# Serum docosahexaenoic acid as a predictor of hospital readmission in chronic obstructive pulmonary disease exacerbation: a retrospective cohort study

## TL;DR

Low levels of DHA in the blood are linked to a higher risk of hospital readmission for COPD flare-ups, suggesting DHA may help prevent these events.

## Contribution

This study identifies serum DHA as an independent predictor of COPD exacerbation-related readmission.

## Key findings

- Patients with COPD readmission had significantly lower DHA levels than those without.
- Low DHA levels were an independent risk factor for COPD exacerbation readmission.
- A DHA-based nomogram showed good predictive performance for readmission risk.

## Abstract

The beneficial effects of omega-3 fatty acids for patients with chronic obstructive pulmonary disease (COPD) had been observed, including attenuating lung function decline and reducing their respiratory symptom burdens. However, the impact of omega-3 fatty acids on COPD exacerbation-related outcomes remains unclear. This study aimed to evaluate whether reduced serum omega-3 fatty acid levels are associated with a higher risk of future hospital readmission due to COPD exacerbation (ECOPD).

This retrospective cohort study included 88 patients hospitalized for ECOPD between April 2017 and March 2018. Clinical data were collected, and serum omega-3 fatty acid levels were analyzed using liquid chromatography-mass spectrometry (LC-MS). All patients were followed up for a median period of 53.5 months and categorized into two groups based on whether they experienced ECOPD-related readmission during the follow-up period. The clinical characteristics and serum levels of omega-3 fatty acid levels, including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), between the two groups were compared. Additionally, patients were categorized into low and high DHA groups based on the median DHA level, and the association between DHA level and ECOPD-related readmission rate was analyzed using a Cox regression model.

Patients who experienced ECOPD-related readmission during the follow-up period (n = 36) had lower serum levels of DHA than those who did not experience readmission. The serum levels of EPA did not significantly differ between groups. Kaplan–Meier curve showed that patients in the low-DHA group exhibited a significantly higher ECOPD-related readmission rate compared to those in the high-DHA group (log-rank p = 0.023). Multivariable Cox regression analysis identified low DHA level as an independent risk factor for ECOPD-related readmission. A nomogram based on DHA levels demonstrated good predictive performance.

A low DHA level serves as an independent risk factor for ECOPD-related readmission, suggesting DHA may have a potential protective effect to reduce the risk of exacerbation in patients with COPD.