To Örebro University

Most previous studies of burnout have focused on work environmental stressors, while familial factors so far mainly have been overlooked. The aim of the study was to estimate the relative importance of genetic influences on burnout (measured with Pines Burnout Measure) in a sample of monozygotic (MZ) and dizygotic (DZ) Swedish twins. The study sample consisted of 20,286 individuals, born 1959–1986 from the Swedish twin registry who participated in the cross-sectional study of twin adults: genes and environment. Probandwise concordance rates (the risk for one twin to be affected given that his/her twin partner is affected by burnout) and within pair correlations were calculated for MZ and DZ same—and opposite sexed twin pairs. Heritability coefficients i.e. the proportion of the total variance attributable to genetic factors were calculated using standard biometrical model fitting procedures. The results showed that genetic factors explained 33% of the individual differences in burnout symptoms in women and men. Environmental factors explained a substantial part of the variation as well and are thus important to address in rehabilitation and prevention efforts to combat burnout.

Sweden has a long tradition of recording cause of death data. The Swedish cause of death register is a high quality virtually complete register of all deaths in Sweden since 1952. Although originally created for official statistics, it is a highly important data source for medical research since it can be linked to many other national registers, which contain data on social and health factors in the Swedish population. For the appropriate use of this register, it is fundamental to understand its origins and composition. In this paper we describe the origins and composition of the Swedish cause of death register, set out the key strengths and weaknesses of the register, and present the main causes of death across age groups and over time in Sweden. This paper provides a guide and reference to individuals and organisations interested in data from the Swedish cause of death register.

Pregnancy-related factors are important for short- and long-term health in mothers and offspring. The nationwide population-based Swedish Medical Birth Register (MBR) was established in 1973. The present study describes the content and quality of the MBR, using original MBR data, Swedish-language and international publications based on the MBR. The MBR includes around 98% of all births in Sweden. From 1982 onwards, the MBR is based on prospectively recorded information in standardized antenatal, obstetric, and neonatal records. When the mother and infant are discharged from hospital, this information is forwarded to the MBR, which is updated annually. Maternal data include information from first antenatal visit on self-reported obstetric history, infertility, diseases, medication use, cohabitation status, smoking and snuff use, self-reported height and measured weight, allowing calculation of body mass index. Birth and neonatal data include date and time of birth, mode of delivery, singleton or multiple birth, gestational age, stillbirth, birth weight, birth length, head circumference, infant sex, Apgar scores, and maternal and infant diagnoses/procedures, including neonatal care. The overall quality of the MBR is very high, owing to the semi-automated data extraction from the standardized regional electronic health records, Sweden's universal access to antenatal care, and the possibility to compare mothers and offspring to the Total Population Register in order to identify missing records. Through the unique personal identity numbers of mothers and live-born offspring, the MBR can be linked to other health registers. The Swedish MBR contains high-quality pregnancy-related information on more than 5 million births during five decades.

Background: The poor survival of patients with gastroesophageal cancers may improve if additional esophageal precursor lesions to Barrett's esophagus and squamous dysplasia are identified. We estimated the risk for gastroesophageal cancers among patients with various histopathological abnormalities in the esophagus, including Barrett's esophagus, subdivided by histopathological types.

Methods: Histopathology data from esophageal biopsies obtained 1979-2014 were linked with several national population-based registers in Sweden. Patients were followed from 2 years after the first biopsy date until cancer, death, emigration, esophagectomy/gastrectomy or end of follow-up, 31st of December 2016, whichever came first. We estimated standardized incidence ratios (SIRs) as measures of relative risk with the Swedish general population as reference.

Results: In total 367 esophageal adenocarcinoma (EAC) cases were ascertained during 831,394 person-years of follow-up. The incidence rate (IR) for EAC was 0.1 per 1000 person-years for normal morphology, 0.2-0.5 for inflammatory changes, and 0.8-2.9 for metaplasia. The IR was 1.0 per 1000 person-years (95% confidence interval 0.7-1.3) among patients with non-dysplastic intestinal metaplasia, 0.9 (0.8-1.1) in non-dysplastic gastric/glandular metaplasia and 2.9 (2.0-4.2) among columnar metaplasia patients with low-grade dysplasia. The SIRs were 11.7 (95% confidence interval 8.6-15.5), 12.0 (10.0-14.2) and 30.2 (20.5-42.8), respectively. The SIRs for gastric cardia adenocarcinoma (GCA) were moderately elevated.

