Showing papers by "Norwegian Institute of Public Health published in 2009"

Self-selection and bias in a large prospective pregnancy cohort in Norway.

Abstract: Self-selection in epidemiological studies may introduce selection bias and influence the validity of study results. To evaluate potential bias due to self-selection in a large prospective pregnancy cohort in Norway, the authors studied differences in prevalence estimates and association measures between study participants and all women giving birth in Norway. Women who agreed to participate in the Norwegian Mother and Child Cohort Study (43.5% of invited; n = 73 579) were compared with all women giving birth in Norway (n = 398 849) using data from the population-based Medical Birth Registry of Norway in 2000-2006. Bias in the prevalence of 23 exposure and outcome variables was measured as the ratio of relative frequencies, whereas bias in exposure-outcome associations of eight relationships was measured as the ratio of odds ratios. Statistically significant relative differences in prevalence estimates between the cohort participants and the total population were found for all variables, except for maternal epilepsy, chronic hypertension and pre-eclampsia. There was a strong under-representation of the youngest women (<25 years), those living alone, mothers with more than two previous births and with previous stillbirths (relative deviation 30-45%). In addition, smokers, women with stillbirths and neonatal death were markedly under-represented in the cohort (relative deviation 22-43%), while multivitamin and folic acid supplement users were over-represented (relative deviation 31-43%). Despite this, no statistically relative differences in association measures were found between participants and the total population regarding the eight exposure-outcome associations. Using data from the Medical Birth Registry of Norway, this study suggests that prevalence estimates of exposures and outcomes, but not estimates of exposure-outcome associations are biased due to self-selection in the Norwegian Mother and Child Cohort Study.

Inflammatory disease processes and interactions with nutrition

Abstract: Inflammation is a stereotypical physiological response to infections and tissue injury; it initiates pathogen killing as well as tissue repair processes and helps to restore homeostasis at infected or damaged sites. Acute inflammatory reactions are usually self-limiting and resolve rapidly, due to the involvement of negative feedback mechanisms. Thus, regulated inflammatory responses are essential to remain healthy and maintain homeostasis. However, inflammatory responses that fail to regulate themselves can become chronic and contribute to the perpetuation and progression of disease. Characteristics typical of chronic inflammatory responses underlying the pathophysiology of several disorders include loss of barrier function, responsiveness to a normally benign stimulus, infiltration of inflammatory cells into compartments where they are not normally found in such high numbers, and overproduction of oxidants, cytokines, chemokines, eicosanoids and matrix metalloproteinases. The levels of these mediators amplify the inflammatory response, are destructive and contribute to the clinical symptoms. Various dietary components including long chain omega-3 fatty acids, antioxidant vitamins, plant flavonoids, prebiotics and probiotics have the potential to modulate predisposition to chronic inflammatory conditions and may have a role in their therapy. These components act through a variety of mechanisms including decreasing inflammatory mediator production through effects on cell signaling and gene expression (omega-3 fatty acids, vitamin E, plant flavonoids), reducing the production of damaging oxidants (vitamin E and other antioxidants), and promoting gut barrier function and anti-inflammatory responses (prebiotics and probiotics). However, in general really strong evidence of benefit to human health through anti-inflammatory actions is lacking for most of these dietary components. Thus, further studies addressing efficacy in humans linked to studies providing greater understanding of the mechanisms of action involved are required.

Biophilia: does visual contact with nature impact on health and well-being?

Abstract: It is concluded that an environment devoid of Nature may act as a "discord", i.e., have a negative effect. While the term mismatch is used for any difference between present living conditions and the environment of evolutionary adaptation, discords are mismatches with a potentially undesirable impact on health or quality of life. The problem is partly due to the visual absence of plants, and may be ameliorated by adding elements of Nature, e.g., by creating parks, by offering a view through windows, and by potted plants. The conclusion is based on an evaluation of some fifty relevant empirical studies.

A sequence variant in ZFHX3 on 16q22 associates with atrial fibrillation and ischemic stroke.

Abstract: Daniel Gudbjartsson and colleagues report a genome-wide association study for atrial fibrillation, a condition associated with increased risk of stroke. They report a variant in ZFHX3 associated with atrial fibrillation as well as ischemic stroke. We expanded our genome-wide association study on atrial fibrillation (AF) in Iceland, which previously identified risk variants on 4q25, and tested the most significant associations in samples from Iceland, Norway and the United States. A variant in the ZFHX3 gene on chromosome 16q22, rs7193343-T, associated significantly with AF (odds ratio OR = 1.21, P = 1.4 × 10−10). This variant also associated with ischemic stroke (OR = 1.11, P = 0.00054) and cardioembolic stroke (OR = 1.22, P = 0.00021) in a combined analysis of five stroke samples.

