Papers by Lars Alfredsson
The P-Value, The P-Value Function and the Confidence Interval
Biostatistics for Epidemiologists, 2017
[Risk of myocardial infarction is increased among transportation and industry workers]
Läkartidningen, Jan 14, 1990
Scandinavian Journal of Work, Environment & Health, 1991
A case-referent study was performed on the possiblerelationship betweenphysicalwork loads and an ... more A case-referent study was performed on the possiblerelationship betweenphysicalwork loads and an increased risk of developing coxarthrosis. The cases were239 male recipients of a hip prosthesis as a result of severe idiopathic coxarthrosis; the referents were 302 men randomly selected from the general population. The work load was assessed through an interview and a self-administered questionnaire on the men's specific work periods. Men highly exposed to dynamic or static work loads had an increasedrelative risk of 2.42 (95 070 confidence interval 1.45-4.04) for developing coxarthrosis when compared with men with low exposure. Men with high exposure to heavy lifting betweenthe ages of 30 and 49 years had the highest relative risk, 3.31 (95 070 confidenceinterval 1.97-5.57). Long-time exposure to physicalwork loads seemsto be a risk factor for severe coxarthrosis among men.
International Journal of Epidemiology, 2001
Coronary heart disease mortality has declined in Sweden during the last decades as in several oth... more Coronary heart disease mortality has declined in Sweden during the last decades as in several other western countries. 1 Over the period 1984-1994 the decline was about 35% in both men and women. There are also large regional differences in coronary heart disease mortality within the country. 2 Thus, there is higher coronary heart disease mortality in the northern part of Sweden and in the mid-west than in the south including the two largest cities of Stockholm and Gothenburg. There is little information as to what extent these temporal changes and population differences apply to the incidence of myocardial infarction. Information about incidence of acute myocardial infarction (AMI) in Sweden is available primarily from the Swedish MONICA centres in Gothenburg and northern Sweden. 3,4 However, the population covered by these two centres represents only about 10% of the Swedish population aged 35-64 years. Thus, we know little about time trends and population differences in the population as a whole. A record linkage method to identify incident cases of AMI based on routinely collected data on hospital discharges and deaths
BMC Public Health, 2012
Background: Job strain (i.e., high job demands combined with low job control) is a frequently use... more Background: Job strain (i.e., high job demands combined with low job control) is a frequently used indicator of harmful work stress, but studies have often used partial versions of the complete multi-item job demands and control scales. Understanding whether the different instruments assess the same underlying concepts has crucial implications for the interpretation of findings across studies, harmonisation of multi-cohort data for pooled analyses, and design of future studies. As part of the 'IPD-Work' (Individual-participant-data meta-analysis in working populations) consortium, we compared different versions of the demands and control scales available in 17 European cohort studies. Methods: Six of the 17 studies had information on the complete scales and 11 on partial scales. Here, we analyse individual level data from 70 751 participants of the studies which had complete scales (5 demand items, 6 job control items). Results: We found high Pearson correlation coefficients between complete scales of job demands and control relative to scales with at least three items (r > 0.90) and for partial scales with two items only (r = 0.76-0.88). In comparison with scores from the complete scales, the agreement between job strain definitions was very good when only one item was missing in either the demands or the control scale (kappa > 0.80); good for job strain assessed with three demand items and all six control items (kappa > 0.68) and moderate to good when items were missing from both scales (kappa = 0.54-0.76). The sensitivity was > 0.80 when only one item was missing from either scale, decreasing when several items were missing in one or both job strain subscales. Conclusions: Partial job demand and job control scales with at least half of the items of the complete scales, and job strain indices based on one complete and one partial scale, seemed to assess the same underlying concepts as the complete survey instruments.
Reverse causality behind the association between reproductive history and MS
Multiple Sclerosis Journal, 2013
Background: Possible associations between childbearing patterns and multiple sclerosis (MS) risk ... more Background: Possible associations between childbearing patterns and multiple sclerosis (MS) risk have been studied for a long time, with conflicting results. We aimed to investigate the influence of reproductive history on MS risk. Methods: Using a Swedish population-based case-control study involving incident cases of MS (1798 cases, 3907 controls), we calculated odds ratios (OR) for MS comparing parents with childless subjects together with 95% confidence intervals (CI) employing logistic regression. Results: Overall, there was an association between having children and reduced MS risk among both sexes. Subjects who had become parents within five years prior to the index year had a substantially reduced risk of developing MS (OR 0.6, 95% CI 0.5–0.8 for women, and OR 0.4, 95% CI 0.3–0.6 for men). No association between having children and MS risk was observed when more than 10 years had passed since the birth of the last child. We found no association between increasing offspring n...
