Table 2 Sensitivity (Sens), specificity (Spec), positive predictive value (PPV) and negative predictive value (NPV) of each variable included in the algorithms

Primary endpoint: all infections (superficial, deep and organ/space infections)

Positive culture

64.5 (62.2–66.8)

94.0 (92.9–95.2)

29.9 (27.6–32.1)

98.5 (98.0–99.1)

≥ 3 microbiological requests

58.1 (55.7–60.5)

93.6 (92.4–94.8)

26.5 (24.3–28.6)

98.3 (97.6–98.9)

Antimicrobial therapy ≥ 7 days

58.1 (55.7–60.5)

92.6 (91.3–93.9)

23.7 (21.6–25.8)

98.2 (97.6–98.9)

Length of hospital stay ≥ 14 days

29.0 (26.8–31.2)

84.1 (82.4–85.9)

6.7 (5.5–8.0)

96.8 (95.9–97.6)

Orthopaedics readmission

53.2 (50.8–55.7)

87.4 (85.8–89.1)

14.4 (12.7–16.1)

97.9 (97.2–98.6)

Orthopaedics re-intervention

59.7 (57.3–62.1)

93.1 (91.8–94.3)

25.3 (23.2–27.5)

98.3 (97.7–98.9)

Emergency department

54.8 (52.4–57.3)

83.8 (82.0–85.6)

11.8 (10.2–13.4)

97.9 (97.2–98.6)

Secondary endpoint: only deep and organ/space infections

Positive culture

87.5 (85.9–89.1)

93.8 (92.6–95.0)

26.1 (24.0–28.3)

99.7 (99.4–100.0)

≥ 3 microbiological requests

82.5 (80.7–84.3)

93.5 (92.3–94.7)

24.3 (22.2–26.4)

99.5 (99.2–99.9)

Antimicrobial therapy ≥ 7 days

85.0 (83.3–86.7)

92.6 (91.3- 93.99

22.4 (20.4–24.4)

99.6 (99.3–100.0)

Length of hospital stay ≥ 14 days

37.5 (35.2–39.9)

84.2 (82.4–85.9)

5.6 (4.5–6.7)

98.2 (97.5–98.8)

Orthopaedics readmission

72.5 (70.3–74.7)

87.4 (85.8–89.0)

12.6 (11.0–14.2)

99.2 (98.8–99.6)

Orthopaedics re-intervention

87.5 (85.9–89.1)

93.0 (91.8–94.3)

24.0 (22.0 ∼ 26.09

99.7 (99.4–100.09

Emergency department

50.0 (47.6–52.4)

83.2 (81.3–85.0)

6.9 (5.7–8.2)

98.5 (97.9–99.1)