Frequency of rhabdomyolysis in <i>Legionella</i> infection and associated outcomes: a retrospective cross-sectional study

Legionella is a common cause of community-acquired pneumonia and can affect multiple organ systems. An association with rhabdomyolysis and acute kidney injury (AKI) have been noted for several decades, but population-based studies are limited and could aid in better understanding the prevalence, associated risk factors, and clinical significance of this complication. We performed a retrospective manual review of the electronic health record on 323 patients with legionellosis identified on the basis of urinary antigen or culture in a large, urban hospital system. Demographic and clinical data were extracted by four physician reviewers. Rhabdomyolysis was assessed on the basis of creatine kinase (CK) values ≥1,000 IU/L or suggestive urinalysis findings. AKI was classified according to Kidney Disease: Improving Global Outcomes (KDIGO) guidelines. Patients were excluded for missing data or potential alternative causes of rhabdomyolysis. Data were analyzed using appropriate parametric and non-parametric statistical tests and multivariate logistic regression analysis. A total of 210 patients were included in the analysis. Fifty patients (23.8%) had evidence of rhabdomyolysis, 20% of whom had severe rhabdomyolysis (CK ≥15,000 IU/L). Rhabdomyolysis was associated with male sex, black race, and age <65. Common comorbidities were not associated with rhabdomyolysis. Rhabdomyolysis was associated with AKI, including for mild cases (CK 1000–5000 IU/L), with longer hospital length of stay, and with higher likelihood of intensive care unit admission, but not with overall mortality, which was 5.1% in the patient cohort. Rhabdomyolysis is a common feature of legionellosis, is associated with AKI, and may be a marker of more severe disease.