Determining the minimally important difference in quadriceps strength in individuals with COPD using a fixed...

Area of Science:

• Pulmonary Medicine
• Rehabilitation Science
• Clinical Measurement

Background:

• Quadriceps muscular force measurement is crucial for COPD patients, especially during pulmonary rehabilitation programs (PRP).
• Standardization of tools and interpretation of quadriceps maximal voluntary contraction (QMVC) measurements remain debated.
• This study aimed to establish the minimally important difference (MID) for QMVC in COPD patients undergoing PRP.

Purpose of the Study:

• To estimate the minimally important difference (MID) of quadriceps maximal voluntary contraction (QMVC) using a fixed dynamometer.
• To provide a benchmark for assessing clinically significant improvements in quadriceps strength following pulmonary rehabilitation in COPD patients.

Main Methods:

• 157 individuals with COPD were enrolled in a pulmonary rehabilitation program (PRP).
• Quadriceps maximal voluntary contraction (QMVC) was measured using a fixed dynamometer (MicroFET2).
• Distribution-based methods were employed to calculate the MID for QMVC.

Main Results:

• Patients showed significant improvements in quadriceps force (8.9±15.6 Nm), 6-minute walk distance (42±50 m), and quality of life scores (SGRQ, HADS) post-PRP.
• The estimated MID for QMVC was 7.5 Nm (empirical rule effect size) and 7.8 Nm (Cohen's effect size).

Conclusions:

• Measurement of QMVC with a fixed dynamometer is a practical method to assess strength gains after PRP in COPD.
• A suggested MID of 7.5 Nm can help identify beneficial changes in quadriceps muscle force following PRP interventions.