id="p0010">CHAID model illustrates multilevel interactions among risk factors to identify stepwise pathways for detecting bacterial coinfection.
id="p0015">PCT was the strongest variable associated with coinfection diagnosis by CHAID model analysis.
id="p0020">Low serum levels of PCT (<0.29 ng/mL) in patients without shock were an accurate predictor for ruling out coinfection.
id="p0025">PCT was a more accurate marker than CRP for coinfection diagnosis.