Summary of the study appraisal
| Swidwa15 | Jaber10 | Harrison12 | Nyarko-Adomfeh11 | Jolliet16 | Gerbeaux13 | Albornoz14 | Thiriet17 | |
|---|---|---|---|---|---|---|---|---|
| Internal validity | ||||||||
| Randomisation | Non-randomised | Randomised but no details of allocation sequence generation or concealment | Non-randomised | Non-randomised | Randomised concealment achieved using sealed envelopes | Non-randomised. Subjects allocated according to clinician preference | Non-randomised | Randomised but no details of concealment of allocation |
| Blinding | No blinding | Subjects blinded but no blinding of clinicians.No blinding of statisticians to results | No blinding | No blinding | Subjects blinded but no blinding of clinicians. No blinding of statisticians to results | Blinding of observers to evolution of patient but not Heliox, blinding of authors to use of Heliox, but not of evolution | No blinding | No blinding |
| Patient attrition | No attrition | Attrition <10%: one patient refused consent. One patient withdrawn due to condition. | No attrition | No details supplied | No attrition | No attrition | No attrition | No attrition |
| Statistical analysis | No details | Appropriate tests | No details | No details | Appropriate test | Appropriate tests | No details | Appropriate tests |
| External validity | ||||||||
| Inclusion/exclusion criteria supplied | Yes | Yes | No details | No details | Yes | Yes | Yes | No details |
| Treatment regimens described | Yes | Yes | Yes but no indication of duration of treatment | Yes but no indication of duration of treatment | Yes | Yes | Yes but no indication of duration of treatment | Yes |
| Summary Jadad quality assessment scale (0–3) | 1 | 2 | 1 | 0 | 3 | 1 | 1 | 2 |