Lactate dehydrogenase to albumin ratio and prognosis in patients with acute exacerbation of chronic obstructive pulmonary disease: a retrospective cohort study

Background Chronic obstructive pulmonary disease (COPD) is a global public health challenge and a major cause of death. The lactate dehydrogenase to albumin ratio (LAR) is a simple and practical indicator of disease prognosis, but its prognostic value in acute exacerbation of COPD (AECOPD) remains unclear. Therefore, we aimed to explore the prognostic value of LAR for the short-term all-cause mortality risk in patients with AECOPD. Methods This retrospective cohort study included 654 patients with AECOPD from the MIMIC-IV database. LAR was analyzed after natural logarithm transformation and the patients were divided into three groups. The clinical outcome was the 1-month and 3-months all-cause mortality. The relationship between LAR and all-cause mortality was assessed using Kaplan-Meier survival analysis and a Cox regression model. Generalized additive models were employed to identify non-linear relationships, and a subgroup analysis was performed to determine the stability of the results. Results The study showed that LAR levels significantly and positively correlated with short-term all-cause mortality in patients with AECOPD. Compared to the low LAR group, patients in the medium LAR group had a significantly increased 1-month all-cause mortality risk, with a hazard ratio (HR) of 1.74 (95% [Confidence Interval, CI] 1.16-2.63, P = 0.008). Patients in the high LAR group had an even higher 1-month all-cause mortality risk, with an HR of 2.58 (95% CI 1.75-3.80, P < 0.001). For 3-month all-cause mortality, patients in the medium LAR group had an HR of 1.54 (95% CI 1.10-2.16, P = 0.012), while those in the high LAR group had an HR of 2.18 (95% CI 1.58-3.01, P < 0.001). The results remained stable in all three adjusted models and in the subgroup analyses. The relationship between LAR and all-cause mortality due to AECOPD was non-linear, with inflection points at 8.13 and 6.05 for 1-month and 3-month all-cause mortality, respectively. Conclusions Elevated LAR is an independent predictive indicator of short-term all-cause mortality risk in patients with AECOPD and can be used to improve decision-making for the clinical management of these patients.