Minimal Clinically Important Difference for Quadriceps Muscle Strength in People with COPD Following Pulmonary Rehabilitation

Quadriceps strength training is a key component of pulmonary rehabilitation (PR). Clinical interpretability of changes in muscle strength following PR is however limited due to the lack of cut-off values to define clinical improvement. This study estimated the minimal clinically important difference (MCID) for the isotonic and isometric quadriceps muscle strength assessed with the one-repetition maximum (1RM) and hand-held dynamometry (HHD) in people with chronic obstructive pulmonary disease (COPD) following PR. A secondary analysis of a real life non-randomised controlled study was conducted in people with COPD enrolled in a 12-week community-based PR programme. Anchor and distribution-based methods were used to compute the MCIDs. The anchors explored were the St. George's respiratory questionnaire (SGRQ) and the six-minute walk test (6MWT) using Pearson's correlations. Pooled MCIDs were computed using the arithmetic weighted mean (2/3 anchor, 1/3 distribution-based methods) and reported as absolute and/or percentage of change values. Eighty-nine people with COPD (84% male, 69.9 ± 7.9 years, FEV1 49.9 ± 18.9% predicted) were included. No correlations were found between changes in 1RM and the SGRQ neither between changes in HHD and the SGRQ and 6MWT (p > 0.05). Thus, anchor-based methods were used only in the MCID of the 1RM with the 6MWT as the anchor. The pooled MCIDs were 5.7Kg and 26.9% of change for the isotonic quadriceps muscle strength with 1RM and 5.2KgF for isometric quadriceps muscle strength assessed with HHD. The MCIDs found are estimates to improve interpretability of community-based PR effects on quadriceps muscle strength and may contribute to guide interventions.

Description

Acknowledgements: This work, was funded by Fundo Europeu de Desenvolvimento Regional (FEDER) - Comissão Diretiva do Programa Operacional Regional do Centro and by Fundação para a Ciência e Tecnologia - FCT (SAICT-POL/23926/2016 and PTDC/SAUSER/28806/2017), and partially funded by Programa Operacional Competitividade e Internacionalização (COMPETE), through COMPETE 2020 (POCI-01-0145FEDER-016701, POCI-01-0145-FEDER-007628 and POCI-01-0145-FEDER-028806) and FCT (UIDB/04501/2020).

Keywords

Minimal important difference Hand held dynamometry 1 repetition maximum COPD Quadriceps muscle strength

URI

http://hdl.handle.net/10400.8/5310

Citation

Oliveira A., Rebelo P., Paixão C., Jácome C., Cruz J., Martins V., Simão P., Brooks D., Marques A. Minimal Clinically Important Difference for Quadriceps Muscle Strength in People with COPD following Pulmonary Rehabilitation. COPD. 2021 Feb 3:1-16. doi: 10.1080/15412555.2021.1874897. Epub ahead of print. PMID: 33533285. (cf. pubmed.ncbi.)