This study aimed to evaluate the screening effects of COPD-PS questionnaire, COPD-SQ questionnaire, PEF, COPD-PS questionnaire + PEF and COPD-SQ + PEF for chronic obstructive pulmonary disease (COPD). The results showed that all five methods had some screening ability for COPD and moderate or above COPD among residents in Haicang District of Xiamen City, China, and that adding PEF improved the performance of the questionnaires. Among the five screening methods, COPD-SQ questionnaire combined with PEF had relatively better diagnostic ability for COPD. However, when screening patients with moderate or above COPD, the sensitivity of COPD-PS questionnaire + PEF and COPD-SQ questionnaire + PEF was (0.630 vs 0.781), specificity was (0.811 vs 0.629), Youden index was (0.441 vs 0.410), and area under the receiver operating characteristic curve (AUROC) was (0.784 vs 0.766). The purpose of this study was to find a suitable screening method for COPD, which required a balance between sensitivity and specificity. Sensitivity is the ability of the screening test to accurately identify patients with a specified disease, and specificity is the ability of the screening test to accurately identify patients without the disease. High sensitivity results mean that there are few false negative results and missed cases. When the disease is serious and treatable in the pre-clinical stage, sensitivity is usually increased at the expense of specificity to increase the potential screening value[24]. Therefore, although COPD-PS questionnaire + PEF had higher Youden index and AUROC than COPD-SQ questionnaire, we suggest using COPD-SQ questionnaire + PEF to screen patients with COPD and moderate or above COPD, considering the preference of screening test for high sensitivity, until further research can potentially optimize the performance of screening tools.
Pulmonary function test (PFT) is the “gold standard” for diagnosing COPD, but it is time-consuming, labor-intensive, and requires trained professionals. Therefore, most COPD screening uses a two-stage strategy: first, a screening questionnaire to assess the risk factors of patients and divide them into “high-risk” and “low-risk” groups; second, a PFT for the high-risk group to confirm the diagnosis of COPD. This strategy is simple, convenient, and more cost-effective than questionnaire or PFT alone. In China, common COPD screening questionnaires include COPD-PS, COPD-SQ, CAPTURE, and COPD-MH. Among them, COPD-PS is currently the most widely used[15, 25]。However, some studies in Beijing and Shanghai found that COPD-SQ had a better screening effect than COPD-PS, which was consistent with this study. However, some studies in Beijing and Shanghai found that COPD-SQ had a better screening effect than COPD-PS [26, 27], which was consistent with this study. Moreover, the Chinese National Chronic Obstructive Pulmonary Disease Screening Program also recommends using COPD-SQ for COPD screening in primary healthcare center [28]. The CAPTURE questionnaire was developed by Martinez et al. in the US, and it covers exposure to risk factors, respiratory problems, environmental effects, life and work impacts, fatigue, and respiratory diseases [8] Pan et al. conducted a large-scale multicenter study based on primary health care institutions in China, and found that the Youden index of CAPTURE was lower than that of COPD-SQ (0.220 vs 0.326), suggesting that COPD-SQ had a better screening performance [29]. COPD-MH is a questionnaire developed by Shi Jindong et al. based on primary community hospitals in Minhang District in 2022. The results showed that COPD-MH had a better screening effect than both COPD-SQ and COPD-PS[27]. However, since COPD-MH was released recently and only studied in Minhang District in Shanghai, its screening effect needs to be further verified. The two-stage screening method also has some limitations. First, the questionnaire may not capture all the characteristics of COPD patients, especially other risk factors in the early stage of COPD. Second, the questionnaire may involve patients recalling past habits, which are subjective and may produce recall bias. In summary, the two-stage screening method is an effective method for COPD screening, but it needs to be constantly adjusted and optimized in practical application.
PEF is a simple, reliable, and low-cost method of lung function testing that measures the highest flow rate during forced expiration and reflects the degree of airflow limitation. PEF are smaller and more portable than spirometers, making them convenient, feasible, and reproducible for screening and monitoring COPD. Previous studies have shown that PEF can predict and detect COPD hospitalization exacerbations[30–33]. COPD screening questionnaires assess the likelihood of COPD by asking patients about their symptoms and signs to assess the likelihood of COPD, but this assessment may be biased by subjective factors. PEF, as an objective indicator of lung function, can directly measure the expiratory flow rate and reflect the degree of airflow limitation. Therefore, combining screening questionnaires with PEF can provide more comprehensive and accurate information and improve the screening performance. In 2016, Martinez et al. applied CAPTURE questionnaire and PEF to screen COPD in 346 subjects in US pulmonary and primary care clinics, and constructed a three-level screening strategy of “Questionnaire-PEF-Spirometry” [7]. They found that combining PEF increased the AUROC of CAPTURE questionnaire from 0.795 to 0.906. In 2023, they expanded the study and applied CAPTURE questionnaire and PEF to screen COPD in 4658 subjects in primary care clinics. They also found that combining PEF increased the AUROC of CAPTURE questionnaire indeed[34]. However, Yang et al. conducted CAPTURE questionnaire, COPD-SQ questionnaire and PEF in residents aged 35 years and above in Beijing primary health care institutions, and found that using COPD-SQ questionnaire alone had the best screening performance, while combining PEF reduced the screening performance of both questionnaires [35]. They attributed this contradiction to the epidemic situation or the poor cooperation between the subjects and the spirometry examiners. This study and Martinez et al.’s study both suggested that PEF can be combined with screening questionnaires to improve the screening ability of primary health care institutions for COPD. In future studies, we hope to further explore the value of PEF in COPD screening, diagnosis, follow-up and prognosis, and provide more valuable information for early, comprehensive, individualized treatment and management of COPD.
This study has important significance for screening COPD in primary health care institutions. Spirometry is often difficult to perform in these settings due to the lack of professional personnel and equipment. Therefore, the screening strategy of COPD-SQ questionnaire combined with PEF can provide a simple, fast, low-cost, and efficient method for primary health care institutions, which can help to improve the diagnosis and treatment of COPD, and enhance the prognosis and quality of life of patients. In the future, training and education for medical staff and patients in primary health care institutions can be strengthened to improve their understanding and mastery of PEF usage methods and significance.
This study has limitations. First, the results of screening tools reflect the clinical characteristics of primary health care cohort in Haicang District of Xiamen City. However, the applicability of COPD screening tools may vary in different regions, different age groups, different severity levels, different risk factors, etc. Second, FEV1/FVC ratio decreases with age increase, using a fixed cut-off point FEV1/FVC < 0.70 to define COPD may overestimate the risk of COPD in elderly subjects[36, 37]. In future studies, we suggest conducting research on more regions and larger samples to verify the results of this study. In addition, further optimization of screening tools’ performance is needed, as well as understanding whether their use will affect clinical outcomes.