Abstract

Background: The Portsmouth Inhaler Technique (PIT) Score is the first validated, UK-developed, device-neutral tool to quantitatively assess inhaler technique across device types and age groups. Developed through a collaborative, iterative and expert-led process involving key respiratory stakeholders, it identifies critical inhaler technique skills and enables standardised assessment to optimise inhaler use. This study reports the final phase of the psychometric evaluation of the PIT Score.
Aim: To assess the discriminant validity, reliability and internal consistency of the Portsmouth Inhaler Technique (PIT) Score.
Methods: Discriminant validity was assessed using data from a single-visit observational inhaler technique study. PIT Scores were compared with Asthma Control Questionnaire-6 (ACQ-6; n=475) and COPD Assessment Test (CAT; n=209) scores using Spearman's rank correlation to determine whether the PIT Score measures inhaler technique rather than disease control.
Inter-rater and intra-rater reliability were evaluated using 14 standardised videos demonstrating good and poor inhaler technique across seven inhaler devices, independently assessed using the PIT Score by 22 trained subject matter experts, with repeat assessments after 3-6 weeks to minimise recall bias. Reliability was assessed using Gwet's AC1 and intraclass correlation coefficients (ICC), while internal consistency was evaluated using Cronbach's alpha and split-half reliability.
Results: Among 684 participants in the discriminant validity analysis, PIT Scores ranged from 2-10 (mean 6.62±1.89). No significant correlation was observed between PIT Scores and ACQ-6 (ρ=0.008, p=0.858) or CAT (ρ=0.077, p=0.267) scores, demonstrating excellent discriminant validity.
A total of 588 video assessments were completed, with 20/22 raters undertaking repeat assessments. Median PIT Scores were 3 for poor technique and 10 for good technique, with a median assessment time of 58 seconds. Overall reliability was excellent (Gwet's AC1=0.9117; ICC=0.9015; both p<0.001). Inter-rater reliability was excellent across all devices (Gwet's AC1>0.99), while intra-rater reliability remained excellent (Gwet's AC1>0.92, both p<0.001). Internal consistency was also excellent (Cronbach's α=0.93; split-half reliability=0.91).
Conclusion: The PIT Score demonstrated excellent psychometric properties, including discriminant validity, inter- and intra-rater reliability, and internal consistency. It provides a robust, standardised and practical tool for assessing inhaler technique across device types, addressing an important gap in respiratory practice and supporting optimisation of inhaler technique.