The authors have declared that no competing interests exist.
Conceived and designed the experiments: AS PA. Performed the experiments: AS. Analyzed the data: AS. Contributed reagents/materials/analysis tools: TH PA. Wrote the paper: AS. Critically revised the manuscript for important intellectual content: TH AR PA. Participated in the interpretation of the data: AS TH AR PA. Approved the final version of the paper: AS TH AR PA.
The role of alcohol consumption for disability pension (DP) is controversial and systematic reviews have not established causality. We aimed to assess the role of adolescent alcohol use for future DP. We wanted to find out whether an increased risk mainly would affect DP occurring early or late in life as well as whether the level of alcohol consumption and patterns of drinking contribute differently in DP receiving.
The study is a 39-year follow-up of 49 321 Swedish men born in 1949–1951 and conscripted for compulsory military service in 1969–1970. As study exposures (i) “risk use” of alcohol composed of measures related to pattern of drinking, and (ii) the level of consumption based on self-reported volume and frequency of drinking had been used. Information on DP was obtained from social insurance databases through 2008. “Risk use” of alcohol was associated with both “early DP” and “late DP”, i.e. granted below and above the approximate age of 40 years, with crude hazard ratio (HR) of 2.89 (95% confidence intervals (CI) 2.47–3.38) and HR of 1.87 (95%CI: 1.74–2.02), respectively. After adjustment for covariates, HR was reduced to 1.32 (95%CI: 1.09–1.59) and 1.14 (95%CI: 1.05–1.25), respectively. Similar patterns were seen for moderate (101–250 g 100% alcohol/week) and high (>250 g) consumption, though the risk disappeared when fully adjusted.
Alcohol use in adolescence, particularly measured as “risk use”, is associated with increased risk of future DP. The association is stronger for “early DP”, but remains significant even for DP granted in older ages. Therefore, pattern of drinking in adolescent should be considered an important marker for future reduced work capacity.
The role of alcohol for disability pension (DP) still remains controversial. Timing of exposure and measure of consumption differ substantially between studies contributing to a high variability in study results over time and place. A 20-year follow-up of Swedish male military conscripts, found an increased risk of DP granted at the age below 40 among those reporting high alcohol consumption as well as problem drinking behavior during adolescence and young adulthood
Two systematic reviews
One of the reasons for the varying results is the complex interplay between a wide range of alcohol-related problems and DP as well as variations in criteria for granting DP
What makes the issue even more intriguing is the fact that several studies reported abstainers to be at a higher risk of DP compared to light or moderate drinkers
Sweden is among the countries with the highest prevalence of DP and the largest public spending on DP benefits
Earlier analyses of a cohort of Swedish men conscripted to military service in 1969–1970 showed an increased risk of DP up to the age of around 40 among those exposed to high alcohol consumption in late adolescence/early adulthood
In several early applications to the Karolinska Institutet Ethical Review Board, we specifically pointed out that due to the character of the data base, it was impossible to trace persons and ask for written or verbal informed consent. Thus, the Institutional Review Board has waived the normal requirement for informed consent, since we only work on record linkage data that have been anonymized. Waiver was obtained in permissions Dnr 121/84 and Dnr 188/91, of which the permissions enumerated below are subsequent follow-ups.
Our study is a follow-up of the cohort of 50 465 Swedish men mandatory conscripted for military service in July 1, 1969- June 30, 1970. At the time only around 2–3% of men were exempted on account of severe mental or physical conditions. The present study includes 49 321 men (97.7% of original cohort) born in 1949–1951, i.e. aged 18–21 at conscription.
Detailed description of the cohort has been presented elsewhere
The
As the second exposure we used a composite variable
Our study outcome was DP granted after the conscription and up to 2008. According to the National Insurance Act, DP may be granted to a person aged 16–65 whose working capacity is estimated to be permanently reduced as a result of physical or mental impairment, irrespective of whether the person is, or ever has been, employed
We categorized the outcome as “early DP” if received at the approximate age below 40, i.e. in 1971–1990, and “late DP”, i.e. after age of 40 in 1991–2008. The categories were similar to previous studies based on the same cohort
The distribution of the exposure measures is presented in
Alcohol habits | No of conscripts (%) |
|
|
- Light consumers (1–100 g) | 33 526 (68.0) |
- Moderate consumers (101–250 g) | 9 547 (19.4) |
- Abstainers (0) | 2 781 (5.6) |
- High consumers (>250 g) | 1 724 (3.5) |
- No answer given |
1 743 (3.5) |
|
|
- No “risk use” of alcohol | 42 263 (85.7) |
- “Risk use” of alcohol |
6 422 (13.0) |
- Not established |
636 (1.3) |
Conscripts provided no answers to the questions on frequency and consumption level of beer, wine and spirit, therefore, the weekly level of consumption could not be calculated.