Pain in Parkinson's disease: Prevalence and characteristics.

Abstract: Parkinson’s disease is a chronic, progressive, incurable neurodegenerative disease. As the disease progresses, motor disturbances and non-motor symptoms represent considerable illness burdens. Symptom relief is the goal for the treatment. Pain is frequently observed in patients with Parkinson’s disease, but its prevalence, characteristics and associations with Parkinson’s disease are poorly documented. These were investigated in 176 home-living PD patients. They underwent a neurological examination and a structured interview for registration of pain characteristics in addition to responding to standardised questionnaires. Pain was reported by 146 (83%) patients. Compared to the general population, the Parkinson’s disease patients experienced significantly more pain as measured by SF-36 Bodily Pain Scale. The average pain during the last 24 h measured by the Brief Pain Inventory was 2.85. Fifty-three percent of the patients reported one, 24% reported two and 5% reported three pain types. Musculoskeletal pain was reported by 70%, dystonic pain by 40%, radicular-neuropathic pain by 20% and central neuropathic pain by 10%. Thirty-four percent were on analgesic medication. Pain was not associated with age, disease duration or severity of the disease; female gender was the only significant predictor of pain. Pain is frequent and disabling, independent of demographic and clinical variables except for female gender, and is significantly more common in Parkinson’s patients compared to the general population. A minority of the Parkinson’s disease patients with pain received analgesic medication. The findings call for improved attention to assessment and treatment of pain in the follow-up of Parkinson’s disease patients.

Health effects of residential wood smoke particles: the importance of combustion conditions and physicochemical particle properties

Abstract: Background: Residential wood combustion is now recognized as a major particle source in many developed countries, and the number of studies investigating the negative health effects associated with wood smoke exposure is currently increasing. The combustion appliances in use today provide highly variable combustion conditions resulting in large variations in the physicochemical characteristics of the emitted particles. These differences in physicochemical properties are likely to influence the biological effects induced by the wood smoke particles. Outline: The focus of this review is to discuss the present knowledge on physicochemical properties of wood smoke particles from different combustion conditions in relation to wood smoke-induced health effects. In addition, the human wood smoke exposure in developed countries is explored in order to identify the particle characteristics that are relevant for experimental studies of wood smoke-induced health effects. Finally, recent experimental studies regarding wood smoke exposure are discussed with respect to the applied combustion conditions and particle properties. Conclusion: Overall, the reviewed literature regarding the physicochemical properties of wood smoke particles provides a relatively clear picture of how these properties vary with the combustion conditions, whereas particle emissions from specific classes of combustion appliances are less well characterised. The major gaps in knowledge concern; (i) characterisation of the atmospheric transformations of wood smoke particles, (ii) characterisation of the physicochemical properties of wood smoke particles in ambient and indoor environments, and (iii) identification of the physicochemical properties that influence the biological effects of wood smoke particles.

Oseltamivir-resistant influenza virus A (H1N1), Europe, 2007-08 season.

Abstract: In Europe, the 2007-08 winter season was dominated by influenza virus A (H1N1) circulation through week 7, followed by influenza B virus from week 8 onward Oseltamivir-resistant influenza viruses A (H1N1) (ORVs) with H275Y mutation in the neuraminidase emerged independently of drug use By country, the proportion of ORVs ranged from 0% to 68%, with the highest proportion in Norway The average weighted prevalence of ORVs across Europe increased gradually over time, from near 0 in week 40 of 2007 to 56% in week 19 of 2008 (mean 20%) Neuraminidase genes of ORVs possessing the H275Y substitution formed a homogeneous subgroup closely related to, but distinguishable from, those of oseltamivir-sensitive influenza viruses A (H1N1) Minor variants of ORVs emerged independently, indicating multiclonal ORVs Overall, the clinical effect of ORVs in Europe, measured by influenza-like illness or acute respiratory infection, was unremarkable and consistent with normal seasonal activity

Time Trends and the Influence of Age and Gender on Serum Concentrations of Perfluorinated Compounds in Archived Human Samples

