Regular Physical Activity Levels and Incidence of Restrictive Spirometry Pattern: A Longitudinal Analysis of 2 Population-Based Cohorts.

We estimated the association between regular physical activity and the incidence of restrictive spirometry pattern. Forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), and physical activity were assessed in 2 population-based European cohorts (European Community Respiratory Health Survey: n = 2,757, aged 39-67 years; and Swiss Study on Air Pollution and Lung and Heart Diseases in Adults: n = 2,610, aged 36-82 years) first in 2000-2002 and again approximately 10 years later (2010-2013). Subjects with restrictive or obstructive spirometry pattern at baseline were excluded. We assessed the association of being active at baseline (defined as being physically active at least 2-3 times/week for ≥1 hour) with restrictive spirometry pattern at follow-up (defined as a postbronchodilation FEV1/FVC ratio of at least the lower limit of normal and FVC of <80% predicted) using modified Poisson regression, adjusting for relevant confounders. After 10 years of follow-up, 3.3% of participants had developed restrictive spirometry pattern. Being physically active was associated with a lower risk of developing this phenotype (relative risk = 0.76, 95% confidence interval: 0.59, 0.98). This association was stronger among those who were overweight and obese than among those of normal weight (P for interaction = 0.06). In 2 large European studies, adults practicing regular physical activity were at lower risk of developing restrictive spirometry pattern over 10 years.

Body mass index and weight change are associated with adult lung function trajectories: the prospective ECRHS study.

BACKGROUND: Previous studies have reported an association between weight increase and excess lung function decline in young adults followed for short periods. We aimed to estimate lung function trajectories during adulthood from 20-year weight change profiles using data from the population-based European Community Respiratory Health Survey (ECRHS). METHODS: We included 3673 participants recruited at age 20-44 years with repeated measurements of weight and lung function (forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1)) in three study waves (1991-93, 1999-2003, 2010-14) until they were 39-67 years of age. We classified subjects into weight change profiles according to baseline body mass index (BMI) categories and weight change over 20 years. We estimated trajectories of lung function over time as a function of weight change profiles using population-averaged generalised estimating equations. RESULTS: In individuals with normal BMI, overweight and obesity at baseline, moderate (0.25-1 kg/year) and high weight gain (>1 kg/year) during follow-up were associated with accelerated FVC and FEV1 declines. Compared with participants with baseline normal BMI and stable weight (±0.25 kg/year), obese individuals with high weight gain during follow-up had -1011 mL (95% CI -1.259 to -763) lower estimated FVC at 65 years despite similar estimated FVC levels at 25 years. Obese individuals at baseline who lost weight (<-0.25 kg/year) exhibited an attenuation of FVC and FEV1 declines. We found no association between weight change profiles and FEV1/FVC decline. CONCLUSION: Moderate and high weight gain over 20 years was associated with accelerated lung function decline, while weight loss was related to its attenuation. Control of weight gain is important for maintaining good lung function in adult life.

Determinants of fractional exhaled nitric oxide in healthy men and women from the European Community Respiratory Health Survey III.

