Background: Measuring medication adherence in patients with COPD is complex. Different forms of therapy and devices must be considered. Consequences of poor adherence are insufficient treatment effects, and frequent exacerbations. The aim of this study was to identify different patient groups regarding their adherence to therapy and to investigate correlations to other risk factors.
Methods: The modified Stendal Adherence with Medication Score (SAMS) was used to assess adherence. In addition to demographic data, the St. George Respiratory Questionnaire (SGRQ), GOLD stage, inhalation device handling errors, and comorbidities were assessed. Preliminary descriptive analysis was performed (mean±SD or median (IQR).
Results: 137 patients (40.9% female, 67.5±9.9 years) with COPD (79.6% GOLD D, 2.5±2.2 exacerbations in the last year) were included. 26.3% were classified as non-adherent, 43.8% as moderately adherent, and 29.9% as fully adherent (SAMS Score: 7.2±8.1, cut-off 12 points). The overall inhalation device handling error rate was 3 (4-1) out of 10 errors. The critical error/total error rate was 33.3% (50-0%) per patient. The updated Charlson Comorbidity Index was 2.2±2.0 and 26.3% had a history of comorbid bronchial asthma. The SGRQ was 60.6±16.4 points. 
Conclusion: Approximately two-thirds of patients were classified as moderate or non-adherent with over a quarter of patients making ?4 errors in device use and the individual rate for critical device handling errors being ?50%. The planned analysis of the preliminary data presented here will address relationships between exacerbation frequency, device handling error rates, and predictors of non-adherence in a multiple regression analysis model.