Cancer incidence among Chernobyl cleanup workers from Estonia: A 34-year follow-up

From 1986 to 1991, 4831 men from Estonia were sent to clean up radioactively contaminated areas near Chernobyl (Chornobyl). Their cancer incidence during 1986 to 2019 was compared to that of the male population of Estonia. The cohort of cleanup workers was linked to national population and cancer registers based on unique personal identification numbers. Nineteen (0.4%) workers could not be traced. A total of 4812 men contributing 120 770 person-years of follow-up were eligible for the analyses. Standardized incidence ratios (SIR) and adjusted relative risks (ARR, expressed as ratios of SIRs) with 95% confidence intervals (CI) were calculated. A total of 687 incident cancer cases were registered in the cohort (SIR 1.11, 95% CI 1.03-1.19). Presumptive radiation-related cancers combined were in excess, but not when smoking- and alcohol-related cancers were excluded (SIR 0.92, 95% CI 0.71-1.18). For smoking-related cancers, the SIR was 1.24 (95% CI 1.13-1.36) and for alcohol-related cancer the SIR was 1.53 (95% CI 1.31-1.75). Less educated workers had a higher risk of all cancers (ARR = 1.21, 95% CI 1.02-1.44) and smoking-related cancers (ARR = 1.42, 95% CI 1.14-1.76). An elevated risk of alcohol-related cancers was evident 15 to 24 years (vs <15 years) after return from the Chernobyl area. This updated register-based follow-up of Chernobyl cleanup workers from Estonia revealed an excess of radiation-related cancer sites combined, but the excess was not apparent after excluding cancers associated with smoking and alcohol.

Suicide and other causes of death among Chernobyl cleanup workers from Estonia, 1986 - 2020: an update

Mortality was studied in a cohort of 4831 men from Estonia who participated in the environmental cleanup of the radioactively contaminated areas around Chernobyl in 1986-1991. Their mortality in 1986-2020 was compared with the mortality in the Estonian male population. A total of 1503 deaths were registered among the 4812 traced men. The all-cause standardized mortality ratio (SMR) was 1.04 (95% CI 0.99-1.09). All-cancer mortality was elevated (SMR 1.16, 95% CI 1.03-1.28). Radiation-related cancers were in excess (SMR 1.20, 95% CI 1.03-1.36); however, the excesses could be attributed to tobacco and alcohol consumption. For smoking-related cancers, the SMR was 1.20 (95% CI 1.06-1.35) and for alcohol-related cancers the SMR was 1.56 (95% CI 1.26-1.86). Adjusted relative risks (ARR) of all-cause mortality were increased among workers who stayed in the Chernobyl area ≥ 92 days (ARR 1.20, 95% CI 1.08-1.34), were of non-Estonian ethnicity (ARR 1.33, 95% CI 1.19-1.47) or had lower (basic or less) education (ARR 1.63, 95% CI 1.45-1.83). Suicide mortality was increased (SMR 1.31, 95% CI 1.05-1.56), most notably among men with lower education (ARR 2.24, 95% CI 1.42-3.53). Our findings provide additional evidence that unhealthy behaviors such as alcohol and smoking play an important role in shaping cancer mortality patterns among Estonian Chernobyl cleanup workers. The excess number of suicides suggests long-term psychiatric and substance use problems tied to Chernobyl-related stressors, i.e., the psychosocial impact was greater than any direct carcinogenic effect of low-dose radiation.

Trends in teenage delivery and abortion rates in Estonia over more than two decades: a nationwide register-based study

BACKGROUND

In the last 30 years, Estonia has undergone major socio-economic changes, including profound educational and healthcare reforms. The study aimed to analyse trends in teenage delivery and induced abortion rates among younger and older teens, including Estonians and non-Estonians, and to study trends in repeat teenage pregnancies in more detail.

METHODS

The register-based study included data on 29 818 deliveries (1992-2019) and 25 865 (1996-2019) induced abortions among 15-19-year-old girls. Delivery and abortion rates per 1000 girls were calculated by age group, ethnicity and reproductive history. Poisson regression models were applied to estimate average annual percentage changes in delivery and abortion rates over the whole period and in two sub-periods with change points in the trend in 2007.

RESULTS

The delivery rate decreased by 5.3% per year, from 49.9 in 1992 to 8.4 in 2019; the abortion rate decreased by 6.0% per year, from 42.4 in 1996 to 8.6 in 2019. A faster decline in delivery rates took place among Estonians than non-Estonians, but the opposite trend occurred in abortion rates. Delivery rates for first and repeat pregnancies decreased nearly at the same pace, while abortion rates for repeat pregnancies decreased faster than those for first pregnancies.

CONCLUSIONS

A decreasing trend in teenage births is evident in parallel with society becoming wealthier. A remarkable decline in teenage abortions occurs when young people's rights to safe abortion, contraception, mandatory sexuality education and youth-friendly services are ensured. There always remains a small group of adolescents who repeatedly become pregnant.

The fall and rise of cancer registration in Estonia: The dangers of overzealous application of data protection

BACKGROUND

The population-based Estonian Cancer Registry (ECR) has maintained a database of cancer cases since 1968. Between 2001 and 2007 the ECR was prohibited from linking cancer records to death certificates. In January 2008, the prohibition was lifted, and two years later the ECR was able to begin tracing back unmatched deaths. This paper estimates the effect of the linkage ban on reported cancer incidence and survival.

METHODS

Incident cancers in 2001-2007 were extracted from the ECR database in May 2018 to allow for late registrations. Two datasets were created: one with all incident cases and another without death-certificate-initiated (DCI) cases. Using both datasets, age-standardised incidence rates (ASIR) and their ratios; age-standardised five-year relative survival ratios (ARSR) and excess mortality rate ratios were calculated.

RESULTS

In 2001-2007, 46,535 incident cancers were registered in the ECR. Of them, 2299 (4.9 %) were DCI cases. The inclusion of DCI cases increased the ASIR for overall cancer by 6 % in men and 3 % in women. An increase ≥10 % in ASIR for lung, liver and pancreatic cancer was observed. The effect of accrued DCI cases to the ARSR was minor. Excess mortality in the dataset without DCI cases was 4 % underestimated in men and 3 % in women.

CONCLUSION

Biases in cancer incidence and survival measures generated by the temporary record linkage ban were largely correctable by using trace-back procedures when this became possible. Nevertheless, this type of ban and the arguments put forward to justify it, harm disease registration and register-based research.

Respiratory tuberculosis incidence and mortality in Estonia: 30-year trends and sociodemographic determinants

OBJECTIVE

To explore time trends in the incidence and mortality of respiratory tuberculosis (TB) over a 30-year period in Estonia, and to evaluate disease disparities according to sex, age, ethnicity and education.

