Recommendations for epidemiological studies on COPD

Bakke, Per; Rönmark, Eva; Eagan, Tomas Mikal; Pistelli, Francesco; Annesi‐Maesano, Isabella; Maly, M.; Meren, M.; Dagger, P. Vermeire; Vestbo, Jørgen; Viegi, G.; Zielinski, J.; Lundbäck, Bo

doi:10.1183/09031936.00193809

Cited by 99 publications

(55 citation statements)

References 140 publications

(139 reference statements)

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“…52 A further strength of our study was the wide range of clinically relevant conditions examined in the context of disease staging, with higher prevalence of respiratory symptoms, respiratory and cardiovascular diseases, breathlessness and poor self-rated health among participants in the tightest definitions of FT and LLN obstruction, confirming similar findings in the USA 5354 While recent guidelines13 46 55 recommend adopting multidimensional definitions of respiratory disease, our study outcomes were defined only using spirometry. While we acknowledge the merits of a multidimensional approach, and agree that neither spirometric cut-off is able to fully characterise the complex diagnostic features of COPD,56 our primary aim was to use up-to-date survey data to evaluate differences in prevalence according to FT and LLN thresholds, to provide baseline data for monitoring purposes in the UK, and promote comparability with international studies.…”

Section: Discussionsupporting

confidence: 68%

“…Analysis of the National Health and Nutrition Examination Survey (NHANES) 2007–2010 showed that FT and LLN prevalence estimates among US adults aged 40–79 years decreased, in relative terms, by approximately one-third after administration of bronchodilators 45. Although recent guidelines from NICE46 and ERS13 recommend use of postbronchodilator spirometry to confirm the presence of airflow obstruction, debate continues over its use in epidemiological settings, with the arguments against including ethical issues such as possible side effects and contraindications 47. Potential misclassification of disease status through bronchodilators not being used was reduced by excluding participants with physician-diagnosed asthma.…”

Section: Discussionmentioning

confidence: 99%

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Estimating population prevalence of potential airflow obstruction using different spirometric criteria: a pooled cross-sectional analysis of persons aged 40–95 years in England and Wales

2014

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ObjectivesConsistent estimation of the burden of chronic obstructive pulmonary disease (COPD) has been hindered by differences in methods, including different spirometric cut-offs for impaired lung function. The impact of different definitions on the prevalence of potential airflow obstruction, and its associations with key risk factors, is evaluated using cross-sectional data from two nationally representative population surveys.DesignPooled cross-sectional analysis of Wave 2 of the UK Household Longitudinal Survey and the Health Survey for England 2010, including 7879 participants, aged 40–95 years, who lived in England and Wales, without diagnosed asthma and with good-quality spirometry data. Potential airflow obstruction was defined using self-reported physician-diagnosed COPD; a fixed threshold (FT) forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC) ratio <0.7 and an age-specific, sex-specific, height-specific and ethnic-specific lower limit of normal (LLN). Standardised questions elicited self-reported information on demography, smoking history, ethnicity, occupation, respiratory symptoms and cardiovascular disease.ResultsConsistent across definitions, participants classed with obstructed airflow were more likely to be older, currently smoke, have higher pack-years of smoking and be engaged in routine occupations. The prevalence of airflow obstruction was 2.8% (95% CI 2.3% to 3.2%), 22.2% (21.2% to 23.2%) and 13.1% (12.2% to 13.9%) according to diagnosed COPD, FT and LLN, respectively. The gap in prevalence between FT and LLN increased in older age groups. Sex differences in the risk of obstruction, after adjustment for key risk factors, was sensitive to the choice of spirometric cut-off, being significantly higher in men when using FT, compared with no significant difference using LLN.ConclusionsApplying FT or LLN spirometric cut-offs gives a different picture of the size and distribution of the disease burden. Longitudinal studies examining differences in unscheduled hospital admissions and risk of death between FT and LLN may inform the choice as to the best way to include spirometry in assessments of airflow obstruction.

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Section: Discussionsupporting

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Estimating population prevalence of potential airflow obstruction using different spirometric criteria: a pooled cross-sectional analysis of persons aged 40–95 years in England and Wales

2014

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“…According to the Global Initiative on Obstructive Lung Disease (GOLD) a post-bronchodilator ratio < 0.7 is defined as not fully reversible airway obstruction [10]. The ERS and American Thoracic Society (ATS) recommend the use of Lower Limit of Normal (LLN) defined as the lower fifth percentile of the distribution for healthy non-smokers to define an abnormally low ratio [11-13]. The LLN definition is dependent on the set of reference values in use.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the global lung function initiative 2012 reference values for spirometry in a Swedish population sample

et al. 2015

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BackgroundThe Global Lung Function Initiative 2012 (GLI) reference values are currently endorsed by several respiratory societies but evaluations of applicability for adults resident in European countries are lacking. The aim of this study was to evaluate if the GLI reference values are appropriate for an adult Caucasian Swedish population.MethodsDuring 2008–2013, clinical examinations including spirometry were performed on general population samples in northern Sweden, in which 501 healthy Caucasian non-smokers were identified. Predicted GLI reference values and Z-scores were calculated for each healthy non-smoking subject and the distributions and mean values for FEV1, FVC and the FEV1/FVC ratio were examined. The prevalence of airway obstruction among these healthy non-smokers was calculated based on the Lower Limit of normal (LLN) criterion (lower fifth percentile) for the FEV1/FVC ratio. Thus, by definition, a prevalence of 5% was expected.ResultsThe Z-scores for FEV1, FVC and FEV1/FVC were reasonably, although not perfectly, normally distributed, but not centred on zero. Both predicted FEV1 and, in particular, FVC were lower compared to the observed values in the sample. The deviations were greater among women compared to men. The prevalence of airway obstruction based on the LLN criterion for the FEV1/FVC ratio was 9.4% among women and 2.7% among men.ConclusionsThe use of the GLI reference values may produce biased prevalence estimates of airway obstruction in Sweden, especially among women. These results demonstrate the importance of validating the GLI reference values in different countries.Electronic supplementary materialThe online version of this article (doi:10.1186/s12890-015-0022-2) contains supplementary material, which is available to authorized users.

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“…24 The ERS Task Force has recently recommended using post-bronchodilator LLN values to define COPD. 25 In addition, the LLN criterion depends on reliable reference values derived from the healthy local population; many countries don't have their own reference values for spirometry, and even if they do, they are in all likelihood based on values obtained from asymptomatic never-smokers. In populations such as the Asia Pacific region, where smoking is not the overwhelming cause of COPD, the 'apparently healthy population' may include many who suffer from asymptomatic undiagnosed airflow limitation due to factors other than tobacco smoking, which may lead to significant underdiagnosis of true COPD in these population studies.…”

mentioning

confidence: 99%