Excessive drinking and history of unemployment and cohabitation in Danish men born in 1953

Transcription

1 European Journal of Public Health, Vol. 21, No. 4, ß The Author Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved. doi: /eurpub/ckq152 Advance Access published on 13 October Excessive drinking and history of unemployment and cohabitation in Danish men born in 1953 Margit Kriegbaum 1, Ulla Christensen 1, Merete Osler 1,2, Rikke Lund 1 1 Department of Social Medicine, Institute of Public Health, University of Copenhagen, Copenhagen, Denmark 2 Research Centre for Prevention and Health, Glostrup University Hospital, Denmark Correspondence: M Kriegbaum, Institute of Public Health, Øster Farimagsgade 5, 1014 Copenhagen, tel: , fax: , makr@sund.ku.dk Received 17 June 2010, accepted 19 September 2010 Introduction Background: Few studies exist on social inequality of excessive drinking in Denmark and differences seem to be less pronounced than in other European countries. The aims of this study were to investigate how history of employment and cohabitation is associated with excessive drinking and to study interaction between both. Methods: Birth-cohort study of 6112 Danish men born in 1953 with follow-up in 2004 on excessive drinking at age 51 years. Results: Excessive drinking (between 22 and 35 per week) differed little depending on history of unemployment and cohabitation. Risk of very excessive drinking (drinking >35 per week) increased with number of job losses ranging from one job-loss [odds ratio (OR) 1.72, 95% confidence interval (CI) ] to three or more job-losses (OR 2.48, 95% CI ) and duration of unemployment ranging from 1 to 5 years (OR 1.34, 95% CI ) to 10 years (OR 4.16, CI ). Very excessive drinking was also associated with number of broken partnerships ranging from one broken partnership (OR 1.43, 95% CI ) to three or more broken partnerships (OR 2.69, 95% CI ) and with living alone for >5 years ranging from 6 to 9 years (OR 1.73, 95% CI ) to 10 years (OR 2.55, 95% CI ). We found an interaction between the number of job-losses and of broken partnerships in relation to very excessive drinking. Conclusions: Very excessive drinking is related to number of job-losses, broken partnerships, living alone and duration of unemployment. Keywords: alcohol drinking, cohabitation, men, unemployment... he social patterning of alcohol consumption is not universal Tand varies by region, gender and by choice of alcohol measure. In many European countries excessive drinking in men varies by level of education and income, with the least educated and those earning lower income being at higher risk, 1 3 but in some countries there is evidence of reverse association regarding occupational status. 4,5 Few studies exist on the social patterning of excessive drinking in the Danish general population. One study found that socio-economic differences in education, occupation and income seemed to be less pronounced than in other countries. 6 The authors explained the findings by the fact that drinking (large amounts of alcohol) is almost universal in Denmark. Approximately 14 18% of Danish men exceed recommended weekly alcohol intake and only 3% do not drink alcohol. 6,7 However, to study the social patterning of excessive drinking might require other measures of social exposures and include more levels of alcohol intake. Unemployment and divorce are stressful life events and alcohol is used by some individuals to reduce tension while undergoing them, and the accumulation (number of events or longer duration of exposure) may increase the risk of excessive drinking. Several studies have found that married men drink less than unmarried men 8,9 and divorce has been associated with increased drinking. 10,11 Previous studies have shown ambiguous evidence for the associations between unemployment and excessive drinking Longitudinal measurement of cohabitation and unemployment could provide a more comprehensive understanding of the associations. Such studies are, however, very scarce. Romelsjö et al. found that the risk of heavy drinking increased with duration of unemployment and number of episodes during a 5-year period, but the study lacked power to make inference. 15 In a study based on the US national Longitudinal Survey of Youth, Mossakowski 16 found that >2 years of unemployment was associated with heavy drinking. Two studies based on the 1958 British Birth Cohort Study, studied the association between duration of unemployment and heavy drinking and found an association when the cohort members were 23 years old, but no statistically significant results when cohort members were 33 years old. To our knowledge none of the studies has focused on the association between accumulation of broken partnerships and excessive drinking. The aim of this article was to study how the history of unemployment and cohabitation is associated with excessive drinking. Additionally, we wished to determine if there was an interaction between job-losses and broken partnerships in relation to excessive drinking. Methods This study is based on a subpopulation of the Metropolit Project, which comprises all boys born within the metropolitan area of Copenhagen in The Project has been described in detail elsewhere. 17,18 In 1968, the Danish Civil Registration System was established, and each Danish

