Minimal Clinically Important Differences in EQ-5D-5L Index and VAS after a Respiratory Muscle Training Program in Individuals Experiencing Long-Term Post-COVID-19 Symptoms
Tamara del Corral, Raúl Fabero‐Garrido, Gustavo Plaza‐Manzano, Marcos José Navarro‐Santana, César Fernández‐de‐las‐Peñas, Ibai López‐de‐Uralde‐Villanueva
Abstract
The primary aim of this study was to determine the minimal clinically important difference (MCID) for the EuroQol-5D questionnaire (EQ-5D-5L) index and visual analogic scale (VAS) in individuals experiencing long-term post-COVID-19 symptoms. In addition, it was pretended to determine which variable discriminates better and to compare changes between individuals classified by the MCID. DESIGN: Secondary analysis of a randomized controlled trial involving 42 individuals who underwent an 8-week intervention in a respiratory muscle training program. RESULTS: A change of at least 0.262 and 7.5 for the EQ-5D-5L index and VAS represented the MCID, respectively. Only the EQ-5D-5L VAS showed acceptable discrimination between individuals who were classified as "improved" and those classified as "stable/not improved" (area under the curve = 0.78), although with a low Youden index (Youden index, 0.39; sensitivity, 46.2%; specificity, 93.1%). Those individuals who exceeded the established MCID for EQ-5D-5L VAS had significantly greater improvements in inspiratory muscle function, exercise tolerance, and peripheral muscle strength compared to participants classified as "stable/not improved". CONCLUSIONS: Only the EQ-5D-5L VAS, especially when MCID was exceeded, showed an acceptable discriminative ability to evaluate the efficacy of an intervention in individuals with long-term post-COVID-19 symptoms.