Serum Creatinine to Cystatin C Ratio is an Effective Indicator for Muscle Strength Decline in Men with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

PURPOSE: This study explored the value of the serum creatinine/cystatin C (Cr/CysC) ratio in diagnosing the reduction of muscle strength in men with acute exacerbation of chronic obstructive pulmonary disease (AECOPD). PATIENTS AND METHODS: In this study, we enrolled 72 male patients with AECOPD and 32 male patients with stable chronic obstructive pulmonary disease (COPD). We compared clinical characteristics between the AECOPD and stable COPD groups. Then, we subdivided AECOPD patients into normal muscle strength and low muscle strength groups; we compared the clinical characteristics between these two groups. We analyzed the relationships of serum creatinine (Cr), cystatin C (CysC), and Cr/CysC ratio with clinical characteristics in male AECOPD patients. We also investigated whether the Cr/CysC ratio could aid in the diagnosis of muscle strength decline via receiver operating characteristic curve and binary logistic regression analysis. RESULTS: We found that handgrip strength, Cr/CysC ratio, serum Cr, FEV(1), FVC, and FEV(1)%pred were lower in AECOPD patients than in stable COPD patients. Among AECOPD patients, BMI, weight, FEV(1), FVC, FEV(1)%pred, and Cr/CysC ratio were lower in the low muscle strength group than in the normal muscle strength group; there were more patients with ≥2 acute exacerbations within the past year in the low muscle strength group. The Cr/CysC ratio was correlated with handgrip strength, FEV(1), FVC, FEV(1)%pred, BMI and weight. The area under curve for low handgrip strength was greater for the Cr/CysC ratio than for Cr. Binary logistic regression analysis showed that a Cr/CysC ratio <0.99 was a risk factor for decreased muscle strength in male patients with AECOPD. CONCLUSION: The Cr/CysC ratio is a useful predictor of muscle strength decline in male AECOPD patients, while a low Cr/CysC ratio is a risk factor for muscle strength decline in male patients with AECOPD.