Predictors of reduced 6-minute walk distance after COVID-19: a cohort study in Mexico

Predictors of reduced 6-minute walk distance after COVID-19: a cohort study in MexicoClinical sequelae after COVID-19 have been well described, including abnormalities in pulmonary function tests, chest imaging, and patient-reported outcome measures. 1,2However, functional outcomes after COVID-19 are not well understood.We sought to identify the presence and underlying mechanisms of functional impairments after COVID-19.We hypothesized that patients with more severe COVID-19 would have a lower 6-minute walk distance (6MWD) at follow-up and that exertional dyspnea, fatigue, and hypoxemia would independently predict a lower 6MWD.This was a consecutively-enrolled prospective cohort study.Patients who were seen in a hospital in Yucatan, Mexico with SARS-CoV-2 confirmed by real-time polymerase chain reaction were referred to a COVID-19 clinic for followup.Patients who were able to complete surveys, pulmonary function tests (PFTs), and 6-minute walk tests (6MWTs) were included.There were no exclusion criteria.PFTs and 6MWTs were conducted according to international guidelines. 3---5Patients did not receive formal physical rehabilitation during their recovery.This study received institutional ethics approval.COVID-19 severity was categorized as mild (no hypoxemia), moderate (hypoxemia without mechanical ventilation), or severe (hypoxemia with mechanical ventilation).The association between COVID-19 severity and 6MWD was determined using multivariable linear regression, and underlying mechanisms for reduced 6MWD were then explored.Unadjusted and adjusted linear regression models were used to determine the association between potential predictor variables (Borg dyspnea, Borg fatigue, and end-exercise SpO 2 ) and 6MWD, first in separate models and then in a final model with both Borg dyspnea and end-exercise SpO 2 as co-primary endpoints to explore the independent relationship of these two predictors with 6MWD.All models were adjusted for age, sex, smoking, body mass index (BMI), and time from symptom onset.Statistical analyses were performed using R version 3.6.3(R Foundation).