DESIGN

Data from the TB Register and the Causes of Death Register were used to assess time trends in age-standardised incidence and mortality rates. The effect of sociodemographic characteristics on TB risk was modelled using Poisson regression around three population censuses.

RESULTS

Respiratory TB incidence and mortality decreased in males and were stable in females in 1987-1991, after which the rates increased sharply in both sexes until 1998 and decreased steadily afterwards. Multidrug-resistant TB (MDR-TB) incidence rose in males until 1998 and in females until 2002, and then started to fall. The incidence of TB and human immunodeficiency virus (HIV) coinfection in males increased until 2007 and decreased thereafter. Less educated people and non-Estonians had a significantly higher relative risk of respiratory TB.

CONCLUSION

Estonia, one of the countries most affected by TB in the World Health Organization European Region, has made considerable progress in reducing the risk of respiratory TB, TB-HIV and MDR-TB. Continuing education- and ethnicity-related disparities in TB risk remain a concern.

Sex disparities in premature adult mortality in Estonia 1995-2016: a national register-based study

OBJECTIVES

To quantify sex disparities in cause-specific premature adult mortality in Estonia, to determine the causes of death with the largest differences, to provide insight into related behaviours and to offer some guidance to public health policy-makers based on the results of the study.

DESIGN

A national register-based study.

SETTING

Estonia.

DATA

Individual records of deaths at ages 20-69 years in 1995-2016 from the Estonian causes of death register; data on tobacco smoking and alcohol consumption in the adult population in 1996-2016 from the biennial postal survey of health behaviour.

MAIN OUTCOME MEASURES

Overall and cause-specific age-standardised mortality rates, average annual percentage changes in mortality, and cause-specific men-to-women mortality rate ratios were calculated. In addition, the age-standardised prevalence proportions of tobacco smoking and alcohol consumption and men-to-women prevalence rate ratios were determined.

RESULTS

Overall premature adult mortality decreased considerably during 1995-2016, but no reduction was observed with respect to the large relative sex disparities. In circulatory disease mortality, the disparities widened significantly over time. Extremely high mortality rate ratios were observed for cancer of the upper aerodigestive tract and for lung cancer. There was a stable, more than fivefold male excess mortality from external causes. A fourfold male disadvantage was evident for alcohol poisoning, mental disorders due to alcohol and alcohol-related degeneration of the nervous system as a group. The prevalence of tobacco smoking and harmful alcohol consumption among men exceeded that among women by factors of two and six, respectively.

CONCLUSIONS

Even though premature adult mortality has markedly decreased over time, there has been no success in diminishing the large sex differences in the mortality patterns, mostly associated with smoking and excessive alcohol consumption, both more prevalent among men. Estonia needs a comprehensive and consistent alcohol policy while maintaining and further developing antitobacco measures.

Dramatically deteriorated quality of life in men with prostatitis-like symptoms

BACKGROUND

Despite widespread occurrence and poor comprehension, prostatitis has been largely under-researched.

OBJECTIVE

To compare complaints, general and sexual health, co-morbidities, risk factors, and lifestyle in men with and without prostatitis-like symptoms (PLS).

MATERIAL AND METHODS

The cross-sectional study included 20- to 59-year-old male residents of Estonia. Questionnaire data of 82 men with PLS and of 711 men without PLS were compared.

RESULTS AND DISCUSSION

A third of men with PLS considered their health poor, with more frequently diagnosed renal diseases, benign prostate hyperplasia, STDs, chronic nervous system diseases, and depression in them than in controls. They reported more cystitis and gynecological inflammations in their partners, and more prostatitis in their close relatives. This familial predisposition indicates possible genetic and immunologic background of PLS that may be associated also with susceptibility to respiratory tract infections revealed for the first time in our study. By the personality type, the men in the PLS group were less calm but more worrying. Hard drinks, antidepressants, sedative, and sleeping pills were more frequently consumed, and nightshift working and continuous stress were more commonly seen among men with than without PLS. PLS disturbed the sexual life as well as everyday activities.

CONCLUSIONS

The men with PLS are characterized by remarkable complex of co-morbidities, habits, and attitudes. PLS possess substantial negative impact on quality of life. Successful work-up of these patients needs multidimensional treatment modalities that take into consideration major factors of syndrome. Genetic factors and central nervous system imbalance but also partner's genital tract microbiota as the potential contributing and/or perpetuating factors to PLS need more scientific attention.

Singleton pregnancies after in vitro fertilization in Estonia: a register-based study of complications and adverse outcomes in relation to the maternal socio-demographic background

Background

An increased risk of adverse conditions related to in vitro fertilization (IVF) pregnancies has been repeatedly reported. Our study aimed to summarize outcome differences between pregnancies after IVF and after spontaneous conception (SC) in Estonia.

Methods

Data on all liveborn singletons to primiparas women aged 25–40 years during the period 2005–2014 were obtained from the Estonian Medical Birth Registry. There were 1778 and 33,555 newborns in the IVF and SC cohort, respectively. The relative risk of pregnancy-related complications and adverse pregnancy outcomes in the IVF cohort in comparison with the SC cohort was quantified by prevalence proportion ratios (RR) with 95% confidence intervals (CI) using modified Poisson regression models adjusted for maternal age, education, ethnicity, marital status and study period.

Results

The cohort of IVF singletons experienced a higher risk of preterm birth (RR 1.51; 95% CI 1.28–1.78), iatrogenic preterm birth (RR 1.62; 95% CI 1.32–1.98), very preterm birth (RR 1.49; 95% CI 1.00–2.23), low birthweight (RR 1.47; 95% CI 1.20–1.80), congenital anomalies (RR 1.51; 95% CI 1.08–2.11), and admission to a neonatal intensive care unit (RR 1.13; 95% CI 1.01–1.26). Somewhat elevated risk of spontaneous preterm birth did not reach statistical significance (RR 1.32; 95% CI 0.97–1.80). IVF mothers were at increased risk of placenta previa (RR 7.15; 95% CI 4.04–12.66), placental abruption (RR 2.12; 1.43–3.14) and cesarean section (RR 1.28; 95% CI 1.20–1.37). The risk of pre-eclampsia was borderline (RR 1.25; 95% CI 0.98–1.59). Adjustment for maternal age attenuated the associations between IVF and adverse outcomes. Maternal education, ethnicity and marital status had no effect on the magnitude of the risk estimates.

Conclusions

The increased risk of pregnancy-related complications and adverse pregnancy outcomes was observed in the Estonian cohort of IVF singletons in comparison with the cohort of SC singletons. The relative risk estimates grew with maternal age but were not influenced by the maternal education, ethnicity and marital status. To monitor the efficacy and safety of the used assisted reproductive technology, a specialized country-wide register should be created in Estonia.

