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Table 2 PCT and CRP versus emergency physician judgement in diagnosing bacterial/parasitic infection

From: Serum procalcitonin measurement as diagnostic and prognostic marker in febrile adult patients presenting to the emergency department

Test and cutoff

Sensitivity (95% CI)

Specificity (95% CI)

PPV (95% CI)

NPV (95% CI)

Accuracy (95% CI)

CRP

     

   ≥ 5 mg/l

0.96 (0.91–0.98)

0.16 (0.09–0.26)

0.71 (0.65–0.77)

0.63 (0.41–0.81)

0.71 (0.64–0.76)

   ≥40 mg/l

0.76 (0.69–0.82)*

0.62 (0.51–0.72)

0.81 (0.74–0.87)

0.54 (0.44–0.64)*

0.71 (0.65–0.77)

   ≥100 mg/l

0.54 (0.46–0.62)

0.90 (0.82–0.95)

0.93 (0.85–0.96)

0.47 (0.39–0.56)

0.65 (0.59–0.71)

PCT

     

   ≥0.1 μg/l

0.90 (0.85–0.94)

0.32 (0.22–0.43)

0.74 (0.68–0.80)

0.60 (0.47–0.74)

0.72 (0.66–0.77)

   ≥0.2 μg/l

0.77 (0.70–0.82)*

0.59 (0.48–0.70)

0.80 (0.74–0.86)

0.54 (0.43–0.64)*

0.71 (0.65–0.77)

   ≥0.5 μg/l

0.63 (0.55–0.70)

0.79 (0.68–0.87)

0.87 (0.80–0.92)

0.49 (0.40–0.58)

0.68 (0.62–0.73)

   ≥2 μg/l

0.36 (0.30–0.44)

0.93 (0.85–0.97)

0.92 (0.83–0.97)

0.40 (0.33–0.47)

0.54 (0.48–0.60)

   ≥5 μg/l

0.23 (0.17–0.30)

0.99 (0.93–1.00)

0.97 (0.87–0.99)

0.37 (0.30–0.44)

0.46 (0.40–0.53)

Emergency physician

0.85 (0.79–0.90)

0.57 (0.45–0.67)

0.81 (0.75–0.86)

0.63 (0.51–0.74)

0.76 (0.70–0.81)

  1. Shown is a comparison of performance of procalcitonin (PCT) and C-reactive protein (CRP) with emergency physician for the diagnosis of bacterial/parasitic infection, with the 'gold standard' being experts diagnosis. *P < 0.05, versus emergency physician. CI, confidence interval; NPV, negative predictive value; PPV, positive predictive value.