Subjects were classified as having “risk use” if at least one of the following condition was fulfilled: having a history of being apprehended for drunkenness, needing an eye-opener to overcome hangover, having been drunk often/quite often, reporting alcohol consumption measured as more than 250 g 100% alcohol/week.
Conscripts provided no answers to any of the questions to compose the variable “risk use” of alcohol of.
Based on earlier studies of this cohort
Information on family SEP was based on data on conscript’s father’s occupation in Census 1960: manual (unskilled, skilled), low non-manual, combined intermediate and high non-manual, and others (farmers, self-employed, unclassified).
Register data combined for this study were provided by Statistics Sweden. Record linkages were made using the unique individual number for each conscript, which was substituted by Statistics Sweden for the original Swedish personal identification number, in order to ensure confidentiality of personal data. We performed linkages between the abovementioned conscripts’ cohort and Census 1960, the Total Population Register (migration status), the National Cause-of-Death Register (date of death), the National Social Insurance Board data sets and a Longitudinal Register of Education and Labor Market Statistics (DP status and date of DP granting).
Person-time (in all 1 779 132 person-years) was counted from October 1, 1969 for two subjects who died in 1969 and from January 1, 1970 for the rest of the conscripts until the date of receiving DP, date of death, date of emigration or until end of follow-up on the July 1, 2008.
Information from social insurance records was missing for 1.8% of conscripts. These men were censored at their last appearance in the population records. Only 3.5% of the conscripts refused to answer questions on frequency and levels of alcohol consumption. For 1.3% of the conscripts the variable “risk use” of alcohol could not be used.
The hazard ratio (HR) and 95% confidence intervals (CI) for DP in relation to the level of consumption and the “risk use” of alcohol was calculated by using Cox’ proportional hazards model. The proportional hazard assumption was checked by log survival plots. Analyses were conducted for total DP as well as for “early DP” and “late DP”.
Variables were included in multivariate analysis if found significant in univariate model and fulfilling the criteria for being confounders
Our uncertainties regarding the role of the abovementioned variables as potential confounders or mediators have been considered by applying different multivariate models as suggested by Rothman
We tested possible effect modification by baseline covariates using logrank test for stratification. The interaction HR was assessed separately for both exposure variables.
Information on the number of subjects included in the analysis at various stages is presented in
Cohort description | N of persons (%) |
Conscripts cohort 1969–1970 (born in 1949–1951) | 49 321 (100) |
Number of persons granted DP in 1971–2008, according to RFV |
6 342 (12.9) |
Among them: | |
- “Early DP” granted in 1971–1990 | 1 038 (2.1) |
- “Late DP” granted in 1991–2008 | 5 304 (10.7) |
Number of persons not granted DP in 1971–2008 according to RFV |
38 767 (78.6) |
Died during follow-up | 2 469 (5.0) |
Emigrated | 844 (1.7) |
Lost to follow-up (no information on DP status) | 899 (1.8) |
Number of conscripts not answering questions on alcohol consumption level (exposure I) in the survey | 1 743 (3.5) |
Number of conscripts not answering any of the four key questions to form a composite variable “risk use” of alcohol(exposure II) | 636 (1.3) |
Number of conscripts included in the final analysis of alcohol consumption level at conscription and DP, i.e. withinformation available for all covariates | 38 671 (78.4%) |
Number of conscripts included in the final analysis of “risk use” of alcohol and DP, i.e. with information availablefor all covariates | 38 899 (78.9%) |
Abbreviations: DP, Disability Pension.
The National Swedish Social Insurance Board database.
The Longitudinal Register of Education and Labor Market Statistics.