Quality of IVF status registration in the Estonian Medical Birth Registry: a national record linkage study

Background

Information regarding in vitro fertilization (IVF) as a pregnancy risk factor (yes/ no) is stored in each birth record of the Estonian Medical Birth Registry (EMBR). This study aimed to assess the validity of registration of newborns’ IVF status in the EMBR.

Methods

To identify the newborns conceived by IVF, the birth records in the EMBR were compared to individual records on the embryo transfer procedures in the Estonian Health Insurance Fund (EHIF) database as a reference. Maternal age was restricted to 40 years, the age limit for IVF treatment covered by the EHIF. The embryo transfer procedures, that dated up to eight weeks before pregnancy, were additionally checked in the infertility treatment clinics. The validity of IVF status was measured by sensitivity, specificity, positive and negative predictive values (PPV and NPV). Relative risk (RR) of unrecorded IVF status among IVF mothers by socio-demographic characteristics and birth plurality was estimated using modified Poisson regression models.

Results

There were 3198 newborns identified as conceived by IVF in the EMBR in 2005–2014. Eight of them were incorrectly entered as born after IVF. The record linkage with the EHIF database revealed 1014 newborns with unrecorded IVF status in the EMBR. A total of 4204 newborns were verified as conceived by IVF, 24.1% of them were not categorized as born after IVF. The sensitivity of the IVF status registration was poor (75.9%), specificity (100.0%), PPV (99.8%) and NPV (99.3%) were high. The misclassifications were significantly more common among mothers of younger age or non-Estonians or with singleton birth.

Conclusion

Information based on mother’s self-report or her antenatal chart does not accurately identify the newborn’s IVF status. The lack of a specialized country-wide assisted reproductive technology register in Estonia requires routine record linkage of the EMBR, EHIF and the infertility treatment clinics’ databases to obtain adequate information regarding IVF status in the EMBR. Electronic record linkages between databases would help considerably to improve the validity of data to be used in medical decision making, in research and for statistical purposes.

Mental disorders among Chernobyl cleanup workers from Estonia: A clinical assessment

OBJECTIVE

To assess, at a clinical level, the mental health of former Chernobyl cleanup workers from Estonia by comparing them with same-age controls.

METHOD

The Mini International Neuropsychiatric Interview (MINI) was administered during 2011-2012 to 99 cleanup workers and 100 population-based controls previously screened for mental health symptoms.

RESULTS

Logistic regression analysis showed that cleanup workers had higher odds of current depressive disorder (odds ratio [OR] = 3.07, 95% confidence interval [CI: 1.34, 7.01]), alcohol dependence (OR = 3.47, 95% CI [1.29, 9.34]), and suicide ideation (OR = 3.44, 95% CI [1.28, 9.21]) than did controls. Except for suicide ideation, associations with Chernobyl exposure became statistically nonsignificant when adjusted for education and ethnicity.

CONCLUSION

A quarter of a century after the Chernobyl accident, Estonian cleanup workers were still at increased risk of mental disorders, which was partly attributable to sociodemographic factors. (PsycINFO Database Record

Cancer incidence and cause-specifi c mortality in male and female physicians: a cohort study in Estonia

Aims: To evaluate whether the presumed knowledge of physicians about healthier lifestyle decreases their risk of cancer and mortality, a retrospective cohort study of male and female physicians was conducted in Estonia. Methods: The cancer incidence and cause-specifi c mortality of 3,673 physicians (870 M, 2,803 F ) in Estonia was compared with the rates of the general population. Information on cancer cases and deaths in the cohort between 1983 and 1998 was obtained from the Estonian Cancer Registry and the mortality database of Estonia. Results: The standardized incidence ratio (SIR) for all cancers was 1.32 (95% confi dence interval (CI) 1.15-1.48) in women and 0.92 (95% CI 0.73-1.13) in men. Female physicians had an elevated risk for breast cancer (SIR 2.03, 95% CI 1.62-2.51) and myeloid leukaemia (SIR 3.69, 95% CI 1.35-8.02). Male physicians had an excess of skin melanoma (SIR 4.88, 95% CI 1.58-11.38). A large defi cit of lung cancer was observed (SIR 0.24, 95% CI 0.11-0.48). The very low all-cause mortality in the cohort (standardized mortality ratio 0.55, 95% CI 0.50-0.61) was mainly due to large defi cits in deaths from lung cancer, cardiovascular diseases and external causes. The suicide rate in the cohort was lower than in the general population. Conclusions: No health risks were observed in the cohort that could be linked to the occupational exposures of physicians. The pattern of cancer incidence and mortality seen in physicians in Estonia is similar to the pattern seen among professional classes in other countries.

Smoking and associated factors among adolescents in Tallinn, Helsinki and Moscow: a multilevel analysis

Aims: To investigate variations in smoking and associated factors on individual and aggregate level among adolescents in Tallinn (Estonia), Helsinki (Finland) and Moscow (the Russian Federation). Methods: The data was collected in Tallinn (N=1268 in Estonian and N=901 in Russian schools), in Helsinki (N=1396) and in Moscow (N=618) from pupils aged 13 - 18 by self-administered questionnaire. Multilevel analysis was used to estimate the possible effects of background characteristics, of the proximity of other smokers and the school context on the tobacco use of pupils. Results: The prevalence rate of smoking among girls in Russian schools in Tallinn (34.6%), among girls in Helsinki (39.5%), and in Moscow (32.1%) was higher than that among girls in Estonian schools in Tallinn (17.6%). Smoking was slightly less prevalent among boys in Helsinki (27.5%), compared to boys in Estonian (33.6%) and Russian (35.6%) schools in Tallinn, and to boys in Moscow (32.8%). Smoking increased with age. Multilevel analysis showed that smoking differed by school among pupils. Individual determinants of smoking as study site, grade, friends', siblings' and parental smoking behaved differently depending upon school. Friends and siblings' smoking showed interaction with study site to the smoking among girls. Conclusions: Strategies aimed at influencing smoking behaviour need to be directed not only towards the individual, but also towards the influences within the child's school environment.