2 Excessive drinking and unemployment in Danish men born 445 resident was registered with a Personal Identification Number (PIN). The members of the original Metropolit population who survived and continued living in Denmark until 1968 were given identification numbers by the authorities. In 2004 the members of the cohort still alive and living in Denmark were sent a questionnaire about lifestyle issues such as diet, alcohol intake and smoking. Of the 9507 eligible cohort members 6292 responded (response rate 66.2%). In 2006 the cohort was linked to registers of socio-economic information in Statistics Denmark using the PIN as a key. The cohort was also linked with the Central Psychiatric Register, the Central Hospital Register and the National Drug Prescription Registry, which contains information about outpatient prescription drug use. In this study, we included only participants with a full record of register data for the years inclusive, who also participated in the 2004 survey (N = 6112). Assessment of alcohol drinking The measure of alcohol intake in this study was based on self-reported information from the 2004 survey, in which the cohort members were asked about their weekly intake of strong and light beers, red and white wine, fortified wine and liquor. We calculated the weekly intake in standard units as the sum of number of drinks consumed in the past week adjusted by the alcohol content of each type of alcoholic drink. We categorized the weekly intake into four categories: none, moderate drinking (1 21 units per week), excessive drinking (22 35 units per week) and very excessive drinking (>35 units per week). The official recommendation for maximum weekly alcohol intake is 21 units per week for males. Assessment of history of unemployment and cohabitation Information on history of unemployment and cohabitation was based on annual records from Statistics Denmark for the period , when cohort members were between 28 and 49 years old. Based on this information we constructed four exposure variables: number of job-losses, years unemployed, number of broken partnerships and years living without a partner. Job-loss was defined as a change in individual labourmarket participation that involved a period of unemployment and was categorized as follows: no job-losses (reference group), one job-loss, two job-losses and three or more job-losses. Job-loss status was assigned to the categories based on change of employer s identification code. We restricted the category of job-loss to men who had been unemployed for 3 months of the calendar-year to exclude those who changed job with short or no intervening period of unemployment. 19 Men with no job-losses were classified as continuously employed and this group included also those who were pre-retirement pensioners throughout the period. We found that this group was too small to constitute a separate category, but preliminary results with separate estimates for this group indicated that they were more similar to those with no job-losses than to those with job-losses. Excluding this group did not change the results. Years unemployed was based on information about main labour-market attachment for every calendar year (determined by source of income). We grouped the men as either working (employed or self-employed) or not working (unemployed, pre-retirement pensioners and persons on social welfare benefits or training). Years unemployed were the sum of years in the non-working group between the ages of 28 and 49 years including years as a pensioner. This information was grouped in four groups: no unemployment (reference group), 1 5 years, 6 9 years and >9 years. In this study, men living either within marriage (heterosexual and homosexual allowed since 1989) or consensual unions (heterosexual only) were grouped. Two individuals living at the same address were classified as living in a consensual union if they had common children or were of the opposite sex, and both were 16 years old, the age difference was <15 years, they were not closely related and there were no other adults in the household. The partner s identification number made it possible to follow changes from one partner to another. We divided the cohort members into five groups according to their history of cohabitation between 1980 and 2003: consistently cohabiting with the same partner (reference