# Predicting Pulmonary Exacerbations in Cystic Fibrosis Using Inflammation-Based Scoring Systems

## TL;DR

This study finds that the CRP/albumin ratio can predict future lung infections in people with cystic fibrosis.

## Contribution

The study identifies CRP/albumin ratio as the most reliable predictor of pulmonary exacerbations in cystic fibrosis patients.

## Key findings

- CRP(log) and CRP/albumin ratio were strongly associated with future pulmonary exacerbations.
- The CRP/albumin ratio outperformed other inflammation-based models in predicting exacerbations.
- Decreased LMR and increased NLR also showed significant associations with exacerbations.

## Abstract

Background: The aim of this study is to identify people with cystic fibrosis (pwCF) at risk for future pulmonary exacerbations (PEx) based on established and unestablished markers of chronic inflammation. There is currently no universal definition of PEx in cystic fibrosis (CF), but it is commonly characterized by clinical deterioration and a drop in FEV1 ≥10% with or without elevations in systemic inflammatory markers. PEx negatively affect clinical outcomes in pwCF; therefore, predicting and preventing PEx is a crucial goal in the treatment of pwCF. Methods: We retrospectively examined pwCF ≥18 years who had ≥2 pulmonary function tests per year for a 3-year period. The first year was marked as the baseline. The follow-up period (FU) was defined as the following two-year period after baseline. PEx were defined as a need for intravenous antibiotic treatment due to clinical deterioration. Various scoring systems and ratios (neutrophil/lymphocyte (NLR), lymphocyte/monocyte (LMR), CRP, CRP/albumin, Glasgow Prognostic Score (GPS), high-sensitivity modified Glasgow Prognostic Score (hs-GPS)) were compared in pwCF with and without PEx during the FU. Logistic regression models were used to determine the best marker for predicting PEx, considering factors such as age, sex, PEx at baseline, BMI, homozygote F508del mutation, diabetes mellitus, chronic bacterial infection, and CFTR (cystic fibrosis transmembrane conductance regulator)-modulator therapy. The results are reported as odds ratios (ORs) with p-values. Results: Out of 283 pwCF, 131 were included in the study. In total, 43.5% were female, and the mean age was 34.0 years. A total of 75 pwCF (57.3%) had PEx during FU. In the multivariate analysis, the following markers at baseline were significantly associated with having a PEx during FU: CRP(log) (OR = 7.29, p = 0.01), CRP/albumin (OR = 1.08, p = 0.006), decreased LMR (OR = 0.51, p = 0.02), increased NLR (OR = 1.52, p = 0.02), and GPS of 1 vs. 0 (OR = 2.75, p = 0.04). The results indicate that the CRP/albumin ratio was the best model for predicting PEx in pwCF during the FU, outperforming other models. Conclusions: While several inflammation-based scoring systems can predict PEx in pwCF, the easily calculated CRP/albumin proved to reliably identify pwCF with an increased risk for PEx, making it a promising tool in clinical practice.