Modified Medical Research Council and COPD Assessment Test Cutoff Points

Area of Science:

• Pulmonology and Respiratory Medicine
• Clinical Assessment Tools
• Physical Activity and Health

Background:

• The modified Medical Research Council (mMRC) scale and COPD Assessment Test (CAT) are commonly used to assess patients with Chronic Obstructive Pulmonary Disease (COPD).
• Understanding the relationship between these assessment tools and daily physical activity levels is crucial for managing COPD.
• Identifying reliable cutoff points can aid in stratifying patients based on their physical activity and predicting clinical outcomes.

Purpose of the Study:

• To determine specific cutoff points for the mMRC scale and CAT that can effectively discriminate between sedentary and active behaviors in COPD patients.
• To validate whether these identified cutoff points can differentiate COPD patients based on pulmonary function, health-related quality of life (HRQOL), functional status, and mortality risk.

Main Methods:

• A cohort of 131 COPD patients (FEV1: 36.7 ± 16.1% predicted) underwent assessments for lung function, mMRC, CAT, HRQOL, functional status, and mortality index.
• Physical activity of daily living (PADL) was objectively measured using a triaxial accelerometer.
• Subjects were classified based on accelerometer data into sedentary/nonsedentary, physically active/inactive, and severe physical inactivity categories using predefined thresholds.

Main Results:

• Receiver Operating Characteristic (ROC) curve analysis identified an mMRC cutoff of ≥ 2 for physical inactivity and sedentary behavior.
• CAT cutoff points of ≥ 16 and ≥ 20 were identified for severe physical inactivity and sedentary behavior, respectively.
• Patients with mMRC ≥ 2 and CAT ≥ 16 (or ≥ 20) exhibited poorer pulmonary function, HRQOL, functional status, and higher mortality index compared to those with lower scores.

Conclusions:

• An mMRC cutoff point of ≥ 2 is recommended for discriminating physical activity levels and sedentary behavior in COPD.
• CAT cutoff points of ≥ 16 and ≥ 20 are valuable for identifying severe physical inactivity and sedentary behavior, respectively.
• These validated cutoff points for mMRC and CAT effectively differentiate COPD patients across key clinical outcomes, aiding in patient management and risk stratification.