Anders Thelin

Unexpected high prevalence of IgG-antibodies to hepatitis E virus in Swedish pig farmers and controls

Hepatitis E virus (HEV) infections are responsible for large waterborne outbreaks in developing countries. Sporadic cases in the developed world are mainly imported via immigrants and travellers from endemic areas. HEV has been suggested to be a zoonotic infection where pigs may be an important reservoir for the disease and specific swine strains of HEV have been identified which can infect also humans. The aim of this study was to analyse if Swedish pig farmers are more exposed to HEV than persons with other occupations. A total of 115 male pig farmers aged 40–60 y and 108 age- and geographically- matched control subjects were tested for IgG anti-HEV antibodies. No statistical difference in anti-HEV prevalence was noted between pig farmers (13.0%) and control subjects (9.3%). The prevalence of anti-HEV antibodies in the pig farmers and controls was higher than that previously reported among other populations in Europe (<1 – 9%). Further studies are needed to elucidate the routes for infection of indigenous HEV and if sub-clinical infections with pig associated HEV strains occur in Sweden.

Knee osteoarthritis and body mass index: a population-based case-control study.

Objective: It is well established that overweight is related to osteoarthritis of the knees. The aim of this study was to investigate the risk of knee osteoarthritis for men and women in relation to body mass index (BMI) within the normal weight range and to assess the effect of former versus current weight. Methods: A population‐based case–control study was carried out in the southern part of Sweden, including 825 cases with X‐ray verified femorotibial osteoarthritis and 825 age‐, sex‐, and county‐matched population controls. Mailed questionnaire data on weight, height, and confounding factors (heredity, smoking, knee injuries, and physical activity) were collected and analysed using logistic regression models. The response frequency was 89%. Results: Mean age of the participants was 63 years, and 57% were women. The adjusted risk of knee osteoarthritis was increased fourfold in men with a current BMI 23 to <25 kg/m2 as compared to men with BMI <23 kg/m2 (OR 4.0, 95% CI 1.7–9.5). The commensurate risk for women was 1.6 (95% CI 0.9–3.1). BMI at 30 years of age was similarly related to knee osteoarthritis. Conclusion: A moderate increase in BMI, within the normal weight range, was significantly related to knee osteoarthritis among men. Overweight at any time was related to knee osteoarthritis.

Musculoskeletal symptoms among farmers and non-farmers : A population-based study

Abstract Farming has been considered a high-risk occupation for musculoskeletal disorders. However, documentation of the increased risk is weak except for hip osteoarthritis. 1,013 full-time farmers in nine Swedish municipalities and 769 non-farmers (referents), matched for age, sex, and residential area, participated in the study. Information about medical history, consultations, and sick leave for musculoskeletal disorders was obtained by questionnaire and interview. The farmers reported significantly more symptoms affecting the hands and forearms, low back, and hips than did the non-farmers, and a non-significant trend in the same direction was found for symptoms from the neck, shoulders, and knees. However, the farmers did not seek medical advice more often than the referents, and they reported significantly less sick leave for these problems. Thus, farmers appear to have more musculoskeletal symptoms than do non-farmers

Knee injuries account for the sports-related increased risk of knee osteoarthritis.

Increased risk of osteoarthritis has been found among athletes active in different kinds of sports. Knee injury is an established risk factor for knee osteoarthritis. In this population‐based case–control study we investigated the risk of knee osteoarthritis with respect to sports activity and previous knee injuries. A total of 825 cases with x‐ray‐verified femorotibial osteoarthritis were identified at six hospitals in southern Sweden. The cases were matched (age, sex and residential area) with 825 controls from the general population. Mailed questionnaire data on sports activity for more than 1 year after the age of 16, knee injuries and confounding variables (weight, height, heredity, smoking and occupation) were collected and analyzed using logistic regression models. The response frequency was 89%. Among men knee osteoarthritis was related to soccer (odds ratio (OR) 1.6, 95% confidence interval (CI) 1.1–2.2), ice hockey (OR 1.9, 95% CI 1.2–3.0) and tennis (OR 2.0, 95% CI 1.1–3.8) but not to track and field sports, cross‐country skiing, and orienteering. After adjustment for confounding variables soccer and ice hockey remained significantly related to knee osteoarthritis, but after adjustment for knee injuries no significant relation remained. The sports‐related increased risk for knee osteoarthritis was explained by knee injuries.