group), never cohabited (did not live with a partner at any time during this period), one broken partnership, two broken partnerships and three or more broken partnerships. We maintained the never cohabited as a separate group because of its size and because other studies of this cohort 20 and of other populations 21 have indicated high mortality in this group. A broken partnership was defined as the end of cohabitation. The classification comprises individuals who were formerly cohabiting but during any year were living without a partner or with a new partner. Very few of the married men became widowers during follow-up and these cases were classified as broken partnerships. Years living without a partner was the sum of years without a partner between the ages of 28 and 49 years and classified into four groups: never living alone (reference group), 1 5, 6 9 and >9 years. Assessment of covariates From the social registers from 1980, we used educational attainment coded into high (at least secondary education) and low (primary education only). Information on alcoholrelated admissions to a psychiatric or somatic hospital wards was retrieved from the Central Psychiatric register ( ) and the Central Hospital Register ( ) and used the International Classification of Disease (ICD) to indentify diagnoses. We included admissions for alcohol psychosis and abuse syndrome ( ; ICD 8/F10.0 F10:9 ICD 10), cirrhosis of the liver and other alcohol-related liver disease (571.09; ICD 8/K70.0 K70.9 ICD 10) and oesophageal varices (456.09; ICD 8/I85.0 I85.9 ICD10). Information about admission to a psychiatric ward was obtained from the Central Psychiatric register for the period , when the cohort members were between 15 and 28 years old. Alcohol-related admissions were grouped with psychiatric admission because there were too few admissions to make separate analyses on this group. We coded the admissions as either no, or at least one admission. In total 259 (4.2%) of the men had been admitted at least once. Information on admissions before events of job-losses or broken partnerships was entered in the models as a confounder. Statistical methods We used logistic regression to analyse the associations between history of cohabitation and job-losses and very excessive drinking. The analyses of very excessive drinking drinkers were based on a comparison only with those who drank 1 35 per week, excluding abstainers (n = 5548). We analysed the exposure variables (number of job-losses, years unemployed, number of broken partnerships and years living without a partner) in four models. We included the covariates one at a time and evaluated the changes in estimates compared with the crude models. Statistical interaction between exposure variables was tested by adding an interaction term to the models. If the result of

3 446 European Journal of Public Health Table 1 Distribution of alcohol consumption by history of job-losses and history of cohabitation (age years) Number of non-drinkers, n (%) consumed 1 21 consumed consumed >35 Sum (%) Total study population 564 (9.2) 3892 (63.7) 1043 (17.1) 613 (10.0) 6112 (100) History of job-losses/unemployment ( ) (7.5) 3001 (66.9) 772 (17.2) 377 (8.4) 4485 (100) (11.6) 571 (58.3) 165 (16.9) 129 (13.2) 979 (100) 2 58 (15.4) 192 (51.1) 63 (16.8) 63 (16.8) 376 (100.1) 3 57 (21.0) 128 (47.1) 43 (15.8) 44 (16.2) 272 (100.1) Number of years unemployed 197 (5.9) 2301 (69.1) 566 (17.0) 267 (8.0) 3331 (100) (9.0) 1256 (62.8) 361 (18.1) 203 (10.2) 1999 (100.1) (18.4) 175 (50.4) 54 (15.6) 54 (15.6) 347 (100) (28.5) 160 (36.8) 62 (14.3) 89 (20.5) 435 (100.1) History of cohabitation ( ) Continuously cohabited ( ) 176 (6.7) 1789 (67.8) 471 (17.9) 201 (7.6) 2637 (100) Never cohabited (18.4) 197 (56.6) 42 (12.1) 45 (12.9) 348 (100) 1 broken partnership 177 (9.9) 1140 (63.6) 293 (16.3) 183 (10.2) 1793 (100) 2 broken partnership 93 (10.9) 505 (59.3) 153 (18.0) 100 (11.8) 851 (100) 3 broken partnership 54 (11.2) 261 (54.0) 84 (17.4) 84 (17.4) 483 (100) Continuously cohabited ( ) 122 (6.6) 1246 (67.2) 349 (18.8) 136 (7.3) 1853 (99.9) Lived without a partner 1 5 years 122 (6.6) 1257 (68.2) 322 (17.5) 141 (7.7) 1842 (100) Lived without a partner 6 9 years 77 (9.6) 514 (64.1) 120 (15.0) 91 (11.4) 802 (100.1) Lived without a partner 10 years 243 (15.1) 875 (54.2) 252 (15.6) 245 (15.2) 1615 (100.1) Educational attainment High 321 (7.9) 2640 (64.8) 727 (17.9) 385 (9.5) 4073 (100.1) Low 243 (11.9) 1252 (61.4) 316 (15.5) 228 (11.2) 2039 (100) Psychiatric or alcohol-related admissions age years (8.7) 3816 (64.1) 1026 (17.2) 593 (10.0) 5953 (100) 1 46 (28.9) 76 (47.8) 17 (10.7) 20 (12.6) 259 (100) this analysis indicated any interaction a stratified analysis was performed to investigate the nature of the interaction. The score test in proc logistic was used to test for trend (Cochran Armitage test) in number of