Chronic respiratory disease surveys in adults in low- and middle-income countries: A systematic scoping review of methodological approaches and outcomes.

BACKGROUND: Chronic respiratory diseases (CRDs) contribute significantly towards the global burden of disease, but the true prevalence and burden of these conditions in adults is unknown in the majority of low- and middle-income countries (LMICs). We aimed to identify strategies - in particular the definitions, study designs, sampling frames, instruments, and outcomes - used to conduct prevalence surveys for CRDs in LMICs. The findings will inform a future RESPIRE Four Country ChrOnic Respiratory Disease (4CCORD) study, which will estimate CRD prevalence, including disease burden, in adults in LMICs. METHODS: We conducted a scoping review to map prevalence surveys conducted in LMICs published between 1995 and 2018. We followed Arksey and O'Malley's six-step framework. The search was conducted in OVID Medline, EMBASE, ISI Web of Science, Global Health, WHO Global Index Medicus and included three domains: CRDs, prevalence and LMICs. After an initial title sift, eight trained reviewers undertook duplicate study selection and data extraction. We charted: country and populations, random sampling strategies, CRD definitions/phenotypes, survey procedure (questionnaires, spirometry, tests), outcomes and assessment of individual, societal and health service burden of disease. RESULTS: Of 36 872 citations, 281 articles were included: 132 from Asia (41 from China). Study designs were cross-sectional surveys (n = 260), cohort studies (n = 11) and secondary data analysis (n = 10). The number of respondents in these studies ranged from 50 to 512 891. Asthma was studied in 144 studies, chronic obstructive pulmonary disease (COPD) in 112. Most studies (100/144) based identification of asthma on symptom-based questionnaires. In contrast, COPD diagnosis was typically based on spirometry findings (94/112); 65 used fixed-ratio thresholds, 29 reported fixed-ratio and lower-limit-of-normal values. Only five articles used the term 'phenotype'. Most studies used questionnaires derived from validated surveys, most commonly the European Community Respiratory Health Survey (n = 47). The burden/impact of CRD was reported in 33 articles (most commonly activity limitation). CONCLUSION: Surveys remain the most practical approach for estimating prevalence of CRD but there is a need to identify the most predictive questions for diagnosing asthma and to standardise diagnostic criteria.

Systematic scoping review protocol of methodologies of chronic respiratory disease surveys in low/middle-income countries.

This protocol describes a systematic scoping review of chronic respiratory disease surveys in low/middle-income countries (LMICs) undertaken as part of the Four Country ChrOnic Respiratory Disease (4CCORD) study within the National Institute for Health Research Global Health Research Unit on Respiratory Health (RESPIRE). Understanding the prevalence and burden of chronic respiratory disease (CRD) underpins healthcare planning. We will systematically scope the literature to identify existing strategies (definitions/questionnaires/diagnostics/outcomes) used in surveys of CRDs in adults in low-resource settings. We will search MEDLINE, EMBASE, ISI WoS, Global Health and WHO Global Health Library [search terms: prevalence AND CRD (COPD, asthma) AND LMICs, from 1995], and two reviewers will independently extract data from selected studies onto a piloted customised data extraction form. We will convene a workshop of the multidisciplinary 4CCORD research team with representatives from the RESPIRE partners (Bangladesh, India, Malaysia, Pakistan and Edinburgh) at which the findings of the scoping review will be presented, discussed and interpreted. The findings will inform a future RESPIRE 4CCORD study, which will estimate CRD burden in adults in Asian LMICs.