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The 40 step test for patients with confirmed or suspected COVID-19.

Three Part Question

[In adults with confirmed or suspected COVID-19 infection attending the Emergency Department], does [the 40 step desaturation test] predict the [requirement for hospital admission and subsequent hospital care]?

Clinical Scenario

One month after social distancing measures were introduced in the UK, a 35 year-old man attends with shortness of breath and is streamed to be seen by you in your COVID-19 assessment area. He has been isolating at home for the last three days after developing myalgia and a fever. He is normally fit and well and has not been tested for COVID-19. His oxygen saturations are 93% at rest on air and his respiratory rate is 22 breaths per minute. You know the NHS England guidance advises you to consider conducting a 40 step test to see if the patient desaturates on exertion. You wonder if this advice is evidence-based.

Search Strategy

On 17 Apr 2020, Pubmed and EMBASE databases searched (via HDAS)

Given the paucity of published papers identified, a Grey Literature search was also conducted at 1200 on 26 April 2020
Title and Abstract: (covid OR coronavirus OR SARS-CoV-2) AND (prognos* OR score OR decision OR predic*), Search terms: 40 step test covid

Search Outcome

Pubmed 451 + EMBASE 290 results published since 01 Jan 2019. 118 titles selected for abstract review, 76 were reviewed in the full text. Top 100 Google results reviewed for relevance. No studies were found that identified desaturation on exercise as predictive of, or correlated with, severe COVID-19 disease.


Given the possibility of health systems becoming overwhelmed during the COVID-19 pandemic, a risk-stratification is required to differentiate between patients who are safe to go home and those more likely to deteriorate. This urgency may account for the fact that the 40 step test is being used clinically without having been validated in the relevant patient population. The literature on COVID-19 is being rapidly updated as understanding of the condition and its management improves. It is likely that future publications will aim to remedy the lack of data for this question. As the pandemic progresses and the need for information outstrips the ability of publishers to keep up, Grey Literature from trusted sources is a valuable resource for clinicians.

Clinical Bottom Line

The 40 step test is not validated for patients with suspected or confirmed COVID-19 attending the Emergency Department. Its use and results should therefore be guided by careful clinical judgement.