Statistical analysis and evaluation of diagnostic accuracy of LUS
Statistical analysis showed that LUS specificity was 95%, with only one finding of pathological ultrasound in an afebrile patient, in the absence of respiratory symptoms and normal inflammation indices. The images matched the CXR ones and were interpreted as leukemic infiltrates present at the onset of the disease.
CXR, performed on 16 patients, showed a specificity of 80% displaying pathological images in two cases of onset of leukemia, in apyretic and asymptomatic patients (non-infected patients), likely correlated to infiltration by leukemic cells.
Sensitivity of LUS for the diagnosis of pulmonary infections was 100%. In all cases with specific symptomatology and/or CXR or CT images compatible with pneumonia, LUS was positive. Five febrile neutropenic patients in whom there were no respiratory symptoms or comparative radiological tests, all resulted negative at LUS, were excluded from the analysis because we did not know if these exams were true or false negatives. Probably these febrile events indicated an infection without pulmonary involvement.
The sensitivity of CXR was 50%. The positive predictive value of LUS was 90% while that of CXR was 50%.
The negative predictive value of LUS was 100% while that of CXR was 80%.