While many people seem intent on convincing the world that COVID infection is no worse than the `flu', evidence continues to stack up that the long-term effects of SARS-CoV-2 go far beyond what we generally expect from influenza-like illnesses.
Whether you call it `Long COVID' or `Post-COVID Syndrome', these persistent after-effects can range from mild or moderate - to disabling - and may even contribute to an early death months or years after the the initial infection.
COCA Call: May 5, 2022: Evaluating and Supporting Patients Presenting with Cognitive Symptoms Following COVID
Some recent studies include:
There are also concerns that other, longer-term impacts, may arise in COVID survivors in the years ahead, including increased incidence of heart failure, and neurological manifestations, including Parkinson's syndrome.
Time will tell.
One of the most common symptoms of COVID infection - reported by 40%-50% of cases - is the loss of taste (ageusia) or smell (anosmia). While less serious than heart failure or neurodegenerative disorders like Parkinson's, these conditions not only affect the quality of life, they may also lead to anorexia, depression, and malnutrition.
For most people, loss of taste and smell is temporary, with roughly 75% of cases resolving within 30 days. But for a substantial number of people - likely tens of millions - the condition persists for 6 months or longer, and may become permanent.
Yesterday the BMJ published an open-access meta-analysis, an editorial, and an opinion on this growing post-COVID cohort - which finds women are more affected than men - and warns that many healthcare services are unprepared to deal with the scale of the problem.
Follow the links to read all three reports in their entirety.
Research
Prognosis and persistence of smell and taste dysfunction in patients with covid-19: meta-analysis with parametric cure modelling of recovery curvesBMJ 2022; 378 doi: https://doi.org/10.1136/bmj-2021-069503 (Published 27 July 2022) Cite this as: BMJ 2022;378:e069503
Benjamin Kye Jyn Tan, Ruobing Han, Joseph J Zhao, Nicole Kye Wen Tan, Emrick Sen Hui Quah, Claire Jing-Wen Tan, Yiong Huak Chan, Neville Wei Yang Teo, Tze Choong Charn, Anna See, Shuhui Xu, Nikita Chapurin, Rakesh K Chandra, Naweed Chowdhury, Rafal Butowt, Christopher S von Bartheld, B Nirmal Kumar, Claire Hopkins, Song Tar Toh, Correspondence to: S T Toh toh.song.tar@singhealth.com.sgAccepted 14 June 2022
Abstract
Objective To clarify in patients with covid-19 the recovery rate of smell and taste, proportion with persistent dysfunction of smell and taste, and prognostic factors associated with recovery of smell and taste.
Design Systematic review and meta-analysis.
Data sources PubMed, Embase, Scopus, Cochrane Library, and medRxiv from inception to 3 October 2021.
Review methods Two blinded reviewers selected observational studies of adults (≥18 years) with covid-19 related dysfunction of smell or taste. Descriptive prognosis studies with time-to-event curves and prognostic association studies of any prognostic factor were included.
Data extraction and synthesis Two reviewers extracted data, evaluated study bias using QUIPS, and appraised evidence quality using GRADE, following PRISMA and MOOSE reporting guidelines. Using iterative numerical algorithms, time-to-event individual patient data (IPD) were reconstructed and pooled to retrieve distribution-free summary survival curves, with recovery rates reported at 30 day intervals for participants who remained alive. To estimate the proportion with persistent smell and taste dysfunction, cure fractions from Weibull non-mixture cure models of plateaued survival curves were logit transformed and pooled in a two stage meta-analysis. Conventional aggregate data meta-analysis was performed to explore unadjusted associations of prognostic factors with recovery.
Main outcome measures The primary outcomes were the proportions of patients remaining with smell or taste dysfunction. Secondary outcomes were the odds ratios of prognostic variables associated with recovery of smell and taste.
Results 18 studies (3699 patients) from 4180 records were included in reconstructed IPD meta-analyses. Risk of bias was low to moderate; conclusions remained unaltered after exclusion of four high risk studies. Evidence quality was moderate to high.
Based on parametric cure modelling, persistent self-reported smell and taste dysfunction could develop in an estimated 5.6% (95% confidence interval 2.7% to 11.0%, I2=70%, τ2=0.756, 95% prediction interval 0.7% to 33.5%) and 4.4% (1.2% to 14.6%, I2=67%, τ2=0.684, 95% prediction interval 0.0% to 49.0%) of patients, respectively. Sensitivity analyses suggest these could be underestimates. At 30, 60, 90, and 180 days, respectively, 74.1% (95% confidence interval 64.0% to 81.3%), 85.8% (77.6% to 90.9%), 90.0% (83.3% to 94.0%), and 95.7% (89.5% to 98.3%) of patients recovered their sense of smell (I2=0.0-77.2%, τ2=0.006-0.050) and 78.8% (70.5% to 84.7%), 87.7% (82.0% to 91.6%), 90.3% (83.5% to 94.3%), and 98.0% (92.2% to 95.5%) recovered their sense of taste (range of I2=0.0-72.1%, τ2=0.000-0.015).
Women were less likely to recover their sense of smell (odds ratio 0.52, 95% confidence interval 0.37 to 0.72, seven studies, I2=20%, τ2=0.0224) and taste (0.31, 0.13 to 0.72, seven studies, I2=78%, τ2=0.5121) than men, and patients with greater initial severity of dysfunction (0.48, 0.31 to 0.73, five studies, I2=10%, τ2<0.001) or nasal congestion (0.42, 0.18 to 0.97, three studies, I2=0%, τ2<0.001) were less likely to recover their sense of smell.
Conclusions A substantial proportion of patients with covid-19 might develop long lasting change in their sense of smell or taste. This could contribute to the growing burden of long covid.
Systematic review registration PROSPERO CRD42021283922.
