Background: Identifying positive bronchodilator reversibility (BDR) helps the diagnosis of asthma. However, not all patients can adequately perform the forced expiration during the spirometry test. An alternative test is required. Impulse oscillometry (IOS) is an effort-independent technique that enables the measurement of lung mechanics during quiet tidal breathing. We investigated the potentiality of IOS to evaluate BDR in untreated adult patients with newly diagnosed asthma (UAPNDS). Methods: All UAPNDS (aged 20–80 years) who never smoke and underwent IOS and spirometry before and after salbutamol inhalation at their initial visit to the hospital from March 22, 2017, to December 31, 2019, were identified. A total of 323 patients were enrolled. Data from the medical record, including demographic characteristics, laboratory examination, spirometric data, and IOS parameters, were retrospectively reviewed. The associations of parameters with the positive BDR and the performance of parameters in predicting the positive BDR were evaluated by statistical methods. Results: Patients (n = 323) had a median age of 64 years and were mostly female (67.5%). Several variables, including serum total immunoglobulin level, blood eosinophil counts, blood eosinophil percentage (%), and two IOS parameters, were found to be different between the positive (n = 93) and negative BDR (n = 230) groups. Multivariate logistic regression analyses after adjustment by cofactors revealed that the percentage change of the area under the reactance curve between 5 Hz and resonant frequency [ΔAx (%)] after salbutamol inhalation was the only independent factor for the positive BDR. The area under the receiver operating characteristic curve of ΔAx (%) in predicting the positive BDR was 0.614 (p = 0.0013), and its optimal cutoff value was −53.8% (sensitivity, 39.78% and specificity, 80.43%). Conclusion: In addition to spirometry, ΔAx (%), an IOS parameter, may serve as a novel indicator to evaluate BDR in UAPNDS.

Patients with asthma are treated in primary healthcare facilities (PHCFs) in Taiwan, where the asthma control status associated with acute exacerbation (AE) and use of oral corticosteroids (OCS) and short-acting β2-agonist (SABA) inhalers remains unclear. A cross-sectional, close-ended, face-to-face questionnaire survey invited board-certified physicians who treat adult asthma patients in PHCFs. The contents of the questionnaire included three parts: rescue OCS to treat AE, regular OCS for asthma control, and AE-related adverse outcomes. There were 445 out of 500 physicians who completed the questionnaire, with 61% of them being non-pulmonologists. A substantial proportion of asthma patients needed rescue OCS or regular OCS each month, or ≥3 canisters of SABA inhalers per year. Approximately 86% of physicians reported their patients with ≥2 AE-related unscheduled visits to clinics or emergency departments in the past year. A total of 41% of physicians reported their patients receiving intubation or intensive care in the past year. A total of 92% of physicians prescribed rescue OCS ≤ 40 mg/day. A total of 92% of physicians prescribed rescue OCS for a duration of ≤7 days for AEs. A total of 85% of physicians prescribed regular OCS ≤ 10 mg/day for asthma control. This is the first study to present the perceptions of asthma-treating physicians on the use of OCS in PHCFs. In summary, 31% of physicians reported ≥ 6% of their patients needed OCS for asthma control and 41% of physicians reported their patients with adverse outcomes in the past year. Thus, the need to improve asthma control in Taiwan is suggested by our study results.

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