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Alcohol Consumption and Disability Pension among Middle-Aged Men
Alcohol Consumption and Disability Pension among Middle-Aged Men ˚ NSSON, MD, PhD, LENNART RA ˚ STAM, MD, PhD, NILS-OVE MA KARL-FREDRIK ERIKSSON, MD, PhD, AND BO ISRAELSSON, MD, PhD
PURPOSE: To analyze the relation between alcohol consumption and the risk of disability pension among middle-aged men. METHODS: In the mid-seventies, complete birth-year cohorts of middle-aged male residents in Malmo¨, Sweden, were invited to participate in a general health survey. The 3751 men with complete data who constituted the cohort in this study were followed for 11 years. Alcohol consumption was estimated from the scores obtained from a test designed to identify subjects with alcohol related problems. RESULTS: Of the 498 men granted disability pension during follow-up, 48 stated to be teetotalers. The cumulative incidence of disability pension among teetotalers was 19%, whereas, it was 12% and 16%, respectively, among men with low and high alcohol consumption. The adjusted relative risk (RR) for acquiring a disability pension (using the group with low alcohol consumption as reference) was 1.8 among abstainers and 1.3 among men with high alcohol consumption. CONCLUSIONS: Alcohol overconsumption, as well as teetotalism, showed a positive relation to disability pension, and a moderate alcohol intake was found to be beneficial with respect to the risk of future disability pension. Ann Epidemiol 1999;9:341–348. 1999 Elsevier Science Inc. All rights reserved. KEY WORDS:
Alcohol, Disability Pension, Early Retirement, Screening, Teetotalism.
INTRODUCTION It is well known that there is a considerable impact of overconsumption of alcohol on morbidity and mortality (1–4). A high prevalence of alcohol-related problems has also been found among men with disability pension (5, 6). In 1977, Swedish legislation was amended to allow more liberal decisions to grant disability pension to alcohol abusers. As a result, the number of alcohol abusers granted disability pension has increased. Still, however, it has been suggested that the diagnosis of alcohol dependence is underrepresented in the mortality statistics as well as among reasons for disability pension, and that this diagnosis may be hidden behind socially more acceptable diagnoses (6–9). If so, it would be of interest to identify other characteristics of those at risk for early retirement due to alcohol abuse, to be able to avoid unnecessary cases of disability pension. Furthermore, a J-shaped association between alcohol consumption and mortality has been found in several studies (10–15). A similar non-linear relation has been found be-
tween alcohol consumption and morbidity (16, 17) but so far, no studies have investigated the consequences of this for the risk of early retirement. The aim of this study was, therefore, to assess the association between alcohol consumption, indicated by scores at an alcohol screening test, and the risk of disability pension. MATERIALS AND METHODS In Sweden, subjects aged 16–64 years, whose working capacity is impaired by at least 50% (from July 1993: 25%) due to disease, can be granted disability pension. If the impairment is not regarded permanent, temporary pension is granted. Full disability pension, including national supplementary pension (ATP), amounts to approximately 65% of the annual income. Supplementary benefits, e.g., housing supplement, constitutes, in many cases, an additional compensation. Applications for disability pension are administered by the public social insurance offices. A doctor’s certificate accompanying the application is required. Subjects
From the Department of Community Medicine (N.-O.M., L.R.), Department of Angiology (K.-F.E.), and Department of Cardiology (B.I.), Lund University, Malmo¨ University Hospital, Malmo¨, Sweden. Address reprint requests to: Dr Nils-Ove Ma˚nsson, Department of Community Medicine, Malmo¨ University Hospital, S-205 02 Malmo¨, Sweden. Received May 7, 1998; revised December 28, 1998; accepted February 22, 1999. 1999 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
The cohort used in this study has been presented in detail elsewhere (18). In 1974–1978, five complete birth-year (1926– 1930) cohorts of middle-aged male residents of Malmo¨, Sweden (251,431 inhabitants as of January 1, 1974), were invited to participate in a screening program (19). A total of 7697 men were invited and 5932 (77.1%) participated. 1047-2797/99/$–see front matter PII S1047-2797(99)00014-9
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Selected Abbreviations and Acronyms ATP 5 national supplementary pension ICD 5 International Classification of Diseases MAST 5 Michigan Alcohol Screening Test Mm-MAST 5 Malmo¨ modification of the Brief MAST S-GT 5 Serum gamma glutamyl transferase S-Chol 5 Serum total cholesterol
Mean age (6 SD) at screening was 48.1 6 0.7 years. According to the original protocol, men born in 1926 should be included in 1974, those born in 1927 should be included in 1975 and so on, and the slight variation in age at screening is explained by temporary deviations from that protocol. In the present study, inclusion was defined by the date of examination, and each subject was followed until death or the end of the calendar year when he turned 58, i.e., a total study period of approximately 11 years. Included in this study were, however, only subjects who, without a previous disability pension, participated after April 1, 1976 (n 5 3757), as this was the date when collection of data on alcohol consumption was commenced. Screening data The following data, used in the present study, was obtained during the initial health examination that included serum gamma glutamyl transferase (S-GT), serum total cholesterol (S-Chol), body height, body weight, blood pressure, alcohol habits, smoking habits, and perceived health. S-GT and SChol were measured in venous blood samples and presented in mcatal/l and mmol/l, respectively. All laboratory analyses were performed using standard methods at the Department of Clinical Chemistry, Malmo¨ University Hospital. Height (to the nearest cm) and weight (to the nearest 0.1 kg) were measured using calibrated scales. Body mass index (BMI), defined as weight (kg) divided by height squared (m2), was used to estimate the degree of over/underweight and was classified as suggested by Bray (20) and as used on the national level by Statistics Sweden in the Surveys of Living Conditions (21). Thus, underweight was defined as BMI , 20.0, normal weight as BMI 20.0–24.9, overweight as BMI 25.0–29.9, and obesity as BMI > 30.0. Blood pressure was measured after 10 minutes rest in the right arm to the nearest 5 mmHg. Hypertension was defined as systolic blood pressure > 160 mmHg, diastolic blood pressure > 95 mmHg, and/or current use of anti-hypertensive medications. Data on teetotalism, smoking habits, and perceived health were obtained from a questionnaire. Teetotalers were those who answered “yes” to the question “Are you a teetotaler?” Smoking was defined as daily smoking of cigarettes, and perceived perfect health was based on an affirmative answer to the question “Do you feel perfectly healthy?”
