ObjectiveTo investigate the clinical value of serum proadrenomedullin (pro-ADM) for diagnosis of ventilator-associated pneumonia(VAP). MethodsA prospective study was carried out in eighty-nine patients with clinically suspected diagnosis of VAP who underwent invasive mechanical ventilation between June 2014 and July 2015.The patients were divided into a VAP group (n=52) and a non-VAP group (n=37) according to clinical and microbiological culture results.The levels of serum pro-ADM were measured by sandwich ELISA on 1st, 3rd and 5th day of VAP suspicion.The diagnostic value of pro-ADM for VAP was assessed by receiver operating characteristic (ROC) curve analysis. ResultsOn 1st day, 3rd day and 5th day, the pro-ADM levels [3.10(2.21, 4.61) nmol/L, 3.01(2.04, 4.75)nmol/L and 1.85(1.12, 3.54)nmol/L, respectively] in the VAP group were significantly higher than those in the non-VAP group [1.53(1.07, 2.24)nmol/L, 1.52(1.05, 2.17) nmol/L and 1.26(1.02, 2.17) nmol/L, respectively] (all P < 0.05).For diagnosis of VAP, the area under the ROC curve (AUC) for pro-ADM on 1st, 3rd and 5th were 0.896 (95%CI 0.799-0.940), 0.863(95%CI 0.791-0.935) and 0.651 (95%CI 0.538-0.765), respectively.When using 2.53 nmol/L as the best cutoff on 1st day, pro-ADM had 84.6% sensitivity and 86.5% specificity.When using 2.40 nmol/L as the best cutoff on 3rd day, pro-ADM had 82.7% sensitivity and 83.8% specificity. ConclusionSerum level of pro-ADM in the diagnosis of VAP has good sensitivity and specificity, which may be used as a marker to diagnose VAP early.