Chernobyl cleanup workers from Estonia: cohort description and related epidemiological research

The Estonian study of Chernobyl cleanup workers was one of the first investigations to evaluate the possible health consequences of working in the Chernobyl area (the 30 km exclusion zone and/or adjacent territories) after the 1986 reactor accident. The cohort consists of 4831 men who were dispatched in 1986-1991 for tasks involving decontamination, construction of buildings, transport, radiation measurement, guard duty or other activities. By 31 December 2012, the follow-up of the cohort yielded 102 158 person-years of observation. Exposure and health data were collected by postal questionnaires, biodosimetry evaluations, thyroid screenings, and record-linkages with cancer, causes of death and health insurance reimbursement registers and databases. These data cover socio-demographic factors, employment history, aspects of health behaviour, medical history, work and living conditions in the Chernobyl area, biomarkers of exposure, cancer and non-cancer disease occurrence and causes of death. Cancer incidence data were obtained for 1986-2008, mortality data for 1986-2011 and non-cancer morbidity data for 2004-2012. Although the cohort is relatively small, it has been extensively examined and benefited from comprehensive nationwide population and health registers. The major finding was an increased risk of suicide. Thyroid examinations did not reveal an association with thyroid nodular disease and radiation dose, but did indicate the importance of accounting for screening when making comparisons with unscreened populations. No risk of leukaemia was observed and risks higher than 2.5-fold could be excluded with 95% confidence. Biodosimetry included GPA analyses and chromosomal translocation analyses and indicated that the Estonian cleanup workers experienced a relatively low mean exposure of the order of 0.1 Gy. One value of the Estonian study is in the methodologic processes brought to bear in addressing possible health effects from the Chernobyl accident. Twenty-five years of research are summarised and opportunities for the future listed.

Non-cancer morbidity among Estonian Chernobyl cleanup workers: a register-based cohort study

OBJECTIVE

To examine non-cancer morbidity in the Estonian Chernobyl cleanup workers cohort compared with the population sample with special attention to radiation-related diseases and mental health disorders.

DESIGN

Register-based cohort study.

SETTING

Estonia.

PARTICIPANTS

An exposed cohort of 3680 men (cleanup workers) and an unexposed cohort of 7631 men (population sample) were followed from 2004 to 2012 through the Population Registry and Health Insurance Fund database.

METHODS

Morbidity in the exposed cohort compared with the unexposed controls was estimated in terms of rate ratio (RR) with 95% CIs using Poisson regression models.

RESULTS

Elevated morbidity in the exposed cohort was found for diseases of the nervous system, digestive system, musculoskeletal system, ischaemic heart disease and for external causes. The most salient excess risk was observed for thyroid diseases (RR=1.69; 95% CI 1.38 to 2.07), intentional self-harm (RR=1.47; 95% CI 1.04 to 2.09) and selected alcohol-related diagnoses (RR=1.25; 95% CI 1.12 to 1.39). No increase in morbidity for stress reactions, depression, headaches or sleep disorders was detected.

CONCLUSIONS

No obvious excess morbidity consistent with biological effects of radiation was seen in the exposed cohort, with the possible exception of benign thyroid diseases. Increased alcohol-induced morbidity may reflect alcohol abuse, and could underlie some of the higher morbidity rates. Mental disorders in the exposed cohort were probably under-reported. The future challenge will be to study mental and physical comorbidities in the Chernobyl cleanup workers cohort.

Site-specific cancer risk in the Baltic cohort of Chernobyl cleanup workers, 1986-2007

OBJECTIVE

To assess site-specific cancer risk in the Baltic cohort of Chernobyl cleanup workers, 1986-2007.

METHODS

The Baltic cohort includes 17,040 men from Estonia, Latvia and Lithuania who participated in the environmental cleanup after the accident at the Chernobyl Nuclear Power Station in 1986-1991 and who were followed up for cancer incidence until the end of 2007. Cancer cases diagnosed in the cohort and in the male population of each country were identified from the respective national cancer registers. The proportional incidence ratio (PIR) with 95% confidence interval (CI) was used to estimate the site-specific cancer risk in the cohort. For comparison and as it was possible, the site-specific standardised incidence ratio (SIR) was calculated for the Estonian sub-cohort, which was not feasible for the other countries.

RESULTS

Overall, 756 cancer cases were reported during 1986-2007. A higher proportion of thyroid cancers in relation to the male population was found (PIR=2.76; 95%CI 1.63-4.36), especially among those who started their mission shortly after the accident, in April-May 1986 (PIR=6.38; 95%CI 2.34-13.89). Also, an excess of oesophageal cancers was noted (PIR=1.52; 95% CI 1.06-2.11). No increased PIRs for leukaemia or radiation-related cancer sites combined were observed. PIRs and SIRs for the Estonian sub-cohort demonstrated the same site-specific cancer risk pattern.

CONCLUSION

Consistent evidence of an increase in radiation-related cancers in the Baltic cohort was not observed with the possible exception of thyroid cancer, where conclusions are hampered by known medical examination including thyroid screening among cleanup workers.

Chernobyl cleanup workers from Estonia: follow-up for cancer incidence and mortality

This study examined cancer incidence (1986-2008) and mortality (1986-2011) among the Estonian Chernobyl cleanup workers in comparison with the Estonian male population. The cohort of 4810 men was followed through nationwide population, mortality and cancer registries. Cancer and death risks were measured by standardised incidence ratio (SIR) and standardised mortality ratio (SMR), respectively. Poisson regression was used to analyse the effects of year of arrival, duration of stay and time since return on cancer and death risks. The SIR for all cancers was 1.06 with 95% confidence interval 0.93-1.20 (232 cases). Elevated risks were found for cancers of the pharynx, the oesophagus and the joint category of alcohol-related sites. No clear evidence of an increased risk of thyroid cancer, leukaemia or radiation-related cancer sites combined was apparent. The SMR for all causes of death was 1.02 with 95% confidence interval 0.96-1.08 (1018 deaths). Excess mortality was observed for mouth and pharynx cancer, alcohol-related cancer sites together and suicide. Duration of stay rather than year of arrival was associated with increased mortality. Twenty-six years of follow-up of this cohort indicates no definite health effects attributable to radiation, but the elevated suicide risk has persisted.

Diminishing trend in alcohol poisoning mortality in Estonia: reality or coding peculiarity?

AIMS

To examine whether the changes in coding practice could reduce alcohol poisoning mortality rates in Estonia.

METHODS

Individual death records in 1983-2009 (age at death 25-64) were used to calculate the 3-year moving averages of age-standardized mortality rates. From 2000 onwards, there was a sharp increase in mortality from mental disorders due to alcohol, and at the same time a remarkable decrease in alcohol poisoning mortality. We calculated expected alcohol poisoning mortality rates for 2000-2009, assuming that mortality rate ratio of alcohol poisoning and mental disorders due to alcohol remained stable.

RESULTS

Alcohol poisoning mortality rates fluctuated considerably, being the lowest in 1988 and the highest in 1994-1995. A sharp decline started in 2000. Expected alcohol poisoning mortality rates continued their growth from 2000 onwards with a small decrease in 2006-2009. Mortality rates of mental disorders due to alcohol followed the same curve as alcohol poisoning rates up to 1999, being roughly 10 times lower than alcohol poisoning rates in both genders. From 2000 onwards, mortality from mental disorders due to alcohol increased rapidly, exceeding alcohol poisoning mortality in 2006.

CONCLUSION

This study demonstrates an obvious misclassification in coding of alcohol poisoning and mental disorders due to alcohol as underlying causes of death in the Estonian Causes of Death Registry.