High body mass index before age 20 is associated with increased risk for multiple sclerosis in both men and women
Multiple Sclerosis Journal, 2012
In a Swedish population-based case-control study (1571 cases, 3371 controls), subjects with diffe... more In a Swedish population-based case-control study (1571 cases, 3371 controls), subjects with different body mass indices (BMIs) were compared regarding multiple sclerosis (MS) risk, by calculating odds ratios (OR) with 95% confidence intervals (95% CI). Subjects whose BMI exceeded 27 kg/m2 at age 20 had a two-fold increased risk of developing MS compared with normal weight subjects. Speculatively, the obesity epidemic may explain part of the increasing MS incidence as recorded in some countries. Measures taken against adolescent obesity may thus be a preventive strategy against MS.
Smokers run increased risk of developing anti-natalizumab antibodies
Multiple Sclerosis Journal, 2013
Background: Smoking may contribute to the induction of neutralizing antibodies to interferon β-1a... more Background: Smoking may contribute to the induction of neutralizing antibodies to interferon β-1a. Objective: In this study, we aimed to investigate the influence of smoking on the risk of developing antibodies to natalizumab, another biological drug in the treatment of multiple sclerosis. Methods: This report is based on 1338 natalizumab-treated multiple sclerosis patients included in either of two Swedish case-control studies in which information on smoking habits was collected. Using logistic regression, patients with different smoking habits were compared regarding risk of developing anti-natalizumab antibodies, by calculating odds ratios with 95% confidence intervals. Results: Compared with nonsmokers, the odds ratio of developing anti-natalizumab antibodies was 2.4 (95% CI 1.2–4.4) for patients who smoked at the time of screening, and a significant trend showed higher risk of developing antibodies with higher intensity of smoking. When smoking within two years prior to screeni...
European journal of neurology : the official journal of the European Federation of Neurological Societies, 2015
The possible interaction between adolescent obesity and past infectious mononucleosis (IM) was in... more The possible interaction between adolescent obesity and past infectious mononucleosis (IM) was investigated with regard to multiple sclerosis (MS) risk. This report is based on two population-based case-control studies, one with incident cases (1780 cases, 3885 controls) and one with prevalent cases (4502 cases, 4039 controls). Subjects were categorized based on adolescent body mass index (BMI) and past IM and compared with regard to occurrence of MS by calculating odds ratios with 95% confidence intervals (CIs) employing logistic regression. A potential interaction between adolescent BMI and past IM was evaluated by calculating the attributable proportion due to interaction. Regardless of human leukocyte antigen (HLA) status, a substantial interaction was observed between adolescent obesity and past IM with regard to MS risk. The interaction was most evident when IM after the age of 10 was considered (attributable proportion due to interaction 0.8, 95% CI 0.6-1.0 in the incident st...
Cigarette smoking is a risk factor for developing primary Sjögren's syndrome with Ro/SSA and La/SSB autoantibodies
Clinical and Experimental Rheumatology, 2018
Cigarette smoking is a risk factor for developing primary Sjogren's syndrome with Ro/SSA and ... more Cigarette smoking is a risk factor for developing primary Sjogren's syndrome with Ro/SSA and La/SSB autoantibodies
Sant eller falskt fynd? Tillämpning av bayesianska principer kan förbättra bedömningen
Läkartidningen, 2007
O18-6 Occupational exposure to textile dust increases the risk of RA: results from a malaysian population-based case-control study
Objectives Lung exposures including cigarette smoking and silica exposure are associated with the... more Objectives Lung exposures including cigarette smoking and silica exposure are associated with the risk of rheumatoid arthritis (RA). We investigated the association between textile dust exposure and the risk of RA in the Malaysian population, with a focus on women who rarely smoke. Methods Data from the Malaysian Epidemiological Investigation of Rheumatoid Arthritis (MyEIRA) population-based case-control study involving 910 female early RA cases and 910 female age-matched controls were analysed. Self-reported information on ever/never occupationally exposed to textile dust was used to estimate the risk of developing anti-citrullinated protein antibody (ACPA)-positive and ACPA-negative RA. Interaction between textile dust and the HLA-DRB1 shared epitope (SE) was evaluated by calculating the attributable proportion due to interaction (AP), with 95% CI. Results Occupational exposure to textile dust was significantly associated with an increased risk of developing RA in the Malaysian female population (OR 2.8, 95% CI: 1.6–5.2). The association between occupational exposure to textile dust and risk of RA was uniformly observed for the ACPA-positive RA (OR 2.5, 95% CI: 1.3–4.8) and ACPA-negative RA (OR 3.5, 95% CI: 1.7–7.0) subsets, respectively. We observed a significant interaction between exposure to occupational textile dust and HLA-DRB1 SE alleles regarding the risk of ACPA-positive RA (OR for double exposed: 39.1, 95% CI: 5.1–297.5; AP: 0.8, 95% CI: 0.5–1.2). Conclusions This is the first study demonstrating that textile dust exposure is associated with an increased risk for RA. In addition a gene-environment interaction between HLA-DRB1 SE and textile dust exposure provides a high risk for ACPA-positive RA.
