Jeong-Lim Kim

Fish consumption and school grades in Swedish adolescents: a study of the large general population

Aim:  To study the associations between fish intake and academic achievement as cognitive parameter among Swedish adolescents.

Changes in IgE sensitization and total IgE levels over 20 years of follow-up

Background Cross-sectional studies have reported a lower prevalence of sensitization in older adults, but few longitudinal studies have examined whether this is an aging or a year-of-birth cohort effect. Objective We sought to assess changes in sensitization and total IgE levels in a cohort of European adults as they aged over a 20-year period. Methods Levels of serum specific IgE to common aeroallergens (house dust mite, cat, and grass) and total IgE levels were measured in 3206 adults from 25 centers in the European Community Respiratory Health Survey on 3 occasions over 20 years. Changes in sensitization and total IgE levels were analyzed by using regression analysis corrected for potential differences in laboratory equipment and by using inverse sampling probability weights to account for nonresponse. Results Over the 20-year follow-up, the prevalence of sensitization to at least 1 of the 3 allergens decreased from 29.4% to 24.8% (−4.6%; 95% CI, −7.0% to −2.1%). The prevalence of sensitization to house dust mite (−4.3%; 95% CI, −6.0% to −2.6%) and cat (−2.1%; 95% CI, −3.6% to −0.7%) decreased more than sensitization to grass (−0.6%; 95% CI, −2.5% to 1.3%). Age-specific prevalence of sensitization to house dust mite and cat did not differ between year-of-birth cohorts, but sensitization to grass was most prevalent in the most recent ones. Overall, total IgE levels decreased significantly (geometric mean ratio, 0.63; 95% CI, 0.58-0.68) at all ages in all year-of-birth cohorts. Conclusion Aging was associated with lower levels of sensitization, especially to house dust mite and cat, after the age of 20 years.

Exposure to traffic and lung function in adults: a general population cohort study

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.

Respiratory symptoms and respiratory-related absence from work among health care workers in Sweden.

Objective. To investigate respiratory symptoms and respiratory-related absence from work among Swedish health care workers (HCWs). Methods. From a postal questionnaire study among a general Swedish working population (n = 12,186), we identified 2156 HCW (555 assistant nurses, 377 nurses, 109 physicians, and 1115 others), including 429 with mainly cleaning tasks (HCW-cleaning). The remaining respondents were classified as non-HCW. Multiple logistic regressions with 95% confidence intervals (CIs) were used to compare respiratory symptoms and respiratory-related absence from work between HCW and non-HCW, adjusting for potential confounders. Results. The prevalence of adult onset asthma was 4.3% in HCW and 3.0% in non-HCW (p = .003). Asthmatic symptoms during the past year were reported mainly by HCW-cleaning, 14.7%, in comparison to 8.3% among non-HCW (p < .0001). HCW had an increased odds ratio (OR) for asthmatic symptoms during the past year (OR 1.3, 95% CI (1.1–1.5)) and more prominent among assistant nurses (OR 1.5, 95% CI (1.1–2.0)) and HCW-cleaning (OR 1.9, 95% CI (1.4–2.5)). Respiratory-related absence from work in the past year was reported by 1.4% of non-HCW, 3.0% of HCW-cleaning, 2.9% of nurses, and 1.6% of assistant nurses. Taking smoking and age into account, there was still significantly increased respiratory-related absence from work in nurses (OR 2.0, 95% CI (1.1–3.8)) and in HCW-cleaning (OR 2.1, 95% CI (1.2–3.7)). Conclusions. HCW in Sweden, especially those with cleaning tasks, reported more respiratory symptoms and respiratory-related absence from work than the general working population. There is a need for longitudinal studies with detailed information on both occupational exposures and socioeconomic factors to explore what influences respiratory-related absence from work among HCW.

Predictors of respiratory sickness absence: an international population-based study.