Primary care consultation, hospital admission, sick leave and disability pension owing to neck and low back pain: a 12-year prospective cohort study in a rural population

BackgroundNeck and low back pain are common musculoskeletal complaints generating large societal costs in Western populations. In this study we evaluate the magnitude of long-term health outcomes for neck and low back pain, taking possible confounders into account.MethodA cohort of 2,351 Swedish male farmers and rural non-farmers (40–60 years old) was established in 1989. In the first survey, conducted in 1990–91, 1,782 men participated. A 12-year follow-up survey was made in 2002–03 and 1,405 men participated at both times. After exclusion of 58 individuals reporting a specific back diagnosis in 1990–91, the study cohort encompassed 1,347 men. The health outcomes primary care consultation, hospital admission, sick leave and disability pension were assessed in structured interviews in 2002–03 (survey 2). Symptoms and potential confounders were assessed at survey 1, with the exception of rating of depression and anxiety, which was assessed at survey 2. Multiple logistic regression generating odds ratios (OR) with 95% confidence intervals (95% CI) was performed to adjust the associations between reported symptoms and health outcomes for potential confounders (age, farming, workload, education, demand and control at work, body mass index, smoking, snuff use, alcohol consumption, psychiatric symptoms and specific back diagnoses during follow up).ResultsOf the 836 men reporting current neck and/or low back pain at survey 1, 21% had had at least one primary care consultation for neck or low back problems, 7% had been on sick leave and 4% had disability pension owing to the condition during the 12 year follow up. Current neck and/or low back pain at survey 1 predicted primary care consultations (OR = 4.10, 95% CI 2.24–7.49) and sick leave (OR = 3.22, 95% CI 1.13–9.22) after potential confounders were considered. Lower education and more psychiatric symptoms were independently related to sick leave. Lower education and snuff use independently predicted disability pension.ConclusionFew individuals with neck or low back pain were on sick leave or were granted a disability pension owing to neck or low back problems during 12 years of follow up. Symptoms at baseline independently predicted health outcomes. Educational level and symptoms of depression/anxiety were important modifiers.

A prospective study of morbidity and mortality rates among farmers and rural and urban nonfarmers

Farmers are known to have lower morbidity and mortality rates than the mean for other occupational groups in the general population. Whether this is due to the urban-rural health gradient or to occupational factors related to farming is not clear. To explore this issue, we conducted a prospective study of farmers and matched rural and urban referents. Official hospital admission and mortality data for the years 1989-1996 were obtained. The relative risk of being admitted to hospital were 10% higher among rural and urban referents than among the farmers. The biggest differences were seen for mental and cardiovascular disorders. The odds of dying during follow-up did not differ between the two rural groups but were doubled among urban referents. In conclusion, the lower morbidity and mortality rates among farmers are partly due to the urban-rural health gradient but in addition salutogenic factors linked to farming seem to be active.

High dairy fat intake related to less central obesity: a male cohort study with 12 years' follow-up.

