for the main comparison.
| Lung volume reduction surgery for diffuse emphysema | ||||||
| Patient or population: patients with diffuse emphysema Setting: hospitals Intervention: lung volume reduction surgery Comparison: standard medical care | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | No. of participants (studies) | Quality of the evidence (GRADE) | Comments | |
| Risk with control | Risk with surgery | |||||
| Early mortality (90 days) | 13 per 1000 | 77 per 1000 (42 to 138) | OR 6.16 (3.22 to 11.79) | 1489 (5 RCTs) | ⊕⊕⊕⊝ MODERATEa | |
| Long‐term mortality (> 36 months) | 547 per 1000 | 478 per 1000 (424 to 534) | OR 0.76 (0.61 to 0.95) | 1280 (2 RCTs) | ⊕⊕⊕⊝ MODERATEa | Substantial differences in follow‐up between the 2 trials measuring this construct |
| Change in total scores SGRQ (end of follow‐up) | End of treatment control group mean SGRQ scores ranged from 57 units to 62.1 units | Mean SGRQ score in the LVRS group was ‐13.78 units lower (‐15.75 to ‐11.78) | ‐ | 1326 (2 RCTs) | ⊕⊕⊕⊝ MODERATEb | Lower score indicates better quality of life. A difference of 4 units or more is thought to be clinically important. |
| Walking distance (end of follow‐up) | Control group walking distance ranged from 303 to 350 metres (in the 4 studies reporting 6MWD) | Standardised mean walking distance in the LVRS group was 0.70 standard deviations higher (0.42 to 0.98) | ‐ | 215 (5 RCTs) | ⊕⊕⊝⊝ LOWc,d | Four studies reported 6MWD test and 1 shuttle walking test. 0.7 standard deviations equates to approximately 70 metres for 6MWD. |
| FEV1 (end of follow‐up) | Control group FEV1 ranged from 0.64 L to 0.7 L FEV1 | Mean FEV1 in the LVRS group was 0.2 L higher (0.13 to 0.28) | ‐ | 188 (4 RCTs) | ⊕⊕⊝⊝ LOWc,e | |
| RV (end of follow‐up) | Control group predicted RV ranged from 213% to 258% predicted | Mean predicted RV in the LVRS group was 44.28% less (‐57.80 to ‐30.75) | ‐ | 177 (4 RCTs) | ⊕⊕⊝⊝ LOWa,c | |
| TLC (end of follow‐up) | Control group predicted RV ranged from 127% to 149% predicted | Mean predicted TLC in the LVRS group was ‐14.83% less (‐20.50 to ‐9.15) | ‐ | 178 (4 RCTs) | ⊕⊕⊝⊝ LOWa,c | |
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). 6MWD: six‐minute walking distance; CI: confidence interval; FEV1: forced expired volume in one second; L: litre; OR: odds ratio; MD: mean difference; RCT: randomised controlled trial; RR: risk ratio; RV: residual volume; SGRQ: St George's Respiratory Questionnaire; SMD: standardised mean difference; TLC: total lung capacity. | ||||||
| GRADE Working Group grades of evidence High quality: We are very confident that the true effect lies close to that of the estimate of effect. Moderate quality: We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of effect but may be substantially different. Low quality: Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of effect. Very low quality: We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect. | ||||||
aDowngraded owing to overall high rates of high and unclear risk of bias in all trials.
bDowngraded owing to risk of performance and detection bias: Studies were not blinded and SGRQ is dependent on patients' subjective responses.
cDowngraded owing to imprecision: low participant number.
dDowngraded owing to risk of performance and detection bias: Studies were not blinded and 6MWD is effort dependent.
eDowngraded owing to risk of performance and detection bias: Studies were not blinded and FEV1 is effort dependent.