Validation of the 'test of the adherence to inhalers' (TAI) for asthma and COPD patients

There are not validated tools that specifically and reliably establish patient9s adherence and non-adherence patterns to inhalers. Objectives: To develop and validate the 9Test of Adherence to Inhalers9 (TAI), a questionnaire designed to assess the adherence to inhalers in patients with COPD or asthma. Methods: A total of 1,009 patients with asthma or COPD were included in a cross-sectional multicentre study. Patients with electronic adherence ≥80% were defined as adherents. Construct validity, internal validity and criterion validity were evaluated. Self-reported adherence was compared with the Morisky-Green questionnaire. Results: Factor analysis demonstrated two factors, factor 1 was coincident with TAI patient domain (items 1 to 10) and factor 2 with TAI health-care professional domain (items 11 and 12). The Cronbach9s alpha was 0.860 and the test-retest reliability 0.883. TAI scores correlated with electronic adherence (ρ=0.293, p=0.01). According to the best cut-off for 10 items (score 50, area under the ROC curve 0.7), 569 (62.5%) patients were classified as non-adherents. Non-adherence behaviour pattern was: erratic 527 (57.9%), deliberate 375 (41.2%) and unwitting 242 (26.6%). As compared to Morisky-Green test, TAI showed better psychometric properties. Conclusions: The 12-item TAI is a reliable and homogeneous questionnaire to easily identify non-adherence and barriers related to the use of inhalers in asthma and COPD.