S19 Screening for undiagnosed COPD: a comparison of screening questionnaire test performance in two countries; Breathe Well Brazil and China

Introduction and Objectives The accuracy of available screening questionnaires for undiagnosed COPD in low/middle income country settings is unknown. We compared test performance of a variety of instruments in Brazil and China. Methods Patients aged ≥40 years from community health centres in China, and hypertension clinics in Basic Health Units in Brazil completed all screening questionnaires (CDQ, CAPTURE, Symptom-based questionnaire[SBP], COPD-SQ) and the reference test (ndd Easy On-PC spirometer). We compared test performance of all questionnaires against the reference test. COPD was defined by the lower limit of normal (LLN-GLI) on the reference test. Results 1162 participants in Brazil and 2445 participants in China completed all tests. Compared to China, the Brazil sample was older (62.3 yrs vs 59.8 yrs), had fewer men (32.5% vs 39.1%) and more ever smokers (51.0% vs 31.1%). The prevalence of study-defined COPD was lower in Brazil (n=91, 7.8%) compared to China (n=333, 13.6%). The SBQ had the best accuracy in both studies, followed by CAPTURE (Table 1). Conclusion The prevalence of study-defined COPD in the Brazil sample was approximately half that detected in the China study. In Brazil and China, the SBQ was the most accurate screening questionnaire overall. Compared to CAPTURE, the SBQ included additional items about age, smoking, weight, wheeze, allergies and childhood chronic respiratory conditions. Performance for all screening questionnaires was lower than reported in previous literature. While questionnaire performance is dependent on context and may not be replicable across settings, explanations for the observed test performances and potential alternative cut-points need to be explored further.