Abstract Objective. To study associations between dairy fat intake and development of central obesity. Design. A prospective population-based cohort study with two surveys 12 years apart. Setting. Nine municipalities selected from different parts of Sweden representing the rural areas in the country. Subjects. 1782 men (farmers and non-farmers) aged 40–60 years at baseline participated in a baseline survey (participation rate 76%) and 1589 men participated at the follow-up. 116 men with central obesity at baseline were excluded from the analyses. Main outcome measures. Central obesity at follow-up defined as waist hip ratio ≥ 1. Results. 197 men (15%) developed central obesity during follow-up. A low intake of dairy fat at baseline (no butter and low fat milk and seldom/never whipping cream) was associated with a higher risk of developing central obesity (OR 1.53, 95% CI 1.05–2.24) and a high intake of dairy fat (butter as spread and high fat milk and whipping cream) was associated with a lower risk of central obesity (OR 0.52, 95% CI 0.33–0.83) as compared with medium intake (all other combinations of spread, milk, and cream) after adjustment for intake of fruit and vegetables, smoking, alcohol consumption, physical activity, age, education, and profession. The associations between dairy fat intake and central obesity were consistent across body mass index categories at baseline. Conclusion. A high intake of dairy fat was associated with a lower risk of central obesity and a low dairy fat intake was associated with a higher risk of central obesity.

Functioning in neck and low back pain from a 12-year perspective : A prospective population-based study

OBJECTIVE The aim of this study was to evaluate the effects of unspecific neck pain and low back pain at a given time (1990-91) with respect to physical and social functioning and role limitations due to emotional problems 12 years later. METHODS A rural male study population (2351 individuals) was established in 1989 and a first survey conducted in 1990-91. A follow-up survey was performed in 2002-03. A total of 1405 persons participated in both surveys. Functioning and role limitations in 2002-03 were evaluated using the SF-36 instrument. Several possible confounders were included in the analyses. RESULTS Unspecific neck pain or low back pain in 1990-91 was shown in a multivariate longitudinal regression model to be significantly related to limited physical (odds ratio (OR)=2.08; 95% confidence interval (CI) 1.51-2.87) and social (OR=1.92; 95% CI 1.33-2.75) functioning 12 years later. The effects were only slightly modified by the confounders analysed. However, higher education independently and significantly predicted a low risk for functional limitations. CONCLUSION Non-specific neck pain and low back pain at a given time impacted on the risk of limited physical and social functioning many years later. Current symptoms of depression and anxiety at the time for the second survey had a high impact on functional limitations.

Mortality and Morbidity among Farmers, Nonfarming Rural Men, and Urban Referents: A Prospective Population-Based Study

Abstract A cohort of 1,220 farmers, 1,130 nonfarming rural men, and 1,087 urban referents from Sweden were monitored for 12 years. Farmers had lower mortality than urban referents for all causes of death (hazard ratio [HR] = 0.51; 95% confidence interval [CI], 0.37–0.71), cancer (HR = 0.44; 95% CI, 0.24–0.78) and cardiovascular diseases (HR = 0.60; 95% CI, 0.36–0.99). Nonfarming rural men had lower mortality than urban referents for all causes of deaths (HR = 0.81; 95% CI, 0.70–0.94). Farmers and nonfarming rural men had significantly lower morbidity risks of cancer and of psychiatric disorders than urban referents. Farmers had significantly lower risk of endocrine disorders, cardiovascular disorders, and respiratory disorders. In general, morbidity was lower among nonfarming rural men compared with urban referents and was even lower among farmers. Urban referents had, however, significantly less musculoskeletal disorder morbidity. An urban–rural factor and a farming occupational or lifestyle factor results in lower mortality and morbidity rates except concerning musculoskeletal disorders.

Psychosocial factors and low back pain, consultations, and sick leave among farmers and rural referents: A population-based study

Farmers have more low back pain (LBP) than nonfarmers. In a previous report, we found that differences between farmers and nonfarmers in physical work exposure did not explain the LBP differences. In this report, we tested the hypothesis that psychosocial factors might explain the differences in LBP reporting, medical consultation, and sick leave. A cross-sectional population-based survey of 1013 middle-aged farmers and 769 matched referents was performed. Data on LBP, consultations, and sick leave during lifetime was obtained along with information on psychosocial, social network, and lifestyle variables. Several of the psychosocial variables were associated with LBP but the difference in LBP prevalence between farmers and nonfarmers could be explained only marginally. Farmers and self-employed referents tended to have lower odds of sick leave because of LBP than employed referents after adjustment for psychosocial factors.