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.

Menstrual cycle and respiratory symptoms in a general Nordic-Baltic population

RATIONALE

There is little knowledge of variations in respiratory symptoms during the menstrual cycle in a general population, and potential modifying factors are not investigated.

OBJECTIVES

To investigate menstrual cycle variation in respiratory symptoms in a large general population, using chronobiology methodology, and stratifying by body mass index (BMI), smoking, and asthma status.

METHODS

A total of 3,926 women with regular cycles less than or equal to 28 days and not taking exogenous sex hormones answered a postal questionnaire regarding the first day of their last menstruation and respiratory symptoms in the last 3 days. Moving 4-day means were computed to smooth uneven records of daily sampling; best-fitting 28-day composite cosine curves were applied to each time series to describe rhythmicity.

MEASUREMENTS AND MAIN RESULTS

Significant rhythmic variations over the menstrual cycle were found in each symptom for all subjects and subgroups. Wheezing was higher on cycle Days 10-22, with a midcycle dip near the time of putative ovulation (approximately Days 14-16) in most subgroups. Shortness of breath was higher on days 7-21, with a dip just before midcycle in many subgroups. Cough was higher just after putative ovulation for subjects with asthma, BMI greater than or equal to 23 kg/m(2), and smokers, or just before ovulation and menses onset for low symptomatic subgroups.

CONCLUSIONS

Respiratory symptoms varied significantly during the menstrual cycle and were most frequent from the midluteal to midfollicular stages, often with a dip near the time of ovulation. The patterns varied by BMI, smoking, and asthma status. These relations link respiratory symptoms with hormonal changes through the menstrual cycle and imply a potential for individualized chronotherapy for respiratory diseases.

Respiratory symptoms in adults are related to impaired quality of life, regardless of asthma and COPD: results from the European community respiratory health survey

BACKGROUND

Respiratory symptoms are common in the general population, and their presence is related to Health-related quality of life (HRQoL). The objective was to describe the association of respiratory symptoms with HRQoL in subjects with and without asthma or COPD and to investigate the role of atopy, bronchial hyperresponsiveness (BHR), and lung function in HRQoL.

METHODS

The European Community Respiratory Health Survey (ECRHS) I and II provided data on HRQoL, lung function, respiratory symptoms, asthma, atopy, and BHR from 6009 subjects. Generic HRQoL was assessed through the physical component summary (PCS) score and the mental component summary (MCS) score of the SF-36.Factor analyses and linear regressions adjusted for age, gender, smoking, occupation, BMI, comorbidity, and study centre were conducted.

RESULTS

Having breathlessness at rest in ECRHS II was associated with mean score (95% CI) impairment in PCS of -8.05 (-11.18, -4.93). Impairment in MCS score in subjects waking up with chest tightness was -4.02 (-5.51, -2.52). The magnitude of HRQoL impairment associated with respiratory symptoms was similar for subjects with and without asthma/COPD. Adjustments for atopy, BHR, and lung function did not explain the association of respiratory symptoms and HRQoL in subjects without asthma and/or COPD.

CONCLUSION

Subjects with respiratory symptoms had poorer HRQoL; including subjects without a diagnosis of asthma or COPD. These findings suggest that respiratory symptoms in the absence of a medical diagnosis of asthma or COPD are by no means trivial, and that clarifying the nature and natural history of respiratory symptoms is a relevant challenge. Several community studies have estimated the prevalence of common respiratory symptoms like cough, dyspnoea, and wheeze in adults. Although the prevalence varies to a large degree between studies and geographical areas, respiratory symptoms are quite common. The prevalences of respiratory symptoms in the European Community Respiratory Health Study (ECRHS) varied from one percent to 35%. In fact, two studies have reported that more than half of the adult population suffers from one or more respiratory symptoms. Respiratory symptoms are important markers of the risk of having or developing disease. Respiratory symptoms have been shown to be predictors for lung function decline, asthma, and even all-cause mortality in a general population study . In patients with a known diagnosis of asthma or chronic obstructive pulmonary disease (COPD), respiratory symptoms are important determinants of reduced health related quality of life (HRQoL). The prevalence of respiratory symptoms exceeds the combined prevalences of asthma and COPD, and both asthma and COPD are frequently undiagnosed diseases. Thus, the high prevalence of respiratory symptoms may mirror undiagnosed and untreated disease.The common occurrence of respiratory symptoms calls for attention to how these symptoms affect health also in subjects with no diagnosis of obstructive airways disease. Impaired HRQoL in the presence of respiratory symptoms have been found in two population-based studies 619, but no study of respiratory symptoms and HRQoL have separate analyses for subjects with and without asthma and COPD, and no study provide information about extensive objective measurements of respiratory health. The ECRHS is a randomly sampled, multi-cultural, population based cohort study. The ECRHS included measurements of atopy, bronchial hyperresponsiveness (BHR), and lung function, and offers a unique opportunity to investigate how respiratory symptoms affect HRQoL among subjects both with and without obstructive lung disease.In the present paper we aimed to: 1) Describe the relationship between respiratory symptoms and HRQoL in an international adult general population and: 2) To assess whether this relationship varied with presence of asthma and/or COPD, or presence of objective functional markers like atopy and BHR.