job-losses, number of years living without a partner, number of broken partnerships and number of years living without a partner. SAS (ver. 9.1) was used for all analysis. Results Table 1 shows the distribution of the population in four categories of weekly alcohol consumption. The cohort consisted of 564 non-drinkers (9.2%), 2892 moderate drinkers (63.7%), 1043 excessive drinkers (17.1%) and 613 very excessive drinkers (10.0%). There was variation in non-drinking in relation to history of unemployment and cohabitation as well as educational attainment, psychiatric and alcohol-related admissions with those in the more disadvantaged positions being more likely to be non-drinkers. The reverse patterns were found in the moderate drinkers with the more advantaged being more frequently moderate drinkers. There were small differences in among excessive drinkers but the patterns tended to be similar to the moderately drinking category with those in more favourable situations being more likely to be excessive drinkers. Those with disadvantage in relation to history of unemployment and cohabitation were more often very excessive drinkers and the same applied to those with low educational attainment or psychiatric or alcohol-related admissions. Table 2 shows the crude and adjusted odds ratios (ORs) of exposure variables and covariates in relation to very excessive drinking among drinkers. Very excessive drinking was associated with job-losses and the OR for very excessive drinking increased with number of events. Very excessive drinking was related to number of years unemployed and the risk increased with number of years. Men with broken partnerships and those never having cohabited had an increased risk of very excessive drinking and the risk increased with number of events. Those men who lived alone for >5 years had an increased risk of very excessive drinking, and living alone for > 9 years added to the risk. Adjusting for educational attainment and psychiatric and alcohol-related admission changed the estimates slightly. We found an indication of statistical interaction between number of job-losses and broken partnerships in relation to very excessive drinking (P = 0.03) and stratified the model of job-losses and heavy drinking on the number of broken partnerships (grouped as none, never cohabited and more than one broken partnership). Table 3 shows the association between job losses and very excessive drinking stratified by history of cohabitation in the drinking population only. The OR of very excessive drinking increased with number of job-losses only in those men who had also experienced broken partnerships. Among the consistently cohabiting, or those never having done so, those with two job-losses had the highest OR of very excessive drinking, but generally the OR of very excessive drinking was higher among men never having cohabited compared with those consistently doing so. Moreover, in individuals with three or more job-losses the OR for very excessive drinking was very similar in all strata of history of cohabitation. Discussion In this study, we found that accumulation in relation to history of unemployment and cohabitation was associated with abstention from alcohol drinking and with very excessive drinking and that the association was reverse for moderate drinking and to a smaller extent for exceeding maximum weekly intake but drinking 35 units per week. In multivariate analyses, we found that among drinkers, very excessive drinking was associated with number of events of job-losses

4 Table 2 Crude and adjusted ORs and 95% CIs for relation between history of job-losses and history of cohabitation (age years) and very excessive drinking among drinkers OR for very excessive drinking OR for very excessive drinking a History of job-losses/unemployment ( ) 0 1 (ref) 1 (ref) ( ) 1.72 ( ) ( ) 2.37 ( ) ( ) 2.48 ( ) Number of years unemployed 1 (ref) 1 (ref) ( ) 1.34 ( ) ( ) 2.50 ( ) ( ) 4.16 ( ) History of cohabitation ( ) Continuously cohabited 1 (ref) 1 (ref) ( ) Never cohabited ( ) 2.06 ( ) 1 broken partnership 1.44 ( ) 1.43 ( ) 2 broken partnerships 1.71 ( ) 1.69 ( ) 3 broken 2.74 ( ) 2.69 ( ) partnerships Number of years living 1 (ref) 1 (ref) without a partner ( ) 1.07 ( ) ( ) 1.73 ( ) ( ) 2.55 ( ) Educational attainment at age 28 years High 1 (ref) Low 1.27 ( ) Psychiatric or alcohol-related admissions age years 0 1 (ref) ( ) a: Adjusted for educational attainment and psychiatric and alcohol-related admissions Table 3 Adjusted ORs and 95% CIs for relation between history of job-losses (age years) and very excessive drinking among drinkers by cohabitation status a History of job-losses/ unemployment ( ) Consistently cohabitant Never cohabitant Broken partnerships 0 1 (ref) 1 (ref) 1 (ref) ( ) 3.32 ( ) 1.55 ( ) ( ) 3.87 ( ) 1.83 ( ) ( ) 1.91 ( ) 2.34 ( ) a: Adjusted for educational