INTRODUCTION: The fractional exhaled nitric oxide (FE NO) is a marker for type 2 inflammation used in diagnostics and management of asthma. In order to use FE NO as a reliable biomarker, it is important to investigate factors that influence FE NO in healthy individuals. Men have higher levels of FE NO than women, but it is unclear whether determinants of FE NO differ by sex. OBJECTIVE: To identify determinants of FE NO in men and women without lung diseases. METHOD: Fractional exhaled nitric oxide was validly measured in 3881 healthy subjects that had answered the main questionnaire of the European Community Respiratory Health Survey III without airways or lung disease. RESULTS: Exhaled NO levels were 21.3% higher in men compared with women P < 0.001. Being in the upper age quartile (60.3-67.6 years), men had 19.2 ppb (95% CI: 18.3, 20.2) higher FE NO than subjects in the lowest age quartile (39.7-48.3 years) P = 0.02. Women in the two highest age quartiles (54.6-60.2 and 60.3-67.6 years) had 15.4 ppb (14.7, 16.2), P = 0.03 and 16.4 ppb (15.6, 17.1), P = <0.001 higher FE NO, compared with the lowest age quartile. Height was related to 8% higher FE NO level in men (P < 0.001) and 5% higher FE NO levels in women (P = 0.008). Men who smoked had 37% lower FE NO levels and women had 30% lower levels compared with never-smokers (P < 0.001 for both). Men and women sensitized to both grass and perennial allergens had higher FE NO levels compared with non-sensitized subjects 26% and 29%, P < 0.001 for both. CONCLUSION AND CLINICAL RELEVANCE: Fractional exhaled nitric oxide levels were higher in men than women. Similar effects of current smoking, height, and IgE sensitization were found in both sexes. FE NO started increasing at lower age in women than in men, suggesting that interpretation of FE NO levels in adults aged over 50 years should take into account age and sex.

Occupational exposures and incidence of chronic bronchitis and related symptoms over two decades: the European Community Respiratory Health Survey.

OBJECTIVES: Chronic bronchitis (CB) is an important chronic obstructive pulmonary disease (COPD)-related phenotype, with distinct clinical features and prognostic implications. Occupational exposures have been previously associated with increased risk of CB but few studies have examined this association prospectively using objective exposure assessment. We examined the effect of occupational exposures on CB incidence in the European Community Respiratory Health Survey. METHODS: Population samples aged 20-44 were randomly selected in 1991-1993, and followed up twice over 20 years. Participants without chronic cough or phlegm at baseline were analysed. Coded job histories during follow-up were linked to the ALOHA Job Exposure Matrix, generating occupational exposure estimates to 12 categories of chemical agents. Their association with CB incidence over both follow-ups was examined with Poisson models using generalised estimating equations. RESULTS: 8794 participants fulfilled the inclusion criteria, contributing 13 185 observations. Only participants exposed to metals had a higher incidence of CB (relative risk (RR) 1.70, 95% CI 1.16 to 2.50) compared with non-exposed to metals. Mineral dust exposure increased the incidence of chronic phlegm (RR 1.72, 95% CI 1.43 to 2.06). Incidence of chronic phlegm was increased in men exposed to gases/fumes and to solvents and in women exposed to pesticides. CONCLUSIONS: Occupational exposures are associated with chronic phlegm and CB, and the evidence is strongest for metals and mineral dust exposure. The observed differences between men and women warrant further investigation.

Effects of smoking bans on passive smoking exposure at work and at home. The European Community respiratory health survey.

This longitudinal study investigated whether smoking bans influence passive smoking at work and/or at home in the same subjects. Passive smoking at work and/or at home was investigated in random population samples (European Community Respiratory Health Survey) in 1990-1995, with follow-up interviews in 1998-2003 and 2010-2014. National smoking bans were classified as partial (restricted to public workplaces) or global (extended to private workplaces). Multivariable analysis was accomplished by three-level logistic regression models, where level-1, level-2, and level-3 units were, respectively, questionnaire responses, subjects, and centers. Passive smoking at work was reported by 31.9% in 1990-1995, 17.5% in 1998-2003, and 2.5% in 2010-2014. Concurrently, passive smoking at home decreased from 28.9% to 18.2% and 8.8%. When controlling for sex, age, education, smoking status, and ECHRS wave, the odds of passive smoking at work was markedly reduced after global smoking bans (OR = 0.45, 95% CI 0.25-0.81), particularly among non-smokers, while the protective effect of global smoking bans on passive smoking at home was only detected in non-smokers. Smoking bans both in public and private workplaces were effective in reducing passive smoking at work in Europe. However, given the inefficacy of smoking bans in current smokers' dwellings, better strategies are needed to avoid smoking indoors.

Leisure-time vigorous physical activity is associated with better lung function: the prospective ECRHS study.

