Kjell Torén

University of Gothenburg, Goeteborg, Västra Götaland, Sweden

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Publications (261)1349.09 Total impact

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    ABSTRACT: Background and purpose: Although the incidence of stroke is on the decline worldwide, this is not the case for early stroke. We aimed to determine whether nonpsychotic mental disorder at the age of 18 years is a risk factor for early stroke, and if adolescent cardiovascular fitness and intelligence quotient might attenuate the risk. Method: Population-based Swedish cohort study of conscripts (n=1 163 845) who enlisted during 1968 to 2005. At conscription, 45 064 males were diagnosed with nonpsychotic mental disorder. Risk of stroke during follow-up (5-42 years) was calculated with Cox proportional hazards models. Objective baseline measures of fitness and cognition were included in the models in a second set of analyses. Results: There were 7770 first-time stroke events. In adjusted models, increased risk for stroke was observed in men diagnosed with depressive/neurotic disorders (hazard ratio [HR], 1.23; 95% confidence interval [CI], 1.11-1.37), personality disorders (HR, 1.52; 95% CI, 1.29-1.78), and alcohol/substance use disorders (HR, 1.61; 95% CI, 1.41-1.83) at conscription. Corresponding figures for fatal stroke were HR, 1.38; 95% CI, 1.06 to 1.79; HR, 2.26; 95% CI, 1.60 to 3.19; and HR, 2.20; 95% CI, 1.63 to 2.96. HRs for stroke were attenuated when fitness level and intelligence quotient were introduced. Associations remained significant for personality disorders and alcohol/substance use in the fully adjusted models. The interaction term was statistically significant for fitness but not for intelligence quotient. Conclusions: Our findings suggest that fitness may modify associations between nonpsychotic disorders and stroke. It remains to be clarified whether interventions designed to improve fitness in mentally ill youth can influence future risk of early stroke.
    No preview · Article · Feb 2016 · Stroke
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    ABSTRACT: Background: There is little knowledge about how oral and respiratory health is interrelated even though the mucosa of the oral cavity and airways constitutes a continuum and the exposures to these are partly similar. Aims: To investigate whether gum bleeding is related to asthma, respiratory symptoms and self-reported COPD. Methods: A postal questionnaire including questions about respiratory and oral health was sent to general population samples in seven Northern European centres. In 13,409 responders, gum bleeding when brushing teeth was reported always/often by 4% and sometimes by 20%. Logistic regressions accounted for age, smoking, educational level, centre and gender. Effects of BMI, cardio-metabolic diseases, early life factors, gastro-oesophageal reflux, dental hygiene, nasal congestion, and asthma medication were addressed. Results: Gum bleeding always/often was significantly associated with ≥3 asthma symptoms (OR 2.58, 95% CI 2.10-3.18), asthma (1.62 [1.23-2.14]) and self-reported COPD (2.02 [1.28-3.18]). There was a dose-response relationship between respiratory outcomes and gum bleeding frequency (≥3 symptoms: gum bleeding sometimes 1.42 [1.25-1.60], often/always 2.58 [2.10-3.18]), and there was no heterogeneity between centres (pheterogeneity = 0.49). None of the investigated risk factors explained the associations. The observed associations were significantly stronger among current smokers (pinteraction = 0.004). Conclusions: A consistent link between gum bleeding and obstructive airways disease was observed, not explained by common risk factors or metabolic factors. We speculate that oral pathogens might have unfavourable impact on the airways, and that the direct continuity of the mucosa of the oral cavity and the airways reflects a pathway that might provide novel opportunities for interventions.
