Pneumonia Lung Ultrasound Score (PLUS): A New Tool for Detecting Pneumonia in the Oldest Patients

Abstract

Objectives: To compare the diagnostic accuracy of lung ultrasound (LUS) and standard chest X-ray (CXR) in older patients admitted to an acute-care geriatric ward for suspected acute pneumonia, and to develop an easy-to-use diagnostic tool, now called Pneumonia Lung Ultrasound Score (PLUS), for early risk stratification.

Design: Prospective, single-center, cohort study.

Setting: Acute-care geriatric ward of tertiary care center.

Participants: Individuals, aged 65 years and older, with suspected acute pneumonia.

Measurements: Participants were stratified according to the Multidimensional Prognostic Index. All the patients underwent CXR and LUS, whereas chest computed tomography was performed in case of mismatch between LUS and CXR. Using logistic multivariate regression, we assessed the influence of age, sex, multimorbidity, cognitive impairment, and clinical biomarkers in the misdiagnosis of acute pneumonia. Finally, an easy-to-perform diagnostic tool based on the combination of biomarkers (brain natriuretic peptide, high-sensitivity C-reactive protein, and partial pressure arterial oxygen/fraction of inspired oxygen ratio) and LUS was realized. A receiver operating characteristic curve was used to verify the predictive accuracy of PLUS, CXR, and LUS in pneumonia diagnosis.

Results: A total of 132 subjects (69% women; mean age = 85.3 ± 6.9 years) were enrolled in the study. Acute pneumonia was diagnosed in 94 of 132 cases. LUS showed higher diagnostic accuracy compared with CXR (0.91 (95% confidence interval (CI) = 0.85-0.93) vs 0.67 (95% CI = 0.58-0.75)) in detecting pneumonic consolidations. A higher degree of cognitive impairment was associated with both LUS and CXR pneumonia misdiagnosis (odds ratio = 1.30 (95% CI = 1.04-1.65)). PLUS showed higher predictive accuracy in the diagnosis of acute pneumonia compared with LUS (AUC = 0.92 (95% CI = 0.87-0.98) vs 0.86 (95% CI = 0.80-0.96); P = .029).

Conclusions: This study confirms the higher diagnostic accuracy of LUS compared with CXR for acute pneumonia in older adults. Nonetheless, the accuracy of PLUS, an easy-to-use, biomarker-derived diagnostic tool, was superior to LUS regardless of patients' degree of frailty.

Keywords: chest X-ray; lung ultrasound; multidimensional geriatric assessment; pneumonia; respiratory failure.