Effectiveness of inhaler types for real-world asthma management: retrospective observational study using the GPRD

Purpose: Results of randomized controlled trials may not predict effectiveness of inhaled corticosteroids (ICS) in real-world clinical practice, where inhaler technique and device characteristics can influence effectiveness. We compared asthma outcomes for ICS delivered via three different inhaler devices: pressurized metered-dose inhaler (pMDI), breath-actuated MDI (BAI), and dry powder inhaler (DPI).

Patients and methods: This retrospective database study evaluated 1-year outcomes for primary care patients with asthma aged 5-60 years prescribed their first ICS (initiation population) by pMDI (n = 39,746), BAI (n = 9809), or DPI (n = 6792), or their first ICS dose increase (step-up population) by pMDI (n = 6245), BAI (n = 1388), or DPI (n = 1536). Co-primary outcome measures were composite proxy measures of asthma control (no hospital attendance for asthma, oral corticosteroids, or antibiotics for lower respiratory infection) and severe exacerbations (unscheduled hospital admission, emergency room attendance, or oral corticosteroids). Outcomes were adjusted for potential confounding factors identified during a baseline year.

Results: In the initiation population, adjusted odds ratios (95% confidence intervals [CI]) for asthma control, as compared with pMDIs, were significantly better for BAIs (1.08 [1.02-1.14]) and DPIs (1.13 [1.06-1.21]), while adjusted exacerbation rate ratios (95% CI) were 1.00 (0.93-1.08) and 0.88 (0.81-0.95), respectively. In the step-up population, adjusted odds of asthma control were 1.21 (1.05-1.39) for BAIs and 1.13 (0.99-1.29) for DPIs; adjusted exacerbation rate ratios were 0.83 (0.71-0.98) for BAIs and 0.85 (0.74-0.98) for DPIs, compared with pMDIs.

Conclusion: Inhaler device selection may have a bearing on clinical outcomes. Differences in real-world effectiveness among these devices require closer evaluation in well-designed prospective trials.