Hormonal factors and respiratory health in women--a review

Sex hormones appear to play an important role in the lung health of women. This is, however, poorly understood and, in most aspects, poorly investigated; and the literature has been contradictory and confusing. This review presents recent research concerning the involvement of sex hormones in respiratory health of adult women, using the population surveys European Community Respiratory Health Survey and Respiratory Health in Northern Europe. Respiratory health varied substantially according to hormonal and metabolic conditions. First, menopause was associated with lower lung function and more respiratory symptoms, especially among lean women. Second, hormonal replacement therapy (HRT) was associated with increased risk for asthma and wheeze; also, this association was particularly strong among lean women. Third, women with irregular menstruations in fertile age had more asthma, particularly allergic asthma, and reduced lung function, independently of body mass index (BMI) and physical activity. The findings were consistent across cultural and geographical borders. Our studies revealed that considering interplay between hormonal and metabolic factors is a clue to understand the effects of female sex hormones on the airways. A BMI of around 24-25 kg/m(2) appeared to be optimal; women with this BMI had no increase in respiratory health problems when reaching menopause or using HRT, and women in fertile age with this BMI had optimal lung function independently of menstrual status. In conclusion, female sex hormones appear to play a most important role for lung health in women. Further research on effects of sex hormones on the airways should take into account potential interplay with metabolic factors.

Norwegian population surveys on respiratory health in adults: objectives, design, methods, quality controls and response rates

BACKGROUND AND AIMS

Quantifying the prevalence of asthma, chronic obstructive pulmonary disease (COPD) and restrictive pulmonary diseases in Norway is needed to document the burden of chronic respiratory inflammatory diseases on disability, health care costs and impaired quality of life. To introduce effective interventions for prevention, cure and care, there is a prerequisite to know the environmental causes. Furthermore, using relevant and precise phenotypes from community-based studies are important for detecting molecular-genetic causes for diseases.

METHODS

The Norwegian Population Survey Initiative on Respiratory Health in Adults has, for four decades, applied international standardised methods for the recording of respiratory symptoms, health status, exposure to risk factors, socio-economic factors and the use of health services. Measurements of spirometry, metacholine bronchial responsiveness, transfer factor for carbon monoxide, atopy as well as chest X-ray examinations have been used advocating the internationally accepted methods. All surveys had similar quality controls, supervision and training of the field-worker team.

RESULTS

From 1965 to 1999, random population samples, altogether including 178 690 individuals, have been invited by random sampling to seven surveys on respiratory health in the counties of Oslo (39 998 people) and Hordaland (138 692 people). The surveys were initiated in 1964, 1972, 1985, 1988, 1991 and two in 1998. The age span of those invited persons varied from 15 to 74 years at baseline. It included 43 330 women and 135 537 men. Altogether 130 075 (73%) persons participated by returning an answered questionnaire. Spirometry results are available from 41 335 persons at baseline. A biobank for DNA and blood markers has been established. Data from longitudinally clinical-epidemiological studies were available by 2007, for three surveys after 20 years, 10 years and 6-7 years, and also for parts of three other surveys, while one survey has been examined for cause-specific mortality after 30 years. The response rates of the baseline studies varied from 90% to 68% of those invited and, in general, it has declined over 35 years. The response rate of the longitudinal studies with follow-ups also declined with time after the baseline study.

CONCLUSIONS

Great challenges for future population-based studies are (i) to keep the participation rates high in community studies; (ii) to standardise the basic clinical-epidemiological methods over decades of follow-up and to systematically transfer these methods into new populations with different languages and cultures and (iii) to focus on important research questions on respiratory health for the community.

