# Characterization of bronchiectasis in lung cancer using German claims data

## TL;DR

This study finds that bronchiectasis diagnosed after lung cancer is linked to higher death risk and more pneumonia, but pre-existing bronchiectasis does not affect survival.

## Contribution

The study identifies incident bronchiectasis as a new predictor of worse outcomes in lung cancer patients.

## Key findings

- Incident bronchiectasis is associated with a 2.22-fold higher risk of death in lung cancer patients.
- Patients with bronchiectasis undergoing therapy are more likely to develop pneumonia.
- Higher healthcare costs in bronchiectasis patients are not significant after adjusting for survival time.

## Abstract

Bronchiectasis is a chronic pulmonary disease characterized by pathological bronchial enlargement due to various underlying etiologies, leading to symptoms such as chronic cough, sputum production, and recurrent respiratory infections. However, the impact of comorbid bronchiectasis on the clinical course of lung cancer remains unclear. This study aims to evaluate the role of bronchiectasis as a comorbidity and complication in patients with lung cancer, specifically in relation to survival, the incidence of pneumonia and healthcare costs. In this retrospective analysis, we utilized claims data from 36,272 German lung cancer patients. Patients with and without comorbid bronchiectasis were matched using propensity score matching (1:1). The minimum follow-up period for all patients was three years. Survival differences were assessed using Kaplan-Meier curves and the Log-Rank test. The occurrence of pneumonia was analyzed using absolute and relative frequencies and compared with a McNemar test for paired samples. To compare costs between the matched groups, we used means with standard deviation and paired t-tests. A total of 572 patients (1.6%) had bronchiectasis, of these, 63.6% were diagnosed prior to lung cancer (PRE bronchiectasis), while 36.4% received the diagnosis thereafter (POST bronchiectasis). No significant difference in survival was observed in the PRE cohort, while the risk for death was significantly higher in bronchiectasis patients in the POST cohort compared to controls (HR = 2.22; 95% CI 1.71–2.87; p < 0.001). Among patients undergoing systemic therapy or radiotherapy, patients with bronchiectasis developed pneumonia more often during follow-up, compared patients without bronchiectasis (PRE: 62.4% vs. 45.3%, p < 0.001; POST: 64.9% vs. 44.2%, p < 0.001). Total costs, as well as expenses for inpatient hospital treatment, doctor visits, and medications, were significantly higher in patients with bronchiectasis. However, after adjusting for survival time, these differences were no longer significant. Pre-existing bronchiectasis does not appear to adversely affect survival in patients with lung cancer. In contrast, incident bronchiectasis developing during follow-up is associated with significantly worse outcomes. Clinically, patients with bronchiectasis should be monitored closely for infectious complications, particularly pneumonia.

The online version contains supplementary material available at 10.1038/s41598-025-34656-2.