The Longitudinal Database Integration for Medical Insurance and Labor Studies.
To address the issue of potential heterogeneity among those reporting abstention from alcohol we ran a series of additional analyses. First, we divided the group of abstainers in two sub-groups by including those who abstained from alcohol and all other substance use, i.e. tobacco smoking, sniffing of solvents and illicit drug use, in a sub-category of “pure abstainers” leaving those who abstained exclusively from alcohol, but not from the other substances in a sub-category of “other abstainers”. Second, we performed a frequency analysis to study the relation between different categories of abstention and other medical, social and behavior characteristics. Third, we repeated the main analysis by assessing HR and 95% CI for DP in relation to different levels of consumption, including both sub-categories of abstainers. Finally, we ran an additional analysis for association of DP with “risk use” of alcohol in a sub-cohort excluding abstainers.
We checked the robustness of our results in sensitivity analyses by repeating the main analyses including all 49 321 conscripts. All reported
Number of Swedish male conscripts granted disability pension (DP) in 1971–2008 and among them number of “risk users”a of alcohol defined at conscription in 1969–1970. aSubjects were classified as having “risk use” if at least one of the following condition was fulfilled: having a history of being apprehended for drunkenness, needing an eye-opener to overcome hangover, having been drunk often/quite often, reporting alcohol consumption measured as more than 250 g 100% alcohol/week.
The measurement levels of each covariate and its distribution among the conscripts with different levels of exposures were presented in the previous articles based on the same cohort
For different levels of consumption, crude analysis showed a strong association with DP (
DP in total | “Early DP” | “Late DP” | |
Approximate age (years) | 20–59 | 20–41 | 40–59 |
Variables controlled for | HR (95% CI) | HR (95% CI) | HR (95% CI) |
|
|||
- 0 (g 100% alcohol/week) abstainers | 1.30 (1.16–1.46) | 2.31 (1.81–2.95) | 1.14 (1.00–1.31) |
- 1–100 light consumers (ref group) | 1.0 | 1.0 | 1.0 |
- 101–250 moderate consumers | 1.32 (1.23–1.41) | 1.60 (1.34–1.89) | 1.27 (1.18–1.37) |
- >250 high consumers | 2.25 (2.00–2.53) | 3.37 (2.61–4.36) | 2.06 (1.81–2.35) |
|
|||
Family background-related exposures |
|||
- 0 | 1.31 (1.17–1.48) | 2.33 (1.82–2.98) | 1.15 (1.01–1.32) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 1.28 (1.19–1.37) | 1.53 (1.28–1.82) | 1.24 (1.15–1.34) |
- >250 | 2.11 (1.87–2.37) | 3.02 (2.33–3.92) | 1.95 (1.70–2.22) |
School-related exposures |
|||
- 0 | 1.34 (1.20–1.51) | 2.46 (1.93–3.14) | 1.17 (1.03–1.34) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 1.26 (1.18–1.35) | 1.45 (1.22–1.73) | 1.23 (1.14–1.33) |
- >250 | 2.09 (1.86–2.35) | 2.89 (2.23–3.76) | 1.94 (1.70–2.22) |
Social and behavior exposures |
|||
- 0 | 1.38 (1.23–1.55) | 2.51 (1.96–3.20) | 1.21 (1.06–1.38) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 1.12 (1.05–1.20) | 1.23 (1.03–1.47) | 1.10 (1.02–1.19) |
- >250 | 1.51 (1.34–1.71) | 1.76 (1.34–2.31) | 1.46 (1.27–1.67) |
Physical and mental health at conscription |
|||
- 0 | 1.23 (1.09–1.38) | 2.03 (1.59–2.59) | 1.09 (0.96–1.25) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 1.20 (1.12–1.29) | 1.32 (1.11–1.57) | 1.18 (1.10–1.28) |
