Population-based studies of body mass index, overweight and systolic blood pressure among Swedish young men

Overweight and obesity has increased in Sweden and worldwide in recent decades. Lifestyle and environmental changes, genetic susceptibility and interactions between these factors are believed to be important. A theoretical framework often referred to, as the fetal origins hypothesis has been extensively debated over the last 15 years. According to this controversial hypothesis, overweight and other components of the metabolic syndrome - such as high blood pressure - might be long-term consequences of impaired fetal growth. The overall objectives of the studies were to investigate the epidemiology of body mass index and overweight among young men in Sweden and to explore relationships between growth in fetal life on the one hand and overweight and systolic blood pressure in young adulthood on the other. Specific aims were to: 1) study time trends and socio- economic differences in body mass index and overweight among young men over the last decades; 2) study the occurrence of overweight among male international adoptees; and, 3) test the fetal origins hypothesis by analyzing relationships between aspects of fetal growth and overweight, and also between fetal growth and systolic blood pressure among singletons and twins in young adulthood. This thesis is based on nationwide data sets created by record linkages between the Medical Birth Register, the Military Service Conscription Register and several other national registers. The twin studies include additional information collected by a mailed questionnaire. The prevalence of overweight among 18-year-old men increased two-fold over a 25-year period. The results show large socio-economic differentials in overweight, with higher prevalence among young men from loweducated families. Socio- economic differentials did not change over time. The prevalence of overweight was 2-3 times higher among young men adopted from Latin America in early childhood than among non-adopted individuals of the same ages. By contrast, the risk of overweight was not higher among adoptees from the Indian subcontinent or the Far East than among non-adopted individuals. The results show a positive relationship between gestational-age-adjusted birthweight and overweight at 18 years of age among singletons. Clearly, this finding does not support the fetal origins hypothesis. However, the hypothesis was further tested in a population-based twin study. A weak positive association was uncovered for the within-pair effects of birthweight on body mass index at the age of 18 among monozygotic twin pairs. The twin brother with the highest birthweight had a slightly higher risk of overweight at age 18 than his co-twin. No between-pairs effect of birthweight on body mass index was observed for monozygotic pairs of twins. And no relationships were observed among dizygotic twin pairs. Neither of these findings supports the fetal origins hypothesis. When studying fetal growth and systolic blood pressure among singletons, a clear inverse association was found between gestational-age-adjusted birthweight and systolic blood pressure at 18 years of age. That there was an independent inverse association between gestational age per se and systolic blood pressure is a novel finding. For monozygotic twins the results show an inverse between-pairs effect of birthweight on systolic blood pressure at age 18. There was an inverse within-pair effect of birthweight on systolic blood pressure among monozygotic twins, although the effect was not significant. No relationships were found among dizygotic twins. Although the results of the singleton study are in accordance with the fetal origins hypothesis, the twin study does not provide substantial support. In sum, the results show a strong increase in overweight over the last decades among young men, and also demonstrate large socio-economic differentials in overweight. Large and unexplained differences in over-weight among international adoptees compared with non-adopted young men were found. The studies addressing the fetal origins hypothesis showed mixed results with clear support for an inverse association between birthweight and blood pressure in the singleton study, weak support in the twin study, and no clear-cut support in either of the two other studies

Fetal growth and systolic blood pressure in young adulthood: the Swedish Young Male Twins Study.

The objective was to test the fetal origins hypothesis by examining the association between fetal growth and systolic blood pressure in a large cohort of adult male twins of known zygosity. This cohort study is based on a record linkage of routinely collected data from the Swedish Medical Birth Registry, the Swedish Military Conscription Registry and a mailed questionnaire. It comprises 886 pairs of same-sex male twins born in Sweden in 1973-79 for whom data were available on size at birth and systolic blood pressure, height and weight at age 17-19 years. Based on self-reported similarity of appearance in childhood, 384 twin pairs were classified as monozygotic (MZ), 269 as dizygotic (DZ) and 233 as of uncertain zygosity (XZ). Differences in systolic blood pressure within and between twin pairs were analysed in relation to birthweight and birthweight-for-gestational-age z-score using random effects linear models. Within twin pairs, a 1 kg difference in birthweight was associated with a difference of -1.30 mmHg in systolic blood pressure [95% confidence interval -4.15, +1.54] for MZ twins and +0.14 [-3.49, +3.76] for DZ twins; for all twins combined it was -0.21 [-2.13, +1.71]. Between twin pairs, a 1 kg difference in birthweight was associated with a difference of -2.68 mmHg in systolic blood pressure [-4.95, -0.42] for MZ twins and +0.28 [-2.35, +2.91] for DZ twins; for all twins combined -1.68 [-3.15, -0.22]. All these estimates included adjustment for age, year and conscription centre of examination, gestational age and height and weight at conscription. These results provide little support for the fetal origins hypothesis. The estimates of the within-pair effect in MZ twins and their wide confidence intervals (including zero) cannot exclude the existence of common genetic mechanisms, but are also not inconsistent with an in utero programming effect. This study highlights some methodological problems with twin studies

Validation of the new Swedish vaccination register – Accuracy and completeness of register data