Conclusions: For the first time, we demonstrate that patients with esophageal inflammatory and other metaplastic abnormalities than Barrett's esophagus have an increased risk of EAC and GCA compared to the general population. Moreover, patients with different histopathologic subtypes of Barrett's esophagus have a comparable risk for EAC.

Obesity is a risk factor for gestational diabetes, whereas the role of the mother's birth weight is more uncertain. We aimed to investigate the combined effect of mothers' birth-weight-for-gestational-age and early pregnancy Body Mass Index (BMI) in relation to risk of gestational diabetes. Between 1973 and 2006, we identified a cohort of 323,083 women included in the Swedish Medical Birth Register both as infants and as mothers. Main exposures were mothers' birth-weight-for-gestational-age (categorized into five groups according to deviation from national mean birth weight) and early pregnancy BMI (classified according to WHO). Rates of gestational diabetes increased with adult BMI, independently of birth-weight-for-gestational-age. However, compared to women with appropriate birth-weight-for-gestational-age [appropriate-for-gestational age (AGA); -1 to +1 SD] and BMI (<25.0), women with obesity class II-III (BMI ≥ 35.0) had an adjusted odds ratio (OR) of 28.7 (95 % confidence interval, CI 17.0-48.6) for gestational diabetes if they were born small-for-gestational-age [small for gestational age (SGA); <-2SD], OR = 20.3 (95 % CI 11.8-34.7) if born large-for-gestational-age [large-for-gestational-age (LGA); >2SD], and OR = 10.4 (95 % CI 8.4-13.0) if born AGA. Risk of gestational diabetes is not only increased among obese women, but also among women born SGA and LGA. Severely obese women born with a low or a high birth-weight-for-gestational-age seem more vulnerable to the development of gestational diabetes compared to normal weight women. Normal pre-pregnancy BMI diminishes the increased risk birth size may confer in terms of gestational diabetes. Therefore, the importance of keeping a healthy weight cannot be overemphasized.

To investigate whether physical and cognitive fitness measured in late adolescence was associated with future risk of Parkinson's disease (PD). The cohort included 1,259,485 Swedish men with physical fitness, body mass index (BMI), resting heart rate (RHR), blood pressure, intelligence quotient (IQ), and stress resilience measured at the age of 17-20 in relation to conscription. Incident cases of PD were ascertained from the Swedish Patient Register. Hazard ratios were estimated from Cox models, after controlling for multiple confounders. We further performed Mendelian randomization (MR) analyses to assess the causality of the associations, using GWAS summary statistics with > 800,000 individuals. During follow-up, we identified 1,034 cases of PD (mean age at diagnosis = 53). Men with an RHR > 100 beats per minute had a higher risk of PD compared to men with an RHR of 60-100 beats per minute (HR = 1.47; 95% CI = 1.08-1.99). Men with IQ above the highest tertile had a higher risk of PD compared to men with an IQ below the lowest tertile (HR = 1.46; 95% CI = 1.19-1.79). We found no association for physical fitness, BMI, blood pressure, or stress resilience. A causal relationship was suggested by the MR analysis between IQ and PD, but not between RHR and PD. RHR and IQ in late adolescence were associated with a higher risk of PD diagnosed at relatively young age. The association of IQ with PD is likely causal, whereas the association of RHR with PD suggests that altered cardiac autonomic function might start before 20 years of age in PD.

