Consistency Between Oscillometry and Spirometry in Patients with Suspected or Confirmed COPD or Asthma: Results from a Multi-Center Study in China.

UNLABELLED: Spirometry is the standard for assessing airflow obstruction but can be challenging and/or time-consuming for patients. Oscillometry offers an effort-independent alternative. This study assessed the consistency between oscillometry and spirometry in Chinese patients with suspected or confirmed chronic obstructive pulmonary disease (COPD) or asthma. This prospective study enrolled patients from 46 Chinese hospitals. All underwent oscillometry with the Ambulatory Lung Diagnosis System followed by spirometry, both before and after salbutamol. The primary outcome was prebronchodilator (pre-BD) test consistency (normal vs. abnormal), evaluated using Cohen's Kappa. Secondary outcomes included the number of attempts to complete each test, post-BD consistency in the COPD group, and BD test consistency overall. From February 8 and August 30, 2024, 801 patients were enrolled; 788 completed both tests and were analyzed (COPD: 197 suspected, 194 confirmed; asthma: 200 suspected, 197 confirmed). Pre-BD results showed moderate test consistency (kappa = 0.4188, 95% CI: 0.3556-0.4820; overall agreement = 70.9%). Overall BD test had only fair agreement (kappa = 0.2722, 95% CI: 0.1870-0.3575; overall agreement = 80.3%) between tests. Post-BD results in the COPD group showed moderate consistency between tests (kappa = 0.4662, 95% CI: 0.3803-0.5521; overall agreement = 73.6%), with a high positive predictive value (87.4%) of abnormal oscillometry for spirometrydefined COPD. For satisfactory results, oscillometry required significantly fewer attempts than spirometry (mean: 8.5 vs. 11.0, p < 0.0001). While oscillometry showed only moderate consistency with spirometry, its high positive predictive value suggests potential as a rule-in test for COPD diagnosis when spirometry is not feasible. An alternative oscillometry-based diagnostic pathway may help improve COPD diagnosis under such circumstances.

CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT06172777).