Table 2.
Comparison of sensitivity, specificity, PPV, and NPV for individual parameters in 498 patients with aseptic loosening and prosthetic joint infection (18 early, 35 delayed and 77 late)
| Diagnostic test | AL | PJI | Specificity (%) | Sensitivity (%) | PPV (%) | NPV (%) | ROC área (95% CI) | P-value* |
|---|---|---|---|---|---|---|---|---|
| TN/total | TP/total | (95% CI) | (95% CI) | (95% CI) | (95% CI) | |||
| CRP (>1) | ||||||||
| All patients | 310/367 | 90/128 | 84.5 (80.4–88.0) | 70.3 (61.6–78.1) | 61.2 (52.8–69.1) | 89.1 (85.3–92.2) | 0.774 (0.730–0.818) | 0.124 |
| Early | 10/13 | 13/16 | 76.9 (46.2–95.0) | 81.3 (54.4–96.0) | 81.3 (54.4–96.0) | 76.9 (46.2–95.0) | 0.791 (0.636–0.946) | |
| Delayed | 20/23 | 29/35 | 87.0 (66.4–97.2) | 82.9 (66.4–93.4) | 90.6 (75.0–98.0) | 76.9 (56.4–91.0) | 0.849 (0.754–0.943) | |
| Late | 280/331 | 48/77 | 84.6 (80.2–88.3) | 62.3 (50.6–73.1) | 48.5 (38.3–58.7) | 90.6 (86.8–93.6) | 0.735 (0.678–0.792) | |
| Synovial fluid culture | ||||||||
| All patients | 310/310 | 53/116 | 100 (98.8–100) | 45.7 (36.4–55.2) | 100 (93.3–100) | 83.1 (78.9–86.8) | 0.728 (0.683–0.774) | 0.039 |
| Early | 13/13 | 9/16 | 100 (75.3–100) | 56.3 (29.9–80.2) | 100 (66.4–100) | 65.0 (40.8–84.6) | 0.781 (0.656–0.906) | |
| Delayed | 18/18 | 20/33 | 100 (81.5–100) | 60.6 (42.1–77.1) | 100 (83.2–100) | 58.1 (39.1–75.5) | 0.803 (0.718–0.888) | |
| Late | 279/279 | 24/67 | 100 (98.7–100) | 35.8 (24.5–48.5) | 100 (85.8–100) | 86.6 (82.4–90.2) | 0.679 (0.621–0.736) | |
| Peri-implant tissue culture | ||||||||
| All patients | 367/368 | 81/130 | 99.7 (98.5–100) | 62.3 (53.4–70.7) | 98.8 (93.4–100) | 88.2 (84.7–91.2) | 0.810 (0.768–0.852) | 0.033 |
| Early | 13/13 | 15/18 | 100 (75.3–100) | 83.3 (58.6–96.4) | 100 (78.2–100) | 81.3 (54.4–96.0) | 0.917 (0.828–1.000) | |
| Delayed | 24/24 | 23/35 | 100 (85.8–100) | 65.7 (47.8–80.9) | 100 (85.2–100) | 66.7 (49.0–81.4) | 0.829 (0.749–0.908) | |
| Late | 330/331 | 43/77 | 99.7 (98.3–100) | 55.8 (44.1–67.2) | 97.7 (88.0–99.9) | 90.7 (87.2–93.4) | 0.778 (0.722–0.834) | |
| Sonicate fluid culture | ||||||||
| All patients | 366/368 | 110/130 | 99.5 (98.1–99.9) | 84.6 (77.2–90.3) | 98.2 (93.7–99.8) | 94.8 (92.1–96.8) | 0.920 (0.889–0.952) | 0.402 |
| Early | 13/13 | 15/18 | 100 (75.3–100) | 83.3 (58.6–96.4) | 100 (78.2–100) | 81.3 (54.4–96.0) | 0.917 (0.828–1.000) | |
| Delayed | 23/24 | 33/35 | 95.8 (78.8–99.9) | 94.3 (80.8–99.3) | 97.1 (84.7–99.9) | 92.0 (74.0–99.0) | 0.951 (0.894–1.000) | |
| Late | 330/331 | 62/77 | 99.7 (98.3–100) | 80.5 (69.9–88.7) | 98.4 (91.5–100) | 95.7 (92.9–97.5) | 0.901 (0.856–0.946) | |
| Histology | ||||||||
| All patients | 368/368 | 100/128 | 100 (99.0–100) | 78.1 (70.0–84.9) | 100 (96.4–100) | 92.9 (89.9–95.3) | 0.891 (0.855–0.927) | 0.190 |
| Early | 13/13 | 14/18 | 100 (75.0–100) | 77.8 (52.4–93.6) | 100 (76.8–100) | 76.5 (50.1–93.2) | 0.889 (0.790–0.987) | |
| Delayed | 24/24 | 29/33 | 100 (85.8–100) | 87.9 (71.8–96.6) | 100 (88.1–100) | 85.7 (67.3–95.9) | 0.939 (0.883–0.996) | |
| Late | 331/337 | 57/77 | 100 (98.9–100) | 74.0 (62.8–83.4) | 100 (93.7–100) | 94.3 (91.3–96.4) | 0.870 (0.821–0.919) | |
AL aseptic loosening, PJI prosthetic joint infection, TN true negative, TP true positive, CI confidence interval, PPV positive predictive value, NPV negative predictive value, CRP C-reactive protein
*Two sided P-value Test of equality of independent ROC areas in the three groups of patients with PJI: early, delayed and late