Objective: The aims of this study are to validate infant vaccination data in the Swedish Vaccination Register (SVR) to the Swedish administrative coverage reports, and to assess differences in register-based vaccination coverage estimates between providers using different data reporting methods. Methods: The study population included all infants born in Sweden with a Swedish Personal Identity Number during 2014 and 2015 (n = 230,220). Data on all National Immunisation Programme vaccinations administered before 24 months of age were collected from the SVR and from administrative coverage reports. Information regarding data registration methods in the SVR were collected from national and regional authorities. Coverage from health care providers using single registration methods, where vaccination data were transferred automatically from the electronic health care record to the SVR, was compared to that from providers using double registration methods where data had to be added into the SVR in a separate process. Results: For 98,4% of the study population at least one vaccination was recorded in the SVR. The coverage of 3-dose DTP-containing (87,1%) and 1 dose MMR (91,1%) in the register did not reach administrative data coverage (97,4% for 3-dose DTP-containing and 97,0% for MMR). Single registration procedures yielded significantly higher coverage than double registration procedures (92,24% vs 87,10%, p < 0,0001). A regional switch from double to single registration increased coverage from 80,0 to 95,2%. Conclusions: The SVR is a valuable data source for vaccination coverage monitoring. For research purposes, the SVR provides valuable data, since every health care provider is obliged to register all vaccine doses given within the national immunisation program. The SVR shows a high completeness validated by comparison to a very well-functioning administrative data system. Single-registration procedures give more complete data and should be supported by health systems while creating health care registers

Post-infection symptoms following two large waterborne outbreaks of Cryptosporidium hominis in Northern Sweden, 2010-2011

Background: In 2010-2011, two large waterborne outbreaks caused by Cryptosporidium hominis affected two cities in Sweden, Ostersund and Skelleftea. We investigated potential post-infection health consequences in people who had reported symptoms compatible with cryptosporidiosis during the outbreaks using questionnaires. Methods: We compared cases linked to these outbreaks with non-cases in terms of symptoms present up to eleven months after the initial infection. We examined if cases were more likely to report a list of symptoms at follow-up than non-cases, calculating odds ratios (OR) and 95 % confidence intervals (CI) obtained through logistic regression. Results: A total of 872 (310 cases) and 743 (149 cases) individuals responded to the follow-up questionnaires in Ostersund and Skelleftea respectively. Outbreak cases were more likely to report diarrhea (Ostersund OR: 3.3, CI: 2.0-5.3. Skelleftea OR: 3.6, CI: 2.0-6.6), watery diarrhea (Ostersund OR: 3.4, CI: 1.9-6.3. Skelleftea OR: 2.8, CI: 1.5-5.1) abdominal pain (Ostersund OR: 2.1, CI: 1.4-3.3, Skelleftea OR: 2.7, CI: 1.5-4.6) and joint pain (Ostersund OR: 2.0, CI: 1.2-3.3, Skelleftea OR: 2.0, CI: 1.1-3.6) at follow-up compared to non-cases. Conclusions: Our findings suggest that gastrointestinal-and joint symptoms can persist several months after the initial infection with Cryptosporidium and should be regarded as a potential cause of unexplained symptoms in people who have suffered from the infection

Weight status at age 18 influences marriage prospects. A population-based study of Swedish men

<p>Abstract</p> <p>Background</p> <p>In a longitudinal population-based study of the relationship between body mass index (BMI) in early adulthood and marital status at 40 years of age, obese men were half as likely to be married compared with men of normal weight. Significant associations between obesity and marital status among men in a longitudinal setting are novel findings.</p> <p>Methods</p> <p>The study cohort comprised Swedish men born from 1951 to 1961. Height and weight at age 18 was gathered from the Military Service Conscription Register and information on marital status at 40 years of age was obtained from population registers by record-linkage using the unique personal identification number. The odds ratio (OR) for being married was calculated by polytomous logistic regression analysis adjusting for birth year, intellectual performance, education, country of birth, residential area, socioeconomic position in childhood and adulthood, parental education and muscle strength.</p> <p>Results</p> <p>Our study included 486 599 Swedish men. Young men who were obese (BMI≥30.0) at 18 years of age had an OR of 0.49 (95% CI: 0.46–0.52) for being married at 40 years of age compared to normal weight men (BMI: 18.5–24.9). Underweight men (BMI≤18.5) had an OR of 0.84 (0.82–0.86) and overweight men (BMI: 25.0–29.9) had an OR of 0.83 (0.80–0.85) for being married at 40 years of age.</p> <p>Conclusion</p> <p>Underweight, overweight and obese men were less likely to be married than their normal weight counterparts. Obese men had the lowest likelihood of being married. Stigmatization and discrimination may partly explain these findings, but further research is needed before firm conclusions can be drawn.</p

TRPV1 and TRPA1 in cutaneous neurogenic and chronic inflammation: pro-inflammatory response induced by their activation and their sensitization

ABSTRACT Cutaneous neurogenic inflammation (CNI) is inflammation that is induced (or enhanced) in the skin by the release of neuropeptides from sensory nerve endings. Clinical manifestations are mainly sensory and vascular disorders such as pruritus and erythema. Transient receptor potential vanilloid 1 and ankyrin 1 (TRPV1 and TRPA1, respectively) are non-selective cation channels known to specifically participate in pain and CNI. Both TRPV1 and TRPA1 are co-expressed in a large subset of sensory nerves, where they integrate numerous noxious stimuli. It is now clear that the expression of both channels also extends far beyond the sensory nerves in the skin, occuring also in keratinocytes, mast cells, dendritic cells, and endothelial cells. In these non-neuronal cells, TRPV1 and TRPA1 also act as nociceptive sensors and potentiate the inflammatory process. This review discusses the role of TRPV1 and TRPA1 in the modulation of inflammatory genes that leads to or maintains CNI in sensory neurons and non-neuronal skin cells. In addition, this review provides a summary of current research on the intracellular sensitization pathways of both TRP channels by other endogenous inflammatory mediators that promote the self-maintenance of CNI