Effects of an outpatient pulmonary rehabilitation program on exercise capacity, muscle fatigue, dyspnea, and functional status in post-COVID-19 patients: non-randomized clinical trial

Abstract

Background COVID-19 may lead to persistent sequelae that impair functional capacity, resulting in dyspnea, fatigue, and limitations in activities of daily living. Objective To evaluate exercise capacity, fatigue, dyspnea, and functional status in patients following hospitalization for COVID-19 who underwent an outpatient pulmonary rehabilitation program (PRP). Methods The study was approved by the Research Ethics Committee of UniEVANGÉLICA (approval number 4,296,707; September 24, 2020) and registered at ClinicalTrials.gov (Identifier: NCT04982042). This prospective single-arm non-randomized clinical trial included symptomatic individuals after COVID-19 infection. Exercise capacity was assessed using the Six-Minute Walk Test, muscle fatigue using the Fatigue Severity Scale (FSS), modified Medical Research Council (mMRC) Dyspnea Scale, and functional status using the Post-COVID-19 Functional Status Scale (PCFS). The PRP consisted of cardiorespiratory training and muscle strengthening exercises performed three times per week for six weeks. Results A total of 54 patients were included (29 in the Ward Group and 25 in the ICU Group). After the PRP, 6MWT distance increased from 428.52 ± 104.5 m to 503.19 ± 98.04 m (p < 0.0001), mMRC dyspnea decreased from 3.50 ± 1.31 to 1.56 ± 0.60 (p < 0.0001), PCFS improved from 2.91 ± 0.59 to 0.63 ± 0.75 (p < 0.001), and FSS decreased from 4.68 ± 1.50 to 2.97 ± 1.55 (p < 0.001). The Ward Group showed greater unadjusted gains than the ICU Group; however, multivariable analysis identified lower baseline 6MWD as the only independent predictor of improvement (β = −0.547; p < 0.001), whereas ICU admission was not independently associated with the magnitude of gain (p = 0.246). Conclusion The outpatient PRP was associated with significant improvements in exercise capacity, fatigue, dyspnea, and functional status. Lower baseline exercise capacity predicted greater improvement, regardless of ICU admission.