Dataset Information

A nationwide survey of the influence of month of birth on the risk of developing multiple sclerosis in Sweden and Iceland.

ABSTRACT: Previous studies have shown that the risk of multiple sclerosis (MS) is associated with season of birth with a higher proportion of MS patients being born in spring. However, this relationship has recently been questioned and may be due to confounding factors. Our aim was to assess the influence from season or month of birth on the risk of developing MS in Sweden and Iceland. Information about month of birth, gender, and phenotype of MS for patients born 1940-1996 was retrieved from the Swedish MS registry (SMSR), and their place of birth was retrieved from the Swedish Total Population Registry (TPR). The corresponding information was retrieved from medical journals of Icelandic MS patients born 1981-1996. The control groups consisted of every person born in Sweden 1940-1996, their gender and county of birth (TPR), and in Iceland all persons born between 1981 and 1996 and their gender (Statistics Iceland). We calculated the expected number of MS patients born during each season and in every month and compared it with the observed number. Adjustments were made for gender, birth year, and county of birth. We included 12,020 Swedish and 108 Icelandic MS patients in the analyses. There was no significant difference between expected and observed MS births related to season or month of birth in Sweden or Iceland. This was even the results before adjustments were made for birth year and birth place. No significant differences were found in subgroup analyses including data of latitude of birth, gender, clinical phenotype, and MS onset of 30 years or less. Our results do not support the previously reported association between season or month of birth and MS risk. Analysis of birth place and birth year as possible confounding factors showed no major influence of them on the seasonal MS risk in Sweden and Iceland.

SUBMITTER: Eliasdottir O

PROVIDER: S-EPMC5760596 | biostudies-literature | 2018 Jan

REPOSITORIES: biostudies-literature

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A nationwide survey of the influence of month of birth on the risk of developing multiple sclerosis in Sweden and Iceland.

Eliasdottir Olöf O Hildeman Anders A Longfils Marco M Nerman O O Lycke J J

Journal of neurology 20171120 1

Previous studies have shown that the risk of multiple sclerosis (MS) is associated with season of birth with a higher proportion of MS patients being born in spring. However, this relationship has recently been questioned and may be due to confounding factors. Our aim was to assess the influence from season or month of birth on the risk of developing MS in Sweden and Iceland. Information about month of birth, gender, and phenotype of MS for patients born 1940-1996 was retrieved from the Swedish ...[more]

PMID: 29159463

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Project description:IntroductionPrevious evidence has been conflicting regarding the effect of coronavirus disease 2019 (COVID-19) pandemic lockdowns on obstetric intervention and preterm birth rates. The literature to date suggests potentially differential underlying mechanisms based on country economic setting. We aimed to study these outcomes in an Icelandic population where uniform lockdown measures were implemented across the country.Material and methodsThe study included all singleton births (n = 20 680) during 2016-2020 identified from the population-based Icelandic Medical Birth Register. We defined two lockdown periods during March-May and October-December in 2020 according to government implemented nationwide lockdown. We compared monthly rates of cesarean section, induction of labor and preterm birth during lockdown with the same time periods in the 4 previous years (2016-2019) using logit binomial regression adjusted for confounders.ResultsOur results indicated a reduction in the overall cesarean section rate, which was mainly evident for elective cesarean section, both during the first (adjusted odd ratio [aOR] 0.71, 95% CI 0.51-0.99) and second (aOR 0.72, 95% CI 0.52-0.99) lockdown periods, and not for emergency cesarean section. No change during lockdown was observed in induction of labor. Our results also suggested a reduction in the overall preterm birth rate during the first lockdown (aOR 0.69, 95% CI 0.49-0.97) and in the months immediately following the lockdown (June-September) (aOR 0.67, 95% CI 0.49-0.89). The reduction during the first lockdown was mainly evident for medically indicated preterm birth (although not statistically significant) and the reduction during June-September was mainly evident for spontaneous preterm birth.ConclusionsThis study suggested a reduction in elective cesarean section during COVID-19 lockdown, possibly reflecting changes in prioritization of non-urgent health care during lockdown. We also found a reduction in overall preterm birth during the first lockdown and spontaneous preterm birth following the first lockdown, but further research is needed to shed light on the underlying mechanisms for these findings.