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TABLE 1. Affirmative answers to different Mm-MAST questions among 3491 non-abstainers Answers Questions 1. Do you usually have a drink before going to a party? 2. Do you usually drink a bottle of wine or corresponding amounts of alcohol over the week-end? 3. Do you have a couple of beers a day to relax? 4. Do you tolerate alcohol better now than you did ten years ago? 5. Do you have to concentrate on drinking about the same quantity of alcohol as the others at a party? 6. Have you ever fallen asleep after drinking without knowing how you got to bed? 7. Do you have a bad conscience after drinking? 8. Do you usually have a beer the day after a party? 9. Do you try to avoid alcoholic beverage for a determined period of time, e.g., a week?
Number
%
670
19.2
933
26.7
216
6.2
337
9.7
100
2.9
191
5.5
292
8.4
582
16.7
687
19.7
The questionnaire used in the health examination also included a modified version of the Brief MAST, an abbreviated version of the Michigan Alcohol Screening Test (MAST) (22, 23). This “Malmo¨ modification of the Brief MAST” (Mm-MAST) is described elsewhere (24) and is based on nine questions, each giving a score of 0 (no) or 1 (yes). MAST-score was calculated and used as an estimate of alcohol consumption for those who were not teetotalers. A score of two or more, considered indicative of alcohol related problems in a previous study (24), was used as the cut-off level between the two categories “highMAST” and “low MAST”. The nine Mm-MAST questions are presented in Table 1. Data on Disability Pension A cumulative data base of all decisions on disability pension—including data on year and month of birth, date of retirement, type (temporary or permanent), and extent (50, 67, or 100% of full time) of the disability pension, marital status, and diagnoses—is, since 1971, maintained by the National Social Insurance Board in Sweden. The diagnoses are coded according to the International Classification of Diseases (ICD). The 8th revision (ICD-8) was used until December 31 1986 and the 9th revision (ICD-9) thereafter. Data on Mortality The underlying cause of death is registered for every subject who is residing in Sweden at the time of death. The deceased person’s identification number and the cause of death, coded
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according to the ICD, are entered into a data base. As for data on disability pension, the 8th revision (ICD-8) was used until December 31 1986 and the 9th revision (ICD9) thereafter. Information about time and cause of death for those in the cohort who died during follow-up was obtained from this database. A high autopsy rate is important for the validity of such a database and in Malmo¨, the frequency was very high from the mid-60s to the late-80s; in 1987 it was 86 and 91%, respectively, for males 50–54 and 55–59 years old (25). Statistical Methods The distribution of S-GT is skewed to the left and in univariate statistical testing S-GT values were used with logarithmic transformation. For presentation and analysis, the first 80 percentiles were split into two groups (1–40 and 41–80), whereas, the upper 20 percentiles constituted the extreme group of S-GT-values. S-Chol was dichotomized at the median. The Chi-square test was used to test for differences in proportions and Student’s t test for differences in means. Multivariate analyses were performed using Cox’s proportional hazards model, in which adjusted relative risks (RR) and their 95% confidence intervals were calculated. The Cox’s model was also used to test for trend. All tests were two-sided. A difference was considered statistically significant when p , 0.05.
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RESULTS Six subjects, lacking complete data, had to be excluded, leaving the final number of subjects included in the study at 3751. Mean S-Chol (6 SD) was 5.81 6 1.06 with a median 5.77 mmol/l. Mean diastolic blood pressure was 89.0 6 13.4 mmHg and mean systolic blood pressure was 132.0 6 16.6 mmHg. The values for S-GT at the 40th and 80th percentiles were 0.47 and 0.91 mcatal/l, respectively, defining the cut-points for “low,” “intermediate,” and “high S-GT.” A total of 1222 (32.6%) of the men were categorized as hypertensives, and 1520 (40.5%) were daily smokers of cigarettes. Of all 3751 men, 2812 (75.0%) perceived their health as perfect. Two hundred and sixty subjects (6.9%) stated to be teetotalers. Of the remaining 3491 men, 2438 (65.0% of all) had a low and 1053 (28.1% of all) had a high MASTscore. The rates of affirmative answers to the nine MmMAST questions are presented in Table 1. Disability Pensioners Four hundred and ninety eight (13.3%) of the men were granted a disability pension after screening, whereas, the remaining 3253 (86.7%) were not. Table 2 summarizes characteristics of these two categories of men. Mean S-Chol did not differ significantly (p 5 0.33). Mean body mass index was, however, significantly higher
TABLE 2. Means and standard deviations (SD) of laboratory tests, body mass index, and blood pressure as well as number and rates of certain variables among subjects with and without disability pension granted during follow-up No pension (n 5 3253) Serum cholesterol Body mass index Systolic blood pressure Diastolic blood pressure Hypertension: Daily smoking: Body mass index:
Perceived perfect health: S-GT:
Alcohol related variables:
yes no yes no , 20.0 20.0–24.9 25.0–29.9 > 30.0 yes no low intermediate high Teetotalers MAST , 2 MAST > 2
mean 5.81 24.86 131.8 88.8 Number 1031 2222 1264 1989 143 1687 1227 196 2563 690 1348 1312 593 212 2158 883
Disability pension (n 5 498) SD 1.05 3.16 16.5 13.8 % 31.7 68.3 38.9 61.1 4.4 51.9 37.7 6.0 78.8 21.2 41.4 40.3 18.2 6.5 66.3 27.1
mean 5.86 25.64 133.2 90.3 Number 191 307 256 242 33 193 201 71 249 249 164 194 140 48 280 170
SD 1.15 4.05 17.2 10.9 % 38.4 61.6 51.4 48.6 6.6 38.8 40.4 14.3 50.0 50.0 32.9 39.0 28.1 9.6 56.2 34.1
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among the pensioners (p , 0.0001), and this was true also for diastolic blood pressure (p 5 0.022) but not for systolic blood pressure (p 5 0.09). Thus, hypertension was significantly more common among the pensioners (p 5 0.0031), and so was daily smoking (p , 0.0001). The distribution of body mass index categories (Table 2) suggested a U-shaped relation, as both the proportions of underweight (p 5 0.028) and obese subjects (p , 0.0001) were higher among the pensioners, whereas, the prevalence of normal weight was significantly lower (p , 0.0001). As further illustrated in Table 2, the proportion of subjects who perceived their health as perfect was significantly lower among the future pensioners (p , 0.0001). Of these, 24 (50%) were teetotalers, 139 (50%) were men with low and 86 (51%) were men with high MAST-scores. In addition, S-GT was higher among the pensioners, as illustrated in Table 1. Thus, a higher proportion of the pensioners had a high (p , 0.0001) and fewer had a low S-GT level (p 5 0.0003). The prevalence of teetotalism at start of follow-up was higher among the future pensioners (p 5 0.011) and so was the proportion that had a high MAST-score (p 5 0.0012). Risk of Future Disability Pension by S-GT Level and MAST-Score Figure 1 shows the cumulative incidence of disability pension after participation in screening, distributed by decile of S-GT. The risk-ratio increased only marginally from the first to the 9th decile, whereas it was almost double in the highest. For the distribution by MAST-score, the risk slope was more continuous and graded (Figure 2). Teetotalers, however, had a risk ratio higher than the non-abstainers with the lowest MAST-scores.
