| Scale | Items | Eigenvalue | Accounted variance | ||
| First component | Second component | First component | First and second components | ||
| SRI-RC | 8 | 3.82 | 1.37 | 48% | 65% |
| SRI-PF | 6 | 2.84 | 1.23 | 47% | 68% |
| SRI-AS | 7 | 3.33 | 1.34 | 48% | 67% |
| SRI-SR | 6 | 3.11 | 0.88 | 52% | 67% |
| SRI-AX | 9 | 3.32 | 0.63 | 66% | 79% |
| SRI-WB | 5 | 4.83 | 0.99 | 54% | 65% |
| SRI-SF | 8 | 4.22 | 0.99 | 53% | 65% |
| SRI-SS | 7 scales | 4.89 | 0.65 | 70% | 79% |
SRI: Severe Respiratory Insufficiency Questionnaire; SRI-RC: respiratory complaints; SRI-PF: physical functioning; SRI-AS: attendant symptoms and sleep; SRI-SR: social relationships; SRI-AX: anxiety; SRI-WB: psychological well-being; SRI-SF: social functioning; SRI-SS: summary scale.