| 1. |
- Bjørnevik, Kjetil, et al.
(author)
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Negative interaction between smoking and EBV in the risk of multiple sclerosis : The EnvIMS study
- 2017
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In: Multiple Sclerosis Journal. - : SAGE Publications. - 1352-4585 .- 1477-0970. ; 23:7, s. 1018-1024
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Journal article (peer-reviewed)abstract
- BACKGROUND: Results from previous studies on a possible interaction between smoking and Epstein-Barr virus (EBV) in the risk of multiple sclerosis (MS) are conflicting.OBJECTIVES: To examine the interaction between smoking and infectious mononucleosis (IM) in the risk of MS.METHODS: Within the case-control study on Environmental Factors In Multiple Sclerosis (EnvIMS), 1904 MS patients and 3694 population-based frequency-matched healthy controls from Norway, Italy, and Sweden reported on prior exposure to smoking and history of IM. We examined the interaction between the two exposures on the additive and multiplicative scale.RESULTS: Smoking and IM were each found to be associated with an increased MS risk in all three countries, and there was a negative multiplicative interaction between the two exposures in each country separately as well as in the pooled analysis (p = 0.001). Among those who reported IM, there was no increased risk associated with smoking (odds ratio (OR): 0.95, 95% confidence interval (CI): 0.66-1.37). The direction of the estimated interactions on the additive scale was consistent with a negative interaction in all three countries (relative excess risk due to interaction (RERI): -0.98, 95% CI: -2.05-0.15, p = 0.09).CONCLUSION: Our findings indicate competing antagonism, where the two exposures compete to affect the outcome.
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| 2. |
- Bjørnevik, Kjetil, et al.
(author)
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Sun exposure and multiple sclerosis risk in Norway and Italy : The EnvIMS study
- 2014
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In: Multiple Sclerosis Journal. - : Sage Publications. - 1352-4585 .- 1477-0970. ; 20:8, s. 1042-1049
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Journal article (peer-reviewed)abstract
- OBJECTIVES:The objective of this paper is to estimate the association between multiple sclerosis (MS) and measures of sun exposure in specific age periods in Norway and Italy.METHODS:A total of 1660 MS patients and 3050 controls from Italy and Norway who participated in a multinational case-control study (EnvIMS) reported sun habits during childhood and adolescence.RESULTS:A significant association between infrequent summer outdoor activity and increased MS risk was found in Norway and in Italy. The association was strongest between the ages of 16 and 18 years in Norway (odds ratio (OR) 1.83, 95% confidence interval (CI) 1.30-2.59), and between birth and age 5 years in Italy (OR 1.56, 95% CI 1.16-2.10). In Italy a significant association was also found during winter (OR 1.42, 95% CI 1.03-1.97). Frequent sunscreen use between birth and the age of 6 years was associated with MS in Norway (OR 1.44, 95% CI 1.08-1.93) after adjusting for outdoor activity during the same period. Red hair (OR 1.67, 95% CI 1.06-2.63) and blonde hair (OR 1.36, 95% CI 1.09-1.70) were associated with MS after adjusting for outdoor activity and sunscreen use.CONCLUSION:Converging evidence from different measures underlines the beneficial effect of sun exposure on MS risk.
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| 3. |
- Boström, Inger, 1946-
(author)
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Epidemiological Studies of Multiple Sclerosis in Sweden with focus on the County of Värmland
- 2012
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Doctoral thesis (other academic/artistic)abstract
- The aim of this thesis was to study the frequency of MS in the suggested high-risk area of Värmland county by investigating the current prevalence and analyzing the development over time; secondly to investigate some aetiological factors – the pattern of industry, both in relation to MS in Värmland and in the whole country, and also to examine the possible relation between the distribution of MS and ALS, as it has previously shown a positive correlation in two studies; finally to analyze the women-to-men ratio of MS in Sweden because of international reports of an increasing ratio.Clinical data was collected from hospitals and other health care units in the county of Värmland, to calculate the prevalence ratio. The prevalence was 170.07 per 100,000 population on the prevalence day, 31 December 2002. The incidence rates analysed during ten years was 6.46 per 100,000 personyears (1991-1995) and 6.39 (1996-2000).The ecological study used data from the beginning of the 20th century on industries in Värmland and in all Sweden, which were correlated with the two MS prevalence studies (1925-1934 and 2002), and the mortality study on the time period 1952-1990. There was a statistical significant association between large sawmills and the prevalence 1925-1934 (p = 0.022). For all Sweden, wood-pulp factories and papermills correlated significantly with MS mortality 1952-1990 (p = <0.05).Collected data from Causes of death Register and from the Total Population Register were used when analysing mortality from ALS and MS. The previously shown correlation between ALS and MS mortality distribution in the Swedish counties was not confirmed in this study. However, the mean MS mortality rate was still highest in the county in Värmland. The mean MS mortality rates for whole Sweden was increased from 1.65 per 100,000 person-years (1952-1992) to 2.04 (1990-2010).For analysing sex ratio in MS, data from the Swedish Multiple Sclerosis Register and data from Total Population Register of the Swedish Statistics Office were used. These data was analysed by birth day cohort and by year of onset. The sex ratios in Sweden showed a stable women-to-men ratio.These investigations give indication that Värmland is a high-risk region of multiple sclerosis, and particularly the municipality of Säffle.We conclude that Värmland is a suitable area for continued epidemiological studies with both an environment and genetic focus.
