The data regarding the influence of concomitant diseases (CDs) on adherence to chronic obstructive pulmonary disease (COPD) treatment is contradictory.

The aim of the study was to assess whether CDs have influence on adherence to COPD treatment.

Methods. The 156 patients with severe and very severe COPD were included into study. The 129 (82.7 %) of them had CDs. The duration of it was 12 months and it consisted of 5 visits.

At each visit the importance of basis therapy taking was discussed with the patients. They also were trained to use inhaler correctly.

All of the patients (n=156) were divided into 4 groups: without CDs (n1 = 27); with 1 CD (n2 = 87), with 2 CDs (n3 = 34), with more than 2 CDs (n4 = 8).

The comparison of average values and reliability assessment of intergroup differences was conducted using one-way analysis of variance (ANOVA).

Results. The initial adherence to COPD treatment was 43.06 ± 2.81 %, 43.98 ± 1.34 %, 44.46 ± 2.52 % and 53.53 ± 3.14 % among the groups of the patients without CDs, with 1 CD, 2 CDs and more than 2 CDs, respectively (p1-4 = 0.009, p2-4 = 0.003, p3-4 = 0.01).

At the completion of the study adherence increased by 31.39 ± 3.36 %, 31.4 ± 1.61 %, 30.83 ± 2.74 % and 22.10 ± 2.22 % in the groups of the patients without CDs, with 1 CD, 2 CDs and more than 2 CDs, respectively (p1-4 = 0.01, p2-4 = 0.0005, p3-4 = 0.009).

Conclusions. The initial adherence was significantly higher in the patients with more than 2 CDs in comparison with other groups. At the same time the absolute increase of adherence to COPD treatment was the lowest in this group of the patients despite of actions for adherence optimization.