Long-term impacts of Legionnaires' disease on health and well-being: rationale, study design and baseline findings of a matched cohort study (LongLEGIO)

BackgroundThe long-term effects of Legionnaires disease beyond the acute infection and their impact on healthcare utilisation remain poorly understood. We present the rationale and study design of a matched prospective observational cohort study (LongLEGIO) aimed at investigating the persistent sequelae on patients health, well-being, and health service use following community-acquired Legionnaires disease, compared to other bacterial pneumonias that tested negative for Legionella. MethodsPatients with Legionnaires disease and other bacterial Legionella test-negative pneumonia are recruited from secondary and tertiary care hospitals and matched for sex, age, hospital-level and date of diagnosis. Semi-structured interviews were conducted at baseline (shortly after the pneumonia diagnosis) and at two, six and 12 months following appropriate antibiotic therapy. Baseline assessments capture pre-existing conditions, illness experience, and disease severity, while follow-up assessments evaluate long-term symptoms, healthcare utilisation, quality of life (EQ-5D-5L), and social/work impacts. Data on case management and the disease severity are extracted from patient records. ResultsA total of 59 patients with community-acquired Legionnaires disease and 60 patients with other bacterial Legionella test-negative pneumonia were enrolled. Both cohorts were representative of their respective condition. Key differences between Legionnaires disease and non-Legionella bacterial pneumonia patient groups emerged in terms of comorbidities, pneumonia severity, and self-reported quality of life. These differences will be accounted for in future analyses as part of the LongLEGIO study. ConclusionsThe LongLEGIO study will advance ongoing research on post-acute infection syndromes and provide a robust data foundation for more accurate assessments of the disease burden associated with Legionnaires disease.