Prognostic Nutritional Index (PNI) as a Potential Prognostic Tool for Exacerbation of COPD in Elderly Patients

Abstract

Purpose

In COPD, exacerbation of the disorder causes a deterioration in the quality-of-life and worsens respiratory dysfunction, leading to a poor prognosis. In recent years, nutritional indices have been reported as significant prognostic factors in various chronic diseases. However, the relationship between nutritional indicators and prognosis in elderly subjects with COPD has not been investigated.

Patients and methods

We enrolled 91 subjects who received COPD assessment tests (CAT), spirometry, blood tests, and multidetector computed tomography (MDCT). We divided the subjects into two groups according to age (<75 years (n=57) and ≥ 75 years (n=34)). The prognostic nutritional index (PNI) was used to assess immune-nutritional status and was calculated as 10 x serum albumin + 0.005 x total lymphocyte count. We then examined the relationship between PNI and clinical parameters, including exacerbation events.

Results

There was no significant correlation between the PNI and CAT, the FEV₁%pred, or low attenuation volume percentage (LAV%). In the elderly group, there were significant differences between the groups with or without exacerbation in the CAT and PNI (p=0.008, p=0.004, respectively). FEV₁%pred, neutrophil-to-lymphocyte ratio (NLR) and LAV% did not differ between the two groups. The analytical model combining CAT and PNI improved the prediction of exacerbations in the elderly subjects (p=0.0068).

Conclusion

In elderly subjects with COPD, CAT were associated significantly with the risk of COPD exacerbation, with PNI also a potential predictor. The combined assessment of CAT and PNI may be a useful prognostic tool in subjects with COPD.

Keywords:

• chronic obstructive pulmonary disease
• exacerbation
• prognostic nutritional index

Abbreviations

BMI, body mass index; CAT, chronic obstructive pulmonary disease assessment test; COPD, chronic obstructive pulmonary disease; FEV₁, forced expiratory volume in 1 second; FEV₁/FVC, forced expiratory volume in 1 second per forced vital capacity; FVC, forced vital capacity; GOLD, Global Initiative for Chronic Pulmonary Obstructive Lung Disease; ICS, inhaled corticosteroid; LAA, low attenuation area; LABA, long-acting β-2 agonist; LAMA, long-acting muscarinic antagonists; LAV, low attenuation volume; LAV%, low attenuation volume percentage; LV, lung volume; MDCT, multi-detector row computed tomography; MRI, magnetic resonance imaging; NLR, neutrophil-to-lymphocyte ratio; PFT, pulmonary function testing; PNI, prognostic nutritional index; TLA, total lung area; VC, vital capacity; %VC, vital capacity percentage; WBC, white blood cell.

Data Sharing Statement

The data sets analyzed during the current study are available from the corresponding author upon reasonable request.

Acknowledgment

The abstract of this paper was presented at the 2020 European Respiratory Society (ERS) International congress in session “Respiratory viruses in the”pre-COVID-19 “era”, with interim findings. The poster’s abstract was published in “Poster Abstracts” in European Respiratory Journal 2020; 56: Suppl. 64, 5114. https://erj.ersjournals.com/content/56/suppl_64/5114.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The author reports no conflicts of interest in this work.

Additional information

Funding

This research was partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (C) (19K12816 and 22K12836), and the Chiba Foundation for Health Promotion & Disease Prevention (No.1272). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.