High blood urea nitrogen to creatinine ratio is associated with increased risk of sarcopenia in patients with chronic obstructive pulmonary disease

Background and aims: Sarcopenia has been reported to be a prognostic factor for chronic obstructive pulmonary disease (COPD). However, the relationship between the ratio of blood urea nitrogen to creatinine (BUN/Cr) and sarcopenia in patients with COPD remain unclear. Therefore, the purpose of this study is to explore whether the ratio can be used as a predictor of sarcopenia in hospitalized COPD patients. Methods: The skeletal muscle area index (SMI) at the level of the 12th thoracic vertebra (T12) was used to assess the risk of sarcopenia in patients. This single center cross-sectional study was conducted by analyzing the clinical parameters and identifying the T12 skeletal muscle area (SMA) and density (SMD) on chest CT images of COPD hospitalized patients admitted to the respiratory department of our hospital from March 2018 to August 2021. The study enrolled 265 hospitalized patients. Based on the different statistical properties of the above variables, differences between groups were measured by independent sample Student t-tests, Mann-Whitney U tests, or Chi-Square tests. Multivariable linear regression analysis was used to evaluate the relationship between the value of BUN/Cr and the risk of sarcopenia. Results: The serum BUN/Cr ratio was negatively correlated with SMI (r = −0.201, p = 0.001) in COPD patients, and multivariate linear regression analysis showed that this ratio was associated with the risk of sarcopenia (β = −0.109, p = 0.041). The optimal cut-off value of BUN/Cr ratio for identifying COPD patients with sarcopenia was 97.893. There was also a significant negative correlation between serum BUN/Cr ratio and forced vital capacity (FVC; r = −0.235, p < 0.001) and forced expiratory volume in the first second (FEV1; r = −0.219, p < 0.001). Conclusion: The BUN/Cr ratio can be used to predict sarcopenia and evaluate pulmonary function in hospitalized COPD patients.