Gender differences in factors associated with sexual intercourse among Estonian adolescents

AIMS

To examine factors associated with early sexual intercourse among 15 to 16-year-old adolescents by gender.

METHODS

The data were collected from a random sample of Estonian basic schools' ninth grade pupils in 1999 using self-completed questionnaires. A multivariate logistic regression analysis for boys and girls was used to test for associations between sexual intercourse, and personal gender role-related attitudes, attitudes towards sexual intercourse, pubertal timing, smoking status and experience of drunkenness.

RESULTS

Of the respondents, 14.6% of boys and 13.1% of girls had experienced sexual intercourse. Traditional gender role-related attitudes were associated with sexual intercourse among girls, but not among boys. Smoking and experience of drunkenness was strongly associated with sexual intercourse for both genders.

CONCLUSIONS

Gender differences in the association between gender role-related attitudes and early sexual intercourse were observed among 15 to 16-year-olds in Estonia. Smoking and experience of drunkenness were strongly related to sexual intercourse for both genders.

Effect of birth weight, maternal education and prenatal smoking on offspring intelligence at school age

To examine the combined effect of birth weight, mothers' education and prenatal smoking on psychometrically measured intelligence at school age 1,822 children born in 1992-1999 and attending the first six grades from 45 schools representing all of the fifteen Estonian counties with information on birth weight, gestational age and mother's age, marital status, education, parity and smoking in pregnancy, and intelligence tests were studied. The scores of Raven's Standard Progressive Matrices were related to the birth weight: in the normal range of birth weight (>or=2500 g) every 500 g increase in birth weight was accompanied by around 0.7-point increase in IQ scores. A strong association between birth weight and IQ remained even if gestational age and mother's age, marital status, education, place of residence, parity and smoking during pregnancy have been taken into account. Maternal prenatal smoking was accompanied by a 3.3-point deficit in children's intellectual abilities. Marriage and mother's education had an independent positive correlation with offspring intelligence. We concluded that the statistical effect of birth weight, maternal education and smoking in pregnancy on offspring's IQ scores was remarkable and remained even if other factors have been taken into account.

Alcohol consumption in Estonia and Finland: Finbalt survey 1994-2006

Background

Alcohol consumption has been regarded as an important contributor to the high premature mortality rates. The objective of this paper was to provide an overview and comparison of alcohol consumption and its socio-demographic determinants among adults in Estonia and Finland.

Methods

The study was based on a 25-64-year-old subsample of nationally representative postal cross-sectional surveys conducted in Estonia (n = 10,340) and Finland (n = 19,672) during 1994-2006. Abstinence, frequency, and the amount of alcohol consumed were examined. Logistic regression models were used to test the socio-demographic differences in alcohol consumption at least once a week. The effect of socio-demographic factors on pure alcohol consumed per week was calculated using linear regression.

Results

The proportion of abstainers was 1.5 times higher among women than men in both countries. Throughout the study period, the amount of alcohol consumed per week increased for both genders in Estonia and for women in Finland, but was stable for men in Finland. In the final study year, medium risk amount of alcohol consumed per week was nearly 1.5 times higher among men in Estonia than in Finland, but about half that among women in Estonia than in Finland. Compared to ethnic majority in Estonia, alcohol consumption at least once a week was lower among men, but amount of pure alcohol drunk per week was higher among women of ethnic minority. In Finland, alcohol consumption at least once a week was more prevalent among women of ethnic minority, but the amount of pure alcohol drunk per week was lower for both gender groups of ethnic minority. Compared to married/cohabiting respondents, alcohol consumption at least once a week was less pronounced among single respondents in Finland, divorced or separated women in both countries, and widowed respondents in Estonia. Greater amount of alcohol consumed per week was more prevalent among single and divorced or separated respondents in Finland, but only among divorced or separated men in Estonia. Frequency of alcohol consumption was lower among less educated than higher educated respondents in Finland, but not in Estonia. The amount of consumed alcohol per week was higher among less educated men in Estonia, but lower among women with basic education in Finland.

Conclusions

Alcohol consumption has increased in Estonia and Finland. National alcohol policies should reflect findings of alcohol epidemiology in order to introduce measures that will reduce alcohol related harm in the population effectively.

Factors related to patient delay in pulmonary tuberculosis in Estonia

The resurgence of tuberculosis (TB) in Estonia, a post-socialist Eastern European country, has coincided with delayed case detection suggested by increase in advanced forms of pulmonary tuberculosis among newly detected cases. We estimated the determinants of patient delay in conditions of negligible HIV infection, insignificant immigration and free access to medical care with TB. All newly-detected symptomatic culture-positive patients aged > or =16 y with pulmonary TB from southern Estonia during 2002-2003 (n=185) were interviewed. Intervals greater than the median (79 d) and the 75th percentile (140 d) between onset of the first symptom and the first medical visit were defined as prolonged and extreme patient delay, respectively. Male gender was associated with both prolonged and extreme patient delay (OR 2.12; 95% CI 1.06-4.23 and OR 3.28; 95% CI 1.30-8.26, respectively), whereas rural residence was associated with prolonged patient delay (OR 2.08; 95% CI 1.06-4.08). Median patient delay was shortest when the first symptom was fever (22 d) and greatest when it was cough with haemoptysis (196 d). The study shows that even in absence of barriers in accessing health care, the median patient delay can be longer than in most former studies, whereas males and rural residents are at greater risk.

Factors related to health system delays in the diagnosis of pulmonary tuberculosis in Estonia

OBJECTIVE

To estimate health system delays (HSD) in the diagnosis of pulmonary tuberculosis (PTB) and its risk factors after major social changes in Estonia, and to assess the ability of a completely reformed health care system to diagnose patients with PTB.

METHODS

All newly detected symptomatic culture-positive patients with PTB aged > or = 16 years from Southern Estonia during 2002-2003 (n = 185) were interviewed. HSD was defined as the interval from a patient's first contact with a medical provider to the date of TB diagnosis.

RESULTS

The factors significantly associated with HSD greater than the median (19 days) and the 75th percentile (40 days) were smear negativity, absence of cough among symptoms, absence of chest X-ray during the first visit and age > 60 years. A significantly shorter HSD was determined in non-Estonians and unemployed patients. HSD was not associated with the specialty of the doctor first contacted by the patient.

CONCLUSION

This study in Southern Estonia shows that the health care system is still managing the diagnosis of PTB without significant delays, even after substantial modifications in the health care system resulting from social reform in a post-socialist country, and that family physicians can manage PTB patients successfully.