OBJECTIVE: We assessed associations between physical activity and lung function, and its decline, in the prospective population-based European Community Respiratory Health Survey cohort. METHODS: FEV1 and FVC were measured in 3912 participants at 27-57 years and 39-67 years (mean time between examinations=11.1 years). Physical activity frequency and duration were assessed using questionnaires and used to identify active individuals (physical activity ≥2 times and ≥1 hour per week) at each examination. Adjusted mixed linear regression models assessed associations of regular physical activity with FEV1 and FVC. RESULTS: Physical activity frequency and duration increased over the study period. In adjusted models, active individuals at the first examination had higher FEV1 (43.6 mL (95% CI 12.0 to 75.1)) and FVC (53.9 mL (95% CI 17.8 to 89.9)) at both examinations than their non-active counterparts. These associations appeared restricted to current smokers. In the whole population, FEV1 and FVC were higher among those who changed from inactive to active during the follow-up (38.0 mL (95% CI 15.8 to 60.3) and 54.2 mL (95% CI 25.1 to 83.3), respectively) and who were consistently active, compared with those consistently non-active. No associations were found for lung function decline. CONCLUSION: Leisure-time vigorous physical activity was associated with higher FEV1 and FVC over a 10-year period among current smokers, but not with FEV1 and FVC decline.

Prevalence of asthma-like symptoms with ageing.

BACKGROUND: Change in the prevalence of asthma-like symptoms in populations of ageing adults is likely to be influenced by smoking, asthma treatment and atopy. METHODS: The European Community Respiratory Health Survey collected information on prevalent asthma-like symptoms from representative samples of adults aged 20-44 years (29 centres in 13 European countries and Australia) at baseline and 10 and 20 years later (n=7844). Net changes in symptom prevalence were determined using generalised estimating equations (accounting for non-response through inverse probability weighting), followed by meta-analysis of centre level estimates. FINDINGS: Over 20 years the prevalence of 'wheeze' and 'wheeze in the absence of a cold' decreased (-2.4%, 95% CI -3.5 to -1.3%; -1.5%, 95% CI -2.4 to -0.6%, respectively) but the prevalence of asthma attacks, use of asthma medication and hay fever/nasal allergies increased (0.6%, 95% CI 0.1 to 1.11; 3.6%, 95% CI 3.0 to 4.2; 2.7%, 95% CI 1.7 to 3.7). Changes were similar in the first 10 years compared with the second 10 years, except for hay fever/nasal allergies (increase seen in the first 10 years only). Decreases in these wheeze-related symptoms were largely seen in the group who gave up smoking, and were seen in those who reported hay fever/nasal allergies at baseline. INTERPRETATION: European adults born between 1946 and 1970 have, over the last 20 years, experienced less wheeze, although they were more likely to report asthma attacks, use of asthma medication and hay fever. Decrease in wheeze is largely attributable to smoking cessation, rather than improved treatment of asthma. It may also be influenced by reductions in atopy with ageing.

Occupational exposures and 20-year incidence of COPD: the European Community Respiratory Health Survey.

BACKGROUND: Occupational exposures have been associated with an increased risk of COPD. However, few studies have related objectively assessed occupational exposures to prospectively assessed incidence of COPD, using postbronchodilator lung function tests. Our objective was to examine the effect of occupational exposures on COPD incidence in the European Community Respiratory Health Survey. METHODS: General population samples aged 20-44 were randomly selected in 1991-1993 and followed up 20 years later (2010-2012). Spirometry was performed at baseline and at follow-up, with incident COPD defined using a lower limit of normal criterion for postbronchodilator FEV1/FVC. Only participants without COPD and without current asthma at baseline were included. Coded job histories during follow-up were linked to a Job-Exposure Matrix, generating occupational exposure estimates to 12 categories of agents. Their association with COPD incidence was examined in log-binomial models fitted in a Bayesian framework. FINDINGS: 3343 participants fulfilled the inclusion criteria; 89 of them had COPD at follow-up (1.4 cases/1000 person-years). Participants exposed to biological dust had a higher incidence of COPD compared with those unexposed (relative risk (RR) 1.6, 95% CI 1.1 to 2.3), as did those exposed to gases and fumes (RR 1.5, 95% CI 1.0 to 2.2) and pesticides (RR 2.2, 95% CI 1.1 to 3.8). The combined population attributable fraction for these exposures was 21.0%. INTERPRETATION: These results substantially strengthen the evidence base for occupational exposures as an important risk factor for COPD.

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.

Ferritin and body mass index predict cardiac dysfunction in female adolescents with anorexia of the restrictive type.

BACKGROUND AND AIM: Decreased left ventricular mass index in anorexia nervosa is amply reported. The aim of this study is to identify non-burdensome predictors of reduced left yentricular mass/height (cLVM) in a cohort of adolescent restrictive anorexic girls. METHODS: This is a retrospective study of all anorexic girls of the restrictive type referred to our tertiary eating disorder unit between September 2002 and December 2012, for somatic assessment of weig ht loss. All subjects fulfilled DMS-IV criteria, without a family history of cardiac or cardiovascular diseases. RESULTS: In all, 283 restrictive anorexic girls (age: 14.63 +/- 1.65 y; body mass index: 15.72 +/- 1.81 kg/m2) were included. Ferritin and body mass index were independent, statistically significant predictors of the corrected left ventricular mass (P <0.05). CONCLUSION: Decreased cLVM is very common in anorexia nervosa of the restrictive type. Two factors predicted decreased cLVM in our population: ferritin and BMI.

Prevalence of 'being at risk of malnutrition' and associated factors in adult patients receiving nursing care at home in Belgium.

Malnutrition is a known problem in hospitals and nursing homes. This study aims to evaluate the prevalence of being at risk of malnutrition in community living adults receiving homecare nursing and to determine factors independently associated with this risk of malnutrition. Furthermore, it also aimed to describe aspects of current nutritional nursing care. Patients (n = 100) are screened with the Malnutrition Universal Screening Tool to evaluate their risk of malnutrition. A patient survey was used to analyse associated factors. In this population, 29% are at risk for malnutrition. Following a multivariate logistic regression analysis, 'loss of appetite' proved the most important factor. A survey for nurses (n = 61) revealed low awareness, poor knowledge, poor communication between stakeholders and a moderate approach of malnutrition. These findings should encourage homecare nurses to use a recommended screening tool for malnutrition and to actively observe and report loss of appetite to initiate the prescription of individual tailored interventions. Belgian homecare nurses' management does not yet fully comply with international recommendations. Additional training in nutritional nursing care and screening methods for malnutrition is needed. Systematic screening should be further developed and evaluated in this at-risk population.

Determinants of baseline lung function and bronchodilator response in 4-year-old children.

The prolonged period required for maturation of the respiratory system makes it vulnerable to environmental exposure. This study aimed to investigate the association between early-life factors and lung function in preschool children. Children aged 4 years, who were included in a prospective birth cohort, underwent lung function testing at baseline (n=535) and after bronchodilation (n=498) by forced oscillations. Information on symptoms and exposures was collected through half-yearly questionnaires. Allergen-specific serum IgE was quantified at 1 and 4 years. Multiple linear regression analysis showed that the baseline respiratory resistance and reactance area were larger in the children with previous wheeze, those with early-onset sensitisation to inhalant allergens and those who were smaller. Furthermore, children with previous lower respiratory tract infections exhibited higher baseline resistance values. The baseline resistance was the only independent determinant of the bronchodilator-induced change in resistance, whereas current height and baseline reactance area were independently associated with the change in reactance area. In conclusion, previous lower respiratory tract infections, the timing of previous wheeze, inhalant sensitisation and current height independently influence the baseline lung function of 4-year-old children, whereas baseline lung function is the principal determinant of the bronchodilator response.

Body mass index trajectory classes and incident asthma in childhood: results from 8 European Birth Cohorts--a Global Allergy and Asthma European Network initiative.

BACKGROUND: The causal link between body mass index (BMI) or obesity and asthma in children is still being debated. Analyses of large longitudinal studies with a sufficient number of incident cases and in which the time-dependent processes of both excess weight and asthma development can be validly analyzed are lacking. OBJECTIVE: We sought to investigate whether the course of BMI predicts incident asthma in childhood. METHODS: Data from 12,050 subjects of 8 European birth cohorts on asthma and allergies were combined. BMI and doctor-diagnosed asthma were modeled during the first 6 years of life with latent growth mixture modeling and discrete time hazard models. Subpopulations of children were identified with similar standardized BMI trajectories according to age- and sex-specific "World Health Organization (WHO) child growth standards" and "WHO growth standards for school aged children and adolescents" for children up to age 5 years and older than 5 years, respectively (BMI-SDS). These types of growth profiles were analyzed as predictors for incident asthma. RESULTS: Children with a rapid BMI-SDS gain in the first 2 years of life had a higher risk for incident asthma up to age 6 years than children with a less pronounced weight gain slope in early childhood. The hazard ratio was 1.3 (95% CI, 1.1-1.5) after adjustment for birth weight, weight-for-length at birth, gestational age, sex, maternal smoking in pregnancy, breast-feeding, and family history of asthma or allergies. A rapid BMI gain at 2 to 6 years of age in addition to rapid gain in the first 2 years of life did not significantly enhance the risk of asthma. CONCLUSION: Rapid growth in BMI during the first 2 years of life increases the risk of asthma up to age 6 years.

Effects of Weight Change and Weight Cycling on Lung Function in Overweight and Obese Adults.

Rationale: Epidemiological studies have reported on the detrimental effects on lung function after natural, and thus limited, weight gain in unselected populations. Studies on bariatric surgery, on the contrary, have indicated large improvements in lung function after substantial weight loss. Objectives: To study the associations between profound weight loss or gain and pulmonary function within the same population. A second objective was to investigate the effect of weight cycling on pulmonary function. Methods: From our lung function database, we selected the records of subjects in follow-up for continuous positive airway pressure therapy for sleep apnea with a weight change of ⩾20 kg within 5 years. Lung function (N = 255) at baseline was normal except for a tendency toward mild restriction in morbid obesity. Within this sample, 73 subjects were identified with significant "weight cycling", defined as a ⩾10-kg opposite change in body weight before or after the ⩾20-kg weight change. Results: Weight change affected pulmonary function more in men than in women (P < 0.001). In men, forced vital capacity (FVC) increased an average of 1.4% predicted per unit of body mass index after weight loss and the reverse after weight gain, whereas women exhibited a smaller change of 0.9% predicted per unit of body mass index. Weight loss slightly increased the ratio of forced expiratory volume in 1 second to FVC and decreased the specific airway resistance, whereas the opposite occurred with weight gain. Greater effects of weight change on lung function were observed in leaner subjects (P = 0.02) and in older subjects (P < 0.002). Changes in total lung capacity followed the changes in FVC, with no change in residual volume, and the greatest change was observed in functional residual capacity. In subjects with weight cycling, the improvement in lung function due to weight loss was reversed by subsequent weight gain and vice versa. Conclusions: This study provides evidence that the detrimental effect of obesity on lung function is a passive and reversible process.

Nocturnal gastro-oesophageal reflux, asthma and symptoms of OSA: a longitudinal, general population study.

