Description of patients according to the occurrence of errors
| No error | Non-critical error | p value | Critical error | p value | |
| Errors n | 857 | 1236 | 1019 | ||
| Age years (mean±sd) | 64.8±11.3 | 66.1±11.1 | <0.05 | 65.7±11.7 | ns |
| Male/female % | 63.5/36.5 | 64.3/35.7 | ns | 62.3/37.7 | ns |
| Mean duration of use of the device months (mean±sd) | 31.9±36.1 | 39.1±44.9 | <0.001 | 39.5±44.8 | <0.001 |
| Demonstration of use at least once | 90 (88.0–92.0) | 85.4 (83.4–87.3) | <0.01 | 83.6 (81.3–85.9) | <0.0001 |
| Reading of leaflet at least once | 69.1 (66.0–72.2) | 58.7 (56.0–61.5) | <0.0001 | 53.9 (50.8–56.9) | <0.0001 |
| Poor adherence | 4.4 (3.1–5.8) | 8.0 (6.5–9.5) | <0.01 | 12.6 (10.5–14.6) | <0.0001 |
| Treatment perceived very efficacious | 40.4 (37.1–43.7) | 28.8 (26.3–31.4) | <0.0001 | 27.8 (25.1–30.6) | <0.0001 |
| Moderate to severe# exacerbation in past 3 months¶ | 32.1 (28.9–35.4) | 35.6 (32.9–38.4) | ns | 38.5 (35.4–41.5) | <0.01 |
| Severe exacerbation+ in past 3 months¶ | 3.3 (2.0–4.5) | 4.6 (3.4–5.8) | ns | 6.9 (5.3–8.5) | <0.01 |
Data are presented as % (95% CI), unless otherwise indicated. ns: non-significant. #: exacerbation with antibiotherapy, corticotherapy, emergency room visit or hospitalisation; ¶: restricted to patients treated for at least 3 months with the device (no error n=794; non-critical error n=1153; critical error n=975); +: exacerbation with emergency room visits or hospitalisation.