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FIGURE 2. Cumulative incidence of disability pension among teetotalers (T) and subjects with different MAST-scores.
For further analysis, the categories of MAST-score presented in Table 2 were used to estimate risk-ratios. Thus, the cumulative incidence of disability pension was calculated for teetotalers and men with a low and a high MAST-score, respectively. While the ratio for subjects with low MASTscores was 11.5%, the corresponding figures for both teetotalers and subjects with high MAST-scores were higher: 18.5% and 16.1%, respectively. The RR for acquiring a disability pension are shown in Table 3. After adjustment for smoking, hypertension, S-Chol, and BMI, the RR decreased among men with high MASTscores but remained unchanged for the abstainers. When perceived health was included among the covariates already adjusted for, RR was marginally reduced (1.7; CI: 1.2–2.3) among abstainers, whereas it remained unchanged (1.3; CI: 1.1–1.6) among men with high MAST-scores. The corresponding figures for the groups with intermediate and high S-GT measures were 1.2 (CI: 1.0–1.6) and 1.6 (CI: 1.3–2.1), respectively. When the three categories were analyzed separately in relation to S-GT, a positive, linear relation was found between ratio of disability pension and S-GT in both the low and the high MAST group (Figure 3). For both, there was a statistically significant increase in RR, before and after adjustment for confounders. For the teetotalers there was a J-shaped pattern in cumulative incidence, but no statistically significant differences in RR. Median age when pension was granted was 56 years for teetotalers and subjects with low MAST-scores, and 55 years for subjects with high MAST-scores. Diagnoses
FIGURE 1. Cumulative incidence of disability pension among subjects in different S-GT deciles.
Three disease categories predominated among the main and concomitant diagnoses that motivated the disability pension
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TABLE 3. MAST-scores, S-GT values, and relative risks (RR) of disability pension
Teetotalers Low MAST-scores High MAST-scores S-GT-percentiles 1–40 S-GT-percentiles 41–80 S-GT-percentiles 81–100 a
Crude RR (95% CI)
Adjusted RRa (95% CI)
1.8 (1.3, 2.4) reference 1.5 (1.2, 1.8) reference 1.4 (1.1, 1.7) 2.1 (1.7, 2.7)
1.8 (1.3, 2.4) reference 1.3 (1.1, 1.6) reference 1.2 (1.0, 1.5) 1.8 (1.4, 2.2)
Adjusted for smoking, hypertension, S-Chol, and BMI.
(Table 4). Main diagnoses of musculoskeletal diseases, mental disorders (including alcohol dependence) and diseases of the circulatory system were present in 73% of all cases. While alcohol dependence occurred as a diagnosis for 7% of the 498 subjects with disability pension, it accounted for 16% among those with MAST-score 2–8, the prevalence more than five times that in the group with low MASTscores (p , 0.0001). One teetotaler was retired because of a diagnosis of alcohol dependence. Restricting the analysis to main diagnoses did not change the results. A similar pattern as that for alcohol dependence was found for the diagnoses injury/poisoning and liver diseases, however, statistically significant only for injury/poisoning. Mortality During follow-up, 231 subjects (6%) died. The predominating causes of death were diseases of the circulatory system (44%), neoplasm (34%), and injury/poisoning (10%). Among subjects with low and high MAST-scores, the mortality rate was 5% and 8%, respectively. The teetotalers were in this respect an intermediary group with a death rate of 6%
FIGURE 3. Cumulative incidence of disability pension among subjects in different S-GT-percentiles after separation into three categories: Teetotalers (m) and men with high (d) and low (s) MAST-scores.
(same as for the entire cohort). The difference in mortality rate was statistically significant (p 5 0.003) between the groups with low and high MAST-scores. RR for premature death, adjusted for smoking, hypertension, S-Chol, BMI, and perceived health (again using the group with low MAST-scores as reference), were 1.3 (CI: 0.7–2.1) among teetotalers and 1.3 (CI: 1.0–1.8) among men with high MAST-scores. The mortality among those with disability pension was higher; 46 (9%) of the 498 pensioners were dead at the end of follow-up. Among these, alcohol dependence was the main (n 5 10) or a concomitant (n 5 3) diagnosis causing the disability pension in 13 cases (28%). Of the 36 men with a diagnosis of alcohol dependence, 13 (36%) died during follow-up, a mortality rate six times that of the entire cohort.
DISCUSSION MAST-scores, commonly used as an indicator of alcohol related problems, was in this study used as an estimation of alcohol consumption. This had of course certain limitations; the amount of the alcohol intake was not measured, which made it impossible to identify the relation between actual alcohol consumption on one hand and disability and mortality on the other hand. The S-GT measurement might have been more suitable in estimating alcohol consumption but, considering the purpose of the study, the MAST-scores were believed to be a better indicator of problem-related consumption of alcohol. The highest cumulative incidence of disability pensions was found among teetotalers when aggregated categories of MAST-scores were used for comparison. Compared with the category of low MAST-scores, the RR for abstainers acquiring a disability pension was significantly higher. This was also true after considering possible confounders, e.g., BMI which, in a previous paper proved to be positively correlated to increased risk for disability pension (26). However, the cut-off level, a MAST-score of two or more, used in accordance with a previous study (24) may, in this study, not have been the most appropriate one to distinguish between subjects with and without alcohol related problems.
