Assessing the prevalence and impact of preserved ratio impaired spirometry in low-income and middle-income countries: a post-hoc cross-sectional analysis.

BACKGROUND: More than 90% of the morbidity and mortality from chronic respiratory disease occurs in low-income and middle-income countries (LMICs), with substantial economic impact. Preserved ratio impaired spirometry (PRISm) is a prevalent lung function abnormality associated with increased mortality in high-income countries. We aimed to conduct a post-hoc analysis of a cross-sectional study to assess the prevalence of, the risk factors for, and the impact of PRISm in three diverse LMIC settings. METHODS: We recruited a random, age-stratified and sex-stratified sample of the population in semi-urban Bhaktapur, Nepal; urban Lima, Peru; and rural Nakaseke, Uganda. Quality-assured post-bronchodilator spirometry was performed to American Thoracic Society standards and PRISm was defined as a forced expiratory volume in one second (FEV1) of less than 80% predicted with a FEV1/forced vital capacity ratio of 0·70 or more. We used t tests and χ2 analyses to assess the relationships between demographic, biometric, and comorbidity variables with PRISm. Multivariable logistic models with random intercept by site were used to estimate odds ratios (ORs) with 95% CIs. FINDINGS: 10 664 participants were included in the analysis, with a mean (SD) age of 56·3 (11·7) years and an equal distribution by sex. The prevalence of PRISm was 2·5% in Peru, 9·1% in Nepal, and 16·0% in Uganda. In multivariable analysis, younger age (OR for each decile of age 0·87, 95% CI 0·82-0·92) and being female (1·37, 1·18-1·58) were associated with increased odds of having PRISm. Biomass exposure was not consistently associated with PRISm across sites. Individuals with PRISm had impairment in respiratory-related quality of life as measured by the St George's Respiratory Questionnaire (OR by decile 1·18, 95% CI 1·10-1·25). INTERPRETATION: The prevalence of PRISm is heterogeneous across LMIC settings and associated with age, female sex, and biomass exposure, a common exposure in LMICs. A diagnosis of PRISm was associated with worse health status when compared with those with normal lung function. Health systems in LMICs should focus on all spirometric abnormalities as opposed to obstruction alone, given the disease burden, reduced quality of life, and size of the undiagnosed population at risk. FUNDING: Medical Research Council.

Discriminative Accuracy of Chronic Obstructive Pulmonary Disease Screening Instruments in 3 Low- and Middle-Income Country Settings.

Importance: Most of the global morbidity and mortality in chronic obstructive pulmonary disease (COPD) occurs in low- and middle-income countries (LMICs), with significant economic effects. Objective: To assess the discriminative accuracy of 3 instruments using questionnaires and peak expiratory flow (PEF) to screen for COPD in 3 LMIC settings. Design, Setting, and Participants: A cross-sectional analysis of discriminative accuracy, conducted between January 2018 and March 2020 in semiurban Bhaktapur, Nepal; urban Lima, Peru; and rural Nakaseke, Uganda, using a random age- and sex-stratified sample of the population 40 years or older. Exposures: Three screening tools, the COPD Assessment in Primary Care to Identify Undiagnosed Respiratory Disease and Exacerbation Risk (CAPTURE; range, 0-6; high risk indicated by a score of 5 or more or score 2-5 with low PEF [<250 L/min for females and <350 L/min for males]), the COPD in LMICs Assessment questionnaire (COLA-6; range, 0-5; high risk indicated by a score of 4 or more), and the Lung Function Questionnaire (LFQ; range, 0-25; high risk indicated by a score of 18 or less) were assessed against a reference standard diagnosis of COPD using quality-assured postbronchodilator spirometry. CAPTURE and COLA-6 include a measure of PEF. Main Outcomes and Measures: The primary outcome was discriminative accuracy of the tools in identifying COPD as measured by area under receiver operating characteristic curves (AUCs) with 95% CIs. Secondary outcomes included sensitivity, specificity, positive predictive value, and negative predictive value. Results: Among 10 709 adults who consented to participate in the study (mean age, 56.3 years (SD, 11.7); 50% female), 35% had ever smoked, and 30% were currently exposed to biomass smoke. The unweighted prevalence of COPD at the 3 sites was 18.2% (642/3534 participants) in Nepal, 2.7% (97/3550) in Peru, and 7.4% (264/3580) in Uganda. Among 1000 COPD cases, 49.3% had clinically important disease (Global Initiative for Chronic Obstructive Lung Disease classification B-D), 16.4% had severe or very severe airflow obstruction (forced expiratory volume in 1 second <50% predicted), and 95.3% of cases were previously undiagnosed. The AUC for the screening instruments ranged from 0.717 (95% CI, 0.677-0.774) for LFQ in Peru to 0.791 (95% CI, 0.770-0.809) for COLA-6 in Nepal. The sensitivity ranged from 34.8% (95% CI, 25.3%-45.2%) for COLA-6 in Nepal to 64.2% (95% CI, 60.3%-67.9%) for CAPTURE in Nepal. The mean time to administer the instruments was 7.6 minutes (SD 1.11), and data completeness was 99.5%. Conclusions and Relevance: This study demonstrated that screening instruments for COPD were feasible to administer in 3 low- and middle-income settings. Further research is needed to assess instrument performance in other low- and middle-income settings and to determine whether implementation is associated with improved clinical outcomes.