Validation and prognostic value of the five-repetition sit-to-stand test in patients with severe exacerbation of COPD

Background A severe exacerbation of COPD (ECOPD) may negatively impact patients’ functioning; however, there is a lack of validated, simple, and low-cost tools to assess physical function in this setting. Thus, the aims of this study were to explore the construct validity of the five-repetition sit-to-stand (5STS) test for assessing muscle strength and exercise tolerance, and to investigate its prognostic value in predicting exacerbation-related readmission risk in patients with severe ECOPD. Methods This was a prospective observational study. Fifty-eight patients hospitalized with a severe ECOPD were included. At hospital discharge, the 5STS, quadriceps force, six-minute walk test (6MWT), COPD Assessment Test (CAT), and modified Medical Research Council scale were assessed. Exacerbation-related readmissions within six months were collected. Statistical analyses included correlation analysis, receiver operating characteristic (ROC) curve, and Kaplan-Meier survival analysis. Results 58 patients (mean age of 69 ± 8 years, 45% male, FEV 1 41 ± 16% predicted) were included. Within six months, 31% were readmitted. The 5STS showed a significant negative correlation with quadriceps force (r = -0.487) and 6MWT (r = -0.415). The ROC curve analysis demonstrated an AUC of 0.720 (95% CI: 0.588–0.853), with a cut-off of ≥13 seconds identifying patients at higher risk of exacerbation-related readmission. Patients with 5STS <13s had a higher probability of remaining hospitalization-free (86.7%) compared to those with 5STS ≥13s (50%). Conclusion The 5STS is correlated with muscle strength and exercise tolerance and has acceptable prognostic value for predicting exacerbation-related admission within six months in patients with severe ECOPD.