Behavioral Phenotypes of Inhaler Technique and Adherence in COPD: A Cross-Sectional Study

Inhaler technique and treatment adherence are both determinants of clinical outcomes in chronic obstructive pulmonary disease (COPD), yet they are typically assessed in isolation. This study classified COPD patients into behavioral phenotypes based on the joint assessment of both dimensions and identified factors associated with phenotype membership.

This cross-sectional study enrolled 700 COPD outpatients at Beijing Chao-Yang Hospital, China, between January and December 2025. Inhaler technique was assessed with a validated 10-step checklist (a perfect score defined as correct), and adherence with the Test of Adherence to Inhalers (a score ≥46 defined as good adherence). Patients were classified into four phenotypes by the 2×2 combination of technique and adherence. Baseline characteristics were compared across phenotypes, and Firth penalized logistic regression with a prespecified covariate set was used to identify factors associated with phenotype membership.

Only 25.3% of patients demonstrated fully correct technique and 59.0% met the threshold for good adherence. Four phenotypes were identified: Standard and Adherent (n=145, 20.7%), Non-adherent but Standard (n=32, 4.6%), Adherent but Non-standard (n=268, 38.3%), and Non-standard and Non-adherent (n=255, 36.4%). Inhaler technique and treatment adherence were frequently discordant. After adjustment, a higher disease-knowledge score was the factor most consistently associated with phenotype membership, being associated with lower odds of the two technique-deficient phenotypes (Group 3 vs 1: OR 0.35, 95% CI 0.27-0.44; Group 4 vs 1: OR 0.30, 95% CI 0.23-0.39) and with lower odds of non-adherence within GOLD assessment groups A and E. Longer disease duration was associated with the adherence dimension in opposite directions across phenotypes. Most other characteristics were not independently associated with phenotype membership.

Inhaler technique and treatment adherence are frequently discordant in COPD, yielding four behavioral phenotypes. Disease-specific knowledge was the factor most consistently associated with these phenotypes, supporting assessing technique and adherence as two separate behavioral targets rather than a single construct.