Table 2.

Gram stain scoring for the diagnosis of VAP

	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	PLR	NLR	Kappa (95% CI)
≥1+	95	61	77	90	2.4	0.08	0.59 (0.45–0.72)
≥2+	77	86	88	73	5.5	0.27	0.62 (0.49–0.75)
≥3+	42	96	94	57	10.5	0.6	0.35 (0.23–0.47)
≥4+	20	96	89	47	5	0.83	0.15 (0.05–0.24)

PPV positive predictive value, NPV negative predictive value, PLR positive likelihood ratio, NLR negative likelihood ratio.