On-the-spot spirometry & combined salbutamol & glycopyrronium reversibility testing in obstructive airway disease: A real-world appraisal

Background & objectives Spirometric glycopyrronium responsiveness, a new advent, needs to be examined at in terms of degree and frequency in different obstructive-airway diseases diagnosed in real world practise. Methods Serial and willing symptomatic affected individuals of suspected airway disease underwent a pragmatic post-consultation spirometry-protocol on the same day with salbutamol followed by glycopyrronium bromide. The diagnosis of asthma (FEV1-reversibility ≥ 200 ml + 12%), chronic obstructive pulmonary disease (COPD) (FEV1/FVC<0.7 and FEV1-reversibility <200 ml and/or 12%), and 'unclassified' (neither asthma nor COPD) were determined on post-salbutamol changes. The performances of the two classes of bronchodilators were compared on FVC, FEV1/FVC, FEV1, and FEF-25-75 while the relative frequency of significant responsiveness for salbutamol (≥200 ml) and glycopyrronium (≥100 ml) were noted. Results Fifteen hundred and eighty study participants consisting of asthma (n=329; 21%), COPD (n=641; 40%), and 'unclassified' (n=610; 39%) were included. Both salbutamol and glycopyrronium had demonstrated improvement across the spirometric parameters. The salbutamol responsiveness was statistically significant in all but COPD in terms of absolute values of FEV1, FEV1/FVC, and FEF25-75 and the glycopyrronium responsiveness was significant in all plus COPD in FVC, FEV1, and FEF25-75 values. While all the asthmatics, 9.83 per cent of 'unclassified' study participants, and none of the COPD affected individuals had significant FEV1 responsiveness to salbutamol, the glycopyrronium responsiveness for the three conditions were 38.3, 40.25 and 24.26 per cent, respectively. The combined reversibility for asthma, COPD, and unclassified were 401.5±173.9, 119.5±109.3, and 158.7±136.3 ml, respectively. Interpretation & conclusions Spirometry with serial salbutamol and glycopyrronium responsiveness may prove helpful in identifying syndromic diagnosis and choosing the bronchodilator treatment of airway diseases.