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Poverty is strongly associated with all-cause and chronic obstructive pulmonary disease (COPD) mortality. Less is known about the contribution of poverty to spirometrically defined chronic airflow obstruction (CAO)—a key characteristic of COPD. Using cross-sectional data from an asset-based questionnaire to define poverty in 21 sites of the Burden of Obstructive Lung Disease study, we estimated the risk of CAO attributable to poverty. Up to 6% of the population over 40 years had CAO attributable to poverty. Understanding the relationship between poverty and CAO might suggest ways to improve lung health, especially in low-income and middle-income countries.

Background Spirometric small airways obstruction (SAO) is common in the general population. Whether spirometric SAO is associated with respiratory symptoms, cardiometabolic diseases, and quality of life (QoL) is unknown. Methods Using data from the Burden of Obstructive Lung Disease study (N = 21,594), we defined spirometric SAO as the mean forced expiratory flow rate between 25 and 75% of the FVC (FEF 25-75 ) less than the lower limit of normal (LLN) or the forced expiratory volume in 3 s to FVC ratio (FEV 3 /FVC) less than the LLN. We analysed data on respiratory symptoms, cardiometabolic diseases, and QoL collected using standardised questionnaires. We assessed the associations with spirometric SAO using multivariable regression models, and pooled site estimates using random effects meta-analysis. We conducted identical analyses for isolated spirometric SAO (i.e. with FEV 1 /FVC ≥ LLN). Results Almost a fifth of the participants had spirometric SAO (19% for FEF 25-75 ; 17% for FEV 3 /FVC). Using FEF 25-75, spirometric SAO was associated with dyspnoea (OR = 2.16, 95% CI 1.77–2.70), chronic cough (OR = 2.56, 95% CI 2.08–3.15), chronic phlegm (OR = 2.29, 95% CI 1.77–4.05), wheeze (OR = 2.87, 95% CI 2.50–3.40) and cardiovascular disease (OR = 1.30, 95% CI 1.11–1.52), but not hypertension or diabetes. Spirometric SAO was associated with worse physical and mental QoL. These associations were similar for FEV 3 /FVC. Isolated spirometric SAO (10% for FEF 25-75 ; 6% for FEV 3 /FVC), was also associated with respiratory symptoms and cardiovascular disease. Conclusion Spirometric SAO is associated with respiratory symptoms, cardiovascular disease, and QoL. Consideration should be given to the measurement of FEF 25-75 and FEV 3 /FVC, in addition to traditional spirometry parameters.

We investigated whether the forced expiratory volume in 6 s (FEV ) can be used as a surrogate for the forced vital capacity (FVC). The Burden of Obstructive Lung Disease is a multinational cohort study. At baseline, data were collected from adults, aged 40 years or older, from 41 sites across 34 countries. Participants from 18 sites were followed-up after a median of 8.3 years. Participants who completed the study core questionnaire and had acceptable post-bronchodilator spirometry were included. We performed receiver operating characteristic analyses to measure the ability of FEV /FEV less than the lower limit of normal (LLN) to correctly classify FEV /FVC less than the LLN, and FEV less than the LLN to correctly classify FVC less than the LLN. We used multilevel regression analyses to assess the association of discordant measurements with respiratory symptoms, quality of life and lung function decline. At baseline, 28 604 participants were included. 53% were female (15 060). 10% (2876) had chronic airflow obstruction for FEV /FVC, compared with 9% (2704) for FEV /FEV . 37% (10 637) had spirometric restriction for FVC, compared with 35% (9978) for FEV . The FEV /FEV had excellent accuracy in identifying FEV /FVC less than the LLN (area under the curve (AUC): 0.90, 95% CI, 0.89 to 0.91, κ coefficient 0.82). The FEV also had excellent agreement in identifying FVC less than the LLN (AUC: 0.95, 95% CI, 0.94 to 0.95, κ coefficient 0.90). Discordant reductions in FEV /FEV (1%, 345) and FEV (1%, 309) were associated with greater odds of having respiratory symptoms and a lower physical quality of life. 3870 participants were followed up. Those with discordant reductions in FEV /FEV and FEV were more likely to have chronic airflow obstruction and spirometric restriction at follow-up. There is strong agreement between the FVC and FEV in the identification of chronic airflow obstruction and spirometric restriction.