How to Save 5 Minutes in Evaluating Patients Post-COVID

BARCELONA -- A 1-minute test that can be performed easily in any clinic or office setting was just as accurate as the conventional, but more resource-intensive, 6-minute walk test (6MWT) for evaluating function in patients recovering from COVID-19, a researcher reported here.

"Strong" correlation was seen for nadir blood oxygen saturation (SpO₂) between the 6MWT and a 1-minute sit-to-stand test (r=0.83, 95% CI 0.73-0.90) in a prospective 55-person trial in which participants served as their own controls, said Maria Marta De Sampaio Nunes Duarte Silva, of Hospital Santa Marta in Lisbon, at the European Respiratory Society (ERS) annual meeting.

The trial also showed "moderate" correlation (r=0.30, 95% CI 0.04-0.53) between the 6MWT distance walked and the number of sit-to-stand repetitions in the 1-minute test, she said.

Other parameters were also similar between the two tests: heart rate was measured at 104.72 bpm in the 1-minute test versus 102.43 bpm with the 6MWT, and dyspnea levels (assessed via the modified Borg RPE Scale) reached 5.21 and 4.79, respectively.

"The 6-minute walk test is a useful test for post-COVID-19 follow-up," she explained. "It has shown to correlate with the severity of acute illness and with function/radiological impairment in the chronic phase. However, it's much more time-consuming, requires a 30-meter corridor, and also a technician or a nurse, which are not always available."

In contrast, the 1-minute sit-to-stand test merely requires an armless chair and someone to count repetitions.

De Sampaio Nunes Duarte Silva said such testing is important because functional deficits during exertion can flag worsening lung pathology, such as development of pulmonary fibrosis -- "the most feared one," she said.

"Detection of impaired pulmonary function can help identify these patients for early referral and appropriate management," she said.

"This topic is on all of our minds as we deal with post-COVID patients," said ERS session co-moderator Georgios Kaltsakas, MD, PhD, of Guy's and St. Thomas's NHS Foundation Trust in London, who called the study "well done."

De Sampaio Nunes Duarte Silva and colleagues recruited adult patients from a post-COVID public clinic in Lisbon, excluding those who were too sick for the testing. Participants first performed the 1-minute test, then rested for 1 hour before proceeding to the 6MWT. SpO₂, heart rate, and dyspnea were evaluated during each test.

Mean participant age was 58. In the testing, they averaged 20.6 repetitions in the 1-minute test and 405 m in the 6MWT.

Unsurprisingly, respiration in participants with the worst overall health (as evaluated with the Post-COVID-19 Functional Status Scale) suffered the most during testing. De Sampaio Nunes Duarte Silva reported that those scoring 3 on this scale, the highest level (i.e., the lowest functional ability), had the lowest SpO₂ levels at nadir: 93% with the 6MWT and 92% with the 1-minute test, whereas those with scores of 0-2 had nadir SpO₂ levels of 95%-96%.

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