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TABLE 4. Main and concomitant diagnoses (1st, 2nd, or 3rd diagnosis) as basis for disability pension among teetotalers and subjects separated by MAST-score. Only pensions granted after screening were considered Teetotalers (n 5 48) Groups of diagnoses Diseases of the musculoskeletal system Mental disorders Alcohol dependencea Diseases of the circulatory system Diseases of the nervous system Diseases of the respiratory system Diseases of the gastrointestinal tract Injury/poisoningb Neoplasms Diabetes Liver diseases Others
MAST-score 0–1 (n 5 280)
MAST-score 2–8 (n 5 170)
Total (n 5 498)
Number
%
Number
%
Number
%
Number
%
28 10 1 9 4 2 — — 2 3 — 7
58 21 2 19 8 4
144 47 8 60 22 22 13 7 12 7 1 30
51 17 3 21 8 8 8 3 4 3 ,1 11
87 29 27 45 11 7 9 14 4 6 5 9
51 17 16 26 6 4 5 8 2 4 3 5
259 86 36 114 37 31 22 21 18 16 6 46
52 17 7 23 7 6 4 4 4 3 1 9
4 6 15
p , 0.0001 for difference between subjects with low and high MAST-score. b p , 0.01. a
In fact, the cumulative incidence of disability pension was lower in the group of teetotalers than in any of the categories with a MAST-score of four or more. There are reasons to believe that the teetotalers constitute a heterogeneous group, including among others former heavy drinkers as well as persons with chronic conditions (27, 28), and one may speculate on the significance of the J-shaped relation in Figure 3. The explanation may, at least in part, be found in characteristics other than alcohol consumption of the teetotalers with low and high levels of S-GT, respectively. Alcohol dependence as well as the alcohol related diagnoses of injury and poisoning were, as expected, significantly less common among teetotaler pensioners. No significant differences in other diagnoses were found between teetotalers and the two groups with different MAST-scores. Higher than expected morbidity and mortality have been demonstrated among teetotalers in many previous investigations (10–12, 14–17). In addition to the presence of exdrinkers among the teetotalers, it has been argued that the habit to abstain from alcohol to some extent is caused by pre-existing illness which in turn would explain the higher morbidity and mortality (29). However, perceived health did not differ between abstainers and drinkers and did not affect the RR of disability pension for the groups of teetotalers and those with high MAST-scores. Differences in mortality were marginal, but lowest among those with low MASTscores. Furthermore, in general, teetotalers were granted their disability pensions later than subjects with high MAST-scores. To summarize these findings: A low alcohol intake, as indicated by a low MAST-score, seemed to be most beneficial with respect to the risk of future disability pension, findings consistent with previous investigations regarding morbidity and mortality. However, the character-
istics of the teetotaler status must be further investigated in order to adequately answer this question. The diagnosis of alcohol dependence was present in 7% (n 5 36) of the records of those with disability pension, or a total of 36 subjects. But how frequent was alcohol overconsumption among subjects without this diagnosis and among those with S-GT-values in the highest percentiles and high MAST-scores? Injury/poisoning as well as cardiac and liver diseases are diagnoses frequently associated with alcohol dependence (4, 30). In addition, mental disorders and musculoskeletal diseases have been found to be more common among abusers of alcohol (8). It could be suspected, therefore, that the true prevalence of alcohol dependence was substantially higher than indicated in these figures, a conclusion that supports previous research (5, 6). Alcohol has been shown to play an important role for premature death in middle-aged men (31) and alcohol dependence is a high risk condition, findings that were supported by this study. In this study, the RR for premature death in the group with high MAST-scores was only slightly raised, although, viewing the problem the other way around reveals a different picture: Almost 30% of the deceased pensioners had a diagnosis of alcohol dependence underlying the disability pension and 36% of those with an explicit diagnosis of alcohol dependence died during follow-up. Furthermore, 10% of the deaths among disability pensioners were caused by injury/poisoning and if other, potentially alcohol-related deaths like coronary heart disease and cirrhosis of the liver, were included, the number of deaths with a probable association with alcohol overconsumption would have been even larger. Methods for detecting alcohol abuse have been investigated in several previous studies (22–24, 32–36). No single
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method exists that, with precision, can identify individual subjects with alcohol problems. However, it seems as if a questionnaire might be successfully used in combination with biochemical tests (24, 37). In this study, the MmMAST was of some value for identifying subjects at risk for disability pension, whereas, S-GT alone seemed to be less efficient. Age at pension has been shown to be lower for certain diagnoses, e.g., mental disorders and alcohol dependence (18, 38). It could be speculated, therefore, that if the screening was carried out among younger men, the ratio of subjects with alcohol overconsumption, but yet without a disability pension, would have been even higher. Furthermore, in this cohort, alcohol dependence was more common among those who refrained to participate in the screening program (18). It is also known from previous investigations that persons with alcohol abuse are under-represented in health surveys (30, 39–43). Consequently, if the non-participants could be reached, trying to identify persons at risk for developing an undesirable habit of alcohol overconsumption by using a survey method like the Mm-MAST might be worth-while. The intention of this health screening program was to identify subjects at risk for disease and premature death. Several forms of interventions were carried out (19) with probable consequences for the findings in this study. However, the effects of alcohol consumption on the incidence of disability pension would probably have been even larger if no intervention had been performed. We conclude that alcohol overconsumption constitutes an important and probably underestimated risk factor for disability pension. The findings in this study also lend support to the hypothesis that the beneficial effect of light or moderate drinking with respect to morbidity and mortality is valid when disability pension is concerned as well. Whether this is a positive effect of alcohol per se or if the difference may be explained by confounding from factors related to a lifestyle encompassing a moderate use of alcohol, is a question that can not be answered by this study. Continued research is needed to investigate the nature and interaction of several factors, biological as well as social, which may affect the relation between alcohol consumption and risk of disability pension. This study was supported by grants from the Faculty of Medicine, Lund University, Malmo¨ City Council and the National Institute of Public Health.
