The serum Cr/CysC ratio could be a convenient substitute for the measurement of muscle atrophy and pulmonary function testing in patients with COPD. A study conducted by a team of researchers at the Department of Respiratory Medicine, Kanazawa Medical University, Ishikawa, Japan, found a close association between the the serum creatinine (Cr)/cystatin C (CysC) ratio and pulmonary function in patients with COPD. The research team analysed 99 patients without COPD and 201 with COPD to find that the Cr/CysC ratio was significantly associated with forced vital capacity (FVC). The researchers highlighted the importance of their research by pointing out how the serum Cr/CysC ratio can be a convenient substitute for the measurement of muscle atrophy and pulmonary function testing in COPD patients, re-establishing the previous studies that found cross-sectional area (CSA) of the erector spinae muscles measured by chest computed tomography (CT) scans as a clinical parameter reflecting disease severity and future prognosis in patients with COPD.