence among men with longer school education and this was followed by a similar non-significant relationship with regard to further education. No association emerged between subjects who has previously lived in rural areas compared to subjects who had always lived in urban areas as regards prevalence rates of migraine and tension-type headache. Comparing the distribution of these social
1140
INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
D
variables in migraineurs and in subjects with tensiontype headache showed no significant differences.
headache groups showed any association with the Lie score (Table 1). The high prevalence of tension-type headache in subjects with high N-score was consistent even when controlling for the effect of the Lie-score. Moreover, adjusting for not only sex and age, but also social variables (cohabitation, education, employment) the N-score remained independently related to tension-type headache and unrelated to migraine. Controlling for the effect of the N-score on the prevalence rates of migraine and tension-type headache, the sex difference in migraine (male: female = 1:3) and in tension-type headache (male: female = 2:3) remained unchanged.
Personality Age-adjusted means of the N- and L-scale among subjects with migraine in the previous year and among subjects with tension-type headache for more than 14 days in the previous year (and no coexisting migraine) are given in Table 1. The age-standardized mean value of the N-score in subjects with pure migraine (excluding subjects with coexisting tension-type headache) showed substantially lower values (5.3 [standard deviation-SD ± 4 . 2 ] in men and 8.6 [SD ± 4 . 1 ] in women) than the combined migraine group. Logistic regression analyses controlling for the effect of age, showed no relation between migraine and personality N-score (males P > 0.3; females P > 0.1) and also after including the Lie score in this analysis no association emerged. A significant association was found between tension-type headache (both sexes) and the Neuroticism score. None of the
Work Conditions and Social Network The trends in the variables that in the univariate analyses proved to be significantly associated with migraine or tension-type headache in the previous year are summarized in Table 2. In all instances the trends were towards more symptoms and/or problems for those who had migraine or tension-type headache
TABLE 1 The Eysenck Personality Questionnaire. Age-adjusted means ± standard deviations
Migraine Personality scale Neuroticism Lie
Men 7. 9 ± 9. 6 ±
3.9 3.2
Tension-type headache
Total sample Men
Women
Men
Women
10.7 ± 5.0 11.2 ± 4.0
•8.4 ± 5.6 10.2 ± 3.8
-10.8 ± 5. 2 11.6 ± 4. 1
7.0 ± 10.0 ±
Women 4.7 4.3
9.8 ± 5. 2 11.3 ± 4 . 1
NB Logistic regression analysis including age as confounding variable: * P < 0.01, ~ P < 0.05. TABLE 2 Trends in variables (Vl-Vl 1) that separately were significantly associated with migraine or tension-type headache. Work conditions and psychosocialfactors Variables VI. V2. V3. V4. V5. V6. V7. V8.
More frequently exposed to fumes or chemicals at work More frequently troubled in handling their job More frequently not able to relax from job after working hours More frequent high workload More frequently too little time to do current job More frequently working in a noisy environment More frequently having nobody (close relatives, friends or others) to talk to about personal matters More frequent feelings of fatigue
V9. More frequently troubled by personal problems V10. More frequently having poor health within the last year I I 1 . More frequent high neuroticism score on EPQ personality score
* Logistic regression analyses including tge as confounding variable. 9 = females cr =. males
Migraine
Tension-type headache
International Journal of Epidemiology © International Eptdemiotogical Association 1992
Migraine and Tension-Type Headache in a General Population: Psychosocial Factors BIRTHE KROGH RASMUSSEN Rasmussen B K (The Glostrup Population Studies, Department of Internal Medicine C, Elevboligen 7. sal, Glostaip Hospital, DK-2600 Glostrup, Denmark). Migraine and tension-type headache in a general population: psychosocial factors. International Journal of Epidemiology 1992; 21: 1138-1143. In a cross-sectional study of headache disorders in a representative general population, the prevalence of migraine and tension-type headache was assessed in relation to various psychosocial factors. The random sample comprised 1000 25-64 year old men and women of whom 740 attended the investigation. The headache disorders were classified on the basis of a clinical interview, a physical and a neurological examination using the operational diagnostic criteria of the International Headache Society. None of the sociodemographic variables: marital status, cohabitation, educational level, occupational category or employment status were significantly associated with migraine or tension-type headache. In the univariate analyses tension-type headache was significantly associated with a high Neuroticism score on the Eysenck Personality Questionnaire whereas migraine was not. Variables on work conditions and psychosocial factors significantly associated with the headache disorders in univariate analyses were subjected to multivariate analysis. Migraine was significantly associated with exposure to chemicals and fumes at work in women and poor selfappraisal of health in men. In the univariate analyses tension-type headache was significantly related to a series of psychosocial variables. In the multivariate analyses it remained associated with a current feeling of fatigue in both sexes, time-pressure at work in women and exposure to fumes in men.
factors. Multivariate analyses were used to trace the jointly significant variables among the many individually informative ones.
