OBJECTIVES

Non-adherence (NA) to medication treatment is common in COPD patients, and is known to be associated with higher exacerbation risk and morbidity. Even if there is a sufficient body of evidence regarding the extent of NA, less is known about patient-specific causes leading to NA in COPD patients. The aim of this study was to develop and validate a questionnaire (Adherence Barriers Questionnaire COPD: ABQ-COPD) detecting those NA causes.

METHODS

The existing ABQ – originally developed and validated in patients with atrial fibrillation - was adapted and submitted to COPD patients through telephone interviews in Germany. Initially, the ABQ-COPD consisted of 16 items formulated as statements (4-point-Likert-scale ranging from “strongly agree” to “strongly disagree”). Evaluation of the questionnaire included an assessment of internal consistency as well as factor analysis to detect existing subscales measuring different classes of patient-specific adherence barriers.

RESULTS

499 of 539 patients (92.6%) were able to complete the ABQ-COPD (mean age: 68.4 years; 37.9% females). The final ABQ-COPD included 11 items and demonstrated a still acceptable internal consistency (Cronbach’s alpha=0.595). 74.4% of the patients had at least one NA barrier (respective item score ≥3). The factor analysis identified 3 subscales. The first subscale contained items referring to patient’s knowledge/to the trust in the physician/therapy (20% of the variance; 5.6% affected patients with at least one barrier). The 4 items loading on the second subdomain could be described as unintentional barriers (e.g. forgetfulness, depression, problems with the use of inhaler; 15% of the variance; 55.5% patients affected). Finally, two items expressing patient’s uncovered need of help were assigned to the third subscale (10% of the variance; 27.7% affected patients).

CONCLUSIONS

The ABQ-COPD is a practical instrument for identifying patient-specific adherence barriers and related patient subgroups in the real-world treatment of COPD.