Table 2.
Diagnostic performance of radiological and non-radiological findings for the diagnosis of infection (overall cohort)
| Variable | Aseptic cases (n [total, %])a | Septic cases (n [total,%])a | Sensitivity (%, 95 CI) |
Specificity (%, 95 CI) |
PPV (%, 95 CI) |
NPV (%, 95 CI) |
Accuracy (%, 95 CI) |
PLR | NLR | DOR (95% CI) | p value |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Radiological findings | |||||||||||
| Radiolucent line | 29 (of 305 cases, 9.5) | 19 (of 116 cases, 16.4) | 16.4 (10.2–24.4) | 90.5 (86.6–93.5) | 39.6 (27.7–52.9) | 74.0 (72.3–75.7) | 70.1 (65.5–74.4) | 1.72 (1.01–2.95) | 0.92 (0.85–1.01) | 1.86 (1.00–3.48) | 0.047 |
| Implant breakage | 43 (305 cases, 14.1) | 9 (116 cases, 7.8) | 7.8 (3.6–14.2) | 85.9 (81.5–89.6) | 17.3 (9.5–29.4) | 71.0 (69.6–72.4) | 64.3 (59.6–69.0) | 0.55 (0.28–1.09) | 1.07 (1.00–1.15) | 0.51 (0.24–1.09) | 0.077 |
| Implant displacement | 32 (305 cases, 10.5) | 13 (116 cases, 11.2) | 11.2 (6.1–18.4) | 89.5 (85.5–92.7) | 28.9 (18.11 42.7) | 72.6 (71.1–74.1) | 67.9 (63.2–72.4) | 1.07 (0.58–19.6) | 0.99 (0.92–1.07) | 1.08 (0.54–2.13) | 0.832 |
| Periosteal reaction | 16 (305 cases, 5.2) | 14 (116 cases, 12.1) | 12.1 (6.8–19.4) | 94.8 (91.6–97.0) |
46.7 (30.6–63.4) |
73.9 (72.5–75.3) | 71.9 (67.4–76.2) | 2.30 (1.16–4.56) | 0.93 (0.86–1.00) | 2.48 (1.17–5.26) | 0.015 |
| Non-radiological findings | |||||||||||
| Increased WBC countb | 16 (193 cases, 8.3) | 21 (93 cases, 22.6) | 22.6 (14.6–32.4) | 91.7 (86.3–95.5) | 56.8 (41.8–70.6) | 71.1 (68.6–73.4) | 69.2 (63.5–74.5) | 2.72 (1.49–4.97) | 0.84 (0.75–0.95) | 3.2 (1.6–6.5) | 0.001 |
| Increased CRP valuec | 32 (193 cases, 16.6) | 41 (93 cases, 44.1) | 44.1 (33.8–54.8) | 83.4 (77.4–88.4) | 56.2 (46.4–65.4) | 75.6 (71.9–78.9) | 70.6 (65.0–75.8) | 2.66 (1.80–3.93) | 0.67 (0.55–0.81) | 3.97 (2.27–7.69) | < 0.0001 |
| Positive tissue cultures | 37 (239 cases, 15.5) | 94 (111 cases, 84.7) | 84.7 (76.6–90.8) | 84.5 (79.3–88.7) | 71.8 (65.2–77.5) | 92.2 (88.4–94.7) | 84.6 (80.4–88.2) | 5.47 (4.03–7.43) | 0.18 (0.12–0.28) | 30.19 (16.17–56.36) | < 0.0001 |
| Positive sonication culture | 89 (305 cases, 29.2) | 107 (116 cases,92.2) | 92.2 (85.8–96.4) | 70.8 (65.4–75.9) | 54.6 (50.0–59.1) | 96.0 (92.7–97.8) | 76.7 (72.4–80.7) | 3.16 (2.63–3.79) | 0.11 (0.06–0.21) | 28.9 (14.0–59.5) | < 0.0001 |
| Combined microbiologyd | 0 | 112 (116 cases, 96.6) | 96.6 (91.4–99.1) | 99.3 (97.7–99.9) | 100.0 | 98.7 (96.7–99.5) | 99.1 (97.6–99.7) | – | 0.03 (0.01–0.09) | 15,275.0 (815.8–286,001.6) | < 0.0001 |
NOTE. PPV Positive predictive value, NPV Negative predictive value, PLR Positive likelihood ratio, NLR Negative likelihood ratio, DOR Diagnostic odds ratio
(a) The denominator of total cases for each comparison is given in parentheses
(b) White blood cell (WBC) count ≥11.000/ mm3
(c) C-reactive protein (CRP) value ≥10 mg/l
(d) Combination of sonication and tissue cultures