Epidemiological studies on the relationship between headache and psychosocial factors are numerous but the findings are not consistent. Estimates of associations based on clinic patients are uncertain, since these comprise less than half of the overall headache sufferers' and selection bias may thus be considerable. Some studies focus on social variables and others on psychological problems. Only a few studies have analysed both these factors simultaneously in a nonselected population.2 In a representative general population the presence of migraine and tension-type headache was ascertained by a structured diagnostic headache interview as well as a neurological and a physical examination of all subjects. The operational diagnostic criteria of the International Headache Society3 (IHS) were used to diagnose the headaches. The aim of this paper is to analyse possible associations between migraine or tension-type headache and various psychosocial
MATERIALS AND METHOD Population A random sample of 1000, 25-64 year old people was drawn from the National Central Person Registry. The subjects lived in the western part of Copenhagen County. The sample was reduced to 975 as 25 subjects could not be contacted (dead, emigrated etc.) All subjects were invited to a free general health examination and 76% (387 men, 353 women) participated. The examination took place between January and July 1989 at the Glostrup Population Studies Center. A detailed description of the general study design, the representativeness of the population, and characteristics of the non-participants has been published previously.4 The project was approved by the ethical committee for Copenhagen County and by the Inspection of Registry.
The Glostrup Population Studies, Department of Internal Medicine C, Glostrup Hospital, University of Copenhagen and Department of Neurology, Gentofte Hospital, University of Copenhagen, Denmark. Reprint requests: Dr Birthe Krogh Rasmussen, The Glostrup Population Studies, Department of Internal Medicine C, Elevboligen 7. sal, Glostrup Hospital, DK-2600 Glostrup, Denmark.
Questionnaire Accompanying the invitation, a detailed questionnaire to be completed at home was enclosed. At the health 1138
MIGRAINE AND TENSION-TYPE HEADACHE, PSYCHOSOCIAL FACTORS
examination, the questionnaire was checked, and unanswered questions were repeated verbatim to obtain an answer. From this questionnaire nine variables related to marital status, cohabitation, residence in various regions of the country, employment status, occupational grouping, and education were included in the study. Occupation and education were recorded according to the International Standard Industrial Classification3 (ISIQ with modifications made by the Danish Statistical Department. Furthermore, the analyses included 16 variables on working conditions (e.g. job satisfaction, night duty, work speed, monotony), three variables on social network, five variables on current problems (e.g. personal, familial, financial) and a variable of self-appraisal of health. In all, 34 items were included. Personality Eysenck's Personality Questionnaire6 (EPQ)(N- and L-scale, 44 items) was given to each participant on the day of examination. The N-scale includes 23 items and is a measure of the personality trait of neuroticism. The scale includes items about a general tendency to worry about one's health. The 'Lie' scale includes 21 items and is a measure of dissimulation. Because the N-scale is constructed by questions the key answer to which is 'yes', it is also a measure of the tendency to answer 'yes' whatever the content of the question. Thus, it is important to compare the results from this scale with the L-scale in order to correct for the effect of dissimulation. Headache Interview, Examination and Diagnoses On the day of examination a clinical structured headache interview, a general physical and a neurological examination were performed for all participants. The interview included an extensive description of the headache history including the headache frequency, duration, location, character of pain, intensity, accompanying symptoms etc. The exact wording and details of the replies to individual questions about various features of migraine and tension-type headache have been published previously.4 Based on this information all headache disorders were classified according to the operational diagnostic criteria of the IHS.3 In this paper the migraine group encompasses all subjects with migraine during the previous year (oneyear prevalence). The migraine group also included subjects with coexisting tension-type headache. A pure migraine group was not used since the numbers for analyses would be too small. Thus 83% of the migraineurs also had tension-type headache/ and
1139