attainment and psychiatric and alcohol-related admissions and broken partnership as well as with duration of unemployment and living without a partner when adjusted for educational attainment and psychiatric and alcohol-related admissions. Based on the 1958 British Birth Cohort Study, two studies have investigated the association between duration of unemployment and heavy drinking. Power and Estaugh 22 studied accumulation of unemployment between the ages of 16 and 23 years and found that among men unemployment for >6 months was associated with drinking >35 units per week. Montgomery et al. 23 studied unemployment between the age 16 and 33 years in the same population and found that the risk of problem drinking increased with duration of unemployment. The risk of heavy drinking was also increased in those with >3 years of unemployment, but this estimate was insignificant using 95% confidence interval (CI). In a study based Excessive drinking and unemployment in Danish men born 447 on 27- to 35-year-olds, Mossakowski 16 found that the OR of heavy drinking and drinking frequency increased with years of involuntary unemployment. However, the estimates were only significant for durations of unemployment for >2 years. These studies support that longer durations of unemployment are associated with heavy drinking. However, in contrast to the present study, they are based on younger men aged 35 and the possible ranges of years unemployed are shorter. The study by Montgomery et al. found that problem drinking is more strongly related with unemployment than heavy drinking. However, this study focused on unemployment at an age range when labour-market participation is initiated. In older men, who are most often a main bread-winners of the household, unemployment may have a different impact such as major loss of household income which in turn might have consequences such as the necessity to sell home and marital conflicts. Further, the presence of children in the household may play a role in how unemployment is experienced. We did not investigate these factors, but the stratified analysis indicated that the association between unemployment and very excessive drinking depends on history of cohabitation. Other Danish 6,7 studies have focused on exceeding official guidelines (21 units per week for males) and found only modest differences according to education, income and occupation. We found that educational attainment as well as accumulation of disadvantage in relation to history of unemployment and cohabitation was related to very excessive drinking but not to excessive drinking. Based on the findings of this study, we suggest that social patterning in alcohol consumption in Denmark lies not in exceeding official guidelines but rather in very excessive drinking. By looking at exceeding official guidelines any excess risk may be driven by the very excessive drinkers. Strengths and limitations The measures of history of employment and cohabitation were based on register data, which provided complete histories of cohabitation and employment from 1980 to 2003 of all cohort members who were alive and living in Denmark, but contain only annual information and have no information on changes that occur within each year. Register data were not available before 1980 when the cohort members were 28 years old, but between ages 28 and 49 years when education has finished and participation in the labour-market and in family life is important are covered by the registers. The size of the study population made it possible to study detailed exposure groups as well as to distinguish between excessive and very excessive drinkers. We had information on admissions for psychiatric reasons and for alcohol-related diseases, which is an advantage because it is possible to rule out some of the possible health selection effects. However those admitted to a hospital are the most severe cases and including this variable in the models affected the associations between history of unemployment and partnership and drinking behaviours only to a small degree. This might be because only the more severe cases of psychiatric illness and alcohol abuse are hospitalized. Milder cases of mental disorders and alcohol abuse might influence the results, but unfortunately this information was unavailable. Unfortunately, alcohol drinking was only measured once and we could not determine the direction of the associations between history of cohabitation and unemployment and excessive drinking. Both health selection and social causation may play a role. Apart from the studies mentioned in the introduction, which support the social-causation hypothesis, some studies have found evidence for health selection or reverse causation Finally, this study included only men and

