BACKGROUND Laryngeal or vocal cord dysfunction has long been regarded as a mimic of asthma; however, recent evidence indicates that it may be a significant comorbid condition in patients with asthma. OBJECTIVE We aimed to systematically estimate the prevalence of comorbid laryngeal dysfunction (LD) in adults with asthma and characterize its clinical impact on asthma. METHODS Electronic databases were searched for relevant studies published until June 2019. Studies were included if LD was objectively defined by direct visualization of laryngeal movement. Outcomes included the prevalence of LD and its association with clinical asthma indicators, such as severity, control, and quality of life. Random effects meta-analyses were performed to calculate the estimates. RESULTS A total of 21 studies involving 1637 patients were identified. Overall, the pooled prevalence of LD in adults with asthma was 25% (95% CI = 15%-37%; I2 = 96%). Prevalence estimates differed according to the diagnostic test utilized, with the lowest overall prevalence (4% [95% CI = 0%-10%; I2 = 90%]) seen when LD was diagnosed by resting laryngoscopy without external stimuli; however, it was much higher when diagnosed by laryngoscopy studies utilizing an external trigger, such as exercise (38% [95% CI = 24%-53%; I2 = 90%]) or in studies using a computed tomography-based diagnostic protocol (36% [95% CI = 24%-49%; I2 = 78%]). Only 7 studies reported the associations between LD and clinical asthma indicators; inconsistencies between studies limited meaningful conclusions. CONCLUSION LD may be a common comorbidity in asthma, affecting about 25% of adult patients. Further prospective studies are needed to better characterize its clinical impact and the benefits of detecting and managing LD in patients with asthma.

中文翻译：

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哮喘合并症喉功能障碍的患病率和影响：系统评价和荟萃分析。

背景技术喉或声带功能障碍长期以来被认为是哮喘的一种模仿。然而，最近的证据表明，这可能是哮喘患者的一种严重的合并症。目的我们旨在系统地评估成年人哮喘合并喉功能障碍（LD）的患病率，并表征其对哮喘的临床影响。方法在电子数据库中搜索直到2019年6月为止发表的相关研究。如果通过直接可视化喉部运动客观地定义了LD，则纳入研究。结果包括LD的患病率及其与临床哮喘指标的关系，例如严重程度，控制和生活质量。进行随机效应荟萃分析以计算估计值。结果共鉴定出21项研究，涉及1637例患者。总体，成人合并LD的患病率为25％（95％CI = 15％-37％； I2 = 96％）。根据静息喉镜在无外部刺激的情况下诊断出LD时，根据使用的诊断测试，患病率估计值有所不同，总患病率最低（4％[95％CI = 0％-10％; I2 = 90％]）；但是，通过使用外部触发器（例如运动）的喉镜检查研究（38％[95％CI = 24％-53％; I2 = 90％]）或使用基于计算机断层扫描的诊断方案进行的研究中诊断出的血脂水平更高（36％[95％CI = 24％-49％; I2 = 78％]）。只有7项研究报道了LD与临床哮喘指标之间的关联。研究之间的不一致限制了有意义的结论。结论LD可能是哮喘的常见合并症，影响约25％的成年患者。