What is the Efficacy and Safety of Rapid Exercise Tests for Exertional Desaturation in Covid-19: A Rapid Systematic Review 

Abstract

BackgroundEven when resting pulse oximetry is normal in the patient with acute Covid-19, hypoxia can manifest on exertion. We sought to summarise the literature on the performance of different rapid tests for exertional desaturation. Main research questionWhat tests have been formally evaluated for the rapid assessment of exertional hypoxia in patients with lung disease against a gold standard exercise test such as the 6MWT and CPET? MethodAMED, CINAHL, EMBASE MEDLINE, Cochrane and PubMed using LitCovid, Scholar and Google databases were searched to September 2020. Studies where participants had Covid-19 or another lung disease and underwent any form of exercise test which was compared to a reference standard were eligible. Risk of bias was assessed using QUADAS 2. Heterogeneity of study design precluded meta-analysis. ResultsOf 47 relevant papers, 15 were empirical studies, of which 11 described an attempt to validate one or more exercise desaturation tests in lung diseases other than Covid-19. In all but one of these, methodological quality was poor or impossible to fully assess. None had been designed as a formal validation study (most used simple tests of correlation). Only one validation study (comparing a 1-minute sit-to-stand test [1MSTST] with the reference standard 6-minute walk test [6MWT] in 107 patients with interstitial lung disease) contained sufficient raw data for us to calculate the sensitivity (88%), specificity (81%), and positive and negative predictive value (79% and 89% respectively) of the 1MSTST. The other 4 empirical studies included two predictive studies on patients with Covid-19, and two on HIV-positive patients with suspected pneumocystis pneumonia. We found no studies on the 40-step walk test (a less demanding test that is widely used in clinical practice to assess Covid-19 patients). DiscussionExertional desaturation tests have not yet been validated in patients with (or suspected of having) Covid-19. Whilst there is limited evidence for the diagnostic accuracy of the 1MSTST in other diseases, specific features of this disease (e.g. exertional hypoxia is common and many assessments are done remotely with no clinician present to resuscitate) may raise safety issues. The less strenuous 40-step walk test should be urgently evaluated.