Diagnostic value of fractional exhaled nitric oxide test in corticosteroid responsive cough patients in China: a meta-analysis

Objective To evaluate diagnostic value of fractional exhaled nitric oxide (FeNO) test in corticosteroid responsive cough (CRC) patients in China, and provide evidences for clinical treatment. Methods We searched China Biology Medicine disc (CBMdisc, in Chinese), Chinese National Knowledge Infrastructure (CNKI, in Chinese), China Science and Technology Journal Database (VIP, in Chinese), Wanfang date (in Chinese), Cochrane library, PubMed, Web of science and Embase databases and selected articles according to the inclusion and exclusion criteria.The outcome indicators included the value of FeNO, sensitivity, specificity and so on.We used Statistical analysis software RevMan5.3 and stata12.0 for meta analysis. Results There were 13 studies selected finally.The results showed that the value of FeNO in CRC patients was significantly higher than that of in non-corticosteroids responsive cough (NCRC) patients [MD=20.44, 95%CI: (15.29-25.59), P<0.05]. In subgroup analysis, we found that the value of FeNO in cough variant asthma (CVA) patients was obviously higher than that of in other patients with chronic cough [MD=30.03, 95%CI: (21.43-38.63), P<0.05]. Similarly, the level of FeNO in eosinophilic bronchitis (EB) patients was also higher than that of in other patients with chronic cough [MD=12.32, 95%CI: (9.02-15.61), P<0.05]. And it was showed that in patients of CRC, the pooled sensitivity was 0.74(95%CI: 0.67-0.80), the pooled specificity was 0.87(95%CI: 0.83-0.91), positive likelihood ratio was 5.8(95%CI: 4.3-7.8), negative likelihood ratio was 0.30(95%CI: 0.23-0.38), diagnostic odds ratio was 20(95%CI: 12-31), and area under SROC curve was 0.89(95%CI: 0.86-0.91). Of that, the pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, diagnostic odds ratio and area under the SROC curve of CVA were 0.80(95%CI: 0.74-0.84), 0.85(95%CI: 0.80-0.90), 5.5(95%CI: 3.8-7.9), 0.24(95%CI: 0.18-0.32), 23(95%CI: 13-42), and 0.89(95%CI: 0.86-0.92). And we could not do diagnostic analysis in EB and AC patients, for there were only 3 and 1 studies included. Conclusions At present, we have showed that the value of FeNO in CRC patients is significantly higher than that of in chronic cough patients with other causes, and FeNO has important clinical significance in the diagnosis of CRC patients in China.It can provide an experiential treatment strategy for chronic cough patients with high FeNO.However, there still needs large-scale studies in the analysis, due to the limitations of the research quality and the sample size. Key words: Nitric oxide; Cough; Glucocorticoids; Diagnosis