Is a poor pregnancy outcome related to young maternal age? A study of teenagers in Estonia during the period of major socio-economic changes (from 1992 to 2002)

OBJECTIVE

To assess the risk of low birth weight, preterm birth, stillbirth, neonatal and postneonatal death among primiparous teenagers having singleton births, compared to a similar group of women aged 20-24 years in Estonia during the period of major socio-economic changes.

STUDY DESIGN

Registry study using the data from the Estonian Medical Birth Registry (EMBR) for years 1992-2002; EMBR data were linked with infant deaths in the Estonian Mortality Database. Study population included 51,890 women aged 13-24 years, arranged into three groups: < or =17, 18-19, and 20-24. Crude odds ratios (OR), adjusted ORs and their 95% confidence intervals (CI) for the different outcomes were estimated using multiple logistic regression analysis.

RESULTS

Compared with women aged 20-24 years, the risk of low birth weight and preterm birth was higher among teenagers. The risk of low birth weight and preterm birth within the study group as a whole did not change during the study period. Increased risks in neonatal and postneonatal death among younger teenagers of an age of 17 years and less seem to be a result of prematurity.

CONCLUSIONS

Despite major socio-economic changes resulting in improvements in obstetric care and growth in incomes, teenagers remained a higher risk group.

Suicide Risk Among Chernobyl Cleanup Workers in Estonia Still Increased: An Updated Cohort Study

PURPOSE

The aim of the study is to examine the mortality experience among Chernobyl cleanup workers.

METHODS

A cohort study of 4786 men from Estonia who participated in the Chernobyl cleanup from 1986 to 1991 and were traced until December 31, 2002. Standardized mortality ratio (SMR) and adjusted mortality rate ratio (RR) derived through Poisson regression analysis were calculated.

RESULTS

During follow-up, 550 deaths occurred, yielding an SMR of 1.01 (95% confidence interval [CI], 0.92-1.09). Increased risks were observed for suicide alone (SMR, 1.32; 95% CI, 1.03-1.67) and suicide combined with undetermined injury (SMR, 1.29; 95% CI, 1.03-1.60). One leukemia death occurred, and no thyroid cancer deaths were found. Elevated mortality also was observed for brain cancer (SMR, 2.78; 95% CI, 1.02-6.05). The adjusted RR for suicide remained stable over the time passed since return from the Chernobyl area, showing RRs of 1.09 (95% CI, 0.56-2.10) for 5 to 9 years and 1.00 (95% CI, 0.48-2.05) for 10 or more years compared with less than 5 years.

CONCLUSIONS

During the 17 years after the accident, suicide risk in the cohort was greater than in the general male population. No elevated risk in overall mortality and radiation-related cancers was observed. The long-term nature of this elevated risk provides concrete evidence that psychological consequences represent the largest public health problem caused by the accident to date.

Major improvements, but persisting inequalities in infant survival in Estonia 1992-2002

BACKGROUND

Inequality in adult health increased in Estonia during the transition period after 1991. We examined inequality in infant survival from 1992 to 2002.

METHODS

All 132 854 singleton live births reported to the Estonian Medical Birth Registry in 1992-2001 were linked to the Estonian Mortality Database. The effect of mother's education, nationality, marital status, and place of residence on neonatal (0-27 days) and post-neonatal (28-364 days) death was evaluated in logistic regression with adjustments for maternal age, parity, smoking, sex of the infant, birth weight, and gestational age.

RESULTS

Infant mortality decreased substantially. Risk of death in neonatal period was lowest in Tartu, with a decline from 4.9/1000 in infants born in 1992-1996 to 2.1/1000 in those born in 1997-2001. Decline in neonatal mortality in other regions was from 9.2/1000 to 5.1/1000. Persisting regional differences were unexplained by mothers' nationality, education, or marital status, or the infants' length of gestation. Decline in post-neonatal mortality was less marked and although risk differences between different socio-economic groups decreased, mothers' marital status and education in particular remained strongly associated with risk of post-neonatal death [odds ratio for infants born to mothers with basic or lower education compared to university education 3.70 (95% confidence interval 2.34-5.85) in 1992-1996 and 3.56 (2.06-6.14) in 1997-2001].

CONCLUSIONS

Infant survival improved appreciably in Estonia after 1991 and risk differences between social groups decreased. The improvements were not accompanied by reduction in the strength of the effects of social characteristics on infant death measured as risk ratios.

Cancer risk among Chernobyl cleanup workers in Estonia and Latvia, 1986-1998

Two cohorts of Chernobyl cleanup workers from Estonia (4,786 men) and Latvia (5,546 men) were followed from 1986 to 1998 to investigate cancer incidence among persons exposed to ionizing radiation from the Chernobyl accident. Each cohort was identified from various independent sources and followed using nationwide population and mortality registries. Cancers were ascertained by linkage with nationwide cancer registries. Overall, 75 incident cancers were identified in the Estonian cohort and 80 in the Latvian cohort. The combined-cohort standardized incidence ratio (SIR) for all cancers was 1.15 (95% confidence interval (CI) = 0.98-1.34) and for leukemia, 1.53 (95% CI = 0.62-3.17; n = 7). Statistically significant excess cases of thyroid (SIR = 7.06, 95% CI = 2.84-14.55; n = 7) and brain cancer (SIR = 2.14, 95% CI = 1.07-3.83; n = 11) were found, mainly based on Latvian data. However, there was no evidence of a dose response for any of these sites, and the relationship to radiation exposure remains to be established. Excess of thyroid cancer cases observed may have been due to screening, the leukemia cases included 2 unconfirmed diagnoses, and the excess cases of brain tumors may have been a chance finding. There was an indication of increased risk associated with early entry to the Chernobyl area and late follow-up, though not statistically significant. Further follow-up of Chernobyl cleanup workers is warranted to clarify the possible health effects of radiation exposure.

Comparison of knowledge, attitudes and behaviour regarding smoking among Estonian and Finnish physicians

OBJECTIVES

To compare smoking behaviour, attitudes and opinions towards smoking and smoking cessation among Estonian and Finnish physicians.

METHODS

A cross-sectional postal survey using a self-administered questionnaire was carried out among 2,480 Estonian and 2,075 Finnish physicians.

RESULTS

Daily smoking prevalence was higher among Estonian physicians than among their Finnish counterparts in both male (18.6% and 6.7%) and female (6.6% and 3.6%). Compared to Estonia, physicians in Finland more often agreed that smoking is very harmful to their health, that trying to convince people to stop smoking is their responsibility and that smoking prevention should be part of the normal and special training of health professionals. In both countries, non-smoking physicians held more unfavourable attitudes towards smoking than those who were smoking.

CONCLUSIONS

Physicians' own smoking patterns and quitting behaviour are important because physicians serve as models for their patients and play a key role in the reinforcement of smoke-free health facilities. These results remain a challenge to medical educators, especially in Estonia. Estonia needs to improve medical education in terms of motivating physicians to ask about the smoking patterns of their patients and of training medical students and resident physicians to counsel their patients to stop smoking.

