Test Characteristics
Respiratory culture testing demonstrated low sensitivity (24.3%) and moderate specificity (85.2%) as screening tests for ARI in children with tracheostomies (Table 4 ), indicative of poor test concordance with clinician diagnosis. Similarly, respiratory cultures demonstrated a poor positive predictive value (36.5%) and only a fair negative predictive value (76.3%), indicating limited effectiveness at identifying ARI in children with tracheostomies. Positive likelihood ratio(+LR) was determined to be 1.64, and negative likelihood ratio(-LR) 0.89. BAL specimens had a higher specificity (90.4%) and negative predictive value (90.1%), but still generally poor test characteristics. TA cultures had very poor test performance as screening tests in all measures (Table 4 ).