Drug treatment options for post-viral olfactory dysfunction
| Author | Year | Study design | No of participants | Interventions | Measures | Outcomes | Numerical results |
| Nguyen et al115 | 2018 | Randomised controlled trial | 138 | Olfactory training with saline irrigations or olfactory training with budesonide irrigations | University of Pennsylvania Smell Identification test | Percentage of patients with clinically relevant improvement in University of Pennsylvania Smell Identification test (change in score of ≥5) | Odds ratio 2.1 (95% confidence interval1.03 to 4.41), P=0.039 |
| Blomqvist et al116 | 2003 | Double blind, randomised controlled | 40 | Flutucasone oroprionate v placebo v control | Butanol odour test | Percentage of patients with at least two step improvement in butanol odour test | No significant difference (P>0.05) |
| Schepens et al118 | 2022 | Double blind, randomised controlled | 115 | Prednisolone 40 mg once daily for 10 days v placebo | Sniffin' Sticks test | Median threshold discrimination identification score | Threshold discrimination identification: placebo median 26.8 (interquartile range 23.6-29.3) v intervention median 28.8 (24.0-30.9), P>0.05 |
| Philpott et al119 | 2017 | Double blind, randomised controlled | 55 | Sodium citrate nasal spray v placebo | Olfactory thresholds for palmitoylethanolamide over 2 hours | Improvement in palmitoylethanolamide threshold | Control median threshold 0 (interquartile range 0-0.5); intervention median threshold 1 (0-2), P=0.014 |
| Whitcroft et al | 2016 | Single blind, controlled trial | 49 | Topical sodium citrate v placebo | Sniffin' Sticks test | Change in composite threshold and identification scores | Mean change in score: sodium citrate 0.33 (standard deviation 2.34); placebo −0.54 (2.62); mean difference 0.87 (2.68); P=0.04 |
| Whitcroft et al120 | 2021 | Controlled trial | 60 | Topical sodium citrate v placebo | Sniffin' Sticks test | Change in composite threshold discrimination identification score for quantitative loss; percentage of patients reporting qualitative loss | No significant difference in mean change in threshold discrimination identification score; no significant difference in total number of patients reporting qualitative loss |
| Hummel et al122 | 2017 | Retrospective, cohort | 170 | Topical vitamin A plus olfactory training v olfactory training alone | Sniffin' Sticks test | Percentage of patients achieving a clinically significant improvement in threshold discrimination identification score (defined as +5.5 points) | Intervention group 37% v control 23% (χ2 7.06, degrees of freedom=2, P=0.03) |
| Reden et al123 | 2012 | Double blind, randomised controlled | 52 | Oral vitamin A v placebo | Sniffin' Sticks test | Mean threshold discrimination identification score | Mean threshold discrimination identification: intervention group 18.34 (standard error of the mean 1.42); placebo group 20.11 (1.43); P=0.47 |
| di Stadio et al124 | 2022 | Double blind, randomised controlled | 185 | Oral PEA-LUT plus olfactory training v olfactory training alone | Sniffin' Sticks test | Mean threshold discrimination identification score | Mean threshold discrimination identification: intervention group 29.8 (standard deviation 7.5); control group 19.5 (7.3); P<0.001 |
| Yan et al127 | 2022 | Prospective, randomised controlled trial | 87 | Oral omega 3 supplementation plus nasal rinse v nasal rinse alone | University of Pennsylvania Smell Identification test | Percentage of patients with clinically significant olfactory loss (≥10% reduction of University of Pennsylvania Smell Identification test scores v patient's own baseline) | Intervention group 4.3% v control 24.4% (P=0.01) |
| Yan et al125 | 2020 | Case series | 7 | Intranasal injection of platelet rich plasma | Sniffin' Sticks test | Mean threshold discrimination identification | Mean threshold discrimination identification: pre-treatment 23.6 v post-treatment 19.5, P=0.026 |
| Yan et al126 | 2022 | Randomised controlled trial | 35 | Three intranasal injection of platelet rich plasma plus budesonide rinse v three intranasal saline injections plus budesonide rinse | Sniffin' Sticks test | Change in mean threshold discrimination identification versus baseline | Mean change from baseline: intervention group 6.25 points (95% confidence interval 3.85 to 8.65) (P<0.001) v control group 1.17 points (−1.99 to 4.32) (P>0.05) |
| Garcia et al128 | 2022 | Case series | 12 | Gabapentin, up titrated from 100 mg to 600 mg, once daily plus olfactory training and budesonide rinse | Subjective assessment of parosmia | Subjective assessment of severity of parosmia | Improvement in 8 of 12 patients |