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Table 3 Diagnostic accuracy of C-reactive protein by infection pair in 210 participants with single target infections

From: C-reactive protein and procalcitonin to discriminate between tuberculosis, Pneumocystis jirovecii pneumonia, and bacterial pneumonia in HIV-infected inpatients meeting WHO criteria for seriously ill: a prospective cohort study

Infectiona

Cut-off (mg/L)

Sensitivity% (95% CI)

Specificity% (95% CI)

PPV% (95% CI)

NPV% (95% CI)

LR+ (95% CI)

LR- (95% CI)

Diagnostic odds ratio (95% CI)

TB vs. CAP

CRP ≥64

90.2 (83.9–94.7)

11.5 (4.7–22.2)

69.0 (61.5–75.7)

35.0 (15.4–59.2)

1.02 (0.92–1.13)

0.85 (0.36–2.03)

1.20 (0.45–3.17)

CRP < 175

65.4 (56.7–73.4)

57.4 (44.1–70.0)

77.0 (68.1–84.4)

43.2 (32.2–54.7)

1.53 (1.12–2.11)

0.60 (0.44–0.83)

2.55 (1.37–4.72)

CAP vs. PJP

CRP ≥ 63

90.2 (79.8–96.3)

18.8 (4.0–45.6)

80.9 (69.5–89.4)

33.3 (7.5–70.1)

1.11 (0.86–1.42)

0.52 (0.15–1.87)

2.12 (0.51–8.94)

CRP ≥ 147

63.9 (50.6–75.8)

87.5 (61.7–98.4)

95.1 (83.5–99.4)

38.9 (23.1–56.5)

5.11 (1.38–18.96)

0.41 (0.28–0.60)

12.41 (2.83–59.7)

PJP vs. TB

CRP ≥33

93.8 (69.8–99.8)

2.3 (0.5–6.5)

10.3 (5.9–16.5)

75.0 (19.4–99.4)

0.96 (0.84–1.09)

2.77 (0.31–25.08)

0.35 (0.03–3.54)

CRP < 147

87.5 (61.7–98.4)

48.9 (40.1–57.7)

17.1 (9.7–27.0)

97.0 (89.6–99.6)

1.71 (1.33–2.19)

0.26 (0.07–0.95)

6.69 (1.46–30.60)

TB vs. CAP/PJP

CRP ≥64

90.2 (83.9–94.7)

13.0 (6.4–22.6)

64.2 (56.8–71.0)

43.5 (23.2–65.5)

1.04 (0.94–1.15)

0.75 (0.35–1.63)

1.38 (0.58–3.25)

CRP ≥150

48.9 (40.1–57.7)

49.4 (37.8–61.0)

62.5 (52.5–71.8)

35.8 (26.8–45.7)

0.96 (0.73–1.28)

1.04 (0.78–1.37)

0.93 (0.53–1.63)

CAP vs. TB/PJP

CRP ≥63

90.2 (79.8–96.3)

10.7 (6.3–16.9)

29.3 (22.9–36.3)

72.7 (49.8–89.3)

1.01 (0.91–1.12)

0.92 (0.38–2.23)

1.10 (0.42–2.87)

CRP ≥175

57.4 (44.1–70.0)

67.8 (59.6–75.2)

42.2 (31.4–53.5)

79.5 (71.5–86.2)

1.78 (1.30–2.45)

0.63 (0.46–0.86)

2.83 (1.54–5.21)

PJP vs. TB/CAP

CRP ≥33

93.8 (69.8–99.8)

2.6 (0.8–5.9)

7.4 (4.2–11.8)

83.3 (35.9–99.6)

0.96 (0.85–1.09)

2.42 (0.30–19.52)

0.40 (0.04–3.62)

CRP < 147

87.5 (61.7–98.4)

53.6 (46.3–60.8)

13.5 (7.6–21.6)

98.1 (93.4–99.8)

1.89 (1.48–2.40)

0.23 (0.06–0.86)

8.09 (1.99–36.55)

  1. Two cut-offs are listed for each infection pair and one infection versus the other two: the first with minimum 90% sensitivity and the second selected using the Liu index (see text for details)
  2. Abbreviations: TB tuberculosis, CAP bacterial community-acquired pneumonia, PJP Pneumocystis jirovecii pneumonia, PPV positive predictive value, NPV negative predictive value, LR Likelihood ratio, CI confidence interval. a Cohort prevalences: TB, 63.3% (95%CI, 56.4–69.9%); CAP, 29.0% (95% CI, 23.0–35.7%); PJP, 7.6% (95% CI, 4.4–12.1%)