Project description:ObjectivesTo explore sequences of annual states of activity and sickness absence (SA) or disability pension (DP) (SA/DP) among working-aged people with multiple sclerosis (PwMS) as well as characteristics associated with the identified types of working-life sequences.DesignNationwide Swedish register-based cohort study from 1 year prior to 5 years after the year of multiple sclerosis (MS) diagnosis.SettingSweden.ParticipantsPwMS diagnosed in 2008-2011 when aged 20-55 (n=2652, 69.9% women).Primary and secondary outcome measuresIndividual-level sequences spanning 7 years were constructed with annual states regarding activity (income from paid work, student allowances, parental leave or unemployment compensation) and/or SA/DP. Types of working-life sequences were identified among the individuals' sequences using hierarchical cluster analysis with optimal matching dissimilarity measures.ResultsSix types of working-life sequences were identified. The largest cluster, Stable High Activity, represented 48.4% of the cohort. Other types were: Stable High SA/DP (14.5%); Other (4.5%); and three types with mixed activity and varying SA/DP regarding the number of days/year and timing (32.6%). Characteristics of the different identified types of sequences were subsequently investigated. All types of sequences had lower odds for university education (OR range: 0.18-0.72) compared with Stable High Activity. Increasingly higher odds of having anxiety/depression compared with Stable High Activity were observed across the types of sequences, by increasing proportions of SA/DP. Stable High SA/DP sequences were less likely than Stable High Activity to be prescribed MS drugs in the MS diagnosis year (OR 0.61; 95% CI 0.47 to 0.78). All types of sequences had higher disposable income in the final study year than the first, except for Stable High SA/DP sequences (Swedish Krona 4669, 95% CI -1892 to 11 230).ConclusionsDiversity in working life was influenced by sociodemographic and clinical characteristics resulting in different activity and SA/DP patterns across the six identified types of working-life sequences.

Project description:Importance:Clinicians' experience and findings from recent natural history studies suggest that multiple sclerosis (MS) may now be running a more slowly progressing course than before. Objective:To investigate whether the risk of reaching MS disability milestones has changed over the last decade in Sweden. Design, Setting, and Participants:A nationwide population-based retrospective cohort study. By April 2017, 12 512 patients with available information on demographics, MS phenotype, and date of MS onset and diagnosis were registered in the Swedish MS Registry of which 7331 patients with at least 2 recorded Expanded Disability Status Scale scores (EDSS) and diagnosed between January 1995 and December 2010 were included. No further exclusion criteria were applied. Patients were followed up until December 2016 with a median duration follow-up of 8.5 (interquartile range, 4.7-13.8) years. Statistical analysis began in April 2017. Main Outcomes and Measures:Patients were followed up from MS onset date to the date of sustained EDSS 3.0, 4.0, and 6.0. To handle interval-censored observations, a Weibull model was fit, and the change in the risk of EDSS 3.0, 4.0, and 6.0 over calendar years was estimated and hazard ratios (HRs) with corresponding CIs were calculated. Results:Of 7331 patients, 5196 (70.9%) were women, and the mean (SD) age at diagnosis was 38.3 (11.7) years. Adjusting for sex, number of clinic visits, diagnostic delay, and onset age, a 3% decrease per calendar year of diagnosis for the risk of sustained EDSS 3.0 (HR, 0.97; 95% CI, 0.96-0.97), a 6% decrease for the risk of EDSS 4.0 (HR, 0.94; 95% CI, 0.93-0.95), and a 7% decrease for the risk of EDSS 6.0 (HR, 0.93; 95% CI, 0.91-0.94) among patients with relapsing-onset MS was found. The trends were not significant for patients with progressive-onset MS (EDSS 3.0: HR, 1.01; 95% CI, 0.98-1.03; EDSS 4.0: HR, 1.00; 95% CI, 0.98-1.02; EDSS 6.0: HR, 1.00; 95% CI, 0.98-1.02). Conclusions and Relevance:Risk of reaching major disability milestones has significantly decreased over the last decade in patients with relapsing-onset MS in Sweden. Several factors could potentially be responsible for this observation. However, given that no change was seen in disability accrual of patients with progressive-onset MS and the absence of efficacious treatment option in this group, increased use of more efficacious disease-modifying treatments could be a possible driver of this change.

Dataset Information

A nationwide survey of the influence of month of birth on the risk of developing multiple sclerosis in Sweden and Iceland.

Publications

A nationwide survey of the influence of month of birth on the risk of developing multiple sclerosis in Sweden and Iceland.

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