In Sweden, conscription around age 18y was mandatory for young men until June 30, 2010. From July 1, 2017, it became mandatory again for both sexes but the proportion of summoned people for standardised testing has so far been low. This paper describes the history, structure and content of the Swedish Military Conscription Register (SMCR). We retrieved information about the SMCR from written sources and through e-mail interviews with key personnel at the Swedish Defence Conscription and Assessment Agency. We also analysed data from the SMCR between 1969 and 2018. Between 1969 and 2018 the SMCR contains digital data on approximately 2 million individuals (98.6% men). Most conscripts were born between 1951 and 1988 (n = 1,900,000; tested between 1969 and 2006). For the 1951-1987 birth cohorts, the register has a population coverage of approximately 90% for men. Conscripts underwent written tests focusing on verbal, spatial, logical and technical ability, medical, physical, and psychological tests. The medical assessment included hearing, vision, muscle and exercise capacity, height, weight, blood pressure and resting heart rate. The SMCR has been widely used to study, e.g., obesity, cardiovascular disease, mental health, crime, cardiovascular fitness, muscle strength, sick leave and disability pension. Severe disease could qualify for exemption from military service. Thus, the prevalence of such diseases is underestimated in the SMCR population. Between 1990 and 2018, about 25,000 women also volunteered for testing. The SMCR contains population-based data on physical and psychological health in about 90% of all men born between 1951 and 1987 (corresponding to testing between 1969 and 2006), and can be used to address a host of research questions.

Celiac disease (CD) is associated with both lymphoproliferative malignancy (LPM) and increased death from LPM. Research suggests that co-existing autoimmune disease may influence survival in LPM. Through Cox regression we examined overall and cause-specific mortality in 316 individuals with CD+LPM versus 689 individuals with LPM only. CD was defined as having villous atrophy according to biopsy reports at any of Sweden's 28 pathology departments, and LPM as having a relevant disease code in the Swedish Cancer Register. During follow-up, there were 551 deaths (CD: n = 200; non-CD: n = 351). Individuals with CD+LPM were at an increased risk of death compared with LPM-only individuals [adjusted hazard ratio (aHR) = 1.23; 95 % confidence interval (CI) = 1.02-1.48]. However, this excess risk was only seen in the first year after LPM diagnosis (aHR = 1.76), with HRs decreasing to 1.09 in years 2-5 after LPM diagnosis and to 0.90 thereafter. Individuals with CD and non-Hodgkin lymphoma (NHL) were at a higher risk of any death as compared with NHL-only individuals (aHR = 1.23; 95 % CI = 0.97-1.56). This excess risk was due to a higher proportion of T cell lymphoma in CD patients. Stratifying for T- and B cell status, the HR for death in individuals with CD+NHL was 0.77 (95 % CI = 0.46-1.31). In conclusion, we found no evidence that co-existing CD influences survival in individuals with LPM. The increased mortality in the first year after LPM diagnosis is related to the predominance of T-NHL in CD individuals. Individuals with CD+LPM should be informed that their prognosis is similar to that of individuals with LPM only. However, this study had low statistical power to rule our excess mortality in patients with CD and certain LPM subtypes.

Education, income, and occupation are factors known to affect health and disease. In this review we describe the Swedish Longitudinal Integrated Database for Health Insurance and Labour Market Studies (LISA, Longitudinell Integrationsdatabas for Sjukforsakrings- och Arbetsmarknadsstudier). LISA covers the adult Swedish population aged16years registered on December 31 each year since 1990 (since 2010 individuals aged15years). The database was launched in response to rising levels of sick leave in the country. Participation in Swedish government-administered registers such as LISA is compulsory, and hence selection bias is minimized. The LISA database allows researchers to identify individuals who do not work because of injury, disease, or rehabilitation. It contains data on sick leave and disability pension based on calendar year. LISA also includes information on unemployment benefits, disposable income, social welfare payments, civil status, and migration. During 2000-2017, an average of 97,000 individuals immigrated to Sweden each year. This corresponds to about 1% of the Swedish population (10 million people in 2017). Data on occupation have a completeness of 95%. Income data consist primarily of income from employment, capital, and allowances, including parental allowance. In Sweden, work force participation is around 80% (2017: overall: 79.1%; men 80.3% and women 77.9%). Education data are available in>98% of all individuals aged 25-64years, with an estimated accuracy for highest attained level of education of 85%. Some information on civil status, income, education, and employment before 1990 can be obtained through the Population and Housing Census data (FoB, Folk- och bostadsrakningen).