    Full-text · Article · Jan 2016 · PLoS ONE
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    ABSTRACT: Objectives Declining participation in epidemiological studies has been reported in recent decades and may lead to biased prevalence estimates and selection bias. The aim of the study was to identify possible causes and effects of non-response in a population-based study of respiratory health in Norway. Design The Telemark study is a longitudinal study that began with a cross-sectional survey in 2013. Setting In 2013, a random sample of 50 000 inhabitants aged 16–50 years, living in Telemark county, received a validated postal questionnaire. The response rate was 33%. In this study, a random sample of 700 non-responders was contacted first by telephone and then by mail. Outcome measures Response rates, prevalence and OR of asthma and respiratory symptoms based on exposure to vapours, gas, dust or fumes (VGDF) and smoking. Causes of non-response. Results A total of 260 non-responders (37%) participated. Non-response was associated with younger age, male sex, living in a rural area and past smoking. The prevalence was similar for responders and non-responders for physician-diagnosed asthma and several respiratory symptoms. The prevalence of chronic cough and use of asthma medication was overestimated in the Telemark study, and adjusted prevalence estimates were 17.4% and 5%, respectively. Current smoking was identified as a risk factor for respiratory symptoms among responders and non-responders, while occupational VGDF exposure was a risk factor only among responders. The Breslow-Day test detected heterogeneity between productive cough and occupational VGDF exposure among responders. Conclusions The Telemark study provided valid estimates for physician-diagnosed asthma and several respiratory symptoms, while it was necessary to adjust prevalence estimates for chronic cough and use of asthma medication. Reminder letters had little effect on risk factor associations. Selection bias should be considered in future investigations of the relationship between respiratory outcomes and exposures.
    Full-text · Article · Jan 2016 · BMJ Open

  • No preview · Article · Jan 2016 · Public Health Nutrition
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    ABSTRACT: Background: Previous studies on stroke recurrence in younger adults often contain small sample size which makes it difficult to study trends in stroke recurrence over a long period of time. Aims: The aim of the present study was to investigate temporal trends in the risk of recurrence in younger patients with a first ischemic stroke. Methods: All men and women aged 18-54 years who had survived at least 28 days after a first ischemic stroke from 1987 to 2006 were identified in the Swedish Inpatient Register. The patients were stratified into four 5-year periods according to their admission period and were followed up for a total of four years after the index event with regard to recurrent ischemic stroke. A Cox regression model was used to analyze the risk of recurrent ischemic stroke. Results: Of the 17,149 ischemic stroke patients who were identified, 2432 (14.2%) had a recurrent ischemic stroke event within four years. From the first to the last periods (1987-1991 versus 2002-2006), the four-year risk of recurrent ischemic stroke decreased by 55% (hazard ratio 0.45, 95% confidence interval 0.39-0.53) in men and 59% (hazard ratio 0.41, 95% confidence interval, 0.33-0.50) in women. The cumulative four-year risk was 11.8% (95% CI 10.55-13.25) in men and 9.8% (95% CI 8.40-11.46) in women during the last five-year period (2002-2006). Conclusions: The risk of recurrence among younger ischemic stroke patients has decreased over the past 20 years. Despite these improvements, younger patients are still at a high risk for recurrent ischemic stroke.
    Preview · Article · Jan 2016 · International Journal of Stroke
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    Mathias Holm · Kjell Torén · Eva Andersson
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    ABSTRACT: Background: Wheeze is a very common respiratory symptom, which is associated with several factors and diseases. Studies on incidence of new-onset wheeze in general adult populations are rare. The present prospective study aimed to investigate the incidence rate of new-onset wheeze, and predictors for wheeze, in a general, middle-aged population. Methods: Individuals, born 1943-1973, who had participated in a previous Swedish study in 1993 (n = 15,813), were mailed a new respiratory questionnaire in 2003. The questionnaire, which included items about respiratory symptoms, atopy, and smoking was answered by 11,463 (72 %). Incidence rates of new-onset wheeze were calculated. Cox regression analyses were performed with incident wheeze as an event and person-years under observation as dependent variable. Results: Among those free of wheeze at baseline (n = 8885), there were 378 new cases of wheeze during the study period (1993-2003). The incidence rate was 4.3/1000 person-years. The adjusted risk was increased in relation to smoking (HR 2.1;95 % CI 1.7-2.7), ex-smoking (HR 1.4;95 % CI 1.1-1.9), young age (HR 1.7;95 % CI 1.3-2.2), chronic bronchitis (HR 2.3;95 % CI 0.96-5.7), and rhinitis (HR 1.8;95 % CI 1.4-2.2) at baseline, and body mass index ≥30 (HR 1.9;95 % CI 1.5-2.6) at follow-up. Conclusions: This is a unique study that presents an incidence rate for new-onset wheeze in a middle-aged, general population sample previously free of adult wheeze. The results indicate that new-onset wheeze is quite common in this age group. Health care staff should bear this in mind since new-onset wheeze could be one of the earliest symptoms of severe respiratory disease. Special attention should be paid to patients with a smoking history, chronic bronchitis, rhinitis or obesity.