Socioeconomic risk factors for lung function decline in a general population

The aim of our study was to examine sex-specific associations between different aspects of socioeconomic status (SES) (educational level, occupational status, income) and lung function in a general adult population. In the Hordaland County Cohort Study, 1,644 subjects aged 26-82 yrs at baseline answered questionnaires and performed post-bronchodilator spirometry both in 1996-1997 and in 2003-2006. We performed adjusted linear regression analysis on the effect of SES on decline in forced experimental volume in 1 s (FEV(1)), forced vital capacity (FVC) and FEV(1)/FVC. Mean annual decline in FEV(1) from baseline to follow-up was 57 mL (se 1.3) and 48 mL (se 1.0) for males and females, respectively. Males had a larger decline in FVC than females, while females had a larger decline in FEV(1)/FVC. Lower education and low occupational status were associated with larger male lung function decline. SES did not affect female lung function decline. However, marital status was a significant predictor; unmarried females had less decline than both married and widowed females in both FEV(1) (adjusted mean annual difference 8 mL and 16 mL) and FVC (adjusted mean annual difference 8 mL and 18 mL). Low SES was associated with increased lung function decline in males. For females, marital status was more important.

Positionally cloned genes and age-specific effects in asthma and atopy: an international population-based cohort study (ECRHS)

BACKGROUND

Several genes identified by positional cloning have been associated with asthma and atopy, but few findings have been replicated. Age at onset of asthma has been associated with different phenotypic characteristics, and with variants at chromosome 17q21 identified through genome-wide association. This study examined the associations and age-specific effects on asthma, atopy and bronchial hyper-responsiveness (BHR) of five candidate genes previously identified by positional cloning (ADAM33, PHF11, NPSR1, DPP10, SPINK5).

METHODS

51 polymorphisms from 2474 participants from 13 countries who took part in the European Community Respiratory Health Survey (1990-2000) were studied. Asthma and age at onset of asthma were assessed by questionnaire data, BHR by methacholine challenge and atopy by specific immunoglobulin E to four common allergens.

RESULTS

Significant associations with asthma, atopy and particularly for asthma with atopy were observed for a large region of 47 kb in the NPSR1 gene, even after Bonferroni correction for multiple comparisons (p<0.001). The associations with NPSR1 were stronger in those reporting a first attack of asthma before the age of 15, with statistically significant interactions with age of onset found for three SNPs. The evidence for ADAM33 and BHR and for an age-specific effect of two SNPs in DPP10 and asthma was weaker.

CONCLUSION

This study provides further evidence for an effect of NPSR1 on asthma, atopy and atopic asthma. In addition, this analysis suggests a role for NPSR1 in early-onset asthma driven by the strong effect of this gene on atopic asthma.

Repeatability of health economic data in COPD

BACKGROUND

Little is known concerning the precision of self-reported health economic data.

AIM

To investigate the repeatability of self-reported health economic cost and utilization data in subjects with chronic obstructive pulmonary disease (COPD).

METHODS

Twelve weeks after inclusion, a physician and a nurse in random order interviewed 29 subjects with post-bronchodilator COPD included from a research registry of COPD patients. The interview recorded healthcare utilization and costs, sick leave, exacerbations and quality of life (QoL). Variation of individual agreement of observations was described estimating kappa statistics and 95% limits of agreement.

RESULTS

Mean age was 63 years (standard deviation (SD) 10) and 17 participants were men. Average FEV(1)% predicted was 56% (SD 15). For sick leave, exacerbation, healthcare provider visit, change of medication, assistance and leisure time the kappa values were 1.00, 0.73, 0.73, 0.66, 0.63 and 0.54, respectively. The physician recorded fewer days of exacerbation and fewer contacts with healthcare providers than the nurse (p=0.01 and p=0.05, respectively). The 95% limits of agreement for costs of drugs were -690 to +710 Norwegian Kroner (NOK), -1200 to +899 NOK for costs of healthcare providers and -20 to +26 for QoL as measured by a visual analogue scale.

CONCLUSION

Repeatability of economic data from COPD patients showed considerable variation. This issue should be addressed when analyzing cost data from interviews and when designing studies on health economy.

