Correlation Between Blood Urea Nitrogen To Creatinine Ratio And Sarcopenia In Patients With Chronic Obstructive Pulmonary Disease

Objective Previous studies have shown that sarcopenia is a prognostic factor in chronic obstructive pulmonary disease(COPD).In this study,clinical data of patients with COPD were collected and skeletal muscle index(SMI)at the level of first lumbar spine(L1)on chest CT was measured to explore the diagnostic value of blood urea nitrogen/creatinine(BUN/Cr)ratio in patients with COPD complicated with sarcopenia.Methods Clinical data of 146 COPD patients diagnosed in the Respiratory Department of Lanzhou University First Hospital from January 2019 to December 2021 were collected.According to the European consensus and related studies,sarcopenia was diagnosed according to the cut-off value of the first lumbar skeletal muscle index(L1 SMI)of sarcopenia,and the patients were divided into the sarcopenia group and the non-sarcopenia group.The general data,pulmonary function indexes and laboratory indexes of the two groups were compared,and the independent risk factors of COPD patients with sarcopenia were analyzed by Logistic regression.Linear regression analysis was used to evaluate the relationship between BUN/Cr and sarcopenia index.The accuracy of blood BUN/Cr ratio in evaluating sarcopenia in COPD patients was investigated according to receiver operating characteristic curve(ROC),and the optimal critical point for predicting sarcopenia was determined.Results1.A total of 146 subjects met the inclusion and exclusion criteria in this study.According to the GOLD scale of lung function,patients with COPD were divided into two groups,including 88 cases(60.3%)in the mild group and 58 cases(39.7%)in the severe group.Age,neutrophil count/lymphocyte count(NLR)and arterial partial blood carbon dioxide pressure(Pa CO2)in severe COPD group were significantly higher than those in mild COPD group(P < 0.05).2.Sarcopenia was diagnosed according to the truncation value of L1 SMI of sarcopenia,and the patients were divided into sarcopenia group and non-sarcopenia group,including 85(58.2%)patients in the sarcopenia group and 61(41.8%)in the nonsarcopenia group.The results showed that male COPD patients were more likely to develop sarcopenia than female patients(P < 0.001),patients with a history of smoking were more likely to develop sarcopenia(P < 0.001),and body mass index(BMI)was significantly lower in COPD patients with sarcopenia than in patients without sarcopenia(P < 0.001).3.The levels of forced expiratory volume in the first second(FVC),measured percentage of FVC to predicted value(FVC%pred),serum creatinine(Cr),cholinesterase(CHE),total cholesterol(TC),triglyceride(TG)and low density lipoprotein cholesterol(LDL-C)in COPD combined with sarcopenia group were significantly lower than those in non-sarcopenia group(P < 0)05);The levels of NLR and BUN/Cr in COPD combined with sarcopenia were significantly higher than those in non-sarcopenia group(P < 0.05).4.Univariate regression analysis showed smoking history [OR=4.440,95%CI:2.200-9.280,P < 0.05],NLR [OR=1.183,95%CI: 1.007-1.390,P < 0.05],BUN/Cr[OR=1.044,95%CI: 1.021-1.067,P < 0.05] are risk factors for sarcopenia in COPD patients.After adjusting for confounding factors,multivariate regression analysis showed that BUN/Cr [OR=1.052,95%CI: 1.009-1.097,P < 0.05] was an independent risk factor for COPD combined with sarcopenia.5.Linear correlation analysis of BMI,Cr,BUN/Cr and muscle index(SMI): BMI(r=0.549,P < 0.001),Cr(r=0.516,P < 0.001)and SMI were positively correlated,BUN/Cr(r=-0.175,P=0.034)and SMI were negatively correlated.6.ROC curve was used to analyze the value of BUN/Cr in predicting the occurrence of sarcopenia in COPD patients.The area AUC under ROC curve was 0.700(95%CI: 0.615-0.786),the Yoden index was 0.385,the optimal cut-off point was 79.938,the sensitivity was 64.7%,and the specificity was 73.8%.Conclusion1.The prevalence of sarcopenia in male COPD patients is significantly higher than that in female COPD patients,and male COPD patients are more likely to develop sarcopenia than female patients.2.In COPD patients,SMI was positively correlated with BMI and blood Cr level,and negatively correlated with blood BUN/Cr ratio.3.Blood BUN/Cr ratio is an independent risk factor for sarcopenia in patients with COPD and can be used to predict sarcopenia in hospitalized patients with COPD.