Abstract: Fifty-seven pooled archived human serum samples were analyzed to assess the time trends as well as influence of age and gender on selected perfluorinated compounds (PFCs) in Norwegian residents. The study comprised determinations of 19 PFCs in serum samples pooled according to year of collection from 28 years in the period 1976 to 2007. A 9-fold increase in the serum concentrations of perfluorooctyl sulfonate, perfluorooctanoic acid, and perfluoroheptyl sulfonate was measured for men (40-50 years) from 1977 to the mid 1990s where the concentrations reached a plateau before starting to decrease around year 2000. A similar trend was also seen for perfluorohexyl sulfonate, perfluorononanoic acid, perfluorodecanoic acid, and perfluoroundecanoic acid, but no clear decline was observed for these PFCs in the recent years. No statistically significant difference was observed between the PFC levels in the male and female serum pools, though the statistical power is low due to few data points. For most PFCs, the concentrations in the human serum samples were found to increase with age in the pools from 2007, while the results for 1976, 1987, and 1998 were more varying. Several PFCs were significantly intercorrelated.

Sleep and depression in postpartum women: a population-based study.

Abstract: Study Objectives: (1) To describe the prevalence of and risk factors for postpartum maternal sleep problems and depressive symptoms simultaneously, (2) identify factors independently associated with either condition, and (3) explore associations between specific postpartum sleep components and depression.

Folic acid supplements in pregnancy and early childhood respiratory health

Abstract: Background: Folate supplementation is recommended for pregnant women to reduce the risk of congenital malformations. Maternal intake of folate supplements during pregnancy might also influence childhood immune phenotypes via epigenetic mechanisms. Objective: To investigate the relationship between folate supplements in pregnancy and risk of lower respiratory tract infections and wheeze in children through 18 months of age. Methods: In the Norwegian Mother and Child Cohort Study, questionnaire data collected at several time points in pregnancy and after birth, from 32,077 children born between 2000 and 2005, were used to assess effects of folate supplements during pregnancy on respiratory outcomes up to 18 months of age, accounting for other supplements in pregnancy and supplementation in infancy. Results: Folate supplements in the first trimester were associated with increased risk of wheeze and respiratory tract infections up to 18 months of age. Adjusting for exposure later in pregnancy and in infancy, the relative risk of wheeze for children exposed to folic acid supplements in the first trimester was 1.06 (95% confidence interval: 1.03, 1.10), for lower respiratory tract infections the relative risk was 1.09 (95% confidence interval: 1.02, 1.15), and for hospitalizations for lower respiratory tract infections the relative risk was 1.24 (95% confidence interval: 1.09, 1.41). Conclusions: Folic acid supplements in pregnancy were associated with a slightly increased risk of wheeze and lower respiratory tract infections up to 18 months of age. Results support possible epigenetic influences of methyl donors in maternal diet during pregnancy on respiratory health in children.

Vitamin D supplementation and reduced risk of preeclampsia in nulliparous women.

Abstract: Background:A recent study showed that nulliparous women who develop preeclampsia had low concentrations of vitamin D in serum sampled in midpregnancy. The aim of the present study was to estimate the association between intake of vitamin D during pregnancy and the risk of preeclampsia in 23,423 null

Oseltamivir-resistant influenza viruses A (H1N1), Norway, 2007-08.

Abstract: In Norway in January 2008, unprecedented levels of oseltamivir resistance were found in 12 of 16 influenza viruses A (H1N1) tested. To investigate the epidemiologic and clinical characteristics of these viruses, we used sequence analysis to test all available subtype H1N1 viruses from the 2007-08 season for resistance. Questionnaires from physicians provided information on predisposing diseases, oseltamivir use, symptoms, and complications. Clinical data were obtained for 265 patients. In total, 183 (67.3%) of 272 viruses were oseltamivir resistant. Resistance was not associated with prior use of antiviral drugs. Symptoms and hospitalization rates did not differ for patients infected with a resistant or a susceptible virus. Oseltamivir-resistant influenza viruses A (H1N1) did not show diminished capability to spread in the absence of selective pressure. The ability of these viruses to sustain their fitness and spread among persons should be considered when shaping future strategies for treating and preventing seasonal and pandemic influenza.

Blood glucose and risk of incident and fatal cancer in the metabolic syndrome and cancer project (me-can): analysis of six prospective cohorts.

Abstract: BackgroundProspective studies have indicated that elevated blood glucose levels may increase the risk of cancer, but the strength of the association is unclear. We examined the association between ...

