Summary of findings 1. Systemic corticosteroids plus intranasal steroid/mucolytic/decongestant compared to no intervention for persistent post‐COVID‐19 olfactory dysfunction.
| Systemic corticosteroids plus intranasal steroid/mucolytic/decongestant compared to no intervention for persistent post‐COVID‐19 olfactory dysfunction | ||||||
| Patient or population: adults with olfactory dysfunction for ≥ 4 weeks following COVID‐19 infection Setting: two hospitals in Italy Intervention: systemic corticosteroids plus intranasal steroid/mucolytic/decongestant Comparison: no intervention | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect (95% CI) | № of participants (studies) | Certainty of the evidence (GRADE) | Comments | |
| Risk with no intervention | Risk with systemic corticosteroids plus intranasal steroid/mucolytic/decongestant | |||||
| Psychophysical testing for recovery of sense of smell Assessed with: CCCRC test score (range 0 to 100, normal olfactory function classed as a score of 90 or 100) Follow‐up: 1 to 3 months |
Study event rate^ | RR 11.00 (0.70 to 173.66) | 18 (1 RCT) | ⊕⊝⊝⊝ very low1,2 | — | |
| 0/9 | 5/9 | |||||
| Disease‐related quality of life | No studies reported on this outcome. | |||||
| Serious adverse events Follow‐up: 1 to 3 months |
Study event rate^ | Not estimable | 18 (1 RCT) | ⊕⊝⊝⊝ very low1,3 | — | |
| No events were reported for either group. | ||||||
| Psychophysical testing for change in sense of smell Assessed with: CCCRC psychophysical testing Follow‐up: 1 to 3 months |
This study reported a median improvement in CCCRC score of +60 (IQR 40) in the group receiving systemic steroids and nasal irrigation compared to a median improvement of +30 (IQR 25) in the control group (P = 0.024). | Not estimable | 18 (1 RCT) | ⊕⊝⊝⊝ very low1,4 | — | |
| Generic quality of life | No studies reported on this outcome. | |||||
| Presence of parosmia | No studies reported on this outcome. | |||||
| Other adverse outcomes Follow‐up: 1 to 3 months |
Study event rate^ | Not estimable | 18 (1 RCT) | ⊕⊝⊝⊝ very low1,3 | — | |
| No events were reported for either group. | ||||||
| *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). ^We present the study event rate as there were no events in the comparator group for this trial. CI: confidence interval; IQR: interquartile range; 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 | ||||||
1Serious risk of performance bias due to a lack of blinding to treatment allocation.
2Very serious imprecision as the sample size does not reach the optimal information size (considered to be 400 participants) and the 95% CI is consistent with the possibility of important benefit or harm.
3Very serious imprecision as the sample size does not reach the optimal information size (considered to be 400 participants) and no estimate of effect could be determined, due to the lack of events in either group.
4Very serious imprecision as the sample size does not reach the optimal information size (considered to be 400 participants) and no estimate of effect could be determined (data presented as median and IQR).