Measurements of pectoral muscle area derived from thoracic CT scans can identify quadriceps muscle weakness, a treatable trait in COPD patients

<bold>Rationale:</bold> In COPD patients, reduced quadriceps strength (QS) is associated with a poor outcome. QS measurements require specific equipment and expertise, which limits their use. Computed tomography (CT) imaging of the chest is routinely performed in COPD patients. The pectoralis muscle area (PMA) can be easily derived from chest CT. We sought to study PMA as a surrogate for QS in stable COPD patients. <bold>Methods:</bold> Chest CT and QS were assessed concurrently. The highest value of QS of the dominant leg was recorded (in kg). PMA (sum of right and left measurements, in cm2) was obtained by two independent examiners. <bold>Results:</bold> 85 COPD patients were studied (age [mean±SD]: 64.7±9.0 years; FEV1: 64±19% predicted). The unadjusted R2 correlation between PMA and QS was 0.32. A formula for calculating QS from PMA was established: QS = 19.4 + 0.26 × PMA cm2 + 0.13 × weight kg - 0.27 × age years + 6.20 for men (R2 adjusted: 0.47). The area under the ROC curve for identifying low SQ (lowest tertile) with PMA was 0.76 (95% CI: 0.65-0.87), with a PMA threshold of 28.5 cm2 (Figure). <bold>Conclusions:</bold> PMA is a good surrogate for QS assessment in the routine management of COPD. The use of PMA should allow better identification of COPD patients eligible for interventions aimed at improving quadriceps function. <fig><object-id>erj;64/suppl_68/PA519/F1</object-id><object-id>F1</object-id><object-id>F1</object-id><graphic></graphic></fig>