5 448 European Journal of Public Health exposures related to labour-market and family life may affect women in a different manner. Acknowledgements The authors thank K Svalastoga, E Høgh, P Wolf, T Rishøj, G Strande-Sørensen, E Manniche, B Holten, IA Weibull and A Ortmann who established the data between 1965 and Funding The Danish Medical Research Council [grant number FSS ], The Danish Health Insurance Fund [grant number 2007B043], Wedell-Wedellsborg Foundation [grant number /766(828)], Krista and Viggo Petersen Foundation. Conflicts of interest: None declared. Key points The risk of very excessive drinking increase with number of job-losses and broken partnerships and with duration of unemployment. Living alone >5 years increase risk of very excessive drinking. Special attention should be given to those exposed to long durations of unemployment, repeated job losses or broken partnerships and to those living without a partner in the design of policies aimed at reducing very excessive drinking. References 1 Bloomfield K, Grittner U, Kramer S, Gmel G. Social inequalities in alcohol consumption and alcohol-related problems in the study countries of the EU concerted action Gender, Culture and Alcohol Problems: a Multi-national Study. Alcohol Alcohol Suppl 2006;41:i van Oers JA, Bongers IM, van de Goor LA, Garretsen HF. Alcohol consumption, alcohol-related problems, problem drinking, and socioeconomic status. Alcohol Alcohol 1999;34: Marmot M. Inequality, deprivation and alcohol use. Addiction 1997;92:S Martikainen P, Ishizaki M, Marmot MG, et al. Socioeconomic differences in behavioural and biological risk factors: a comparison of a Japanese and an English cohort of employed men. Int J Epidemio 2001;30: Lahelma E, Lallukka T, Laaksonen M, et al. Social class differences in health behaviours among employees from Britain, Finland and Japan: the influence of psychosocial factors. Health Place 2010;16: Bloomfield K, Grittner U, Rasmussen HB, Petersen HC. Socio-demographic correlates of alcohol consumption in the Danish general population. Scand J Pub Health 2008;36: Hvidtfeldt UA, Hansen ABG, Grønbæk M, Tolstrup JS. Alkoholforbrug i Danmark Kvantificering of karakteristik af storforbrugere og afhængige Statens Institut for Folkesundhed, Syddansk Universitet. 8 Schoenborn CA. Marital status and health: United States, Adv Data 2004;351: Leonard KE, Rothbard JC. Alcohol and the marriage effect. J Stud Alcohol Suppl 1999;13: Power C, Rodgers B, Hope S. Heavy alcohol consumption and marital status: disentangling the relationship in a national study of young adults. Addiction 1999;94: Veenstra MY, Lemmens PH, Friesema IH, et al. A literature overview of the relationship between life-events and alcohol use in the general population. Alcohol Alcohol 2006;41: Hammer T. Unemployment and use of drug and alcohol among young people: a longitudinal study in the general population. Br J Addict 1992;87: Morris JK, Cook DG, Shaper AG. Non-employment and changes in smoking, drinking, and body weight. BMJ 1992;304: Gallo WT, Bradley EH, Siegel M, Kasl SV. The impact of involuntary job loss on subsequent alcohol consumption by older workers: findings from the health and retirement survey. J Gerontol B Psychol Sci Soc Sci 2001;56:S Romelsjo A, Hasin D, Hilton M, et al. The relationship between stressful working conditions and high alcohol consumption and severe alcohol problems in an urban general population. Br J Addict 1992;87: Mossakowski KN. Is the duration of poverty and unemployment a risk factor for heavy drinking? Soc Sci Med 2008;67: Osler M, Lund R, Kriegbaum M, et al. Cohort profile: the Metropolit 1953 Danish male birth cohort. Int J Epidemiol 2006;35: Osler M, Andersen AM, Lund R, et al. Revitalising the Metropolit 1953 Danish male birth cohort: background, aims and design. Paediatr Perinat Epidemiol 2004;18: Kriegbaum M, Christensen U, Lund R, Osler M. Job losses and accumulated number of broken partnerships increase risk of premature mortality in Danish men born in J Occup Environ Med 2009;51: Lund R, Holstein BE, Osler M. Marital history from age 15 to 40 years and subsequent 10-year mortality: a longitudinal study of Danish males born in Int J Epidemiol 2004;33: Modin B. Born out of wedlock and never married it breaks a man s heart. Soc Sci Med 2003;57: Power C, Estaugh V. Employment and drinking in early adulthood: a longitudinal perspective. Br J Addict 1990;85: Montgomery SM, Cook DG, Bartley MJ, Wadsworth MEJ. Unemployment, cigarette smoking, alcohol consumption and body weight in young British men. Eur J Pub Health 1998;8: Kasl SV, Cobb S. The experience of losing a job: some effects on cardiovascular functioning. Psychother Psychosom 1980;34: Fu H, Goldman N. The association between health-related behaviours and the risk of divorce in the USA. J Biosoc Sci 2000;32: Collins RL, Ellickson PL, Klein DJ. The role of substance use in young adult divorce. Addiction 2007;102: