Longterm follow-up in European respiratory health studies - patterns and implications

Maternal age at delivery, lung function and asthma in offspring: a population-based survey

There is limited information about potential impact of maternal age on the respiratory health of offspring. We investigated the association of maternal age at delivery with adult offspring's lung function, respiratory symptoms and asthma, and potential differences according to offspring sex.10 692 adults from 13 countries participating in the European Community Respiratory Health Survey (ECRHS) II responded to standardised interviews and provided lung function measurements and serum for IgE measurements at age 25-55 years. In logistic and linear multilevel mixed models we adjusted for participants' characteristics (age, education, centre, number of older siblings) and maternal characteristics (smoking in pregnancy, education) while investigating for differential effects by sex. Maternal age was validated in a subsample using data from the Norwegian birth registry.Increasing maternal age was associated with increasing forced expiratory volume in 1 s (2.33 mL per year, 95% CI 0.34-4.32 mL per year), more consistent in females (p_trend 0.025) than in males (p_trend 0.14). Asthma (OR 0.85, 95% CI 0.79-0.92) and respiratory symptoms (OR 0.87, 95% CI 0.82-0.92) decreased with increasing maternal age (per 5 years) in females, but not in males (p_interaction 0.05 and 0.001, respectively). The results were consistent across centres and not explained by confounding factors.Maternal ageing was related to higher adult lung function and less asthma/symptoms in females. Biological characteristics in offspring related to maternal ageing are plausible and need further investigation.

An Official American Thoracic Society Workshop Report: Presentations and Discussion of the Sixth Jack Pepys Workshop on Asthma in the Workplace

The Sixth Jack Pepys Workshop on Asthma in the Workplace focused on six key themes regarding the recognition and assessment of work-related asthma and airway diseases: (1) cleaning agents and disinfectants (including in swimming pools) as irritants and sensitizers: how to evaluate types of bronchial reactions and reduce risks; (2) population-based studies of occupational obstructive diseases: use of databanks, advantages and pitfalls, what strategies to deal with biases and confounding?; (3) damp environments, dilapidated buildings, recycling processes, and molds, an increasing problem: mechanisms, how to assess causality and diagnosis; (4) diagnosis of occupational asthma and rhinitis: how useful are recombinant allergens (component-resolved diagnosis), metabolomics, and other new tests?; (5) how does exposure to gas, dust, and fumes enhance sensitization and asthma?; and (6) how to determine probability of occupational causality in chronic obstructive pulmonary disease: epidemiological and clinical, confirmation, and compensation aspects. A summary of the presentations and discussion is provided in this proceedings document. Increased knowledge has been gained in each topic over the past few years, but there remain aspects of controversy and uncertainty requiring further research.

Airway responsiveness to methacholine and incidence of COPD: an international prospective cohort study

Background

It has been debated, but not yet established, whether increased airway responsiveness can predict COPD. Recognising this link may help in identifying subjects at risk.

Objective

We studied prospectively whether airway responsiveness is associated with the risk of developing COPD.

Methods

We pooled data from two multicentre cohort studies that collected data from three time points using similar methods (European Community Respiratory Health Survey and Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults). We classified subjects (median age 37 years, 1st–3rd quartiles: 29–44) by their level of airway responsiveness using quintiles of methacholine dose–response slope at the first examination (1991–1994). Then, we excluded subjects with airflow obstruction at the second examination (1999–2003) and analysed incidence of COPD (postbronchodilator FEV₁/FVC below the lower limit of normal) at the third examination (2010–2014) as a function of responsiveness, adjusting for sex, age, education, body mass index, history of asthma, smoking, occupational exposures and indicators of airway calibre.

Results

We observed 108 new cases of COPD among 4205 subjects during a median time of 9 years. Compared with the least responsive group (incidence rate 0.6 per 1000/year), adjusted incidence rate ratios for COPD ranged from 1.79 (95% CI 0.52 to 6.13) to 8.91 (95% CI 3.67 to 21.66) for increasing airway responsiveness. Similar dose–response associations were observed between smokers and non-smokers, and stronger associations were found among subjects without a history of asthma or asthma-like symptoms.

Conclusions

Our study suggests that increased airway responsiveness is an independent risk factor for COPD. Further research should clarify whether early treatment in patients with high responsiveness can slow down disease progression.

Body silhouettes as a tool to reflect obesity in the past

Life course data on obesity may enrich the quality of epidemiologic studies analysing health consequences of obesity. However, achieving such data may require substantial resources.

We investigated the use of body silhouettes in adults as a tool to reflect obesity in the past. We used large population-based samples to analyse to what extent self-reported body silhouettes correlated with the previously measured (9–23 years) body mass index (BMI) from both measured (European Community Respiratory Health Survey, N = 3 041) and self-reported (Respiratory Health In Northern Europe study, N = 3 410) height and weight. We calculated Spearman correlation between BMI and body silhouettes and ROC-curve analyses for identifying obesity (BMI ≥30) at ages 30 and 45 years. Spearman correlations between measured BMI age 30 (±2y) or 45 (±2y) and body silhouettes in women and men were between 0.62–0.66 and correlations for self-reported BMI were between 0.58–0.70. The area under the curve for identification of obesity at age 30 using body silhouettes vs previously measured BMI at age 30 (±2y) was 0.92 (95% CI 0.87, 0.97) and 0.85 (95% CI 0.75, 0.95) in women and men, respectively; for previously self-reported BMI, 0.92 (95% CI 0.88, 0.95) and 0.90 (95% CI 0.85, 0.96). Our study suggests that body silhouettes are a useful epidemiological tool, enabling retrospective differentiation of obesity and non-obesity in adult women and men.

Father's environment before conception and asthma risk in his children: a multi-generation analysis of the Respiratory Health In Northern Europe study

Background

Whereas it is generally accepted that maternal environment plays a key role in child health, emerging evidence suggests that paternal environment before conception also impacts child health. We aimed to investigate the association between children's asthma risk and parental smoking and welding exposures prior to conception.

Methods

In a longitudinal, multi-country study, parents of 24 168 offspring aged 2-51 years provided information on their life-course smoking habits, occupational exposure to welding and metal fumes, and offspring's asthma before/after age 10 years and hay fever. Logistic regressions investigated the relevant associations controlled for age, study centre, parental characteristics (age, asthma, education) and clustering by family.

Results

Non-allergic early-onset asthma (asthma without hay fever, present in 5.8%) was more common in the offspring with fathers who smoked before conception {odds ratio [OR] = 1.68 [95% confidence interval (CI) = 1.18-2.41]}, whereas mothers' smoking before conception did not predict offspring asthma. The risk was highest if father started smoking before age 15 years [3.24 (1.67-6.27)], even if he stopped more than 5 years before conception [2.68 (1.17-6.13)]. Fathers' pre-conception welding was independently associated with non-allergic asthma in his offspring [1.80 (1.29-2.50)]. There was no effect if the father started welding or smoking after birth. The associations were consistent across countries.

Conclusions

Environmental exposures in young men appear to influence the respiratory health of their offspring born many years later. Influences during susceptible stages of spermatocyte development might be important and needs further investigation in humans. We hypothesize that protecting young men from harmful exposures may lead to improved respiratory health in future generations.

Challenges in the implementation of the EAACI AIT guidelines: A situational analysis of current provision of allergen immunotherapy

PURPOSE

The European Academy of Allergy and Clinical Immunology (EAACI) has produced Guidelines on Allergen Immunotherapy (AIT). We sought to gauge the preparedness of primary care to participate in the delivery of AIT in Europe.

METHODS

We undertook a mixed-methods, situational analysis. This involved a purposeful literature search and two surveys: one to primary care clinicians and the other to a wider group of stakeholders across Europe.

RESULTS

The 10 papers identified all pointed out gaps or deficiencies in allergy care provision in primary care. The surveys also highlighted similar concerns, particularly in relation to concerns about lack of knowledge, skills, infrastructural weaknesses, reimbursement policies and communication with specialists as barriers to evidence-based care. Almost all countries (92%) reported the availability of AIT. In spite of that, only 28% and 44% of the countries reported the availability of guidelines for primary care physicians and specialists, respectively. Agreed pathways between specialists and primary care physicians were reported as existing in 32%-48% of countries. Reimbursement appeared to be an important barrier as AIT was only fully reimbursed in 32% of countries. Additionally, 44% of respondents considered accessibility to AIT and 36% stating patient costs were barriers.

CONCLUSIONS

Successful working with primary care providers is essential to scaling-up AIT provision in Europe, but to achieve this, the identified barriers must be overcome. Development of primary care interpretation of guidelines to aid patient selection, establishment of disease management pathways and collaboration with specialist groups are required as a matter of urgency.

Residents' Self-Reported Health Effects and Annoyance in Relation to Air Pollution Exposure in an Industrial Area in Eastern-Estonia

Eastern Estonia has large oil shale mines and industrial facilities mainly focused on electricity generation from oil shale and shale oil extraction, which produce high air pollution emissions. The "Study of the health impact of the oil shale sector-SOHOS" was aimed at identifying the impacts on residents' health and annoyance due to the industrial processing. First, a population-wide survey about health effects and annoyance was carried out. Second, the total and oil shale sectors' emitted concentrations of benzene, phenol, and PM2.5 were modelled. Third, the differences between groups were tested and relationships between health effects and environmental pollution studied using multiple regression analysis. Compared to the control groups from non-industrial areas in Tartu or Lääne-Viru, residents of Ida-Viru more frequently (p < 0.05) reported wheezing, chest tightness, shortness of breath, asthma attacks, a long-term cough, hypertension, heart diseases, myocardial infarction, stroke, and diabetes. All health effects except asthma were reported more frequently among non-Estonians. People living in regions with higher levels of PM2.5, had significantly higher odds (p < 0.05) of experiencing chest tightness (OR = 1.13, 95% CI 1.02-1.26), shortness of breath (1.16, 1.03-1.31) or an asthma attack (1.22, 1.04-1.42) during the previous year. People living in regions with higher levels of benzene had higher odds of experiencing myocardial infarction (1.98, 1.11-3.53) and with higher levels of phenol chest tightness (1.44, 1.03-2.00), long-term cough (1.48, 1.06-2.07) and myocardial infarction (2.17, 1.23-3.83). The prevalence of adverse health effects was also higher among those who had been working in the oil shale sector. Next to direct health effects, up to a quarter of the residents of Ida-Viru County were highly annoyed about air pollution. Perceived health risk from air pollution increased the odds of being annoyed. Annoyed people in Ida-Viru had significantly higher odds of experiencing respiratory symptoms during the last 12 months, e.g., wheezing (2.30, 1.31-4.04), chest tightness (2.88, 1.91-4.33 or attack of coughing (1.99, 1.34-2.95).

Polycystic ovary syndrome, body mass index and hypertensive disorders in pregnancy

OBJECTIVE

Some studies of women with polycystic ovary syndrome (PCOS) report increased prevalence of hypertensive disorders in pregnancy, while others do not. Several of these studies do not control for obesity. We aimed to study whether PCOS is associated with hypertensive disorders in pregnancy and whether it is dependent on body mass index (BMI).

STUDY DESIGN

We present a cross-sectional analysis of 3732 women from Denmark, Estonia, Iceland, Norway and Sweden, born in 1945-72, who participated in the Respiratory Health In Northern Europe (RHINE) study and answered an extensive women's health questionnaire on menstruation, PCOS, infertility, pregnancy history and childbirth. The main outcome measurement was hypertensive disorders of pregnancy. We adjusted for smoking, age, infertility treatment and study center. Effect modification by BMI was assessed.

RESULTS

PCOS was related to hypertensive disorders in pregnancy with a relative risk (RR) of 1.62 (95% CI 1.09-2.42). This relationship was found among underweight women with a BMI of <18.5 kg/m² [RR = 5.2 (95% CI 1.66-16.5)] and obese women with a BMI of ≥30 kg/m² [RR = 2.36 (95% CI 1.29-4.31)], but not among normal-weight women, BMI 18.5-25 kg/m² [1.08 (0.53-2.20)], or overweight women, BMI 25-30 kg/m² [1.24 (0.50-3.08)] (p-interaction = 0.041).

CONCLUSION

Polycystic ovary syndrome is associated with hypertensive disorders in pregnancy. This association only occurs among underweight and obese women and not among normal-weight and slightly overweight women.

Predictors of smoking cessation: A longitudinal study in a large cohort of smokers

BACKGROUND

There are few studies on predictors of smoking cessation in general populations. We studied the smoking cessation rate in relation to several potential predictors, with special focus on respiratory and cardiovascular disease.

METHODS

Smokers (n = 4636) from seven centres in Northern Europe, born between 1945 and 1973, who answered a questionnaire in 1999-2001 (the RHINE study) were followed up with a new questionnaire in 2010-2012. Altogether 2564 answered the questionnaire and provided complete data on smoking. Cox regression analyses were performed to calculate hazard ratios (HRs).

RESULTS

A total of 999 subjects (39%) stopped smoking during the study period. The smoking cessation rate was 44.9/1000 person-years. Smoking cessation was more common with increasing age, higher education and fewer years of smoking. Asthma, wheeze, hay fever, chronic bronchitis, diabetes and hypertension did not significantly predict smoking cessation, but smokers hospitalized for ischaemic heart disease during the study period were more prone to stopping smoking (HR 3.75 [2.62-5.37]).

CONCLUSIONS

Successful smoking cessation is common in middle-aged smokers, and is associated with few smoking years and higher education. A diagnosis of respiratory disease does not appear to motivate people to quit smoking, nor do known cardiovascular risk factors; however, an acute episode of ischaemic heart disease encouraged smoking cessation in our study population.

Validation of maternal reported pregnancy and birth characteristics against the Medical Birth Registry of Norway

Studies using mothers' self-reported information on birth and pregnancy characteristics are common, but the validity of such data is uncertain. We evaluated questionnaire data from the RHINE III study on reproductive health provided by 715 mothers from Bergen, Norway, about their 1629 births between 1967 and 2010, using the Medical Birth Registry of Norway (MBRN) as gold standard. Validity of dichotomous variables (gender, preterm birth [<37 weeks' gestation], postterm birth [>42 weeks' gestation], induction of labour, forceps delivery, vacuum delivery, caesarean section, were assessed by sensitivity, specificity, positive and negative predictive values (PPV and NPV) and Cohen's kappa. Paired t-test, Pearson's correlation coefficient and Bland-Altman plots were used to validate birthweight, stratified by mother's level of education, parity, birth year and child's asthma status. Child's gender and caesarean section showed high degree of validity (kappa = 0.99, sensitivity and specificity 100%). Instrumental delivery and extremely preterm birth showed good agreement with sensitivity 75-92%. Preterm birth and induction of labour showed moderate agreement. Post-term delivery was poorly reported. The validity appeared to be independent of recall time over 45 years, and of the child's asthma status. Maternally reported birth and pregnancy information is feasible and cheap, showed high validity for important birth and pregnancy parameters, and showed similar risk-associations compared to registry data.

A population-based cohort of adults with asthma: mortality and participation in a long-term follow-up

Background and objective: Asthma is a major public health concern. The aim of this study was to characterize a large population-based cohort of adults with asthma, and to study factors associated with all-cause mortality and non-participation in a long-term follow-up. Design: Random and stratified samples from five population-based cohorts were clinically examined during 1986-2001, and all subjects with asthma were included in the study (n = 2055, age 19-72 years, 55% women). Independent associations between different risk factors and (i) mortality and (ii) non-participation in a clinical follow-up in 2012-2014 were estimated. Results: In 1986-2001, 95% reported any wheeze and/or attacks of shortness of breath in the past 12 months, and/or asthma medication use. Over the up to 28 years of follow-up time, the cumulative mortality was 22.7%. Male gender, current smoking, and lower forced expiratory volume in 1 sec of predicted (FEV₁% of predicted) were independent risk factors for mortality, while obesity was associated with non-participation in the follow-up. Older ages, ischemic heart disease, and low socioeconomic status were associated with both mortality and non-participation. Conclusions: The risk factors associated with mortality in this adult population-based asthma cohort were similar to those commonly identified in general population samples, i.e. male gender, current smoking, and lower FEV₁% of predicted, while obesity was associated with non-participation in a long-term follow-up. Ischemic heart disease, low socioeconomic status, and older ages were associated with both mortality and non-participation.

Absolute values of lung function explain the sex difference in breathlessness in the general population

Activity-related breathlessness is twice as common among females as males in the general population and is associated with adverse health outcomes. We tested whether this sex difference is explained by the lower absolute forced expiratory volume in 1 s (FEV1) or forced vital capacity (FVC) in females.

This was a cross-sectional analysis of 3250 subjects (51% female) aged 38−67 years across 13 countries in the population-based third European Community Respiratory Health Survey. Activity-related breathlessness was measured using the modified Medical Research Council (mMRC) scale. Associations with mMRC were analysed using ordered logistic regression clustering on centre, adjusting for post-bronchodilator spirometry, body mass index, pack-years smoking, cardiopulmonary diseases, depression and level of exercise.

Activity-related breathlessness (mMRC ≥1) was twice as common in females (27%) as in males (14%) (odds ratio (OR) 2.21, 95% CI 1.79−2.72). The sex difference was not reduced when controlling for FEV1 % predicted (OR 2.33), but disappeared when controlling for absolute FEV1 (OR 0.89, 95% CI 0.69−1.14). Absolute FEV1 explained 98−100% of the sex difference adjusting for confounders. The effect was similar within males and females, when using FVC instead of FEV1 and in healthy never-smokers.

The markedly more severe activity-related breathlessness among females in the general population is explained by their smaller spirometric lung volumes.

Women with symptoms of sleep-disordered breathing are less likely to be diagnosed and treated for sleep apnea than men

BACKGROUND

Women are often underrepresented at sleep clinics evaluating sleep-disordered breathing (SDB). The aim of the present study was to analyze gender differences in sleep apnea diagnosis and treatment in men and women with similar symptoms of SDB.

METHODS

Respiratory Health in Northern Europe (RHINE) provided information about snoring, excessive daytime sleepiness (EDS), BMI and somatic diseases at baseline (1999-2001) and follow-up (2010-2012) from 4962 men and 5892 women. At follow-up participants were asked whether they had a diagnosis of and/or treatment for sleep apnea.

RESULTS

Among those with symptoms of SDB (snoring and EDS), more men than women had been given the diagnosis of sleep apnea (25% vs. 14%, p < 0.001), any treatment (17% vs. 11%, p = 0.05) and CPAP (6% vs. 3%, p = 0.04) at follow-up. Predictors of receiving treatment were age, BMI, SDB symptoms at baseline and weight gain, while female gender was related to a lower probability of receiving treatment (adj. OR 0.3, 95% CI 0.3-0.5). In both genders, the symptoms of SDB increased the risk of developing hypertension (adj OR, 95% CI: 1.5, 1.2-1.8) and diabetes (1.5, 1.05-2.3), independent of age, BMI, smoking and weight gain.

CONCLUSIONS

Snoring females with daytime sleepiness may be under-diagnosed and under-treated for sleep apnea compared with males, despite running a similar risk of developing hypertension and diabetes.

A clear urban-rural gradient of allergic rhinitis in a population-based study in Northern Europe

BACKGROUND

The protective effect of farm upbringing on allergic rhinitis is well known, but how upbringing in other environments influences the development of allergic rhinitis is scarcely investigated. The aim of this study was to investigate the association between place of upbringing and pet keeping in childhood and allergic rhinitis and nasal symptoms in adulthood.

METHODS

The population-based Respiratory Health in Northern Europe study includes subjects from Denmark, Norway, Sweden, Iceland, and Estonia born in 1945-1973. This paper analyses 13,376 participants of the third study wave. Six categories of place of upbringing were defined: farm with livestock, farm without livestock, village in rural area, small town, city suburb, and inner city. Pets in the home at birth and during childhood were recorded. Data were analysed using adjusted logistic regression models.

RESULTS

Livestock farm upbringing predicted less adult allergic rhinitis [odds ratio (OR) 0.68, 0.54-0.85] and nasal symptoms (OR 0.82, 0.68-0.99) than city upbringing, and an urban-rural gradient with decreasing risk per level of urbanisation was observed (OR 0.92, 0.88-0.94). Pets in the home at birth (OR 0.78, 0.68-0.88) and during childhood (OR 0.83, 0.74-0.93) were associated with less subsequent allergic rhinitis. Pet keeping did not explain the protective effect of place of upbringing.

CONCLUSION

Risk of allergic rhinitis and nasal symptoms in adulthood was inversely associated with the level of urbanisation during upbringing. Pets at birth decreased the risk further, but did not explain the urban-rural gradient. Persistent beneficial effects of microbial diversity in early life might be an explanation for the findings.

Self-reported exposure to traffic pollution in relation to daytime sleepiness and habitual snoring: a questionnaire study in seven North-European cities

OBJECTIVE/BACKGROUND

Little is known about associations between traffic exposure and sleep disturbances. We examined if self-reported exposure to traffic is associated with habitual snoring and daytime sleepiness in a general population.

METHODS

In the RHINE III study, 12184 adults answered questions on sleep disturbances and traffic exposure. We analysed bedrooms near roads with traffic, bedrooms with traffic noise, and travelling regularly along busy roads as proxies for traffic exposures, using logistic regression. Adjustment factors were study centre, gender, age, smoking habits, educational level, body mass index, physical activity, obstructive sleep apnoea, and sleep duration.

RESULTS

One in ten lived near a busy road, 6% slept in a bedroom with traffic noise, and 11% travelled regularly along busy roads. Habitual snoring affected 25% and daytime sleepiness 21%. More men reported snoring and more women reported daytime sleepiness. Having a bedroom with traffic noise was associated with snoring (adjusted OR 1.29, [95% CI 1.12, 1.48]). For daytime sleepiness, on the other hand, bedroom with traffic noise and high exposure to traffic pollution have significant risk factors (adjusted ORs 1.46 [1.11, 1.92] and 1.65 [1.11, 2.45]). Results were consistent across study centres.

CONCLUSIONS

Daytime sleepiness is associated with traffic pollution and traffic noise, while habitual snoring is only associated with traffic noise. Self-reported traffic exposure should be taken into account when diagnosing and planning treatment for patients with sleep disturbances, because reducing noise and pollution exposure in the bedroom may have a beneficial effect.

Smoking and New-Onset Asthma in a Prospective Study on Italian Adults

BACKGROUND

The existence of a cause-effect relation between active smoking and new-onset asthma in adults, although supported by several studies, has not been proven yet.

AIMS

We aimed to prospectively study asthma incidence as a function of smoking habits in the Italian adult population.

METHODS

A population-based cohort of 5,241 non-asthmatics was enrolled in Verona and Sassari in 1998-2000. The cohort was contacted again in 2007-2009 within the Gene-Environment Interactions in Respiratory Diseases study, and 3,187 subjects (60.8%) answered a screening questionnaire on smoking habits and respiratory disorders. The relation between smoking habits and self-reported new-onset asthma, defined as asthma attacks/use of medicines for asthma, was investigated by a multivariable logistic model.

RESULTS

During follow-up, 145 new cases of asthma were observed, yielding a cumulative incidence of 4.6% (95% CI 3.9-5.4); cumulative incidence of asthma did not significantly differ among never-smokers (76/1,666 = 4.6%), ex-smokers (30/554 = 5.4%) and current smokers (39/883 = 4.4%) (p = 0.641). In a multivariable analysis, the most important risk factor for asthma onset was allergic rhinitis (OR = 4.00, 95% CI 3.68-4.35). Compared to never-smokers, the risk of asthma onset was slightly increased in ex-smokers (OR = 1.28, 1.09-1.49) but not in current smokers (OR 1.01, 0.66-1.53). Current smoking became a significant predictor only when both new-onset wheezing and new-onset asthma were considered as the outcome (OR = 2.03, 1.35-3.05).

CONCLUSIONS

In this prospective study, current smoking was not a risk factor for new-onset asthma, unless new-onset wheezing was also considered. The increase in asthma incidence among ex-smokers was likely due to reverse causation.

Validation of self-reported figural drawing scales against anthropometric measurements in adults

OBJECTIVE

The aim of the present study was to validate figural drawing scales depicting extremely lean to extremely obese subjects to obtain proxies for BMI and waist circumference in postal surveys.

DESIGN

Reported figural scales and anthropometric data from a large population-based postal survey were validated with measured anthropometric data from the same individuals by means of receiver-operating characteristic curves and a BMI prediction model.

SETTING

Adult participants in a Scandinavian cohort study first recruited in 1990 and followed up twice since.

SUBJECTS

Individuals aged 38-66 years with complete data for BMI (n 1580) and waist circumference (n 1017).

RESULTS

Median BMI and waist circumference increased exponentially with increasing figural scales. Receiver-operating characteristic curve analyses showed a high predictive ability to identify individuals with BMI > 25·0 kg/m2 in both sexes. The optimal figural scales for identifying overweight or obese individuals with a correct detection rate were 4 and 5 in women, and 5 and 6 in men, respectively. The prediction model explained 74 % of the variance among women and 62 % among men. Predicted BMI differed only marginally from objectively measured BMI.

CONCLUSIONS

Figural drawing scales explained a large part of the anthropometric variance in this population and showed a high predictive ability for identifying overweight/obese subjects. These figural scales can be used with confidence as proxies of BMI and waist circumference in settings where objective measures are not feasible.

The Association of Gum Bleeding with Respiratory Health in a Population Based Study from Northern Europe

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 (p(heterogeneity) = 0.49). None of the investigated risk factors explained the associations. The observed associations were significantly stronger among current smokers (p(interaction) = 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.

Non-response in a cross-sectional study of respiratory health in Norway

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.

The Urban-Rural Gradient In Asthma: A Population-Based Study in Northern Europe

The early life environment appears to have a persistent impact on asthma risk. We hypothesize that environmental factors related to rural life mediate lower asthma prevalence in rural populations, and aimed to investigate an urban-rural gradient, assessed by place of upbringing, for asthma. The population-based Respiratory Health In Northern Europe (RHINE) study includes subjects from Denmark, Norway, Sweden, Iceland and Estonia born 1945–1973. The present analysis encompasses questionnaire data on 11,123 RHINE subjects. Six categories of place of upbringing were defined: farm with livestock, farm without livestock, village in rural area, small town, city suburb and inner city. The association of place of upbringing with asthma onset was analysed with Cox regression adjusted for relevant confounders. Subjects growing up on livestock farms had less asthma (8%) than subjects growing up in inner cities (11%) (hazard ratio 0.72 95% CI 0.57–0.91), and a significant urban-rural gradient was observed across six urbanisation levels (p = 0.02). An urban-rural gradient was only evident among women, smokers and for late-onset asthma. Analyses on wheeze and place of upbringing revealed similar results. In conclusion, this study suggests a protective effect of livestock farm upbringing on asthma development and an urban-rural gradient in a Northern European population.

Incidence of new-onset wheeze: a prospective study in a large middle-aged general population

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.

Respiratory symptoms/diseases prevalence is still increasing: a 25-yr population study

BACKGROUND

Few epidemiological surveys on general population samples estimated changes in prevalence of respiratory symptoms/diseases over a long time interval; our study aims to quantify the temporal changes in the prevalence rates of asthma, allergic rhinitis and Chronic Obstructive Pulmonary Disease (COPD) after 25 years from baseline.

METHODS

A general population sample participated in 3 cross-sectional surveys carried out in Central Italy (Pisa) in 1985-88 (n = 3865), 1991-93 (n = 2841), 2009-11 (n = 1620). 2276 (47%) subjects participated in at least 1 survey, 1723 (35.5%) in at least 2 surveys and 849 (17.5%) in all the 3 surveys. All subjects filled in a standardized questionnaire about health status and risk factors; a sub-sample performed spirometry. Chi-square test was used to compare adjusted prevalence rates of respiratory symptoms/diseases and descriptive characteristics among the surveys. Generalised estimating equations (GEE) were used to analyze the association between respiratory symptoms/diseases and risk factors.

RESULTS

There was an increasing trend in prevalence rates of all respiratory symptoms/diseases throughout the surveys: current asthma attacks (1st-3rd survey prevalence: 3.4-7.2%), allergic rhinitis (16.2-37.4%), usual phlegm (8.7-19.5%) and COPD (2.1-6.8%) more than doubled. The GEE model confirmed these increasing trends, indicating higher risk of having respiratory symptoms/diseases in the second and third surveys.

CONCLUSIONS

While asthma and allergic rhinitis increasing trends were confirmed, with respect to other international studies, also a COPD increasing prevalence rates was shown.

Respiratory Health in Cleaners in Northern Europe: Is Susceptibility Established in Early Life?

RATIONALE

There is some evidence that maternal smoking increases susceptibility to personal smoking's detrimental effects. One might question whether early life disadvantage might influence susceptibility to occupational exposure.

OBJECTIVES

In this cross-sectional study we investigated respiratory symptoms, asthma and self-reported chronic obstructive pulmonary disease (COPD) as related to working as a cleaner in Northern European populations, and whether early life factors influenced susceptibility to occupational cleaning's unhealthy effects.

METHODS

The RHINE III questionnaire study assessed occupational cleaning in 13,499 participants. Associations with respiratory symptoms, asthma and self-reported COPD were analysed with multiple logistic regressions, adjusting for sex, age, smoking, educational level, parent´s educational level, BMI and participating centre. Interaction of occupational cleaning with early life disadvantage (maternal smoking, severe respiratory infection <5 years, born during winter months, maternal age at birth >35 years) was investigated.

MAIN RESULTS

Among 2138 ever-cleaners the risks of wheeze (OR 1.4, 95% CI 1.3-1.6), adult-onset asthma (1.5 [1.2-1.8]) and self-reported COPD (1.7 [1.3-2.2]) were increased. The risk increased with years in occupational cleaning (adult-onset asthma: ≤1 year 0.9 [0.7-1.3]; 1-4 years 1.5 [1.1-2.0]; ≥4 years 1.6 [1.2-2.1]). The association of wheeze with cleaning activity ≥4 years was significantly stronger for those with early life disadvantage than in those without (1.8 [1.5-2.3] vs. 1.3 [0.96-1.8]; pinteraction 0.035).

CONCLUSIONS

Occupational cleaners had increased risk of asthma and self-reported COPD. Respiratory symptom risk was particularly increased in persons with factors suggestive of early life disadvantage. We hypothesize that early life disadvantage may increase airway vulnerability to harmful exposure from cleaning agents later in life.

Severity of allergic rhinitis and asthma development in children

Allergic rhinitis (AR) is a relevant risk factor for the development of asthma in children. We recruited a cohort of 104 children with AR and re-evaluated them after 5 years. We considered the ARIA classification. All patients, who had moderate to severe persistent AR at baseline, developed asthma symptoms. These results strongly indicate that the severity of AR may be an important factor that increases the risk of asthma development in children.

Are allergen batch differences and the use of double skin prick test important?

Background

Skin prick tests (SPT) are widely used both in clinical diagnostics and in research. The standardization of allergen extracts is well documented to be crucial for the validity of SPT, whereas less emphasis has been placed on reproducibility and the SPT procedure itself. The objectives of this study are to clarify how the double skin prick test procedure influence the sensitivity and specificity of the test and to analyse the differences in weal size in skin prick tests between two batches of allergen extracts from the same vendor.

Methods

The association between rhinitis and SPT was assessed among 1135 persons from a general population sample. SPT was performed twice with 10 common aeroallergens. In a subsample of 90 persons SPT was performed simultaneously with five of the allergens using different batches.

Results

Thirty percent had at least one positive SPT. Among asthmatics this number was 62%. Only minor differences were seen between the sizes of two weals from the same batch. A second SPT with the same batch did not change the association between rhinitis and sensitization. When performing SPT with two different batches disagreement was observed in 2% (Birch) to 11% (Cat) of the subjects.

Conclusions

Performing SPT twice with the same allergen batch does not enhance the validity of the test, and value of double testing can be questioned. Considerable differences in SPT response with different batches from the same manufacturer were observed. Thus inter batch differences in allergen extracts might be a source of variability.

Place of upbringing in early childhood as related to inflammatory bowel diseases in adulthood: a population-based cohort study in Northern Europe

Background The two inflammatory bowel diseases (IBD), ulcerative colitis and Crohn's disease, has increased rapidly during the twentieth century, but the aetiology is still poorly understood. Impaired immunological competence due to decreasing biodiversity and altered microbial stimulation is a suggested explanation. Objective Place of upbringing was used as a proxy for the level and diversity of microbial stimulation to investigate the effects on the prevalence of IBD in adulthood. Methods Respiratory Health in Northern Europe (RHINE) III is a postal follow-up questionnaire of the European Community Respiratory Health Survey (ECRHS) cohorts established in 1989–1992. The study population was 10,864 subjects born 1945–1971 in Denmark, Norway, Sweden, Iceland and Estonia, who responded to questionnaires in 2000–2002 and 2010–2012. Data were analysed in logistic and Cox regression models taking age, sex, smoking and body mass index into consideration. Results Being born and raised on a livestock farm the first 5 years of life was associated with a lower risk of IBD compared to city living in logistic (OR 0.54, 95 % CI 0.31; 0.94) and Cox regression models (HR 0.55, 95 % CI 0.31; 0.98). Random-effect meta-analysis did not identify geographical difference in this association. Furthermore, there was a significant trend comparing livestock farm living, village and city living (p < 0.01). Sub-analyses showed that the protective effect was only present among subjects born after 1952 (OR 0.25, 95 % CI 0.11; 0.61). Conclusion This study suggests a protective effect from livestock farm living in early childhood on the occurrence of IBD in adulthood, however only among subjects born after 1952. We speculate that lower microbial diversity is an explanation for the findings.