- >250 | 1.56 (1.39–1.76) | 1.70 (1.31–2.22) | 1.53 (1.34–1.75) |
Psychological status and sociability at conscription |
|||
- 0 | 1.17 (1.04–1.32) | 1.83 (1.43–2.34) | 1.05 (0.92–1.20) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 1.17 (1.09–1.25) | 1.27 (1.07–1.51) | 1.15 (1.07–1.24) |
- >250 | 1.52 (1.35–1.71) | 1.69 (1.30–2.19) | 1.48 (1.29–1.69) |
Substance use at conscription |
|||
- 0 | 1.61 (1.43–1.82) | 2.91 (2.25–3.76) | 1.41 (1.23–1.62) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 1.08 (1.01–1.16) | 1.24 (1.04–1.49) | 1.06 (0.98–1.14) |
- >250 | 1.62 (1.43–1.84) | 2.20 (1.66–2.91) | 1.52 (1.32–1.74) |
|
|||
- 0 | 1.34 (1.19–1.52) | 1.95 (1.51–2.52) | 1.22 (1.07–1.40) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 0.99 (0.92–1.07) | 1.06 (0.88–1.28) | 0.98 (0.91–1.06) |
- >250 | 1.05 (0.92–1.19) | 1.06 (0.79–1.41) | 1.05 (0.91–1.21) |
|
|||
- 0 | 1.20 (1.07–1.35) | 1.90 (1.48–2.43) | 1.08 (0.95–1.23) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 1.13 (1.05–1.21) | 1.20 (1.00–1.43) | 1.12 (1.04–1.21) |
- >250 | 1.44 (1.27–1.62) | 1.51 (1.16–1.98) | 1.41 (1.23–1.62) |
|
|||
- 0 | 1.35 (1.20–1.51) | 2.45 (1.92–3.13) | 1.18 (1.03–1.34) |
- 1–100 | 1.0 | 1.0 | 1.0 |
- 101–250 | 1.23 (1.15–1.32) | 1.41 (1.18–1.68) | 1.20 (1.11–1.30) |
- >250 | 1.98 (1.75–2.23) | 2.64 (2.02–3.44) | 1.85 (1.61–2.11) |
Corresponds to father’s socioeconomic position, father’s drinking habits, and parental divorce.
Corresponds to truancy and remedial class.
Corresponds to contact with police and childcare authorities, ever run away from home, and being unemployed for more than 3 months after finishing school.
Corresponds to self-assessed health, medication to nervous problems, and any psychiatric diagnosis reported/detected at conscription.
Corresponds to emotional control, social maturity, and cognitive ability assessed at conscription.
Corresponds to smoking, sniffing of solvents, and drug use reported at conscription.
Adjusted for all covariates in the table.
Adjusted for family background, school-related exposures and exposures related to psychological status and sociability.
Adjusted for family background and school-related exposures.
There was a strong association between “risk use” and DP regardless of adjustment and the highest risk was again seen for “early DP” (
DP in total | “Early DP” | “Late DP” | |
Approximate age | 20–59 | 20–41 | 40–59 |
Variables controlled for | HR (95% CI) | HR (95% CI) | HR 95% CI |
|
|||
- No “risk use” of alcohol (ref group) | 1.0 | 1.0 | 1.0 |
- “Risk use” of alcohol | 2.02 (1.89–2.17) | 2.89 (2.47–3.38) | 1.87 (1.74–2.02) |
|
|||
Family background-related exposures |
1.88 (1.76–2.02) | 2.64 (2.25–3.10) | 1.75 (1.62–1.89) |
School-related exposures |
1.94 (1.81–2.07) | 2.66 (2.27–3.12) | 1.81 (1.67–1.95) |
Social and behavior exposures |
1.46 (1.35–1.58) | 1.81 (1.51–2.16) | 1.39 (1.28–1.52) |
Physical and mental health at conscription |
1.66 (1.55–1.78) | 1.93 (1.63–2.27) | 1.60 (1.48–1.73) |
Psychological status and sociability at conscription |
1.51 (1.40–1.62) | 1.71 (1.45–2.01) | 1.46 (1.35–1.58) |
Substance use at conscription |
1.68 (1.56–1.80) | 2.37 (2.00–2.81) | 1.56 (1.44–1.69) |
|
1.17 (1.08–1.27) | 1.32 (1.09–1.59) | 1.14 (1.05–1.25) |
|
1.44 (1.34–1.55) | 1.61 (1.36–1.90) | 1.40 (1.29–1.51) |
|
1.81 (1.69–1.94) | 2.46 (2.09–2.89) | 1.70 (1.57–1.83) |
Corresponds to father’s socioeconomic position, father’s drinking habits, and parental divorce.
