Summary of findings for the main comparison. Quinidine compared to placebo or no treatment for maintaining sinus rhythm after cardioversion of atrial fibrillation.
| Quinidine compared to placebo or no treatment for maintaining sinus rhythm after cardioversion of atrial fibrillation | ||||||
| Patient or population: adults in sinus rhythm after cardioversion of atrial fibrillation Setting: hospital/community Intervention: quinidine Comparison: placebo or no treatment | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with placebo or no treatment | Risk with quinidine | |||||
| All‐cause mortality follow‐up: median 12 months | Study population | RR 2.01 (0.84 to 4.77) | 1646 (6 RCTs) | ⊕⊕⊝⊝ Lowa,b | — | |
| 8 per 1000 | 15 per 1000 (6 to 36) | |||||
| Withdrawals due to adverse effects follow‐up: median 12 months | Study population | RR 1.56 (0.87 to 2.78) | 1669 (7 RCTs) | ⊕⊕⊕⊝ Moderatec,d,e | Heterogeneity was high for the main analysis (I2 = 67%), but the test for subgroup differences indicated that the RR was higher in older studies which used a higher dose. | |
| 163 per 1000 | 254 per 1000 (142 to 452) | |||||
| Proarrhythmia follow‐up: median 12 months | Study population | RR 2.05 (0.95 to 4.41) | 1676 (7 RCTs) | ⊕⊕⊕⊕ Highc,f | — | |
| 11 per 1000 | 22 per 1000 (10 to 48) | |||||
| Stroke follow‐up: median 12 months | Study population | RR 0.97 (0.25 to 3.83) | 1107 (4 RCTs) | ⊕⊕⊝⊝ Lowa,g | — | |
| 5 per 1000 | 5 per 1000 (1 to 19) | |||||
| Recurrence of atrial fibrillation follow‐up: median 12 months | Study population | RR 0.83 (0.78 to 0.88) | 1624 (7 RCTs) | ⊕⊕⊕⊕ Highc | — | |
| 80.5 per 100 | 66.8 per 100 (62.8 to 70.8) | |||||
| *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). CI: confidence interval; RCT: randomised controlled trial; RR: risk ratio. | ||||||
| GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate: the true effect is likely to be substantially different from the estimate of effect. | ||||||
aDowngraded one level for study limitations: majority of studies were at low or unclear risk of bias for at least one of the key domains (allocation concealment, blinding, incomplete outcome data). bDowngraded one level for imprecision: confidence interval included no effect, the possibility of a beneficial effect and a strong harmful effect. cNot downgraded for study limitations, as the two studies contributing majority of weight were at low risk for key domains (allocation concealment, blinding, incomplete outcome data). dNot downgraded for inconsistency: although heterogeneity was high for the main analysis, this was partially explained by subgroup analysis. eDowngraded one level for imprecision: confidence interval included possibility of no effect or small beneficial effect as well as harmful effect. fNot downgraded for imprecision, although CI just included null. gDowngraded one level for imprecision: confidence interval included both important benefits and harms, and event rate was very low.