Department of Public Health University of Helsinki SOCIOECONOMIC DIFFERENCES IN SMOKING IN ESTONIA: National and international comparisons Kersti Pärna Helsinki 2005 Supervisors: Docent Helena Mussalo-Rauhamaa, MD, PhD Department of Public Health University of Helsinki Professor Mati Rahu, PhD Department of Epidemiology and Biostatistics National Institute for Health Development, Tallinn Reviewers: Professor Pekka Jousilahti, MD, PhD Department of Epidemiology and Health Promotion National Public Health Institute (KTL), Helsinki Docent Sakari Karvonen, PhD Welfare Research Group National Research and Development Centre for Welfare and Health (STAKES), Helsinki Opponent: Professor Lasse Kannas, PhD Department of Health Sciences Research Centre for Health Promotion University of Jyväskylä The author of the photograph in the front cover: Mati Rahu ISBN 952-10-1369-9 (paperback), ISBN 952-10-2853-X (PDF) ISSN 0355-7979 Yliopistopaino Helsinki 2005 In memory of Heino To my children Katri and Kaur CONTENTS ABSTRACT...........................................................................................................7 YHTEENVETO (Summary in Finnish) .................................................................9 KOKKUVÕTE (Summary in Estonian)...............................................................11 LIST OF ORIGINAL PUBLICATIONS .............................................................13 ABBREVIATIONS..............................................................................................14 1. INTRODUCTION ............................................................................................15 2. LITERATURE REVIEW .................................................................................17 2.1. Definition of smoking in epidemiological studies......................................17 2.2. The smoking epidemic................................................................................17 2.2.1. The smoking epidemic among physicians as representatives of the higher socioeconomic bracket ..........................................................18 2.3. Smoking situation in Estonia compared to other countries ........................18 2.3.1. Smoking among adolescents.............................................................19 2.3.2. Smoking among adults .....................................................................21 2.3.3. Smoking among physicians ..............................................................22 2.3.4. Tobacco legislation...........................................................................23 2.4. Measurement of socioeconomic status .......................................................23 2.4.1. Indicators of socioeconomic status for adolescents ..........................24 2.4.2. Indicators of socioeconomic status for adults...................................25 2.4.3. Specific features of socioeconomic stratification in Estonia ............26 2.5. Validity of self-reported smoking...............................................................28 2.5.1. Measuring cotinine to validate self-reported smoking status............28 2.6. Previous studies of socioeconomic differences in smoking .......................29 2.6.1. Socioeconomic differences in smoking within countries .................29 2.6.1.1. Smoking among adolescents................................................29 2.6.1.2. Smoking among adults ........................................................31 2.6.2. Socioeconomic differences in smoking between countries: Eastern and Western Europe..........................................................................32 2.6.2.1. Smoking among adolescents................................................33 2.6.2.2. Smoking among adults ........................................................33 2.6.3. Smoking among physicians ..............................................................34 2.6.4. Socioeconomic differences in the validity of self-reported smoking status among pregnant women..........................................................35 3. OBJECTIVES OF THE STUDY......................................................................37 4. MATERIAL AND METHODS ........................................................................38 4.1. Overall description of the studies ...............................................................38 4.2. Data sources and subjects...........................................................................38 4.3. Data collection............................................................................................40 4.4. Study variables ...........................................................................................41 4.4.1. Smoking status..................................................................................41 4.4.2. Socioeconomic status........................................................................42 4.4.3. Other variables..................................................................................42 4.5. Statistical methods......................................................................................44 5. RESULTS .........................................................................................................46 5.1. Smoking among adolesents (I, III) .............................................................46 5.2. Smoking among adults (II).........................................................................49 5.3. Smoking among physicians (IV, V) ...........................................................49 5.4. Smoking among pregnant women in Estonia (VI) .....................................52 6. DISCUSSION ...................................................................................................54 6.1. Methodological considerations...................................................................54 6.1.1. Data sets and study design................................................................54 6.1.2. Definitions of smoking and use of socioeconomic factors ...............56 6.1.3. Methods ............................................................................................56 6.2. Description of the key results .....................................................................57 6.2.1. Socioeconomic differences in adolescent smoking ..........................57 6.2.2. Socioeconomic differences in adult smoking ...................................60 6.2.3. Smoking among physicians as representatives of the higher socioeconomic bracket......................................................................62 6.2.4. Socioeconomic differences in misclassification of smoking status among pregnant women....................................................................64 7. SUMMARY AND CONCLUSIONS ...............................................................67 8. REFERENCES..................................................................................................69 9. ACKNOWLEDGEMENTS ..............................................................................83 PUBLICATIONS .................................................................................................85 ABSTRACT The present thesis compares socioeconomic differences in smoking in Estonia and its neighbouring countries. The objectives were (1) to study socioeconomic features of smoking among adolescents in Estonia compared to adolescents in Finland and Russia, (2) to examine socioeconomic differences in smoking among adults in Estonia, (3) to study smoking among physicians as representatives of a higher socioeconomic bracket compared to the general population in Estonia and compared to physicians in Finland, and (4) to investigate socioeconomic diffe- rences in the misclassification of one’s smoking status among pregnant women in Estonia. Four separate studies were used to accomplish these objectives. The first one was designed as a cross-sectional study among the 13–18-year-old adolescents in Tallinn, Helsinki, and Moscow. The second study was based on a subsample of the 30–59-year-old adult population of the Estonian Health Interview Survey. The third study was designed as a cross-sectional postal survey among physicians in Estonia and Finland. The fourth one was based on a subsample of the cross- sectional Human Papillomavirus Type-16 Seroprevalence Study in Tallinn. Serum cotinine assays of the pregnant women, who were determined to deliver, were performed. The serum cotinine-validated smoking level was compared with the subjects’ self-reported smoking levels obtained from the records of the Estonian Medical Birth Registry. The socioeconomic status of adolescents was measured by the level of education of the head of the family, whereas, among adults, the level of education, employment status, and income were used. The socioeconomic status of the individuals was categorized according to basic sociodemographic and socio- environmental indicators. Logistic regression analysis was applied to assess association between smoking and socioeconomic status. The present study confirms that the socioeconomic differences in smoking represent a complex and multifaceted phenomenon. The comparison of adolescents in Tallinn, Helsinki, and Moscow revealed that the prevalence of smoking was higher among boys compared to girls in Tallinn and Moscow, but was higher among girls compared to boys in Helsinki. The prevalence of smoking among girls in Estonian schools in Tallinn was much lower than among girls in the other study samples, but no such difference existed when comparing