Maternal body composition in relation to twinning

Monozygotic (MZ) twinning is considered to be a random event whereas spontaneous dizygotic (DZ) twinning is influenced by several factors. Thus, secular changes in twinning rates are usually explained by changes in DZ twinning alone. Maternal body mass index (BMI) before pregnancy and maternal height are believed to be significant drivers of twinning. Our aim in this study was to explore to what degree maternal body composition influences twinning. Data on births and maternal height and BMI from the Medical Birth Registry Norway (MBRN) was analyzed applying multivariate logistic regression analysis. The results showed that increasing maternal BMI and height has a positive association with twinning. There is an increased risk of DZ twinning for a maternal BMI > 25, OR 1.31-1.43 and for maternal height ≥ 173 cm, OR 1.28. In explaining secul

Health problems account for a small part of the association between socioeconomic status and disability pension award. Results from the Hordaland Health Study

<p>Abstract</p> <p>Background</p> <p>Low socioeconomic status is a known risk factor for disability pension, and is also associated with health problems. To what degree health problems can explain the increased risk of disability pension award associated with low socioeconomic status is not known.</p> <p>Methods</p> <p>Information on 15,067 participants in the Hordaland Health Study was linked to a comprehensive national registry on disability pension awards. Level of education was used as a proxy for socioeconomic status. Logistic regression analyses were employed to examine the association between socioeconomic status and rates of disability pension award, before and after adjusting for a wide range of somatic and mental health factors. The proportion of the difference in disability pension between socioeconomic groups explained by health was then calculated.</p> <p>Results</p> <p>Unadjusted odds ratios for disability pension was 4.60 (95% CI: 3.34-6.33) for the group with elementary school only (9 years of education) and 2.03 (95% CI 1.49-2.77) for the group with high school (12 years of education) when compared to the group with higher education (more than 12 years). When adjusting for somatic and mental health, odds ratios were reduced to 3.87 (2.73-5.47) and 1.81 (1.31-2.52). This corresponds to health explaining only a marginal proportion of the increased level of disability pension in the groups with lower socioeconomic status.</p> <p>Conclusion</p> <p>There is a socioeconomic gradient in disability pension similar to the well known socioeconomic gradient in health. However, health accounts for little of the socioeconomic gradient in disability pension. Future studies of socioeconomic gradients in disability pension should focus on explanatory factors beyond health.</p

Social inequalities in reception of social welfare support: A population based twin study

Social welfare support runs in families. Recent studies using Nordic registry data have found individual differences in genetic factors to be of substantial importance for medical benefits. However, to date there has been no genetically informative studies on receiving social welfare support. To prevent young adults to not drop out of the work life and become recipients of social welfare support, it is of substantial interest to clarify to what extent the familiarity of social welfare support is due to genetic or social differences between families. We used data from the Historical-Event Database on 7,698 Norwegian twins born 1967-1979 to estimate the relative contribution of genetic factors, the effective familial environment (i.e. the “shared environment”), and individual-specific environmental factors. We found that the two forms of familial risk, genetic and shared environmental, explained 39% and 45%, respectively, of the risk for receiving social welfare support among young Norwegian twins. Only 17% of the variance in risk factors could be explained by individual-specific risk factors. It appears that risk for receiving social welfare support can to a great extent be explained by environmental differences between families. Therefore prevention strategies targeting social inequalities between families would indeed be effective. Furthermore, genetic risk factors are also important in explaining risk for receiving social welfare support. These effects could be mediated through heritable traits related to substance abuse, psychiatric disorders, and personality. Individual-specific risk factors were of very little importance. Hence, with regard to receiving social welfare support, family matters

Socioeconomic status and sick leave granted for mental and somatic disorders: a prospective study of young adult twins

Background Low socioeconomic status (SES), indicated by low income and education, has consistently been found to be a strong predictor of sick leave. Several possible pathways from SES to sick leave have been described in previous literature, but there are also evidence indicating that the association can be confounded by common underlying factors. This study utilizes a population-based sample of employed young adult twins to estimate (i) the degree to which education and income are prospectively related to sick leave granted for mental, somatic, and any disorder, and (ii) whether these associations are confounded by familial factors. Methods Registry data on educational attainment and income at age 30 and subsequent sick leave were available for 6,103 employed young adult twins, among which there were 2,024 complete twin pairs. The average follow-up time was 6.57 years. Individual-level associations and fixed effects within twin pairs were estimated. Results Low education and income were associated with sick leave granted for both mental and somatic disorders, and with sick leave granted for any disorder. Associations were attenuated within dizygotic twin pairs and reduced to non-significance within monozygotic twin pairs, suggesting influence of familial factors on the associations between SES and sick leave. Conclusions Low SES is associated with a higher level of sick leave granted for both mental and somatic disorders among young adults, but these associations are confounded by factors that are common to co-twins. Education and income are therefore not likely to strongly affect sick leave in young adulthood

Agrárpiaci Jelentések Gabona és ipari növények

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Advantages of linking national registries with twin registries for epidemiological research

