Accuracy of different screening strategies for undiagnosed COPD in primary care in China: a Breathe Well study

Background: Undiagnosed COPD is a major problem in China but the optimal screening strategy to identify new cases is unclear. Aims and objectives: To evaluate the accuracy and cost-effectiveness of COPD screening tests and strategies amongst primary care patients in China Methods: Test accuracy study in four municipalities. Participants completed six index tests (CDQ, CAPTURE, Chinese Symptom-based questionnaire [C-SBQ], COPD-SQ, microspirometry [COPD-6], peak flow [USPE]) and the reference test (post-bronchodilator ndd Easy On-PC). Cases were those with FEV1/FVC below the lower limit of normal (LLN) on the reference test. Performance of individual screening tests and strategies was analysed, with cost-effectiveness analyses providing cost per additional true case detected. Results: 2445 participants (mean age 59.8 years, 39.1% [n=956] male) completed the study, 68.9% (n=1684) were never-smokers and 9.7% (n=237) had an existing COPD diagnosis. 13.6% (n=333) had spirometry-confirmed airflow obstruction. Airflow measurement devices (sensitivities 64.9% and 67.3%, specificities 89.7% and 82.6% for microspirometry and peak flow respectively) generally performed better than questionnaires, the most accurate of which was C-SBQ (sensitivity 63.1%, specificity 74.2%). The combination of C-SBQ and microspirometry used in parallel, maximised sensitivity (81.4%) and had specificity of 68%, with an incremental cost-effectiveness ratio of £64.20 (CNY385) per additional case detected compared with peak flow. Conclusions: Simple screening tests to identify undiagnosed COPD within the primary care setting in China are possible, and a combination of C-SBQ and microspirometry is the most sensitive.