Self-Reported and Serum Cotinine-Validated Smoking in Pregnant Women in Estonia

OBJECTIVES

Although widely used in epidemiological studies, self-report has been shown to underestimate the prevalence of smoking among pregnant women. Objectives of this study were to examine the discrepancy between self-reported and cotinine-validated smoking status, and the sociodemographic characteristics associated with the misclassification of real smoking status among pregnant women in Tallinn, the capital of Estonia.

METHODS

Serum cotinine assays were performed on a subsample (n = 1360) of the pregnant women, who had participated in a recent study of human papillomavirus type 16 (HPV-16) seroprevalence in Estonia. In the present study, serum concentrations > or = 15 ng/ml were used to distinguish current smokers from nonsmokers. The serum-validated smoking level was compared with the self-reported level in the records of the Estonian Medical Birth Registry. For the group of self-reported non-smokers, the differences between the cotinine-validated smokers and the cotinine-validated nonsmokers, with respect to their sociodemographic characteristics (age, ethnicity, educational level, employment status, marital status, parity), were estimated by logistic regression.

RESULTS

Of 1239 women who reported being nonsmokers, 259 (20.9%) had serum cotinine levels > or = 15 ng/ml, and can be regarded as current smokers. Among self-reported nonsmokers, nondisclosure of current smoking was significantly more frequent in non-Estonian, less educated, socially inactive, cohabiting and multiparous women.

CONCLUSIONS

Self-reported data on smoking in pregnant women underestimates the real smoking prevalence in Estonia. Maternal unwillingness to declare smoking during pregnancy needs to be taken into account in the practice of maternal and child health to better target prenatal smoking cessation interventions.

Modest increase in seasonal allergic rhinitis and eczema over 8 years among Estonian schoolchildren

We studied time trends in the prevalence of asthma and allergic diseases in Estonian children born before and after the collapse of the Soviet Union, as this event markedly altered the lifestyle in Estonia. Two identical cross-sectional studies were performed as part of phase I and phase III of the International Study of Asthma and Allergies in Childhood (ISAAC). Children, aged 6-7 yr (n = 3070 in 1993-94 and 2383 in 2001-02) and 13-14 yr (n = 3476 and 3576, respectively), completed ISAAC core-written questionnaires, and 13-14-yr olds (n = 3427 and 3259, respectively) also video questionnaires. The prevalence of respiratory symptoms was mostly similar in the two studies. Despite this, the prevalence of diagnosed asthma increased. This was probably due to modified diagnostic criteria and increased awareness. Furthermore, the prevalence of rhinitis during the pollen season increased, e.g., rhinitis in May from 1.7% to 3.5%; sex-adjusted prevalence odds ratio (POR) 2.09 (95% confidence interval 1.47-2.96) in 6-7-yr olds, and from 2.6% to 5.5%; POR 2.22 (1.72-2.87) in 13-14-yr olds. The prevalence of flexural dermatitis also increased from 12.0% to 13.5%; POR 1.20 (1.02-1.41) in 6-7-yr olds, and from 7.7% to 9.4%; POR 1.26 (1.07-1.50) in 13-14-yr olds. The increase was similar in children born before and after the regaining of Estonian independence, indicating that the influence of factors related to a Western lifestyle and affecting the prevalence of allergic symptoms is not restricted to infancy, but may be operative throughout childhood.

Smoking habits and attitudes towards smoking among Estonian physicians

OBJECTIVES

This study examined the smoking habits and attitudes towards smoking among Estonian physicians.

STUDY DESIGN AND METHODS

Cross-sectional data for 2668 physicians were gathered by a self-administered postal survey.

RESULTS

The current smoking prevalence was 24.9% for male physicians and 10.8% for female physicians. The percentages of ex-smokers were 32.9 and 16.8%, respectively. Smoking prevalence among physicians was below the levels reported for the highest educational bracket of the total population in Estonia. Non-smoking physicians had more unfavourable views towards smoking than those who smoked. The majority of physicians were aware of the association between smoking and various diseases, with significant differences between smokers and non-smokers. Non-smoking physicians were more active in asking patients about smoking habits than those who smoked. Most Estonian physicians, especially those who smoked, failed to perceive themselves as positive role models.

CONCLUSIONS

This study found a lower prevalence of smoking among physicians compared with the general population, and demonstrated the impact of personal smoking on physicians' attitudes towards smoking. The results provide an important challenge to medical education in Estonia.

Suicides among cancer patients in Estonia: a population-based study

The objective of this study was to determine the suicide risk among cancer patients in Estonia. This risk was examined in a cohort of 65,419 persons diagnosed with cancer in 1983-1998. Standardised mortality ratios (SMR) were calculated using the suicide rates of the population of Estonia as a reference. During 192,078 person-years of follow-up between 1983 and 2000, 197 suicides occurred in the cohort. An increased suicide risk was found for men (SMR=1.73; 95% Confidence Interval (CI) 1.45-2.01), but not for women (SMR=0.50; 95% CI 0.37-0.66). Men had the highest risk 90-179 days following their diagnosis (SMR=4.27; 95% CI 2.81-6.21). During this time interval, among men, the risk was more pronounced for cancers of the oesophagus (SMR=35.63; 95% CI 9.71-91.22) and pancreas (SMR=14.53; 95% CI 1.76-52.50). This study provides further evidence that cancer is a risk factor for suicide, at least in men.

Cancer incidence and cause-specific mortality in male and female physicians: a cohort study in Estonia

AIMS

To evaluate whether the presumed knowledge of physicians about healthier lifestyle decreases their risk of cancer and mortality, a retrospective cohort study of male and female physicians was conducted in Estonia.

METHODS

The cancer incidence and cause-specific mortality of 3,673 physicians (870 M, 2,803 F) in Estonia was compared with the rates of the general population. Information on cancer cases and deaths in the cohort between 1983 and 1998 was obtained from the Estonian Cancer Registry and the mortality database of Estonia.

RESULTS

The standardized incidence ratio (SIR) for all cancers was 1.32 (95% confidence interval (CI) 1.15-1.48) in women and 0.92 (95% CI 0.73-1.13) in men. Female physicians had an elevated risk for breast cancer (SIR 2.03, 95% CI 1.62-2.51) and myeloid leukaemia (SIR 3.69, 95% CI 1.35-8.02). Male physicians had an excess of skin melanoma (SIR 4.88, 95% CI 1.58-11.38). A large deficit of lung cancer was observed (SIR 0.24, 95% CI 0.11-0.48). The very low all-cause mortality in the cohort (standardized mortality ratio 0.55, 95% CI 0.50-0.61) was mainly due to large deficits in deaths from lung cancer, cardiovascular diseases and external causes. The suicide rate in the cohort was lower than in the general population.