Although vaccines against influenza can reduce maternal morbidity and mortality, large-scale data on adverse effects in the offspring are scarce. Historical cohort study in Stockholm County, Sweden. We linked H1N1 vaccination data (Pandemrix(A (R)), a mono-valent AS03 adjuvanted H1N1 vaccine) with pregnancy and birth data from 21,087 women with singleton offspring conceived between February 2009 and January 2010 (vaccinated during pregnancy: n = 13,297 vs. unvaccinated: n = 7,790). Data were analysed by conceptualizing the observational cohort as a series of nested cohorts defined at each week of gestation. Logistic regression estimated odds ratios (ORs) for low birth weight (LBW, < 2,500 g), preterm birth (< 37 completed weeks), small-for-gestational age (SGA, < 10th percentile of the gestational age-specific birth weight within the cohort), low 5-min Apgar score (< 7), and caesarean section. Data were adjusted for potential confounders, including maternal age, body mass index, smoking, parity, civil status and comorbidities. Compared with infants of non-vaccinated women, infants of vaccinated women had similar adjusted ORs (95 % CI) for LBW (0.91; 0.79-1.04), preterm birth (0.99; 0.89-1.10), SGA (0.97; 0.90-1.05), low Apgar score (1.05, 0.84-1.31), and a marginal risk reduction for caesarean section (0.94, 0.89-0.99). H1N1 vaccination during pregnancy, using an AS03-adjuvanted vaccine, does not appear to adversely influence offspring risks of LBW, preterm birth, SGA, or low Apgar score. Our results suggest that this vaccine is safe for the offspring when used in different stages of pregnancy.

The impact of many unfavorable childhood traits or diseases, such as low birth weight and mental disorders, is not limited to childhood and adolescence, as they are also associated with poor outcomes in adulthood, such as cardiovascular disease. Insight into the genetic etiology of childhood and adolescent traits and disorders may therefore provide new perspectives, not only on how to improve wellbeing during childhood, but also how to prevent later adverse outcomes. To achieve the sample sizes required for genetic research, the Early Growth Genetics (EGG) and EArly Genetics and Lifecourse Epidemiology (EAGLE) consortia were established. The majority of the participating cohorts are longitudinal population-based samples, but other cohorts with data on early childhood phenotypes are also involved. Cohorts often have a broad focus and collect(ed) data on various somatic and psychiatric traits as well as environmental factors. Genetic variants have been successfully identified for multiple traits, for example, birth weight, atopic dermatitis, childhood BMI, allergic sensitization, and pubertal growth. Furthermore, the results have shown that genetic factors also partly underlie the association with adult traits. As sample sizes are still increasing, it is expected that future analyses will identify additional variants. This, in combination with the development of innovative statistical methods, will provide detailed insight on the mechanisms underlying the transition from childhood to adult disorders. Both consortia welcome new collaborations. Policies and contact details are available from the corresponding authors of this manuscript and/or the consortium websites.

Previous studies have shown inconsistent results with respect to hepatitis B (HBV), hepatitis C (HCV) and pregnancy outcome. The aim of this study was to investigate pregnancy outcome in women with HBV or HCV. In a nationwide cohort of births between 2001 and 2011 we investigated the risks of adverse pregnancy outcomes in 2990 births to women with HBV and 2056 births to women with HCV using data from Swedish healthcare registries. Births to women without HBV (n = 1090 979), and births without HCV (n = 1091 913) served as population controls. Crude and adjusted relative risks (aRR) were calculated using Poisson regression analysis. Women with HCV were more likely to smoke (46.7 vs. 8.0%) and to have alcohol dependence (18.9 vs. 1.3%) compared with population controls. Most women with HBV were born in non-Nordic countries (91.9%). Maternal HCV was associated with a decreased risk of preeclampsia (aRR: 0.39, 95% CI: 0.24-0.64), but an increased risk of preterm birth (aRR: 1.32, 95% CI: 1.08-1.60) and late neonatal death (7-27 days: aRR: 3.79, 95% CI: 1.07-13.39) Preterm birth were also more common in mothers with HBV, aRR: 1.21 (95% CI: 1.02-1.45). Both HBV and HCV are risk factors for preterm birth, while HCV seems to be associated with a decreased risk for preeclampsia. Future studies should corroborate these findings.