    Preview · Article · Dec 2015 · BMC Pulmonary Medicine
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    ABSTRACT: Background: Despite improvements in treatment, acute coronary syndrome remains a substantial cause for prolonged sick absences and premature retirement. Knowledge regarding what benefits return to work is limited, especially the effect of psychological processes and psychosocial work factors. The purposes of this cross-sectional study were two-fold: to examine associations between adverse psychosocial job conditions and fear-avoidance beliefs towards work, and to determine whether such beliefs mediated the relationship between work conditions and expected return to work in acute coronary syndrome survivors. Methods: Study inclusion criteria: acute myocardial infarction or unstable angina diagnosis, below 65 years of age, being a resident in the West county of Sweden and currently working. In all, 509 individuals (21.8 % women) accepted study participation and for whom all data of study interest were available for analysis. Psychosocial work variables; job demand-control and effort-reward imbalance, were assessed with standard questionnaire batteries. Linear regression models were used to investigate relationships between psychosocial factors and fear-avoidance, and to evaluate mediator effects for fear-avoidance. Both total sample and gender stratified analyses were calculated. Results: Fear-avoidance beliefs about work were associated to psychosocial job environments characterized by high strain (β 1.4; CI 1.2-1.6), active and passive work and high effort-reward imbalance (β 0.6; CI 0.5-0.7). Further, such beliefs also mediated the relationship between adverse work conditions and expected time for return to work. However, these results were only observed in total sample analyses or among or male participants. For women only high strain was linked to fear-avoidance, and these relationships became non-significant when entering chosen confounders.
    Full-text · Article · Dec 2015 · BMC Public Health
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    Full-text · Article · Sep 2015 · European Respiratory Journal
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    ABSTRACT: Background: Although active tobacco smoking is the main risk factor for COPD, COPD is not uncommon also among never-smokers. Different study locations along with different spirometric definitions of COPD have historically yielded different prevalence estimates of the disease. Aim: To study current prevalence and risk factors of COPD among never-smokers in two areas of Sweden. Methods: Data collected in 2008-2012 within the West Sweden Asthma Study and Obstructive Lung Disease in Northern Sweden Studies was pooled. The study population consisted of 1839 subjects who participated in spirometry and interviews. COPD was defined as post-bronchodilator a) FEV1/(F)VC < 0.7, b) FEV1/FVC < 0.7 and c) FEV1/FVC < lower limit of normal. Results: Of the 1839 subjects, 967 (52.6%) were never-smokers. Among the never-smoking subjects, the prevalence of COPD according to definitions a-c was 7.7%, 4.9% and 3.0%, respectively. The corresponding prevalence of GOLD grade ≥2 was 2.0%, 1.4% and 1.3%. No significant difference in prevalence between the two study areas was observed. In never-smokers, occupational exposure to gas, dust or fumes (GDF) was significantly associated with both COPD (OR 1.85, 95% CI 1.03-3.33), and GOLD ≥2 (OR 4.51, 1.72-11.9) according to definition a), after adjusting for age, educational level and exposure to passive smoking at work. Conclusion: Depending on definition, prevalence of COPD among never-smokers was 3.0-7.7%, whereas GOLD ≥2 was present in 1.3-2.0%. Occupational exposure to GDF remained independently and significantly associated with COPD regardless of spirometric definition of the disease.