Feasible and simple exclusion criteria for pulmonary reference populations

BACKGROUND

International guidelines recommend that pulmonary reference populations consist of never-smokers without respiratory diseases or symptoms, but the diseases and symptoms are not clearly specified. The present study aimed to identify simple exclusion criteria for defining pulmonary reference populations.

METHODS

Based on a random sample from a general population (the parent population), 2,358 subjects aged 26-82 years performed spirometric tests. From this sample, subjects were stepwise excluded according to self-reported obstructive lung diseases, symptoms and smoking history. Four increasingly more healthy respiratory reference populations were formed. Prediction equations for the median and lower limit of normal lung function were derived using quantile regression analysis.

RESULTS

Subjects without self-reported obstructive lung diseases or the cardinal respiratory symptoms of breathlessness, cough or wheeze (population B), never-smokers without cardinal symptoms (population C) and never-smokers without any respiratory symptoms (population D) constituted 50% (n = 1,184), 23% (n = 539) and 14% (n = 331) of the parent population (population A), respectively. The largest discrepancy between prediction equations was found between the parent population and the population without cardinal respiratory symptoms (population B) (p<0.05). Minor changes in the reference equations were also seen when excluding ever-smokers (population C). There was no additional change with exclusion of other respiratory symptoms (population D). Age-related decline in lung function was steepest in the parent population.

CONCLUSIONS

Obstructive lung diseases, smoking history, breathlessness, cough and wheeze are optimal exclusion criteria for a pulmonary reference population. Further validation of the exclusion criteria identified in this study is recommended with identical wording in other and larger multinational populations.

Post-bronchodilator spirometry reference values in adults and implications for disease management

RATIONALE

International guidelines promote the use of post-bronchodilator spirometry values in the definition and severity classification of chronic obstructive pulmonary disease. However, post-bronchodilator reference values have not yet been developed.

OBJECTIVES

To derive reference values for post-bronchodilator forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC, and to compare these reference values with locally derived and existing pre-bronchodilator reference values.

METHODS

Based on a random sample of a general adult population, 2,235 subjects (70% of invited subjects) performed spirometry with reversibility testing. A reference population of healthy never-smokers constituted 23% of the study population (n=515). Reference values for median and lower-limit-of-normal pre- and post-bronchodilator lung function and bronchodilator response were modeled using quantile regression analyses.

MAIN RESULTS

The reference population had equal proportions of men and women in the age range 26-82 yr. Both FEV1 and FVC decreased with age and increased with height. FEV1/FVC decreased with age, although this trend was not statistically significant for men after bronchodilatation. Linear models gave the best overall fit. Lower-limit-of-normal post-bronchodilator FEV1/FVC exceeded 0.7 for both sexes. Post-bronchodilator prediction equations gave higher predicted FEV1 and FEV1/FVC than both locally derived and existing pre-bronchodilator equations. The bronchodilator response decreased with age.

CONCLUSIONS

The present study is the first to develop reference values for post-bronchodilator lung function. Post-bronchodilator prediction equations can facilitate better management of patients with chronic obstructive pulmonary disease by avoiding falsely high FEV1% predicted with a subsequent underestimation of disease severity.

Maternal atopy and changes in parity

BACKGROUND

Atopic women tend to have fewer children, although atopy may favour conception.

OBJECTIVE

To assess whether atopy is associated with the number of new births and whether changes in parity are associated with a change in atopy in a cohort of young women.

METHODS

Women had atopy (defined as the presence of serum-specific IgE against common aeroallergens) measured in the European Community Respiratory Health Study during the years 1991--92 (n=4580). About 9 years later, 2844 (62.1%) were recontacted and 2414 (52.7%) had atopy measured again.

RESULTS

Atopic women had fewer children at baseline than non-atopic women but the association disappeared at the end of the follow-up. Atopy tended to increase parity during the follow-up, but in a non-statistically significant way (relative risk=1.08; 0.86-1.35, after adjusting for number of children at baseline, age, length of follow-up, education or social class). Prevalence of atopy during the follow-up changed by the same magnitude whatever the birth cohort and the change in the number of children (P for interaction >0.7).

CONCLUSION

Atopic women did not have a significantly higher fertility rate but they may postpone having their first child compared with non-atopic women. We are unable to confirm the hypothesis that atopy in women may decrease with successive pregnancies.