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PURPOSE: To analyze the relation between alcohol consumption and the risk of disability pension among middle-aged men. METHODS: In the mid-seventies, complete birth-year cohorts of middle-aged male residents in Malmo¨, Sweden, were invited to participate in a general health survey. The 3751 men with complete data who constituted the cohort in this study were followed for 11 years. Alcohol consumption was estimated from the scores obtained from a test designed to identify subjects with alcohol related problems. RESULTS: Of the 498 men granted disability pension during follow-up, 48 stated to be teetotalers. The cumulative incidence of disability pension among teetotalers was 19%, whereas, it was 12% and 16%, respectively, among men with low and high alcohol consumption. The adjusted relative risk (RR) for acquiring a disability pension (using the group with low alcohol consumption as reference) was 1.8 among abstainers and 1.3 among men with high alcohol consumption. CONCLUSIONS: Alcohol overconsumption, as well as teetotalism, showed a positive relation to disability pension, and a moderate alcohol intake was found to be beneficial with respect to the risk of future disability pension. Ann Epidemiol 1999;9:341–348. 1999 Elsevier Science Inc. All rights reserved. KEY WORDS:
Alcohol, Disability Pension, Early Retirement, Screening, Teetotalism.
INTRODUCTION It is well known that there is a considerable impact of overconsumption of alcohol on morbidity and mortality (1–4). A high prevalence of alcohol-related problems has also been found among men with disability pension (5, 6). In 1977, Swedish legislation was amended to allow more liberal decisions to grant disability pension to alcohol abusers. As a result, the number of alcohol abusers granted disability pension has increased. Still, however, it has been suggested that the diagnosis of alcohol dependence is underrepresented in the mortality statistics as well as among reasons for disability pension, and that this diagnosis may be hidden behind socially more acceptable diagnoses (6–9). If so, it would be of interest to identify other characteristics of those at risk for early retirement due to alcohol abuse, to be able to avoid unnecessary cases of disability pension. Furthermore, a J-shaped association between alcohol consumption and mortality has been found in several studies (10–15). A similar non-linear relation has been found be-
tween alcohol consumption and morbidity (16, 17) but so far, no studies have investigated the consequences of this for the risk of early retirement. The aim of this study was, therefore, to assess the association between alcohol consumption, indicated by scores at an alcohol screening test, and the risk of disability pension. MATERIALS AND METHODS In Sweden, subjects aged 16–64 years, whose working capacity is impaired by at least 50% (from July 1993: 25%) due to disease, can be granted disability pension. If the impairment is not regarded permanent, temporary pension is granted. Full disability pension, including national supplementary pension (ATP), amounts to approximately 65% of the annual income. Supplementary benefits, e.g., housing supplement, constitutes, in many cases, an additional compensation. Applications for disability pension are administered by the public social insurance offices. A doctor’s certificate accompanying the application is required. Subjects
From the Department of Community Medicine (N.-O.M., L.R.), Department of Angiology (K.-F.E.), and Department of Cardiology (B.I.), Lund University, Malmo¨ University Hospital, Malmo¨, Sweden. Address reprint requests to: Dr Nils-Ove Ma˚nsson, Department of Community Medicine, Malmo¨ University Hospital, S-205 02 Malmo¨, Sweden. Received May 7, 1998; revised December 28, 1998; accepted February 22, 1999. 1999 Elsevier Science Inc. All rights reserved. 655 Avenue of the Americas, New York, NY 10010
The cohort used in this study has been presented in detail elsewhere (18). In 1974–1978, five complete birth-year (1926– 1930) cohorts of middle-aged male residents of Malmo¨, Sweden (251,431 inhabitants as of January 1, 1974), were invited to participate in a screening program (19). A total of 7697 men were invited and 5932 (77.1%) participated. 1047-2797/99/$–see front matter PII S1047-2797(99)00014-9
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Selected Abbreviations and Acronyms ATP 5 national supplementary pension ICD 5 International Classification of Diseases MAST 5 Michigan Alcohol Screening Test Mm-MAST 5 Malmo¨ modification of the Brief MAST S-GT 5 Serum gamma glutamyl transferase S-Chol 5 Serum total cholesterol
Mean age (6 SD) at screening was 48.1 6 0.7 years. According to the original protocol, men born in 1926 should be included in 1974, those born in 1927 should be included in 1975 and so on, and the slight variation in age at screening is explained by temporary deviations from that protocol. In the present study, inclusion was defined by the date of examination, and each subject was followed until death or the end of the calendar year when he turned 58, i.e., a total study period of approximately 11 years. Included in this study were, however, only subjects who, without a previous disability pension, participated after April 1, 1976 (n 5 3757), as this was the date when collection of data on alcohol consumption was commenced. Screening data The following data, used in the present study, was obtained during the initial health examination that included serum gamma glutamyl transferase (S-GT), serum total cholesterol (S-Chol), body height, body weight, blood pressure, alcohol habits, smoking habits, and perceived health. S-GT and SChol were measured in venous blood samples and presented in mcatal/l and mmol/l, respectively. All laboratory analyses were performed using standard methods at the Department of Clinical Chemistry, Malmo¨ University Hospital. Height (to the nearest cm) and weight (to the nearest 0.1 kg) were measured using calibrated scales. Body mass index (BMI), defined as weight (kg) divided by height squared (m2), was used to estimate the degree of over/underweight and was classified as suggested by Bray (20) and as used on the national level by Statistics Sweden in the Surveys of Living Conditions (21). Thus, underweight was defined as BMI , 20.0, normal weight as BMI 20.0–24.9, overweight as BMI 25.0–29.9, and obesity as BMI > 30.0. Blood pressure was measured after 10 minutes rest in the right arm to the nearest 5 mmHg. Hypertension was defined as systolic blood pressure > 160 mmHg, diastolic blood pressure > 95 mmHg, and/or current use of anti-hypertensive medications. Data on teetotalism, smoking habits, and perceived health were obtained from a questionnaire. Teetotalers were those who answered “yes” to the question “Are you a teetotaler?” Smoking was defined as daily smoking of cigarettes, and perceived perfect health was based on an affirmative answer to the question “Do you feel perfectly healthy?”