CONCLUSIONS

No health risks were observed in the cohort that could be linked to the occupational exposures of physicians. The pattern of cancer incidence and mortality seen in physicians in Estonia is similar to the pattern seen among professional classes in other countries.

Patterns of smoking in Estonia

AIMS

To describe the pattern of current smoking and its relation to socio-demographic factors in Estonia.

DESIGN

Nationwide cross-sectional survey.

SETTING

Estonia in 1996.

PARTICIPANTS

Stratified random sample of 2086 adults aged 30-59.

MEASUREMENTS

Prevalence of current smoking; socio-demographic factors related to smoking, investigated by logistic regression analysis.

FINDINGS

The prevalence of current smoking was 57.9% among men and 25.7% among women. For both genders, smoking rates were consistently lowest in the age group 50-59 years and highest in the age group 30-39 years. Smoking was significantly more common among divorced and widowed people. Education was associated with smoking among men but not among women. No relationship, however, was established between smoking and ethnicity, type of residence, and household income.

CONCLUSIONS

Estonia needs an effective antismoking policy. Public health efforts need to be focused on quitting smoking in younger adults and prevention efforts should target less educated socio-economic groups.

Similar prevalence of respiratory symptoms and atopy in Estonian schoolchildren with changing lifestyle over 4 yrs

The prevalence of allergic sensitization and clinical manifestations is low in Eastern Europe, despite a continuous increase in industrialized countries with a market economy. The aim of the present study was to study changes in the prevalence of respiratory symptoms and atopic sensitization over time among schoolchildren in Estonia, in relation to environmental changes as the country transformed into a market economy. A cross-sectional study of 10-yr-old children was carried out between October 1996 and April 1997, employing a questionnaire regarding the prevalence of wheezing, rhinitis and itching rash (n=979) and skin-prick tests with seven inhalant allergens (n=640). The results were compared with those of a similar study performed in 1992-1993. The 12-month prevalence of wheeze was 8.3%, as compared to 9.4% in 1992-1993 (NS) and of asthma was 2.5 versus 3.2% (NS). The prevalence of a positive skin-prick test result was 14.3% in both studies. Furthermore, the prevalence of sensitivity to the individual allergens was similar, except for a significantly higher prevalence of dog sensitivity in 1996-1997 (4.7 versus 2.0%). The prevalence of respiratory and other potentially allergic symptoms, as well as the prevalence of atopic sensitization, remains low in Estonian 10-yr-old children, despite a changing lifestyle over the past 4 yrs. This could indicate that the time period was too short for environmental changes to affect the prevalence of allergy, or alternatively that risk factors associated with a "western lifestyle" are of particular significance earlier in life.

Wood dust exposure and cancer incidence: a retrospective cohort study of furniture workers in Estonia

BACKGROUND

Occupational wood dust exposure is associated with increased risk of sinonasal cancer in men. However, little is known whether it is associated with sinonasal cancer in women or with malignancies of other sites.

METHODS

In a retrospective cohort study of furniture workers, cancer incidence in 3723 men and 3063 women between 1968 and 1995 was compared to the incidence in the general population of Estonia. Cancer risks were analyzed by employment duration and occupation.

RESULTS

The standardized incidence ratio (SIR) for all cancers did not differ significantly from one. Two men and one woman had sinonasal cancer (expected 1.07 and 0.53, respectively). Significantly increased risk of colon cancer was seen in the cohort (SIR 1.65, 95% confidence interval (CI) 1.22-2.17). Subjects employed for 10 years and over had significant excess of colon cancer (SIR 2.29, 95% CI 1.28-3.77) and rectal cancer (SIR 2.10, 95% CI 1.05-3.76) in the analysis by employment duration using exposure with a latency of 20 years. The nonsignificant excess of pharyngeal cancer in men (SIR 1.82) and lung cancer in women (SIR 1.43) was restricted to short-term workers.

CONCLUSIONS

This study found an excess of colon and rectal cancer in furniture workers. There was no increase in total cancer risk.

Social determinants of birthweight and length of gestation in Estonia during the transition to democracy

BACKGROUND

To investigate social variation in birthweight and length of gestation in Estonia in the period of transition to a democracy and market economy.

METHODS

All live births resulting from singleton pregnancies reported to the Estonian Medical Birth Registry in 1992-1997 (n = 84, 629) were studied with respect to social variation in birthweight and preterm delivery (<37 weeks gestation). The results were adjusted for maternal age, parity, education, nationality, marital status, smoking in pregnancy, sex of the infant (and gestational age).

RESULTS

Between 1992 and 1997, mean birthweight increased from 3,465g to 3,497g (P < 0.001) and the preterm rate fell from 5.8% to 5.1% (P = 0.001). Maternal education, marital status and nationality were all independently related to the mean birthweight and the risk of preterm birth. The mean difference in birthweight between children of mothers with basic and university education was 87 g (95% CI : 74-100). Children born to mothers of non-Estonian compared to Estonian nationality were on average 77 g lighter (95% CI: 70-84). While the effect of nationality and marital status on birthweight was relatively stable during the study period, differences in birth outcome by maternal education became stronger.

CONCLUSIONS

The mean birthweight increased and the preterm rate decreased in Estonia as a whole during the transition. However, the improvements were not shared equally by all social groups. An increase in variation in birthweight by maternal education was particularly notable.

Feasibility of cohort studies in Estonia

OBJECTIVES

To describe the methodology and feasibility of follow up for vital status in retrospective cohort studies in Estonia.

METHODS

A cohort of 7412 workers who had been employed at two factories in Tallinn between 1946 and 1988 was followed up for vital status from the date of first employment until death, emigration, or the end of the study, 31 December 1995, whichever occurred first. The cohort was electronically linked with the National Population Registry of Estonia that was created in 1992 and includes personal identification numbers of Estonian citizens and residents, and the Mortality Database that contains information from death certificates issued in 1983-95. A manual search was carried out on several non-computerised population data sources and archives.

RESULTS

By 31 December 1995, the vital status of 6780 (91.5%) subjects could be traced (4495 (60.6%) subjects were alive, 1993 (26.9%) had died, and 292 (3.9%) had emigrated). Analysis by calendar period of leaving work showed that the proportion of subjects traced was lowest in the group of workers who had left work between 1946 and 1955 (58.4%), especially those whose age at leaving work was < 30 (53.2%) or > 60 years (42.3%). Among subjects who left work in 1956-65, 1966-75, and 1976-88, the follow up rate was 84.7%, 94.6%, and 98.2%, respectively.

CONCLUSIONS

The findings, which are especially important for occupational epidemiology, confirm the feasibility of conducting retrospective cohort studies in Estonia. Most of the issues discussed in the paper apply to other former Soviet countries.