Occupational exposures and small airway obstruction in the UK Biobank Cohort

Small Airways Obstruction and Mortality: Findings From the UK Biobank

BACKGROUND

Small airways obstruction (SAO) is common in general populations. It has been associated with respiratory symptoms, cardiometabolic diseases, and progression to COPD over time. Whether SAO predicts mortality is largely unknown.

RESEARCH QUESTION

Is spirometry-defined SAO associated with increased mortality?

METHODS

Data were analyzed from 252,877 adult participants, aged 40 to 69 years at baseline, in the UK Biobank who had provided good-quality spirometry measurements. SAO was defined as the ratio of the forced expiratory volume in 3 s to the forced expiratory volume in 6 s less than the lower limit of normal. SAO was considered to be isolated if present when the FEV1/forced expiratory volume in 6 s ratio was normal (ie, greater than the lower limit of normal). A multivariable Cox regression model was used to assess the association of SAO, and isolated SAO, with all-cause and disease-specific mortality. Sex differences were investigated in these associations, and the primary analysis was repeated, excluding those who ever smoked. All models were adjusted for potential confounders such as sex, BMI, smoking status, smoking pack-years, assessment center, Townsend deprivation index, and ethnicity.

RESULTS

A total of 59,744 participants with SAO were identified, of whom 24,004 had isolated SAO. A total of 5,009 deaths were reported over a median of 12.8 years of follow-up. Participants with SAO had increased all-cause (hazard ratio [HR], 1.31; 95% CI, 1.26-1.36), cardiovascular (HR, 1.39; 95% CI, 1.29-1.51), respiratory (HR, 2.20; 95% CI, 1.92-2.51), and neoplasm (HR, 1.23; 95% CI, 1.17-1.29) mortality risk. These associations were not modified by sex. However, in those who never smoked, only respiratory and cardiovascular mortality risk was associated with SAO. Isolated SAO was also associated with an increased mortality risk (HR, 1.14; 95% CI, 1.07-1.20).

INTERPRETATION

Individuals with SAO have an increased risk of all-cause and disease-specific mortality. Further studies are needed to determine whether SAO causes mortality or is a marker of underlying disease.

EAACI guidelines on environmental science for allergy and asthma: The impact of short-term exposure to outdoor air pollutants on asthma-related outcomes and recommendations for mitigation measures

The EAACI Guidelines on the impact of short-term exposure to outdoor pollutants on asthma-related outcomes provide recommendations for prevention, patient care and mitigation in a framework supporting rational decisions for healthcare professionals and patients to individualize and improve asthma management and for policymakers and regulators as an evidence-informed reference to help setting legally binding standards and goals for outdoor air quality at international, national and local levels. The Guideline was developed using the GRADE approach and evaluated outdoor pollutants referenced in the current Air Quality Guideline of the World Health Organization as single or mixed pollutants and outdoor pesticides. Short-term exposure to all pollutants evaluated increases the risk of asthma-related adverse outcomes, especially hospital admissions and emergency department visits (moderate certainty of evidence at specific lag days). There is limited evidence for the impact of traffic-related air pollution and outdoor pesticides exposure as well as for the interventions to reduce emissions. Due to the quality of evidence, conditional recommendations were formulated for all pollutants and for the interventions reducing outdoor air pollution. Asthma management counselled by the current EAACI guidelines can improve asthma-related outcomes but global measures for clean air are needed to achieve significant impact.

Isolated small airways obstruction predicts future chronic airflow obstruction: a multinational longitudinal study

BACKGROUND

Chronic airflow obstruction is a key characteristic of chronic obstructive pulmonary disease. We investigated whether isolated small airways obstruction is associated with chronic airflow obstruction later in life.