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TABLE 1. Affirmative answers to different Mm-MAST questions among 3491 non-abstainers Answers Questions 1. Do you usually have a drink before going to a party? 2. Do you usually drink a bottle of wine or corresponding amounts of alcohol over the week-end? 3. Do you have a couple of beers a day to relax? 4. Do you tolerate alcohol better now than you did ten years ago? 5. Do you have to concentrate on drinking about the same quantity of alcohol as the others at a party? 6. Have you ever fallen asleep after drinking without knowing how you got to bed? 7. Do you have a bad conscience after drinking? 8. Do you usually have a beer the day after a party? 9. Do you try to avoid alcoholic beverage for a determined period of time, e.g., a week?
Number
%
670
19.2
933
26.7
216
6.2
337
9.7
100
2.9
191
5.5
292
8.4
582
16.7
687
19.7
The questionnaire used in the health examination also included a modified version of the Brief MAST, an abbreviated version of the Michigan Alcohol Screening Test (MAST) (22, 23). This “Malmo¨ modification of the Brief MAST” (Mm-MAST) is described elsewhere (24) and is based on nine questions, each giving a score of 0 (no) or 1 (yes). MAST-score was calculated and used as an estimate of alcohol consumption for those who were not teetotalers. A score of two or more, considered indicative of alcohol related problems in a previous study (24), was used as the cut-off level between the two categories “highMAST” and “low MAST”. The nine Mm-MAST questions are presented in Table 1. Data on Disability Pension A cumulative data base of all decisions on disability pension—including data on year and month of birth, date of retirement, type (temporary or permanent), and extent (50, 67, or 100% of full time) of the disability pension, marital status, and diagnoses—is, since 1971, maintained by the National Social Insurance Board in Sweden. The diagnoses are coded according to the International Classification of Diseases (ICD). The 8th revision (ICD-8) was used until December 31 1986 and the 9th revision (ICD-9) thereafter. Data on Mortality The underlying cause of death is registered for every subject who is residing in Sweden at the time of death. The deceased person’s identification number and the cause of death, coded
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according to the ICD, are entered into a data base. As for data on disability pension, the 8th revision (ICD-8) was used until December 31 1986 and the 9th revision (ICD9) thereafter. Information about time and cause of death for those in the cohort who died during follow-up was obtained from this database. A high autopsy rate is important for the validity of such a database and in Malmo¨, the frequency was very high from the mid-60s to the late-80s; in 1987 it was 86 and 91%, respectively, for males 50–54 and 55–59 years old (25). Statistical Methods The distribution of S-GT is skewed to the left and in univariate statistical testing S-GT values were used with logarithmic transformation. For presentation and analysis, the first 80 percentiles were split into two groups (1–40 and 41–80), whereas, the upper 20 percentiles constituted the extreme group of S-GT-values. S-Chol was dichotomized at the median. The Chi-square test was used to test for differences in proportions and Student’s t test for differences in means. Multivariate analyses were performed using Cox’s proportional hazards model, in which adjusted relative risks (RR) and their 95% confidence intervals were calculated. The Cox’s model was also used to test for trend. All tests were two-sided. A difference was considered statistically significant when p , 0.05.
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RESULTS Six subjects, lacking complete data, had to be excluded, leaving the final number of subjects included in the study at 3751. Mean S-Chol (6 SD) was 5.81 6 1.06 with a median 5.77 mmol/l. Mean diastolic blood pressure was 89.0 6 13.4 mmHg and mean systolic blood pressure was 132.0 6 16.6 mmHg. The values for S-GT at the 40th and 80th percentiles were 0.47 and 0.91 mcatal/l, respectively, defining the cut-points for “low,” “intermediate,” and “high S-GT.” A total of 1222 (32.6%) of the men were categorized as hypertensives, and 1520 (40.5%) were daily smokers of cigarettes. Of all 3751 men, 2812 (75.0%) perceived their health as perfect. Two hundred and sixty subjects (6.9%) stated to be teetotalers. Of the remaining 3491 men, 2438 (65.0% of all) had a low and 1053 (28.1% of all) had a high MASTscore. The rates of affirmative answers to the nine MmMAST questions are presented in Table 1. Disability Pensioners Four hundred and ninety eight (13.3%) of the men were granted a disability pension after screening, whereas, the remaining 3253 (86.7%) were not. Table 2 summarizes characteristics of these two categories of men. Mean S-Chol did not differ significantly (p 5 0.33). Mean body mass index was, however, significantly higher
TABLE 2. Means and standard deviations (SD) of laboratory tests, body mass index, and blood pressure as well as number and rates of certain variables among subjects with and without disability pension granted during follow-up No pension (n 5 3253) Serum cholesterol Body mass index Systolic blood pressure Diastolic blood pressure Hypertension: Daily smoking: Body mass index:
Perceived perfect health: S-GT:
Alcohol related variables:
yes no yes no , 20.0 20.0–24.9 25.0–29.9 > 30.0 yes no low intermediate high Teetotalers MAST , 2 MAST > 2
mean 5.81 24.86 131.8 88.8 Number 1031 2222 1264 1989 143 1687 1227 196 2563 690 1348 1312 593 212 2158 883
Disability pension (n 5 498) SD 1.05 3.16 16.5 13.8 % 31.7 68.3 38.9 61.1 4.4 51.9 37.7 6.0 78.8 21.2 41.4 40.3 18.2 6.5 66.3 27.1
mean 5.86 25.64 133.2 90.3 Number 191 307 256 242 33 193 201 71 249 249 164 194 140 48 280 170
SD 1.15 4.05 17.2 10.9 % 38.4 61.6 51.4 48.6 6.6 38.8 40.4 14.3 50.0 50.0 32.9 39.0 28.1 9.6 56.2 34.1
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among the pensioners (p , 0.0001), and this was true also for diastolic blood pressure (p 5 0.022) but not for systolic blood pressure (p 5 0.09). Thus, hypertension was significantly more common among the pensioners (p 5 0.0031), and so was daily smoking (p , 0.0001). The distribution of body mass index categories (Table 2) suggested a U-shaped relation, as both the proportions of underweight (p 5 0.028) and obese subjects (p , 0.0001) were higher among the pensioners, whereas, the prevalence of normal weight was significantly lower (p , 0.0001). As further illustrated in Table 2, the proportion of subjects who perceived their health as perfect was significantly lower among the future pensioners (p , 0.0001). Of these, 24 (50%) were teetotalers, 139 (50%) were men with low and 86 (51%) were men with high MAST-scores. In addition, S-GT was higher among the pensioners, as illustrated in Table 1. Thus, a higher proportion of the pensioners had a high (p , 0.0001) and fewer had a low S-GT level (p 5 0.0003). The prevalence of teetotalism at start of follow-up was higher among the future pensioners (p 5 0.011) and so was the proportion that had a high MAST-score (p 5 0.0012). Risk of Future Disability Pension by S-GT Level and MAST-Score Figure 1 shows the cumulative incidence of disability pension after participation in screening, distributed by decile of S-GT. The risk-ratio increased only marginally from the first to the 9th decile, whereas it was almost double in the highest. For the distribution by MAST-score, the risk slope was more continuous and graded (Figure 2). Teetotalers, however, had a risk ratio higher than the non-abstainers with the lowest MAST-scores.