    No preview · Article · Sep 2015 · Respiratory medicine

  • No preview · Article · Sep 2015 · European Respiratory Journal

  • No preview · Article · Sep 2015 · European Respiratory Journal

  • No preview · Article · Sep 2015 · European Respiratory Journal
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    Full-text · Article · Sep 2015 · European Respiratory Journal
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    Full-text · Article · Sep 2015 · European Respiratory Journal
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    ABSTRACT: Welding-related asthma is well recognised but less is known about rhinitis in relation to welding. The aim here, was to study associations between welding, rhinitis and asthma in a general population sample, and factors influencing selection into and out of a welding occupation.Adult-onset asthma and non-infectious rhinitis were investigated in the international multicentre population-based Respiratory Health in Northern Europe (RHINE) study, including 16 191 responders aged 26-54 years. Ever welding (n=2181), welding >25% of working time (n=747), and welding in stainless steel >6 months (n=173) were assessed by questionnaire. Subjects with rhinitis or asthma onset when aged <18 years were excluded. Incidence rates for asthma and rhinitis were calculated from year of disease onset, and start and end of welding job. Cox's proportional hazard models adjusting for age, sex, parental education and study centre, and Kaplan-Meier curves were used.Rhinitis incidence was higher among welders (hazard ratio (HR) 1.4, 95% CI 1.3-1.6), consistent in men and women, and across centres (pheterogeneity=0.4). In men, asthma incidence was higher among welders (HR 1.4, 95% CI 1.04-1.97). Quitting welding was indicated higher after adult-onset rhinitis (HR 1.1, 95% CI 1.0-1.3).Adult-onset rhinitis and asthma was higher among welders, consistent across population samples from Northern Europe. No pre-employment selection was found, whereas selection out of welding jobs was suggested. Copyright ©ERS 2015.
    No preview · Article · Jul 2015 · European Respiratory Journal
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    ABSTRACT: Objectives To investigate the association between living near dense traffic and lung function in a cohort of adults from a single urban region. Design Cross-sectional results from a cohort study. Setting The adult-onset asthma and exhaled nitric oxide (ADONIX) cohort, sampled during 2001–2008 in Gothenburg, Sweden. Exposure was expressed as the distance from participants’ residential address to the nearest road with dense traffic (>10 000 vehicles per day) or very dense traffic (>30 000 vehicles per day). The exposure categories were: low (>500 m; reference), medium (75–500 m) or high (<75 m). Participants The source population was a population-based cohort of adults (n=6153). The study population included 5441 participants of European descent with good quality spirometry and information about all outcomes and covariates. Outcome measures Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were measured at a clinical examination. The association with exposure was examined using linear regression adjusting for age, gender, body mass index, smoking status and education in all participants and stratified by sex, smoking status and respiratory health status. Results We identified a significant dose–response trend between exposure category and FEV1 (p=0.03) and borderline significant trend for FVC (p=0.06) after adjusting for covariates. High exposure was associated with lower FEV1 (−1.0%, 95% CI −2.5% to 0.5%) and lower FVC (−0.9%, 95% CI −2.2% to 0.4%). The effect appeared to be stronger in women. In highly exposed individuals with current asthma or chronic obstructive pulmonary disease, FVC was lower (−4.5%, 95% CI −8.8% to −0.1%). Conclusions High traffic exposure at the residential address was associated with lower than predicted FEV1 and FVC lung function compared with living further away in a large general population cohort. There were particular effects on women and individuals with obstructive disease.
