Sufficient inspiratory effort for a Dry Powder Inhaler - do we have to measure it, or can we observe it? Post hoc analysis of the PIFotal study

Abstract

<b>Background:</b> The PIFotal study found that nearly a third of COPD patients on dry powder inhaler (DPI) maintenance therapy did not generate an optimal peak inspiratory flow (PIF) for their device during a typical inhalation manoeuvre.&nbsp;PIF can be assessed by either observing inhalation technique or by measuring it objectively. However, it is unclear whether these methods differ in their accuracy to guide optimal DPI use. <b>Method:</b> Cross-sectional observational multinational study in 1,389 COPD patients (mean±SD: 69±9yrs) on DPI maintenance therapy. PIF was assessed by 1) videorecording and rated with checklists (i.e. ‘inspiratory effort’) and 2) measurement at the resistance of patient’s DPI with In-Check Dial G16. Health status was assessed with Clinical COPD Questionnaire. <b>Results:</b> Patients with sufficient inspiratory effort, as assessed with video (n = 987), but with suboptimal PIF (sPIF n = 365), as measured with In-Check Dial G16, had significantly worse health status compared to patients with optimal PIF and sufficient inspiratory effort (Fig. 1, β* 0.19; 95%CI [0.03, 0.35]; p = 0.02). <b>Conclusion:</b> Even when PIF was observed to be sufficient, 37% of patients had sPIF when measured. Thus, observations were inadequate to identify sPIF, a factor associated with poorer health status. Objective measurements of PIF should guide the DPI selection process.