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FIGURE 2. Cumulative incidence of disability pension among teetotalers (T) and subjects with different MAST-scores.
For further analysis, the categories of MAST-score presented in Table 2 were used to estimate risk-ratios. Thus, the cumulative incidence of disability pension was calculated for teetotalers and men with a low and a high MAST-score, respectively. While the ratio for subjects with low MASTscores was 11.5%, the corresponding figures for both teetotalers and subjects with high MAST-scores were higher: 18.5% and 16.1%, respectively. The RR for acquiring a disability pension are shown in Table 3. After adjustment for smoking, hypertension, S-Chol, and BMI, the RR decreased among men with high MASTscores but remained unchanged for the abstainers. When perceived health was included among the covariates already adjusted for, RR was marginally reduced (1.7; CI: 1.2–2.3) among abstainers, whereas it remained unchanged (1.3; CI: 1.1–1.6) among men with high MAST-scores. The corresponding figures for the groups with intermediate and high S-GT measures were 1.2 (CI: 1.0–1.6) and 1.6 (CI: 1.3–2.1), respectively. When the three categories were analyzed separately in relation to S-GT, a positive, linear relation was found between ratio of disability pension and S-GT in both the low and the high MAST group (Figure 3). For both, there was a statistically significant increase in RR, before and after adjustment for confounders. For the teetotalers there was a J-shaped pattern in cumulative incidence, but no statistically significant differences in RR. Median age when pension was granted was 56 years for teetotalers and subjects with low MAST-scores, and 55 years for subjects with high MAST-scores. Diagnoses
FIGURE 1. Cumulative incidence of disability pension among subjects in different S-GT deciles.
Three disease categories predominated among the main and concomitant diagnoses that motivated the disability pension
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TABLE 3. MAST-scores, S-GT values, and relative risks (RR) of disability pension
Teetotalers Low MAST-scores High MAST-scores S-GT-percentiles 1–40 S-GT-percentiles 41–80 S-GT-percentiles 81–100 a
Crude RR (95% CI)
Adjusted RRa (95% CI)
1.8 (1.3, 2.4) reference 1.5 (1.2, 1.8) reference 1.4 (1.1, 1.7) 2.1 (1.7, 2.7)
1.8 (1.3, 2.4) reference 1.3 (1.1, 1.6) reference 1.2 (1.0, 1.5) 1.8 (1.4, 2.2)
Adjusted for smoking, hypertension, S-Chol, and BMI.
(Table 4). Main diagnoses of musculoskeletal diseases, mental disorders (including alcohol dependence) and diseases of the circulatory system were present in 73% of all cases. While alcohol dependence occurred as a diagnosis for 7% of the 498 subjects with disability pension, it accounted for 16% among those with MAST-score 2–8, the prevalence more than five times that in the group with low MASTscores (p , 0.0001). One teetotaler was retired because of a diagnosis of alcohol dependence. Restricting the analysis to main diagnoses did not change the results. A similar pattern as that for alcohol dependence was found for the diagnoses injury/poisoning and liver diseases, however, statistically significant only for injury/poisoning. Mortality During follow-up, 231 subjects (6%) died. The predominating causes of death were diseases of the circulatory system (44%), neoplasm (34%), and injury/poisoning (10%). Among subjects with low and high MAST-scores, the mortality rate was 5% and 8%, respectively. The teetotalers were in this respect an intermediary group with a death rate of 6%
FIGURE 3. Cumulative incidence of disability pension among subjects in different S-GT-percentiles after separation into three categories: Teetotalers (m) and men with high (d) and low (s) MAST-scores.
(same as for the entire cohort). The difference in mortality rate was statistically significant (p 5 0.003) between the groups with low and high MAST-scores. RR for premature death, adjusted for smoking, hypertension, S-Chol, BMI, and perceived health (again using the group with low MAST-scores as reference), were 1.3 (CI: 0.7–2.1) among teetotalers and 1.3 (CI: 1.0–1.8) among men with high MAST-scores. The mortality among those with disability pension was higher; 46 (9%) of the 498 pensioners were dead at the end of follow-up. Among these, alcohol dependence was the main (n 5 10) or a concomitant (n 5 3) diagnosis causing the disability pension in 13 cases (28%). Of the 36 men with a diagnosis of alcohol dependence, 13 (36%) died during follow-up, a mortality rate six times that of the entire cohort.
DISCUSSION MAST-scores, commonly used as an indicator of alcohol related problems, was in this study used as an estimation of alcohol consumption. This had of course certain limitations; the amount of the alcohol intake was not measured, which made it impossible to identify the relation between actual alcohol consumption on one hand and disability and mortality on the other hand. The S-GT measurement might have been more suitable in estimating alcohol consumption but, considering the purpose of the study, the MAST-scores were believed to be a better indicator of problem-related consumption of alcohol. The highest cumulative incidence of disability pensions was found among teetotalers when aggregated categories of MAST-scores were used for comparison. Compared with the category of low MAST-scores, the RR for abstainers acquiring a disability pension was significantly higher. This was also true after considering possible confounders, e.g., BMI which, in a previous paper proved to be positively correlated to increased risk for disability pension (26). However, the cut-off level, a MAST-score of two or more, used in accordance with a previous study (24) may, in this study, not have been the most appropriate one to distinguish between subjects with and without alcohol related problems.