Preterm birth is associated with overall cardiovascular mortality in young adulthood, but which specific conditions that underlie this association is unknown. We studied mortality and morbidity from cerebrovascular and ischemic heart disease in individuals born preterm. In a nationwide Swedish study, we included 1,306,943 individuals without congenital malformations born between 1983 and 1995, followed from 15 years of age to December 31st, 2010. Of these, 73,489 (5.6 %) were born preterm (< 37 weeks of gestation). Cox proportional hazards regression analysis was used to calculate hazard ratios (HR) with 95 % confidence intervals (CI), after adjusting for maternal characteristics and birth weight for gestational age. Of 955 incident cases of cerebrovascular disease, 58 (6.1 %) occurred in preterm born subjects. The corresponding numbers of ischemic heart disease cases were 180 and 13 (7.2 %), respectively. Birth before 32 weeks was associated with a nearly twofold increased risk of cerebrovascular disease; adjusted HR, (95 % CI) = 1.89 (1.01-3.54) compared to term born individuals, whereas individuals born at 32-36 weeks were not at increased risk. Preterm birth was not associated with later ischemic heart disease; no cases of ischemic heart disease were recorded among those born before 32 weeks and the HR (95 % CI) for those born at 32-36 weeks of gestation was 1.45 (0.81-2.57), compared to term-born individuals. Birth before 32 weeks is associated with increased risk of cerebrovascular disease in young adulthood. Our data suggest that cardiovascular health promotion in follow-up programs after very preterm birth may be beneficial.

Attention-deficit/hyperactivity (ADHD) symptoms have been associated with the decision to become self-employed. Although these symptoms are generally regarded as disadvantageous, there may also be a bright side. To our knowledge, however, there has been no systematic, epidemiological evidence to support this claim. This paper examines the association between ADHD symptoms and self-employment in a population-based sample from the STAGE cohort of the Swedish Twin Registry (N = 7208). For replication, we used a sample of Dutch students who participated in the Global University Entrepreneurial Spirit Students' Survey (N = 13,112). In the Swedish sample, we found a positive association with self-employment for both general ADHD symptoms [odds ratio (OR) 1.13; 95 % confidence intervals (CI) 1.04-1.23] and hyperactivity symptoms [OR 1.19; 95 % CI 1.08-1.32], whereas no association was found for attention-deficit symptoms [OR 0.99; 95 % CI 0.89-1.10]. The positive association between hyperactivity and self-employment was replicated in the Dutch student sample [OR 1.09; 95 % CI 1.03-1.15]. Our results show that certain aspects of ADHD, in particular hyperactivity, can have a bright side, as they are positively associated with self-employment.

The etiologic role of physical activity in prostate cancer development is unclear. We assessed the association between lifetime total physical activity and prostate cancer risk in a Swedish population-based case–control study comprising 1,449 incident prostate cancer cases and 1,118 unaffected population controls. Information regarding physical activity was obtained via a self-administered questionnaire assessing occupational, household, and recreational activity separately at various ages throughout an individual’s lifetime. Clinical data (TNM-classification, Gleason sum and PSA) was obtained from linkage to the National Prostate Cancer Registry. Overall, we observed no association between lifetime total physical activity and prostate cancer risk (odds ratio [OR] = 1.04, 95% confidence interval [CI] = 0.77–1.41 for ≥49.7 vs. <41.9 metabolic equivalent-hours per day). There was a significantly increased risk of prostate cancer in the most active men compared with the least active men in household (OR = 1.44, 95% CI = 1.08–1.92) and recreational physical activity (OR = 1.56, 95% CI = 1.16–2.10). Comparing the most active with the least active men, total physical activity was not associated with either localized disease (OR = 0.95, 95% CI = 0.67–1.34) or advanced disease (OR = 1.19, 95% CI = 0.83–1.71). These findings do not support the hypothesis that physical activity uniformly protects against prostate cancer development.