Validating a clinical prediction score for Legionella-related community acquired pneumonia
Rosalie R. A. L. Beekman, Ruud Duijkers, Dominic Snijders, Menno M. van der Eerden, Martijn Kross, Wim Boersma
Abstract
Abstract Background Legionella- related community acquired pneumonia (CAP) is a disease with an increasing incidence and a high mortality rate, especially if empirical antibiotic therapy is inadequate. Antibiotic treatment highly relies on clinical symptoms, although proven non-specific, because currently available diagnostic techniques provide insufficient accuracy for detecting Legionella CAP on admission. This study validates a diagnostic scoring system for detection of Legionella -related CAP, based on six items on admission (Legionella prediction score). Methods We included patients with Legionella -related CAP admitted to five large Dutch hospitals between 2006 and 2016. Controls were non- Legionella -related CAP patients. The following six conditions were rewarded one point if present: fever > 39.4 °C; dry cough; hyponatremia (sodium) < 133 mmol/L; lactate dehydrogenase (LDH) > 225 mmol/L; C-reactive protein (CRP) > 187 mg/L and platelet count < 171 × 10 9 /L. The accuracy of the prediction score was assessed by calculating the area under the curve (AUC) through logistic regression analysis. Results We included 131 cases and 160 controls. A score of 0 occurred in non- Legionella- related CAP patients only, a score of 5 and 6 in Legionella- related CAP patients only. A cut-off ≥ 4 resulted in a sensitivity of 58.8% and a specificity of 93.1%. The AUC was 0.89 (95% CI 0.86–0.93). The strongest predictors were elevated LDH, elevated CRP and hyponatremia. Conclusions This multi-centre study validates the Legionella prediction score, an easily applicable diagnostic scoring system, in a large group of patients and finds high diagnostic accuracy. The score shows promise for future prospective validation and could contribute to targeted antibiotic treatment of suspected Legionella CAP.