Linking national registries with twin data represents an opportunity to produce epidemiological research of high quality. National registries contain information on a broad array of variables, some of which cannot be measured reliably in regular health surveys. By taking kinship into consideration, twin studies have the benefit of being able to identify confounding stemming from genetic or shared environmental sources. In this paper, we use examples from our own interview and questionnaire-based twin studies from the Norwegian Twin Registry (NTR) on mental disorders, alcohol use and socioeconomic status linked to registry data on medical benefits to demonstrate the value. In the first example, we examined to what extent genetic and environmental factors contributed to sick leave and disability pension and the association between these two types of benefits. In the second example, we explored the genetic and environmental relationship between personality disorders and sick leave. In the third example, a co-twin control design was applied to explore whether there is a true protective relationship between moderate alcohol consumption and health. The fourth example shows to what degree anxiety and depression are associated with later sick leave granted for not only mental disorders, but also somatic disorders, adjusted for confounding by genetic and shared environmental factors. In the fifth example, we address the socioeconomic gradient in sick leave, adjusting for non-observed confounders associated with the family in a co-twin control design. Our examples illustrate some of the potentials obtainable by linking national registries with twin data. The efforts that have been made to create the NTR in Norway and the International Network of Twin Studies (INTR) internationally make these types of linkage studies easier to conduct and available to more researchers. As there are still many areas to explore, we encourage epidemiological researchers to make use of this possibility

Musculoskeletal pain and work absence – a 10 year follow-up study of Norwegian young adult twins

Background and aims: Sickness absence (SA) and disability pension (DP) are increasingly recognized as major public problems. Musculoskeletal disorders are among the most common diagnoses set by physicians granting SA and DP. Results from recent twin studies have established that SA and DP are influenced not only by environmental and social factors, but also moderately to substantially by genes. The aim of the current study was to examine to what degree musculoskeletal complaints in young adults predict SA and DP, including SA granted for other diagnoses. As the participants were twins, we were able to perform within pair analyses, to see if the associations between musculoskeletal pain and later DP or SA were confounded by unmeasured genetic and shared environmental factors. Materials and methods: The Norwegian twin registry includes a questionnaire conducted in 1998. From this, we included three measures of recurrent pain (lower back, neck/shoulders and muscular) as well as symptoms of anxiety and depression (measured by the Symptom Checklist-5 (SCL-5)). The questionnaire has been linked to highly reliable official registries on SA and DP, as well as a range of sociodemographic variables, for a ten-year follow up period. We applied logistic (DP as dependent variable) and binomial regression (SA as dependent variable) analyses to explore the relationship between musculoskeletal pain and DP and SA. In the final models, we adjusted for sociodemographic factors and symptoms of anxiety and depression. Differences between twins in a pair were explored by applying fixed effect models. All analyses were conducted using STATA version 13.1. Results: The final sample of 7,626 twins included 3,055 complete pairs (488 monozygotic (MZ) male, 349 dizygotic (DZ) male, 747 MZ female, 589 DZ female, and 882 opposite sex twin pairs) and 1,516 singletons. By the end of follow up, 181 subjects (44 men and 137 women) received DP, and 63.7% of the sample (47.4% of males and 76.0% of females) had at least one period of SA extending 16 days. Pain at any site was significantly associated with DP in both sexes. Any increase in the number of pain sites reported was associated with about a 60% increased risk for receiving DP (OR 1.6, 95% CI 1.4-1.9), and the strength of the association was only marginally reduced when adjusted for symptoms of mental disorders (1.4, 1.2- 1.7). In the within pair analyses the effect was no longer significant, indicating possible confounding from genetic and shared environmental effects. As for all cause SA, musculoskeletal pain predicted SA independently of all measured confounders, and the results remained significant in the within pair analyses (Incidence Rate Ratio (IRR) 1.12, 95% CI 1.03-1.23). Conclusion: In young adults, musculoskeletal pain strongly predicted SA and DP for a 10 year follow-up period. Musculoskeletal pain was associated with higher levels of all cause SA, even within discordant MZ twin pairs. Our results indicate that interventions to prevent musculoskeletal pain in young adults can reduce levels of SA and DP

The Norwegian Twin Registry

The Norwegian Twin Registry (NTR) is a large population based twin cohort for research purposes. At present, the registry has 14 692 complete twin pairs with information on zygosity and to varying degree information on somatic and mental health, lifestyle and demographics. The registry covers birth years 1895-1960 and 1967- 1991. NTR was established in 2009, at the Norwegian Institute of Public Health, as a merger of three major twin panels, the oldest originating in the 1960s. Since then Norwegian twin research has been a notable contributor to twin research internationally. Norwegian twin researchers have published over 250 papers based on Norwegian twin data, spanning a broad range of somatic and mental health phenotypes. In twin studies of heritability a data structure with both variance within and between pairs is required. Therefore a large sample is necessary, especially when studying rare diseases and conditions, and it is of vital importance to expand the registry. NTR is actively recruiting new twins, both young and older, but declining response rates are a challenge. The value of NTR is greatly enhanced through the linkage possibilities offered by Norway’s many nationwide registries (medical, demographic, and socio-economic). Access to data is permitted by the NTR steering group and will in most instances need permission from the Regional Ethics Committee