Corresponds to truancy and remedial class.
Corresponds to contact with police and childcare authorities, ever run away from home, and being unemployed for more than 3 months after finishing school.
Corresponds to self-assessed health, medication to nervous problems, and any psychiatric diagnosis reported/detected at conscription.
Corresponds to emotional control, social maturity, and cognitive ability (IQ) assessed at conscription.
Corresponds to smoking, sniffing of solvents, and drug use reported at conscription.
Adjusted for all covariates in the table.
Adjusted for family background, school-related exposures and exposures related to psychological status and sociability.
Adjusted for family background and school-related exposures.
Further subdivision within the group of abstainers revealed that 80% (2 218 out of 2 781) of those reporting never drinking any alcohol also reported abstention from use of other substances. However, a J-shaped curve was found in the distribution of medical, social and behavioral risk factors for “pure abstainers” as well as for “other abstainers” compared to other levels of consumption similar to that seen for the entire cohort. For example, 31% of “pure abstainers” and 41% of “other abstainers” were found to have the lowest level of emotional control, while only 26% of light alcohol consumers were found in this stratum. For 31% and 34% of “pure” and “other” abstainers, respectively, the level of social maturity was defined as “low and very low” compared to 19% of light consumers.
The results of
Stratification by each covariate revealed only slight effect modification from some of the variables. Inclusion of interaction terms did not alter the results (data not shown).
The robustness of the results was tested in sensitivity analysis with all 49 321 conscripts included, showing no difference in crude associations with the results from
We found that alcohol use in adolescence is associated with an increased risk of DP, in particular “early DP”. “Risk users” of alcohol have a statistically significant increased risk regardless of adjustment. Controlling for family background and school-related exposures slightly attenuated the increased risk, while more pronounced reduction was observed when all covariates were controlled for; though the risk persisted in all models. Moderate and high consumers also had a statistically significant increased risk of DP, which gradually reduced when expanding the number of controlled covariates and disappeared when the most conservative model for adjustment had been used. Our findings are consistent with previous results where high alcohol consumption
The J-shaped distribution of alcohol consumption related to social and emotional maturity and physical and mental health puts our findings in line with previous results from this and other cohorts and it is similar to the J-shaped curve for the relation between alcohol consumption and mortality, morbidity and DP
“Risk use” of alcohol was more strongly associated with DP regardless of adjustment than high consumption. A similar relation was seen in the Norwegian HUNT study
The complex association between pattern of drinking and various health outcomes was highlighted by Room et al.
A major methodological challenge deals with the complicated nature of associations between reported social, mental and behavioral conditions and alcohol use. We could not test for mediation since data on exposures and covariates were collected at one point of time and the temporal order for some variables was not clear. Thus, we could not definitely conclude that the risk reduction is due to mediation. A pragmatic approach was, therefore, to study the association in three models, in which we can assume that our most conservative model is more likely to result in overadjustment, since some of the variables may act as mediators
One of the major strengths of this study is the size that ensures considerable statistical power. Due to the high response rate, the population-based nature of the cohort and availability of data from numerous registers, the information on DP, drinking habits and levels of consumption as well as on various medical and social conditions was available for almost each conscript. The completeness of the follow-up data in the Swedish social insurance databases minimizes any bias due to selective non-response by problem drinkers or poor registration of outcome.
One limitation is that the study only concerns men. Another important limitation is lack of data on alcohol consumption later in life. It has, however, been previously shown on the same material that there is a strong association between levels of alcohol reported at conscription and later alcohol-related hospitalization
In addition, we acknowledge that self-reported data on alcohol use may be a subject for underreporting, even though in studies on youngsters, overreporting can also be present
We conclude that the early life exposure to alcohol is associated with increased risk of future DP. The association is particularly strong for “early DP” but remains significant among those granted DP up to the age of 59 emphasizing the public health and socio-economic burden of the outcome. Pattern of drinking was a more pronounced risk factor for DP and, therefore, drinking behavior in adolescent should be considered an important marker for future work incapacity.
Our findings add knowledge on the health consequences of early alcohol use. In addition to early mortality and morbidity, early alcohol use is an indicator of future work problems and exclusion from the labor market.