Sequence Diversity of the Factor H Binding Protein Vaccine Candidate in Epidemiologically Relevant Strains of Serogroup B Neisseria meningitidis

Abstract: Background. Recombinant forms of Neisseria meningitidis human factor H binding protein (fHBP) are undergoing clinical trials in candidate vaccines against invasive meningococcal serogroup B disease. We report an extensive survey and phylogenetic analysis of the diversity of fhbp genes and predicted protein sequences in invasive clinical isolates obtained in the period 2000–2006. Methods. Nucleotide sequences of fhbp genes were obtained from 1837 invasive N. meningitidis serogroup B (MnB) strains from the United States, Europe, New Zealand, and South Africa. Multilocus sequence typing (MLST) analysis was performed on a subset of the strains. Results. Every strain contained the fhbp gene. All sequences fell into 1 of 2 subfamilies (A or B), with 60%– 75% amino acid identity between subfamilies and at least 83% identity within each subfamily. One fHBP sequence may have arisen via inter-subfamily recombination. Subfamily B sequences were found in 70% of the isolates, and subfamily A sequences were found in 30%. Multiple fHBP variants were detected in each of the common MLST clonal complexes. All major MLST complexes include strains in both subfamily A and subfamily B. Conclusions. The diversity of strains observed underscores the importance of studying the distribution of the vaccine antigen itself rather than relying on common epidemiological surrogates such as MLST. Invasive disease caused by Neisseria meningitidis is a rapidly progressing, disseminated infection with a case fatality rate of ∼10% [1], and 10%–20% of survivors experience serious permanent sequelae (eg, neurological impairment, digit, limb, or hearing loss). Vaccines for meningococcal serogroups A, C, Y, and W135,

Spirometry Centile Charts for Young Caucasian Children The Asthma UK Collaborative Initiative

Abstract: RATIONALE: Advances in spirometry measurement techniques have made it possible to obtain measurements in children as young as 3 years of age; however, in practice, application remains limited by the lack of appropriate reference data for young children, which are often based on limited population-specific samples. OBJECTIVES: We aimed to build on previous models by collating existing reference data in young children (aged 3-7 years), to produce updated prediction equations that span the preschool years and that are also linked to established reference equations for older children and adults. METHODS: The Asthma UK Collaborative initiative was established to collate lung function data from healthy young children aged 3-7 years. Collaborators included researchers with access to pulmonary function test data in healthy preschool children. Spirometry centiles were created using the LMS (Lambda-Mu-Sigma) method and extend previously published equations down to 3 years of age. MAIN RESULTS: The Asthma UK centiles charts for spirometry are based on the largest sample of healthy young Caucasian children aged 3-7 years (n=3777) from 15 centers across 11 countries and provide a continuous reference with a smooth transition into adolescence and adulthood. These equations improve existing pediatric equations by considering the between-subject variability to define a more appropriate age-dependent lower limit of normal. The collated dataset reflects a variety of equipment, measurement protocols and population characteristics and may be generalizable across different populations. CONCLUSIONS: We present prediction equations for spirometry for preschool children and provide a foundation which will facilitate continued updating.

A Dietary Pattern Characterized by High Intake of Vegetables, Fruits, and Vegetable Oils Is Associated with Reduced Risk of Preeclampsia in Nulliparous Pregnant Norwegian Women

Abstract: Several dietary substances have been hypothesized to influence the risk of preeclampsia. Our aim in this study was to estimate the association between dietary patterns during pregnancy and the risk of preeclampsia in 23,423 nulliparous pregnant women taking part in the Norwegian Mother and Child Cohort Study (MoBa). Women participating in MoBa answered questionnaires at gestational wk 15 (a general health questionnaire) and 17-22 (a FFQ). The pregnancy outcomes were obtained from the Medical Birth Registry of Norway. Exploratory factor analysis was used to assess the associations among food variables. Principal component factor analysis identified 4 primary dietary patterns that were labeled: vegetable, processed food, potato and fish, and cakes and sweets. Relative risks of preeclampsia were estimated as odds ratios (OR) and confounder control was performed with multiple logistic regression. Women with high scores on a pattern characterized by vegetables, plant foods, and vegetable oils were at decreased risk [relative risk (OR) for tertile 3 vs. tertile 1: 0.72; 95% CI: 0.62, 0.85]. Women with high scores on a pattern characterized by processed meat, salty snacks, and sweet drinks were at increased risk [OR for tertile 3 vs. tertile 1: 1.21; 95% CI: 1.03, 1.42]. These findings suggest that a dietary pattern characterized by high intake of vegetables, plant foods, and vegetable oils decreases the risk of preeclampsia, whereas a dietary pattern characterized by high consumption of processed meat, sweet drinks, and salty snacks increases the risk.