Nocturnal gastro-oesophageal reflux (nGOR) is associated with asthma and obstructive sleep apnoea (OSA). Our aim was to investigate whether nGOR is a risk factor for onset of asthma and onset of respiratory and OSA symptoms in a prospective population-based study. We invited 2640 subjects from Iceland, Sweden and Belgium for two evaluations over a 9-year interval. They participated in structured interviews, answered questionnaires, and underwent spirometries and methacholine challenge testing. nGOR was defined by reported symptoms. Subjects with persistent nGOR (n=123) had an independent increased risk of new asthma at follow-up (OR 2.3, 95% CI 1.1-4.9). Persistent nGOR was independently related to onset of respiratory symptoms (OR 3.0, 95% CI 1.6-5.6). The risk of developing symptoms of OSA was increased in subjects with new and persistent nGOR (OR 2.2, 95% CI 1.3-1.6, and OR 2.0, 95% CI 1.0-3.7, respectively). No significant association was found between nGOR and lung function or bronchial responsiveness. Persistent symptoms of nGOR contribute to the development of asthma and respiratory symptoms. New onset of OSA symptoms is higher among subjects with symptoms of nGOR. These findings provide evidence that nGOR may play a role in the genesis of respiratory symptoms and diseases.

Adverse effects of low occupational cadmium exposure on renal and oxidative stress biomarkers in solderers.

OBJECTIVES: Recent studies suggest adverse health effects after low exposure to cadmium (Cd). Brazing with Cd-containing solder exposes workers to Cd. The purpose of this study was to assess: (1) indicators of Cd exposure in blood (Cd-B)/ urine (Cd-U); (2) the association between Cd-B, Cd-U and renal and oxidative stress biomarkers. METHODS: In this cross-sectional study Cd-B, Cd-U, renal (ie, N-acetyl-ß-D-glucosaminidase/urinary intestinal alkaline phosphatase (IAP)/microalbumin/beta-2-microglobulin/retinol binding protein and oxidative stress markers (ie, derivatives of reactive oxygen metabolites/glutathione peroxidase/superoxide dismutase (SOD)/ advanced oxidation protein products/8-hydroxy-2'-deoxyguanosin/8-isoprostanes) were determined in 36 solderers. RESULTS: Multiple linear regression analysis adjusting for age and pack-years of smoking show that IAP is statistically significantly associated with Cd-B (B=0.24; SE=0.11) and Cd-U (B=0.15; SE=0.07). Also SOD is statistically significantly associated with Cd-B (B=62.96; SE=29.62). The association between SOD and Cd-U is of borderline statistical significance (B=37.69; SE=19.59). CONCLUSIONS: While there is still some debate as whether the Cd-induced tubular effects are reversible or not, IAP and SOD appear as sensitive and potentially useful early biomarkers for the health surveillance of workers exposed to low levels of Cd.

Knowledge, Perceptions and Reporting Practices of Theoretical Design in Causal Observational Epidemiological Studies on the Role of Antibiotic Use in the Occurrence of Asthma in Children.

Good research is driven by study design encompassing theoretical design, design of data collection and design of data processing. In epidemiological research, theoretical design is based on a functional relationship between the occurrence and determinants studied (occurrence function) and should also define that part of the theoretical population and the context to which the results pertain (domain). Both are essential for the design of data collection, the design of data processing and the interpretation of the study results and should be explicitly reported. In order to gain insight into the role of theoretical design in the entire research process before publication, it was decided to informally question the corresponding authors of a selection of 30 articles (20 most recent and 10 less recent) reporting on causal observational epidemiological studies on asthma and early life exposure to antibiotics. The objective was to appraise the perceived knowledgeability of theoretical design among the authors of the selected articles. Fifteen authors responded. Authors were asked to indicate their knowledgeability with the concepts of theoretical design, causal theory, confounding and effect modification on a 5-level Likert scale. Other questions were related to the theoretical design of their study. The vast majority of the authors perceived themselves to be moderately to extremely knowledgeable with confounding and effect modification. Perceived knowledgeability of theoretical design and causal theory was more diverse. When provided with options for an occurrence function, almost all authors indicated "current occurrence as a function of past exposure" for their study. Nevertheless, half of these authors conducted their study based on "future occurrence as a function of current exposure". Even though the authors perceive themselves to be knowledgeable with theoretical design, this is not reflected in their articles. Theoretical design should be well known, implemented and explicitly reported.