    Full-text · Article · Jun 2015 · BMJ Open
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    ABSTRACT: Cardiopulmonary diseases are major causes of death worldwide, but currently recommended strategies for diagnosis and prevention may be outdated because of recent changes in risk factor patterns. The Swedish CArdioPulmonarybioImage Study (SCAPIS) combines the use of new imaging technologies, advances in large-scale 'omics' and epidemiological analyses to extensively characterize a Swedish cohort of 30 000 men and women aged between 50 and 64 years. The information obtained will be used to improve risk prediction of cardiopulmonary diseases and optimize the ability to study disease mechanisms. A comprehensive pilot study in 1111 individuals, which was completed in 2012, demonstrated the feasibility and financial and ethical consequences of SCAPIS. Recruitment to the national, multicentre study has recently started. © 2015 The Authors. Journal of Internal Medicine published by John Wiley & Sons Ltd on behalf of Association for Publication of The Journal of Internal Medicine.
    No preview · Article · Jun 2015 · Journal of Internal Medicine
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    ABSTRACT: Low cardiovascular fitness (fitness) in mid- and late life is a risk factor for stroke. However, the respective effects on long-term stroke risk of fitness and muscle strength in early adulthood are unknown. Therefore, we analyzed these in a large cohort of young men. We performed a population-based longitudinal cohort study of Swedish male conscripts registered in 1968 to 2005. Data on fitness (by the cycle ergometric test; n=1 166 035) and muscle strength (n=1 563 750) were trichotomized (low, medium, and high). During a 42-year follow-up, risk of stroke (subarachnoidal hemorrhage, intracerebral hemorrhage, and ischemic stroke) and fatality were calculated with Cox proportional hazards models. To identify cases, we used the International Classification of Diseases-Eighth to Tenth Revision in the Hospital Discharge Register and the Cause of Death Register. First-time stroke events were identified (subarachnoidal hemorrhage, n=895; intracerebral hemorrhage, n=2904; ischemic stroke, n=7767). For all stroke and fatality analysis any type of first-time stroke was recorded (n=10 917). There were inverse relationships in a dose-response fashion between fitness and muscle strength with any stroke (adjusted hazard ratios for the lowest, compared with the highest, tertile of each 1.70 [1.50-1.93] and 1.39 [1.27-1.53], respectively). There were stronger associations for fatal stroke. All 3 stroke types displayed similar associations. Associations between fitness and stroke remained when adjusted for muscle strength, whereas associations between muscle strength and stroke weakened/disappeared when adjusted for fitness. At the age of 18 years, low fitness and to a lesser degree low muscle strength were independently associated with an increased future stroke risk. © 2015 American Heart Association, Inc.
    No preview · Article · Jun 2015 · Stroke
  • Paul D Blanc · Bengt Järvholm · Kjell Torén
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    ABSTRACT: The association between occupational exposure and autoimmune disease is well recognized for silica and suspected for other inhalants. We used a large cohort to estimate the risks rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis and dermatomyositis associated with silica and other occupational exposures. We analyzed data for male Swedish construction industry employees. Exposure was defined by a job exposure matrix for silica and for other inorganic dusts those with other job exposure matrix exposures but not to either of the two inorganic dusts categories were excluded. National hospital treatment data were linked for ICD-10 coded diagnoses of rheumatoid arthritis (seronegative and positive), systemic lupus erythematosus, systemic sclerosis, and dermatomyositis. The two occupational exposures were tested as independent predictors of prospective hospital-based treatment for these diagnoses using age adjusted Poisson multivariable regression analyses to calculate relative risk (RR). We analyzed hospital-based treatment data (1997 through 2010) for 240,983 males aged 30 to 84. There were 713 incident cases of rheumatoid arthritis (467 seropostive; 195 seronegative; 51 not classified) and 128 cases combined for systemic lupus erythematosus, systemic