Prediction in multilevel generalized linear models

Abstract: We discuss prediction of random effects and of expected responses in multilevel generalized linear models. Prediction of random effects is useful for instance in small area estimation and disease mapping, effectiveness studies and model diagnostics. Prediction of expected responses is useful for planning, model interpretation and diagnostics. For prediction of random effects, we concentrate on empirical Bayes prediction and discuss three different kinds of standard errors; the posterior standard deviation and the marginal prediction error standard deviation (comparative standard errors) and the marginal sampling standard deviation (diagnostic standard error). Analytical expressions are available only for linear models and are provided in an appendix. For other multilevel generalized linear models we present approximations and suggest using parametric bootstrapping to obtain standard errors. We also discuss prediction of expectations of responses or probabilities for a new unit in a hypothetical cluster, or in a new (randomly sampled) cluster or in an existing cluster. The methods are implemented in gllamm and illustrated by applying them to survey data on reading proficiency of children nested in schools. Simulations are used to assess the performance of various predictions and associated standard errors for logistic random-intercept models under a range of conditions. © 2009 Royal Statistical Society.

An evaluation of classification systems for stillbirth

Abstract: Background Audit and classification of stillbirths is an essential part of clinical practice and a crucial step towards stillbirth prevention. Due to the limitations of the ICD system and lack of an international approach to an acceptable solution, numerous disparate classification systems have emerged. We assessed the performance of six contemporary systems to inform the development of an internationally accepted approach.

Correlates of regular exercise during pregnancy: the Norwegian Mother and Child Cohort Study.

Abstract: The aims of this study were to describe the level of exercise during pregnancy and to assess factors associated with regular exercise. Using data from the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health, 34 508 pregnancies were included in the present study. Data were collected by self-completed questionnaires in gestational weeks 17 and 30, and analyzed by logistic regression analysis. The results are presented as adjusted odds ratios (aOR) with a 95% confidence interval. The proportion of women exercising regularly was 46.4% before pregnancy and decreased to 28.0 and 20.4% in weeks 17 and 30, respectively. Walking and bicycling were the most frequently reported activities before and during pregnancy. The prevalence of swimming tended to increase from prepregnancy to week 30. Exercising regularly prepregnancy was highly related to regular exercise in week 17, aOR=18.4 (17.1-19.7) and 30, aOR 4.3 (4.1-4.6). Low gestational weight gain was positively associated with regular exercise in week 30, aOR=1.2 (1.1-1.4), whereas being overweight before pregnancy was inversely associated with regular exercise in week 17, aOR=0.8 (0.7-0.8) and 30, aOR=0.7 (0.6-0.7). Also, women experiencing a multiple pregnancy, pelvic girdle pain, or nausea were less likely to exercise regularly.

Reduction of late stillbirth with the introduction of fetal movement information and guidelines - a clinical quality improvement

Abstract: We have performed a full cross-validation of this clinical Femina data collection against the routinely collected data of the Medical Birth Registry of Norway to validate the estimates of reduced mortality in the total population. The original estimate of fewer deaths during the intervention with OR 0.7 remains virtually unchanged for the original data collection.

Oxidative damage to DNA and repair induced by Norwegian wood smoke particles in human A549 and THP-1 cell lines.

Abstract: Genotoxic effects of traffic-generated particulate matter (PM) are well described, whereas little data are available on PM from combustion of biomass and wood, which contributes substantially to air pollution world wide. The aim of this study was to compare the genotoxicity of wood smoke particulate matter (WSPM), authentic traffic-generated particles, mineral PM and standard reference material (SRM2975) of diesel exhaust particles in human A549 lung epithelial and THP-1 monocytic cell lines. DNA damage was measured as strand breaks (SB) and formamidopyrimidine DNA glycosylase (FPG) sites by the comet assay, whereas cell cytotoxicity was determined as lactate dehydrogenase release. The exposure to WSPM generated SB and FPG sites in both cell lines at concentrations from 2.5 or 25 microg/ml, which were not cytotoxic. Compared to all other studied particles, WSPM generated greater responses in terms of both SB and FPG sites. Organic extracts of WSPM and SRM2975 elicited higher levels of SB than native and washed PM at 25 and 100 microg/ml, whereas assay saturation precluded reliable assessment of FPG sites. During a 6h post-exposure period, in which the medium with PM had been replaced by fresh medium, 60% of the DNA lesions generated by WSPM were removed. In conclusion, WSPM generated more DNA damage than traffic-generated PM per unit mass in human cell lines, possibly due to the high level of polycyclic aromatic hydrocarbons in WSPM. This suggests that exposure to WSPM might be more hazardous than PM collected from vehicle exhaust with respect to development of lung cancer.