Peak Inspiratory Flow and Inhaler Prescription Strategies in a Specialized COPD Clinical Program: A Real-World Observational Study.

Background: COPD inhaler regimens should be appropriate for the patient's peak inspiratory flow (PIF) and should ideally consist of single or similar device(s).

Research questions: In a subspecialized COPD clinic: (1) What is the prevalence of patients with suboptimal PIF and with inappropriate device(s) for measured PIF? (2) Are there patient-related risk factors associated with suboptimal PIF? (3) What is the prevalence of patients with non-single inhaler therapy (SIT)/nonsimilar devices? (4) Does point-of-care PIF affect clinical decision-making?

Study design and methods: In this single-center real-world observational study, PIF was measured systematically at every outpatient visit in a subspecialized COPD clinic, and point-of-care results were provided to the clinician. Coprimary outcomes were the prevalence of outpatients with suboptimal PIF and with inappropriate devices for measured PIF. Secondary outcomes were patient-related risk factors associated with suboptimal PIF, the prevalence of non-SIT/nonsimilar devices, the prevalence of regimens consisting of either inappropriate device(s) for measured PIF and/or non-SIT/nonsimilar devices, and the effect of point-of-care PIF on clinical decision-making.

Results: Suboptimal PIF was identified in 45 of 161 participants (28%), and inappropriate device(s) for measured PIF were identified in 18 participants (11.2%). Significant associations were observed between suboptimal PIF and age (1.09; 95% CI, 1.04-1.15), female sex (10.30; 95% CI, 4.45-27.10), height (0.92; 95% CI, 0.88-0.96), BMI (0.90; 95% CI, 0.84-0.96), and FEV₁ (0.09; 95% CI, 0.03-0.26). After adjustment for age and sex, the association between suboptimal PIF and BMI, but not height, remained significant. Non-SIT and/or nonsimilar devices were identified in 50 participants (31.1%). Regimens consisting of either inappropriate device(s) for measured PIF and/or non-SIT/nonsimilar devices were observed in 59 participants (36.6%). Inhaler prescription changes were observed in this latter group (3.39; 95% CI, 1.76-6.64), as well as in patients with suboptimal PIF who already had SIT/similar regimens (2.93; 95% CI, 1.07-7.92).

Interpretation: Suboptimal PIF and inappropriate devices for measured PIF are highly prevalent among outpatients from a subspecialized COPD clinic. Female sex, reduced FEV₁, and low BMI are important, readily identifiable risk factors for suboptimal PIF, and point-of-care PIF can inform clinical decision-making.