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| 4. |
- Boström, Inger, et al.
(author)
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Mortality Statistics Studies of Multiple Sclerosis and Amyotrophic Lateral Sclerosis in Sweden
- 2012
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In: Neuroepidemiology. - : S. Karger. - 0251-5350 .- 1423-0208. ; 38:4, s. 245-249
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Journal article (peer-reviewed)abstract
- Background: Multiple sclerosis (MS) and amyotrophic lateral sclerosis (ALS) are chronic neurologic diseases where distinct explanations of the pathogenesis are lacking. Two large Swedish register studies have rather unexpectedly detected a correlation between MS and ALS.The aim of this study was to investigate if an association between ALS and MS could be demonstrated as has been shown earlier.Material and methods: Data on mortality from ALS and MS, 1990-2010 were collected from the Swedish national statistics office. In all there were 5,696 deaths due to ALS and 3,941 deaths due to MS. Age- and sex-adjusted mortality rates were calculated.Results: There was no correlation between the mortality rates of ALS and MS in the 21 counties of Sweden for the period 1990 to 2010 (Spearman’s rho = - 0.052; p = 0.822; n = 21).The national mean mortality rate for ALS throughout the period of 1990 to 2010 was 2.98 per 100 000 person-years (95% CI 2.87 – 3.08). For MS the national mean mortality rate was 2.04 per 100 000 person-years (95% CI 1.95 – 2.12). Both ALS and MS mortality showed significant variation between the counties. Conclusion: This study did not confirm the previously shown association between MS and ALS in Sweden.
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| 5. |
- Kirkeleit, Jorunn, et al.
(author)
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Early life exposures contributing to accelerated lung function decline in adulthood – a follow-up study of 11,000 adults from the general population
- 2023
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In: eClinicalMedicine. - : Elsevier. - 2589-5370. ; 66
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Journal article (peer-reviewed)abstract
- Background: We aimed to assess whether exposure to risk factors in early life from conception to puberty continue to contribute to lung function decline later in life by using a pooled cohort comprising approx. 11,000 adults followed for more than 20 years and with up to three lung function measurements. Methods: Participants (20–68 years) in the ECRHS and NFBC1966 cohort studies followed in the periods 1991–2013 and 1997–2013, respectively, were included. Mean annual decline in maximum forced expired volume in 1 s (FEV1) and forced vital capacity (FVC) were main outcomes. Associations between early life risk factors and change in lung function were estimated using mixed effects linear models adjusted for sex, age, FEV1, FVC and height at baseline, accounting for personal smoking. Findings: Decline in lung function was accelerated in participants with mothers that smoked during pregnancy (FEV1 2.3 ml/year; 95% CI: 0.7, 3.8) (FVC 2.2 ml/year; 0.2, 4.2), with asthmatic mothers (FEV1 2.6 ml/year; 0.9, 4.4) (FEV1/FVC 0.04 per year; 0.04, 0.7) and asthmatic fathers (FVC 2.7 ml/year; 0.5, 5.0), and in women with early menarche (FVC 2.4 ml/year; 0.4, 4.4). Personal smoking of 10 pack-years contributed to a decline of 2.1 ml/year for FEV1 (1.8, 2.4) and 1.7 ml/year for FVC (1.3, 2.1). Severe respiratory infections in early childhood were associated with accelerated decline among ever-smokers. No effect-modification by personal smoking, asthma symptoms, sex or cohort was found. Interpretation: Mothers’ smoking during pregnancy, parental asthma and early menarche may contribute to a decline of FEV1 and FVC later in life comparable to smoking 10 pack-years. Funding: European Union's Horizon 2020; Research Council of Norway; Academy of Finland; University Hospital Oulu; European Regional Development Fund; Spanish Ministry of Science and Innovation; Generalitat de Catalunya.
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| 6. |
- Kirkeleit, Jorunn, et al.
(author)
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Early life origins of lung ageing : A study of lung function decline the ECRHS and NFBC1966 cohorts
- 2020
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In: European Respiratory Journal. - : ERS Publications. - 0903-1936 .- 1399-3003. ; 56
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Journal article (other academic/artistic)abstract
- Objective: To determine whether early life factors associated with poor lung growth and submaximal attained lung function contribute to accelerated lung function decline later in life.Methods: Participants in the European Community Respiratory Health Survey (ECRHS) and the Northern Finland Birth Cohort 1966 (NFBC1966) with lung function measured in a first (n=10,971), second (n=7,981) and third wave (n=4,849), aged 20 – 68 years, were included. Mean annual decline in maximum forced expired volume in 1 second (FEV1) and forced vital capacity (FVC) were main outcomes. Information on early life factors was provided by standardized interviews and questionnaires. We estimated the effect of early life factors including maternal age, parental smoking, season of birth, parental asthma and respiratory infections using mixed effects models, adjusted for age, FEV1 and FVC at baseline, height, and smoking habits.Results: Decline in FEV1 was accelerated in women born of a mother with asthma (β = 2.4 ml; 95% CI 0.6-4.3) or who smoked during pregnancy (1.9; 0.2-3.6), and in men having a father with asthma (3.5; 0.2-6.9) or born by Cesarean section (7.9; 1.6-14.2). Accelerated decline in FVC was associated with paternal asthma in men (4.3; 0.1-8.5) and early menarche (<12 years) in women (2.4; 0.4-4.4). No statistically significant effect on lung function decline was found for other investigated early life factors.Conclusion: Early life risk factors contribute to an accelerated lung function decline with ageing, following sex-specific patterns. Decline in FEV1 versus FVC showed slightly different patterns.