[Increased risk of arthrosis of the knee and hip among workers with heavy weight on the legs]
PubMed, Dec 19, 1990
[Multi-levels, fewer differences. Possibly misleading picture based on current analysis of hospitals' results]
PubMed, Feb 15, 2005
[Contemporary contraceptives are efficient and safe. Prevention of thrombosis should be considered in certain cases]
PubMed, Sep 11, 1996
[True or false findings? Application of Bayes principles can improve the assessment]
PubMed, Apr 3, 2007
Children's dental health in Europe. Clinical calibration of dental examiners in eight EU countries
PubMed, 1995
An epidemiological investigation has been initiated from Sweden with the aim to study and compare... more An epidemiological investigation has been initiated from Sweden with the aim to study and compare dental health, dental treatment needs and attitudes to dental care in two well-defined age-groups, children of 5 and 12 years of age, in eight EU countries. To ensure comparability of the clinical registrations, data collection was preceded by clinical calibrations of the examiners from the participating countries. All the examiners participated in a workshop with initial calibration exercises. Agreement, expressed as sensitivity, was measured between the Swedish examiner acting as the reference examiner and each of the other examiners in turn, and assessed separately for the two age-groups. For DMFS/dmfs, agreement ranged from 44.3% to 82.2%. These results were discussed and where necessary the criteria were modified and/or made more stringent, so that they were clearcut and could be adhered to consistently. In a second calibration between the Swedish and the national examiner undertaken in each of the seven countries, the inter-examiner agreement (sensitivity) varied between 85.4% and 100%. The mean sensitivity for DMFS/dmfs after the total calibration procedures was 89.5% for the 12-year olds and 91.7 for the 5-year olds. The mean sensitivity for both age-groups together was 90.6% and the corresponding value for specificity was 98.9%.
Finnish men have higher coronary heart disease (CHD) mortality than Swedish men do. To assess the... more Finnish men have higher coronary heart disease (CHD) mortality than Swedish men do. To assess the impact of migration to a country with lower CHD mortality on subclinical atherosclerosis, we measured early functional and structural atherosclerotic vascular changes in twins discordant for migration from Finland to Sweden. Conventional CHD risk factors, flow-mediated dilatation (FMD) of the brachial artery, carotid intima-media thickness, and carotid artery compliance were measured in 74 male twin pairs (20 monozygous, 54 dizygous), aged 42 to 69 years, in which co-one twin had migrated more than 20 years ago permanently to Sweden. There were no significant differences in CHD risk factors except for diastolic blood pressure and body fat percentage, which were higher in Sweden. In all subjects, mean FMD was non-significantly higher in Sweden (5.7Ϯ4.3% vs 4.9Ϯ4.2%, Pϭ0.22), but in monozygous twins the difference in FMD was highly significant (7.2Ϯ4.4 vs 3.7Ϯ2.9%, Pϭ0.003). There was no significant difference in intima-media thickness or carotid artery compliance between Sweden and Finland. We conclude that in Finnish monozygous twins the endothelial function is better among the twins that have migrated to a country with lower CHD prevalence.
Modifiable and other risk factors for rheumatoid arthritis: A basis for prevention and better therapy
Oxford University Press eBooks, Sep 1, 2020
Rheumatoid arthritis (RA) is a heterogeneous disease, consisting of distinct subsets with partly ... more Rheumatoid arthritis (RA) is a heterogeneous disease, consisting of distinct subsets with partly distinct aetiologies and risk factors. Such risk factors are environmental, including lifestyle mediated and genetic, and these factors must always be considered in the context of stochastic (i.e. chance) factors. As RA is a disease where immune reactions often precede symptoms, and where symptoms that do not involve joint inflammation such as joint pain, bone loss, and fatigue may precede arthritis, and where severe symptoms and comorbidities may follow after the first episode of joint inflammation, we also have to consider risk factors during these different phases of disease development. This chapter focuses on environmental, including lifestyle, factors, and on when and how during disease development such factors are active. The chapter also describes pathogenic mechanisms that may be triggered by such risk factors. Particular emphasis is on recognition of modifiable environmental/lifestyle factors as such knowledge can be used in primary as well as secondary prevention and also to improve effects of current pharmacological treatments.
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Papers by Lars Alfredsson