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TABLE 4. Main and concomitant diagnoses (1st, 2nd, or 3rd diagnosis) as basis for disability pension among teetotalers and subjects separated by MAST-score. Only pensions granted after screening were considered Teetotalers (n 5 48) Groups of diagnoses Diseases of the musculoskeletal system Mental disorders Alcohol dependencea Diseases of the circulatory system Diseases of the nervous system Diseases of the respiratory system Diseases of the gastrointestinal tract Injury/poisoningb Neoplasms Diabetes Liver diseases Others
MAST-score 0–1 (n 5 280)
MAST-score 2–8 (n 5 170)
Total (n 5 498)
Number
%
Number
%
Number
%
Number
%
28 10 1 9 4 2 — — 2 3 — 7
58 21 2 19 8 4
144 47 8 60 22 22 13 7 12 7 1 30
51 17 3 21 8 8 8 3 4 3 ,1 11
87 29 27 45 11 7 9 14 4 6 5 9
51 17 16 26 6 4 5 8 2 4 3 5
259 86 36 114 37 31 22 21 18 16 6 46
52 17 7 23 7 6 4 4 4 3 1 9
4 6 15
p , 0.0001 for difference between subjects with low and high MAST-score. b p , 0.01. a
In fact, the cumulative incidence of disability pension was lower in the group of teetotalers than in any of the categories with a MAST-score of four or more. There are reasons to believe that the teetotalers constitute a heterogeneous group, including among others former heavy drinkers as well as persons with chronic conditions (27, 28), and one may speculate on the significance of the J-shaped relation in Figure 3. The explanation may, at least in part, be found in characteristics other than alcohol consumption of the teetotalers with low and high levels of S-GT, respectively. Alcohol dependence as well as the alcohol related diagnoses of injury and poisoning were, as expected, significantly less common among teetotaler pensioners. No significant differences in other diagnoses were found between teetotalers and the two groups with different MAST-scores. Higher than expected morbidity and mortality have been demonstrated among teetotalers in many previous investigations (10–12, 14–17). In addition to the presence of exdrinkers among the teetotalers, it has been argued that the habit to abstain from alcohol to some extent is caused by pre-existing illness which in turn would explain the higher morbidity and mortality (29). However, perceived health did not differ between abstainers and drinkers and did not affect the RR of disability pension for the groups of teetotalers and those with high MAST-scores. Differences in mortality were marginal, but lowest among those with low MASTscores. Furthermore, in general, teetotalers were granted their disability pensions later than subjects with high MAST-scores. To summarize these findings: A low alcohol intake, as indicated by a low MAST-score, seemed to be most beneficial with respect to the risk of future disability pension, findings consistent with previous investigations regarding morbidity and mortality. However, the character-
istics of the teetotaler status must be further investigated in order to adequately answer this question. The diagnosis of alcohol dependence was present in 7% (n 5 36) of the records of those with disability pension, or a total of 36 subjects. But how frequent was alcohol overconsumption among subjects without this diagnosis and among those with S-GT-values in the highest percentiles and high MAST-scores? Injury/poisoning as well as cardiac and liver diseases are diagnoses frequently associated with alcohol dependence (4, 30). In addition, mental disorders and musculoskeletal diseases have been found to be more common among abusers of alcohol (8). It could be suspected, therefore, that the true prevalence of alcohol dependence was substantially higher than indicated in these figures, a conclusion that supports previous research (5, 6). Alcohol has been shown to play an important role for premature death in middle-aged men (31) and alcohol dependence is a high risk condition, findings that were supported by this study. In this study, the RR for premature death in the group with high MAST-scores was only slightly raised, although, viewing the problem the other way around reveals a different picture: Almost 30% of the deceased pensioners had a diagnosis of alcohol dependence underlying the disability pension and 36% of those with an explicit diagnosis of alcohol dependence died during follow-up. Furthermore, 10% of the deaths among disability pensioners were caused by injury/poisoning and if other, potentially alcohol-related deaths like coronary heart disease and cirrhosis of the liver, were included, the number of deaths with a probable association with alcohol overconsumption would have been even larger. Methods for detecting alcohol abuse have been investigated in several previous studies (22–24, 32–36). No single
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method exists that, with precision, can identify individual subjects with alcohol problems. However, it seems as if a questionnaire might be successfully used in combination with biochemical tests (24, 37). In this study, the MmMAST was of some value for identifying subjects at risk for disability pension, whereas, S-GT alone seemed to be less efficient. Age at pension has been shown to be lower for certain diagnoses, e.g., mental disorders and alcohol dependence (18, 38). It could be speculated, therefore, that if the screening was carried out among younger men, the ratio of subjects with alcohol overconsumption, but yet without a disability pension, would have been even higher. Furthermore, in this cohort, alcohol dependence was more common among those who refrained to participate in the screening program (18). It is also known from previous investigations that persons with alcohol abuse are under-represented in health surveys (30, 39–43). Consequently, if the non-participants could be reached, trying to identify persons at risk for developing an undesirable habit of alcohol overconsumption by using a survey method like the Mm-MAST might be worth-while. The intention of this health screening program was to identify subjects at risk for disease and premature death. Several forms of interventions were carried out (19) with probable consequences for the findings in this study. However, the effects of alcohol consumption on the incidence of disability pension would probably have been even larger if no intervention had been performed. We conclude that alcohol overconsumption constitutes an important and probably underestimated risk factor for disability pension. The findings in this study also lend support to the hypothesis that the beneficial effect of light or moderate drinking with respect to morbidity and mortality is valid when disability pension is concerned as well. Whether this is a positive effect of alcohol per se or if the difference may be explained by confounding from factors related to a lifestyle encompassing a moderate use of alcohol, is a question that can not be answered by this study. Continued research is needed to investigate the nature and interaction of several factors, biological as well as social, which may affect the relation between alcohol consumption and risk of disability pension. This study was supported by grants from the Faculty of Medicine, Lund University, Malmo¨ City Council and the National Institute of Public Health.
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