therefore the use of a pure migraine group may lead to non-representative results (diagnostic purity bias7). The tension-type headache group included subjects with tension-type headache for more than 14 days in the previous year and who had never had migraine. STATISTICAL METHODS Data for each sex were analysed separately. In the univariate analyses the x2 test was used for nominal variables and a logistic regression analysis for continuous variables; 5% was chosen as the level of statistical significance. To account for any associations between the independent variables, a multiple logistic regression analysis was performed by means of the BMDP (Biomedical Computer Program) estimating the association between each variable and migraine/tension-type headache adjusting for the influence of the other variables. The logistic coefficient (log coeff) and standard error were estimated. The odds ratio (OR) was calculated by exp (log coeff) and 95% confidence limits (CL) were used. Variables on working conditions were analysed only for those participants who were gainfully employed at the time of examination. When these variables were included in the multivariate analyses, the analyses were restricted to participants gainfully employed. The multivariate analyses were done both with and without inclusion of the occupational variables. RESULTS The age-adjusted one-year prevalence of migraine was 10% (n = 77); among men 6% (n = 23) and among women 15% (n = 54). The age-adjusted prevalence of tension-type headache for more than 14 days in the previous year was 22% (n = 167); among men 17% (n = 65) and among women 28% (n = 102). No significant associations between age and the dependent variables used in the present study were found. Sociodemographic Factors No significant relationships were found between migraine or tension-type headache and marital status, employment status, category of industry or education. There was a non-significant trend in the direction of higher migraine prevalence among men with longer school education and this was followed by a similar non-significant relationship with regard to further education. No association emerged between subjects who has previously lived in rural areas compared to subjects who had always lived in urban areas as regards prevalence rates of migraine and tension-type headache. Comparing the distribution of these social
1140
INTERNATIONAL JOURNAL OF EPIDEMIOLOGY
D
variables in migraineurs and in subjects with tensiontype headache showed no significant differences.
headache groups showed any association with the Lie score (Table 1). The high prevalence of tension-type headache in subjects with high N-score was consistent even when controlling for the effect of the Lie-score. Moreover, adjusting for not only sex and age, but also social variables (cohabitation, education, employment) the N-score remained independently related to tension-type headache and unrelated to migraine. Controlling for the effect of the N-score on the prevalence rates of migraine and tension-type headache, the sex difference in migraine (male: female = 1:3) and in tension-type headache (male: female = 2:3) remained unchanged.
Personality Age-adjusted means of the N- and L-scale among subjects with migraine in the previous year and among subjects with tension-type headache for more than 14 days in the previous year (and no coexisting migraine) are given in Table 1. The age-standardized mean value of the N-score in subjects with pure migraine (excluding subjects with coexisting tension-type headache) showed substantially lower values (5.3 [standard deviation-SD ± 4 . 2 ] in men and 8.6 [SD ± 4 . 1 ] in women) than the combined migraine group. Logistic regression analyses controlling for the effect of age, showed no relation between migraine and personality N-score (males P > 0.3; females P > 0.1) and also after including the Lie score in this analysis no association emerged. A significant association was found between tension-type headache (both sexes) and the Neuroticism score. None of the
Work Conditions and Social Network The trends in the variables that in the univariate analyses proved to be significantly associated with migraine or tension-type headache in the previous year are summarized in Table 2. In all instances the trends were towards more symptoms and/or problems for those who had migraine or tension-type headache
TABLE 1 The Eysenck Personality Questionnaire. Age-adjusted means ± standard deviations
Migraine Personality scale Neuroticism Lie
Men 7. 9 ± 9. 6 ±
3.9 3.2
Tension-type headache
Total sample Men
Women
Men
Women
10.7 ± 5.0 11.2 ± 4.0
•8.4 ± 5.6 10.2 ± 3.8
-10.8 ± 5. 2 11.6 ± 4. 1
7.0 ± 10.0 ±
Women 4.7 4.3
9.8 ± 5. 2 11.3 ± 4 . 1
NB Logistic regression analysis including age as confounding variable: * P < 0.01, ~ P < 0.05. TABLE 2 Trends in variables (Vl-Vl 1) that separately were significantly associated with migraine or tension-type headache. Work conditions and psychosocialfactors Variables VI. V2. V3. V4. V5. V6. V7. V8.
More frequently exposed to fumes or chemicals at work More frequently troubled in handling their job More frequently not able to relax from job after working hours More frequent high workload More frequently too little time to do current job More frequently working in a noisy environment More frequently having nobody (close relatives, friends or others) to talk to about personal matters More frequent feelings of fatigue
V9. More frequently troubled by personal problems V10. More frequently having poor health within the last year I I 1 . More frequent high neuroticism score on EPQ personality score
* Logistic regression analyses including tge as confounding variable. 9 = females cr =. males
Migraine
Tension-type headache