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| 7. |
- Landtblom, Anne-Marie, 1953-, et al.
(author)
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Distribution of multiple sclerosis in Sweden based on mortality and disability compensation statistics
- 2002
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In: Neuroepidemiology. - : S. Karger AG. - 0251-5350 .- 1423-0208. ; 21:4, s. 167-179
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Journal article (peer-reviewed)abstract
- Previous studies have shown the Fennoscandian region to be a high-risk area for multiple sclerosis (MS). In order to investigate the distribution of MS in Sweden, mortality (1952-1992) and disability pensioning statistics (1971-1994) were studied. A total of 11,414 cases with a disability pension and 5,421 cases with MS on their death certificate were analysed according to county and time period and the results were compared with the mortality figures for amyotrophic lateral sclerosis (ALS) and disability pensioning statistics for Parkinson's disease. We found increasing rates of both MS mortality and disability pensioning. Disability pensioning correlated well with mortality 10 years later (r = 0.42, p = 0.04). We also found a marked geographical variation. VΣrmland county had the highest mortality, with 14 out of its 16 municipalities having higher rates than the national mean. Unexpectedly, we found a high correlation between mortality due to MS and ALS (r = 0.60, p = 0.002). Copyright ⌐ 2002 S. Karger AG, Basel.
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| 8. |
- Lossius, Andreas, et al.
(author)
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Season of infectious mononucleosis and risk of multiple sclerosis at different latitudes; the EnvIMS Study
- 2014
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In: Multiple Sclerosis Journal. - : SAGE Publications (UK and US). - 1352-4585 .- 1477-0970. ; 20:6, s. 669-674
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Journal article (peer-reviewed)abstract
- Background: Seasonal fluctuations in solar radiation and vitamin D levels could modulate the immune response against Epstein-Barr virus (EBV) infection and influence the subsequent risk of multiple sclerosis (MS). Methods: Altogether 1660 MS patients and 3050 controls from Norway and Italy participating in the multinational case-control study of Environmental Factors In Multiple Sclerosis (EnvIMS) reported season of past infectious mononucleosis (IM). Results: IM was generally reported more frequently in Norway (p=0.002), but was associated with MS to a similar degree in Norway (odds ratio (OR) 2.12, 95% confidence interval (CI) 1.64-2.73) and Italy (OR 1.72, 95% CI 1.17-2.52). For all participants, there was a higher reported frequency of IM during spring compared to fall (pless than0.0005). Stratified by season of IM, the ORs for MS were 1.58 in spring (95% CI 1.08-2.31), 2.26 in summer (95% CI 1.46-3.51), 2.86 in fall (95% CI 1.69-4.85) and 2.30 in winter (95% CI 1.45-3.66). Conclusions: IM is associated with MS independently of season, and the association is not stronger for IM during spring, when vitamin D levels reach nadir. The distribution of IM may point towards a correlation with solar radiation or other factors with a similar latitudinal and seasonal variation.
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| 9. |
- Magalhaes, Sandra, et al.
(author)
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The EnvIMS Study: Design and Methodology of an International Case-Control Study of Environmental Risk Factors in Multiple Sclerosis
- 2015
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In: Neuroepidemiology. - : Karger. - 0251-5350 .- 1423-0208. ; 44:3, s. 173-181
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Journal article (peer-reviewed)abstract
- Background: Multiple sclerosis (MS) is a chronic disease of the central nervous system, often resulting in significant neurological disability. The causes of MS are not known; however, the incidence of MS is increasing, thereby suggesting that changes in lifestyle and/or environmental factors may be responsible. On this background, the Environmental Risk Factors in MS Study or EnvIMS study was designed to further explore the etiology of MS. The design and methodology are described, providing details to enable investigators to (i) use our experiences to design their own studies; (ii) take advantage of, and build on the methodological work completed for, the EnvIMS study; (iii) become aware of this data source that is available for use by the research community. Methods: EnvIMS is a multinational case-control study, enrolling 2,800 cases with MS and 5,012 population-based controls in Canada, Italy, Norway, Serbia and Sweden. The study was designed to investigate the most commonly implicated risk factors for MS etiology using a self-report questionnaire. Results/Conclusions:The use of a common methodology to study MS etiology across several countries enhances the comparability of results in different geographic regions and research settings, reduces the resources required for study design and enhances the opportunity for data harmonization.
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| 10. |
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