METHODS

We used longitudinal data from 3957 participants of the multinational Burden of Obstructive Lung Disease study. We defined isolated small airways obstruction using the prebronchodilator mean forced expiratory flow rate between 25% and 75% of the forced vital capacity (FVC) (FEF25-75) if a result was less than the lower limit of normal (

RESULTS

Median follow-up time was 8.3 years. Chronic airflow obstruction was more likely to develop in participants with isolated small airways obstruction at baseline (FEF25-75 less than the LLN, OR: 2.95, 95% CI 1.02 to 8.54; FEV3/FVC less than the LLN, OR: 1.94, 95% CI 1.05 to 3.62). FEF25-75 was better than the FEV3/FVC ratio to discriminate future chronic airflow obstruction (AUC: 0.764 vs 0.692). Results were similar among participants of the UK Biobank study.

CONCLUSION

Measurements of small airways obstruction can be used as early markers of future obstructive lung disease.

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Key Words

• COPD epidemiology
• Lung Physiology

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MESH Headings

• Humans
• Longitudinal Studies
• Pulmonary Disease, Chronic Obstructive/complications
• Pulmonary Disease, Chronic Obstructive/diagnosis
• Airway Obstruction/diagnosis
• Airway Obstruction/etiology
• Vital Capacity
• Forced Expiratory Volume

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Grants

• Wellcome Trust
• 085790/Z/08/Z Wellcome Trust
• MR/R011192/1 Medical Research Council
• AstraZeneca
• UK Biobank

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Affiliation(s)

Ben Knox-Brown National Heart and Lung Institute, Imperial College London, London, UK
James Potts National Heart and Lung Institute, Imperial College London, London, UK
Valentina Quintero Santofimio National Heart and Lung Institute, Imperial College London, London, UK
Cosetta Minelli National Heart and Lung Institute, Imperial College London, London, UK NIHR Imperial Biomedical Research Centre, London, UK
Jaymini Patel National Heart and Lung Institute, Imperial College London, London, UK
Najlaa Mohammed Abass College of Medicine, Alshaab Teaching Hospital, Bahri University, Khartoum, Sudan
Dhiraj Agarwal Vadu Rural Health Program, KEM Hospital Pune Research Centre, Pune, India
Rana Ahmed The Epidemiological Laboratory, Khartoum, Sudan
Padukudru Anand Mahesh Respiratory Medicine, JSS Medical College, Mysore, Karnataka, India
Jayaraj Bs Respiratory Medicine, JSS Medical College, Mysore, Karnataka, India
Meriam Denguezli Faculte de Medecine de Sousse, Universite de Sousse, Sousse, Tunisia
Frits Franssen Respiratory medicine, Maastricht University Medical Centre+, Maastricht, Netherlands Research and Education, CIRO, Horn, Netherlands
Thorarinn Gislason Department of Sleep, Landspitali University Hospital, Reykjavik, Iceland Faculty of Medicine, University of Iceland, Reykjavik, Iceland
Christer Janson Department of Medical Sciences Respiratory, Allergy and Sleep Research, Uppsala University, Uppsala, Sweden
Sanjay K Juvekar Vadu Rural Health Program, KEM Hospital Pune Research Centre, Pune, India
Parvaiz Koul Sher-i-Kashmir Institute of Medical Sciences, Srinagar, Jammu and Kashmir, India
Andrei Malinovschi Department of Medical Sciences Respiratory, Allergy and Sleep Research, Uppsala University, Uppsala, Sweden
Asaad Ahmed Nafees Department of Community Health Sciences, The Aga Khan University, Karachi, Sindh, Pakistan
Rune Nielsen Department of Thoracic Medicine, University of Bergen, Bergen, Hordaland, Norway
Stefanni Nonna M Paraguas Philippine College of Chest Physicians, Quezon City, Philippines Philippine Heart Center, Quezon City, Manila, Philippines
Sonia Buist Oregon Health & Science University, Portland, Oregon, USA
Peter Gj Burney National Heart and Lung Institute, Imperial College London, London, UK
Andre F S Amaral National Heart and Lung Institute, Imperial College London, London, UK

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