Clinical role of the prognostic nutritional index in patients presenting with acute exacerbation of chronic obstructive pulmonary disease

Abstract Background Chronic obstructive pulmonary disease is a respiratory condition frequently accompanied by acute exacerbations and systemic consequences, including nutritional deterioration. Malnutrition in patients with chronic obstructive pulmonary disease is associated with increased morbidity and adverse outcomes. The Prognostic Nutritional Index, derived from serum albumin and peripheral lymphocyte counts, reflects nutritional and immunological status and may aid in risk stratification during acute exacerbations. Methods This retrospective observational cohort study investigated the relationship between Prognostic Nutritional Index levels and clinical outcomes in 60 patients presenting to the emergency department with acute exacerbation of chronic obstructive pulmonary disease between February and April 2024. The Prognostic Nutritional Index was calculated using the formula: 10 × serum albumin (g/dL) + 0.005 × lymphocyte count (/mm³). Patients were classified as the low Prognostic Nutritional Index group (Prognostic Nutritional Index < 40) or the high Prognostic Nutritional Index group (Prognostic Nutritional Index ≥ 40), and clinical, laboratory, and functional variables were compared. Prognostic performance was assessed using receiver operating characteristic curve and locally estimated scatterplot smoothing analyses. Results Among the patients, 33 were in the low Prognostic Nutritional Index group and 27 were in the high Prognostic Nutritional Index group. The low Prognostic Nutritional Index group exhibited higher hospitalisation rates (87.9% vs. 66.7%; p = 0.047) and more frequent intensive care unit admission at presentation (39.4% vs. 7.4%; p = 0.009). Descriptive analyses additionally demonstrated longer intensive care unit stays in the low Prognostic Nutritional Index group. The area under the curve for the Prognostic Nutritional Index in predicting the composite adverse clinical outcome was 0.712 (95% confidence interval: 0.559–0.865, p = 0.020). Locally estimated scatterplot smoothing analysis indicated 40 as a potential inflection point. Conclusions Lower Prognostic Nutritional Index values on admission were associated with adverse short-term clinical outcomes in patients presenting with acute exacerbation of chronic obstructive pulmonary disease. The Prognostic Nutritional Index reflects both nutritional and inflammatory status and may complement the initial assessment of these patients as an inexpensive and readily obtainable parameter.