Asthma occurrence in children and early life systemic antibiotic use: an incidence density study.

BACKGROUND: Results of studies evaluating the relationship between asthma occurrence and early life antibiotic use have been conflicting. The aim of this study was to investigate the relationship between occurrence of asthma in children and systemic antibiotic use in the first year of life based on an incidence density study with careful consideration of the temporal aspects of the determinant-outcome relationship. METHODS: We conducted an incidence density study nested in a data collection project with information on 1128 mother-child pairs. Systemic antibiotic use in the first year of life was defined as excessive (≥ 4 courses) vs. non-excessive (< 4 courses) use based on information from weekly diaries. Events (cases) were defined as the first parent-reported occurrence of asthma in a child between 1 and 10 years of age. Population time 'at risk' was probed by sampling population moments (controls). Missing data were imputed. Multiple logistic regression was used to assess the association between current first asthma occurrence (incidence density) and systemic antibiotic use in the first year of life, to evaluate effect modification and adjust for confounding. RESULTS: Forty-seven first asthma events and 147 population moments were included. Excessive systemic antibiotic use in the first year of life showed more than twice the incidence density of asthma compared to non-excessive use (adjusted IDR [95% CI]: 2.18 [0.98, 4.87], p = 0.06). The association was more pronounced in children who have had lower respiratory tract infections (LRTIs) in the first year of life compared to children who had no LRTIs in the first year of life (adjusted IDR [95% CI]: 5.17 [1.19, 22.52] versus 1.49 [0.54, 4.14]). CONCLUSIONS: Excessive use of systemic antibiotics in the first year of life may play a role in the genesis of asthma in children. This effect is modified by the occurrence of LRTIs in the first year of life, with a stronger association observed in children experiencing LRTIs in the first year of life.

Self-reported body weight and height on admission to hospital: a reliable method in multi-professional evidence-based nutritional care?

Screening patients' nutritional status on admission to hospital is recommended by evidence-based guidelines on malnutrition. In practice, self-reported values for body weight and height are often used by nurses and dieticians. This study assessed the accuracy of self-reported body weight and height and whether these self-reported values might be influenced by the nature of the health-care worker involved. Patients (n = 611) on admission reported their body weight and height to a nurse and a dietician. Reported values were analysed and compared with the measured values. Self-reported values for body weight and height on admission are not always accurate. Patients do report different values to different health-care workers. Self-reported values for body weight to nurses were more accurate as compared with dieticians. Self-reported values for body weight and height are subject to observer bias and should be used with caution in nutritional screening and multi-professional nutritional care.

The Association between the Occurrence of Asthma and Antecedents of Exposure to Environmental Tobacco Smoke in the Previous Year in Children: An Incidence-Density Study.

In previous studies, the strength of the association between childhood asthma and environmental tobacco smoke (ETS) differed depending on the way ETS was assessed and the type of study conducted. We investigated the relationship between asthma occurrence in children and recent exposure to ETS based on an incidence-density study driven by the explicit formulation of a theoretical design. Additionally, we assessed whether the relationship is modified by perinatal ETS exposure and parental inhalation atopy. The event was conceptualized as 'first doctor's diagnosis of asthma'. Population time was probed by sampling population moments. Exposure to ETS was conceptualized as recent exposure (1 year prior to diagnosis or at sampling) and perinatal exposure (in utero and/or during the first year of life). Thirty-nine events and 117 population moments were included. There was no indication for effect modification by perinatal exposure to ETS or parental inhalation atopy. After adjustment for confounding, an association was observed between occurrence of a first asthma diagnosis and recent ETS exposure: incidence-density ratio 4.94 (95% confidence interval 1.21, 20.13). Asthma occurrence in children is associated with recent exposure to ETS, and this association seems not to be modified by perinatal ETS exposure or parental inhalation atopy.