International Journal of COPD (Mar 2023)
U-Shaped Relationship Between Serum Lactate Dehydrogenase with All-Cause Mortality in Patients with Chronic Obstructive Pulmonary Disease
Abstract
Lihua Huang,1,* Zhanpeng Lu,2,* Xiaoqing Zhou,3 Liuliu He,1 Xiaoyan You,1 Chunmei Chen,1 Chunsheng Zou1 1Department of Clinical Laboratory, The Second Affiliated Hospital of Gannan Medical University, Ganzhou, People’s Republic of China; 2Department of Critical Care,The Eighth Affiliated Hospital of Sun Yat sen University, Shenzhen, People’s Republic of China; 3General Surgery Department, The Second Affiliated Hospital of Gannan Medical University, Ganzhou, People’s Republic of China*These authors contributed equally to this workCorrespondence: Lihua Huang, Department of Clinical Laboratory, The Second Affiliated Hospital of Gannan Medical University, 331 Yingbin Dadao, Xinfeng County, Ganzhou, Jiangxi Province, People’s Republic of China, Tel +86 18970771329, Email [email protected]: In the anaerobic metabolic pathway, lactate dehydrogenase (LDH) plays an important role in hypoxia, inflammation, and cell damage, making it a potential biomarker for the progression of chronic obstructive pulmonary disease (COPD). We aimed to examine the relationship between LDH levels and all-cause mortality in participants with COPD.Patients and Methods: Data of participants in the US National Health and Nutrition Examination Surveys (NHANES) 2007– 2012 aged ≥ 20 years who underwent spirometry tests were examined, and follow-up mortality data were obtained. According to serum LDH levels, participants with COPD were divided into five groups (59– 111, 112– 123, 124– 135, 136– 150, and 151– 344 U/L). To evaluate whether LDH levels were independently associated with COPD mortality, we used multivariate Cox regression analysis and smooth curve fitting.Results: We included 1320 subjects, 64 with stage III or IV COPD and 541 with stage II COPD. Over a median follow-up of 9.7 years (IQR: 7.8, 11.2), 252 of the 1320 subjects died. The mean LDH level was 132.5 U/L (standard deviation [SD], 27.0). A U-shaped relationship was observed between LDH levels and all-cause mortality. Below and above the inflection point, which was approximately 110 U/L, we found different slopes for the correlation between LDH and all-cause mortality of patients with COPD. Below the threshold, per 1-standard deviation (1SD) increase in LDH resulted in a 68% reduced risk of all-cause mortality (hazard ratio [HR] 0.32, 95% confidence interval [CI] 0.13– 0.81, P=0.016); conversely, above the threshold, per 1SD increase in LDH accelerated the risk of all-cause mortality (HR 1.23, 95% CI: 1.08– 1.41, P= 0.002).Conclusion: Using the nationally representative NHANES data, we found a U-shaped association between LDH level and all-cause mortality in participants with COPD. An optimal LDH level of approximately 110 U/L was associated with the lowest risk of all-cause mortality.Keywords: lactate dehydrogenase, pulmonary disease, chronic obstructive, nutrition surveys, nonlinear, threshold