Implications of reversibility testing on prevalence and risk factors for chronic obstructive pulmonary disease: a community study

BACKGROUND

The Global Initiative for Obstructive Lung Disease (GOLD) has defined chronic obstructive pulmonary disease (COPD) as a post-bronchodilator ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) of <0.7. In the first general population based study to apply post-bronchodilator values, the prevalence and predictors of GOLD defined COPD were assessed and the implications of beta2 agonist reversibility testing examined.

METHODS

Based on a random population sample, 2235 subjects (77%) aged 26-82 years performed spirometric tests before and 15 minutes after inhaling 0.3 mg salbutamol.

RESULTS

The prevalence of GOLD defined COPD was 7.0% (95% confidence interval (CI) 5.9 to 8.0). This estimate was 27% lower than COPD defined without bronchodilatation. One percent of the population had severe or very severe COPD. Compared with women, men had 3.1 (95% CI 2.1 to 4.8) times higher odds for COPD. Subjects with a smoking history of more than 20 pack years had an odds ratio (OR) of 6.2 (95% CI 3.4 to 11.0) for COPD relative to never-smokers, while subjects older than 75 years had an OR of 18.0 (95% CI 9.2 to 35.0) relative to those below 45 years. Subjects with primary education only had an OR of 2.8 (95% CI 1.4 to 5.3) compared with those with university education. Subjects with body mass index (BMI) <20 kg/m2 were more likely than subjects with BMI 25-29.9 kg/m2 to have COPD (OR 2.4, 95% CI 1.1 to 5.3). The adjusted proportion of COPD attributable to smoking was 68%.

CONCLUSIONS

These results indicate that community programmes on prevention of COPD should focus on anti-smoking, nutritional aspects, and socioeconomic conditions. The effect of beta2 reversibility testing on prevalence estimates of COPD was substantial.

Adjustable maintenance dosing with budesonide/formoterol compared with fixed-dose salmeterol/fluticasone in moderate to severe asthma

BACKGROUND

Current asthma guidelines recommend that patients are educated to adjust their medication according to their asthma severity using physician-guided self-management plans. However, many patients take a fixed dose of their controller medication and adjust their reliever medication according to asthma symptoms.

OBJECTIVES

This study examined whether asthma control improved if patients adjusted the maintenance dose of budesonide/formoterol (Symbicort Turbuhaler* 160/4.5 microg) according to asthma severity compared with traditional fixed dosing (FD) regimens.

METHODS

Symptomatic patients with asthma (n = 658, mean symptom score 1.5, mean inhaled corticosteroids 735 microg/day, mean forced expiratory volume in 1 second [FEV(1)] 84% predicted) were randomised after 2 weeks' run-in to either: budesonide/formoterol adjustable maintenance dosing (AMD), budesonide/formoterol FD or salmeterol/fluticasone (Seretide Diskus dagger 50/250 microg) FD. In a 4-week double-blind period, both budesonide/formoterol AMD and FD groups received two inhalations twice daily (bid) and salmeterol/fluticasone FD patients received one inhalation bid. In the following 6-month open extension, both FD groups continued with the same treatment. Patients in the AMD group with well-controlled asthma stepped down to one inhalation bid; others continued with two inhalations bid. All AMD patients could increase to four inhalations bid for 7-14 days if symptoms worsened. All patients used terbutaline or salbutamol for symptom relief throughout. The primary variable was the odds of achieving a well-controlled asthma week (WCAW).

RESULTS

The odds ratio for achieving a WCAW did not differ between the FD regimens; however, during the open period, budesonide/formoterol AMD increased the odds of achieving a WCAW vs. budesonide/formoterol FD (odds ratio 1.335; 95% CI: 1.001, 1.783; p = 0.049) despite a 15% reduction in average study drug use. Budesonide/formoterol AMD patients had a lower exacerbation rate over the study: 40% lower vs. salmeterol/fluticasone FD (p = 0.018); 32% lower vs. budesonide/formoterol FD (NS). During the double-blind period, there were no clinically relevant differences between the budesonide/formoterol FD and salmeterol/fluticasone FD groups. Budesonide/formoterol AMD patients used less reliever medication in the open extension: 0.58 vs. 0.92 occasions/day for budesonide/formoterol FD (p = 0.001) and 0.80 occasions/day for salmeterol/fluticasone FD (p = 0.011).

CONCLUSIONS

Adjustable maintenance dosing with budesonide/formoterol provides more effective asthma control by reducing exacerbations and reliever medication usage compared with fixed-dose salmeterol/fluticasone.