sclerosis, and dermatomyositis. Adjusted for smoking, age, the two occupational exposures (silica and other inorganic dusts) were each associated with increased risk of rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis , and dermatomyositis combined: RR 1.39 (95% CI 1.17-1.64) and RR 1.31 (95% CI 1.11-1.53), respectively. Among ever smokers, both silica and other inorganic dust exposure were associated with increased risk of rheumatoid arthritis (RRs 1.36; 95% CI 1.11-1.68 and 1.42; 95% CI 1.17-1.73, respectively), while among never smokers neither exposure was associated with statistically significant increased risk of rheumatoid arthritis. This analysis reaffirms the link between occupational silica and a range of auto-immune diseases, while also suggesting that other inorganic dusts, may also impart excess risk of such disease. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · May 2015 · The American journal of medicine
  • Shadi Amid Hägg · Kjell Torén · Eva Lindberg
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    ABSTRACT: This population-based cohort study was performed to assess the association between sleep disturbances and the risk of occupational accidents among women. Data were collected by questionnaires on two different occasions (2000 and 2010) and data on work injuries were also collected from Swedish government records (ISA). Insomnia symptoms were defined as having severe or very severe problems with (i) difficulty initiating sleep, (ii) difficulty maintaining sleep, or (iii) early morning awakening. Symptom of obstructive sleep apnea syndrome (OSAS) was defined as reporting both snoring and daytime sleepiness. Working-age respondents (20-67 years of age) who responded to both baseline and follow-up questionnaires and had worked for part or all of the 10-year follow-up period (N=4320) were included in the study. Of the subjects responding to the questionnaire, 12.2% reported ≥1 accident and 6.3% reported an accident requiring sick leave in the government register. Blue-collar workers and night and shift work were more common in the group with occupational accidents. Subjects with insomnia symptoms both at baseline and follow-up (persistent insomnia symptoms) ran a higher risk of being involved in an self-reported occupational accident [adjusted OR (OR adj) 1.5, 95% confidence interval (95% CI) 1.2-2.0] after adjusting for age, body mass index, smoking, alcohol dependency, white- or blue-collar worker, years at work, night work, and physical activity. Persistent insomnia symptoms did not reach statistical significance as an independent predictor of register-reported occupational accident with sick leave (OR adj1.4, 95% CI 0.99-2.1). No significant association was found between symptoms of OSAS and self-reported or register-based occupational accidents. Persistent insomnia symptoms were associated with an increased risk of self-reported occupational accidents, while no significant association was found with occupational accidents with sick leave reported to government register.
    No preview · Article · Apr 2015 · Scandinavian Journal of Work, Environment & Health

Publication Stats

8k Citations
1,349.09 Total Impact Points


  • 2005-2016
    • University of Gothenburg
      • • Unit of Occupational and Environmental Medicine
      • • Department of Internal Medicine and Clinical Nutrition
      • • Institute of Medicine
      • • Department of Public Health and Community Medicine
      Goeteborg, Västra Götaland, Sweden
  • 2013-2015
    • Università degli Studi di Perugia
      Perugia, Umbria, Italy
  • 1991-2015
    • Sahlgrenska University Hospital
      • Department of Cardiology
      Goeteborg, Västra Götaland, Sweden
  • 2014
    • Haukeland University Hospital
      • Department of Thoracic Medicine
      Bergen, Hordaland, Norway
  • 2004-2013
    • Karolinska Institutet
      • • Institute of Environmental Medicine - IMM
      • • Department of Physiology and Pharmacology
      Solna, Stockholm, Sweden
  • 2010
    • Public Health Agency of Sweden
      Tukholma, Stockholm, Sweden
  • 2007
    • University of Verona
      Verona, Veneto, Italy
    • Mid Sweden University
      Härnösand, Västernorrland, Sweden
  • 2004-2005
    • Umeå University
      • Department of Public Health and Clinical Medicine
      Umeå, Västerbotten, Sweden
  • 2000
    • University of California, San Francisco
      • Department of Medicine
      San Francisco, California, United States