Serrano T L I, Antonio M A, Giacomin L T, Morcillo A M, Dirceu Ribeiro J, Sakano E
Department of Ophthalmology and Otorhinolaryngology, State University of Campinas (Unicamp), Campinas, São Paulo, Brazil.
Department of Paediatrics, State University of Campinas (Unicamp), Campinas, São Paulo, Brazil.
Rhinology. 2025 Jun 1;63(3):325-333. doi: 10.4193/Rhin24.081.
Olfactory training is the most widely recommended treatment for smell loss; however, there are no randomised placebo-controlled trials evaluating its effectiveness in COVID-19. We aimed to evaluate the efficacy of isolated training and factors associated to olfactory recovery.
This is a prospective randomised double-blind controlled trial, using standard olfactory training (OT) and placebo (PB) in COVID-19 patients experiencing smell loss. They were followed up for 180 days and assessed with the Connecticut olfactory test (CCCRC) and with subjective methods on a monthly basis.
A total of 123 participants completed follow-up: 68 in the OT group and 55 in the PB group. Overall, 84.5% achieved normosmia, with full recovery (FR) significantly higher in PB. At baseline, OT had lower olfactory scores and higher corticosteroid use. Multivariate analysis showed no significant differences in outcomes between groups. Baseline olfactory test scores were the strongest predictors of recovery. Exploratory analyses stratified participants by time to treatment initiation (early < 30 days; late > 30 days), showing a 58% higher chance of FR in the early group for similar CCCRC scores, regardless of management type.
OT is not superior to PB for treating COVID-19-related smell loss. Better results of first evaluation indicate great chance of full recovery and the use of systemic corticosteroid, in persistent olfactory loss, has not affected outcome.
嗅觉训练是嗅觉丧失最广泛推荐的治疗方法；然而，尚无随机安慰剂对照试验评估其在新冠肺炎中的有效性。我们旨在评估单独训练的疗效以及与嗅觉恢复相关的因素。
这是一项前瞻性随机双盲对照试验，对嗅觉丧失的新冠肺炎患者使用标准嗅觉训练（OT）和安慰剂（PB）。对他们进行180天的随访，并每月用康涅狄格嗅觉测试（CCCRC）和主观方法进行评估。
共有123名参与者完成随访：OT组68名，PB组55名。总体而言，84.5%的患者恢复正常嗅觉，安慰剂组的完全恢复率（FR）显著更高。在基线时，嗅觉训练组的嗅觉评分较低，使用皮质类固醇的比例较高。多变量分析显示两组之间的结果无显著差异。基线嗅觉测试分数是恢复的最强预测因素。探索性分析按开始治疗的时间（早期<30天；晚期>30天）对参与者进行分层，结果显示，在CCCRC评分相似的情况下，早期组的完全恢复几率比晚期组高58%，与治疗类型无关。
对于治疗新冠肺炎相关的嗅觉丧失，嗅觉训练并不优于安慰剂。首次评估结果较好表明完全恢复的可能性很大，而在持续性嗅觉丧失中使用全身性皮质类固醇并未影响结果。