BACKGROUND Respiratory tract-related occupational disability is common among adults of working age. We examined occupational vapors, gas, dust, or fume (VGDF) exposure as a predictor of disability, based on respiratory sickness absence among the actively employed, at an early point at which prevention may be most relevant. METHODS Currently employed European Community Respiratory Health Survey II participants (n = 6,988) were classified into three mutually exclusive, condition/symptom-based categories: physician-diagnosed asthma, self-reported rhinitis, and wheeze/breathlessness (n = 4,772). Logistic regression analysis estimated the odds of respiratory sickness absence (past 12 months) by VGDF exposure. RESULTS In the condition/symptom groups, 327 (6.9%) reported respiratory sickness absence. Exposure to VGDF was associated with increased odds of respiratory sickness absence: asthma odds ratio [OR] 2.0 (95% confidence interval [CI] 1.1-3.6), wheeze/breathlessness OR 2.2 (95% CI 1.01-4.8); rhinitis OR 1.9 (95% CI 1.02-3.4). CONCLUSION One in 15 currently employed with asthma, breathlessness, or rhinitis reported respiratory sickness absence. VGDF exposure doubled the odds of respiratory sickness absence, suggesting a focus for disability prevention.

Spirometric reference equations for Swedish adults

New spirometric reference equations for Swedish adults are required. Three different older sets of reference equations clinically used in Sweden have various drawbacks and the recently published ‘The Global Lung Function 2012 (GLI) equations’ have been shown not to be adequate for Swedish normal, healthy non‐smokers. We have recently concluded that a piecewise linear model presented by Lubinski and Gólczewski accurately describes the distribution of spirometric variables in a large Swedish random population sample. This piecewise linear model also offers the important advantage of implementing easily physiologically interpretable coefficients. The present study aimed at presenting piecewise linear reference equations for Swedish adults based on a random population sample of 6685 individuals aged 25–75 years. Predicted normal values by the piecewise linear reference equations and lower limit normal (LLN) were compared with the three reference equations frequently used clinically in Sweden and the GLI equations. We found predicted normal values according to the present piecewise linear reference equations close to 100% predicted normal as expected, whereas the other equations either overestimated or underestimated normal subjects. Concerning LLN, the present equations, i.e. 1·645 × RSD, showed the least deviation from the expected 5% and, e.g., the GLI equations systematically identified too few subjects below LLN. We conclude that the present piecewise linear reference equations, based on a relatively large general population sample, ought to be considered for clinical use in Sweden. Application of 1·645 × RSD below predicted value gave an acceptably accurate LLN.

Lipid composition of particles in exhaled air (PEx) from workers exposed to welding fumes

More than two million workers are exposed to pneumotoxic welding aerosols and there is a need for biomarkers of effects on the respiratory system. The lipid composition of the respiratory tract lining fluid (RTLF) is such a potential marker. The most abundant pulmonary surfactant phospholipid is dipalmitoylphosphocholine (DPPC). It is specific for the airways, while palmitoyloleoylphosphatidylcholine (POPC) is a common lipid in tissues and body fluids. We hypothesize that the amounts of or ratio between DPPC and DOPC are changed due to short term and/or long term exposure to welding fumes. We have developed a method for the collection of PEx, based on counting of the exhaled particles and subsequent collection by impaction on a teflon membrane. We have also developed a method for analysis of lipids in PEx based on LC/MS. We measured the exposure to iron, manganese, chromium and nickel of 18 stainless steel welders and also analyzed DPPC and DOPC in PEx samples taken at the end of the exposure measurement day. The welders working history was also recoded and summarized as welding years. Spirometry and nitrogen multiple breath wash out were also measured but the results are not yet evaluated. There were no significant correlations between the short term exposure to either iron, manganese, chromium or nickel and the fraction of DPPC in PEx or the ratio DPPC/DOPC. However, there was a tendency of correlation (Spearman correlation coefficient= 0.407 with p-value 0.09) between welding years and the DPPC/DOPC ratio. In this pilot study we could not establish short term effects of welding exposure on the RTFL lipid composition but a tendency of change due the long time exposure.