Table 2.
Sensitivity, specificity, and area under receiver operator characteristic curve (AUROCC) results for admission, convalescent, and all samples for a range of diagnostic cut-off values of the InBios Scrub Typhus Detect™ IgM ELISA for IFA ≥1:3200 on admission or 4-fold rise to ≥3200. The shaded sections indicate the suggested cut-off OD for Chittagong, Bangladesh.
| Sample Timing | Cut-off OD | % Sensitivity (95% CI *) | % Specificity (95% CI) | AUROCC (95% CI) |
|---|---|---|---|---|
| Admission samples | ≥0.00 | 100 | 0 | |
| ≥0.25 | 95.8 (99.1–88.1) | 71.6 (76.3–66.4) | 0.84 (0.87–0.80) | |
| ≥0.50 | 94.4 (98.4–86.2) | 84.2 (87.9–79.8) | 0.89 (0.93–0.86) | |
| ≥0.75 | 91.5 (96.8–82.5) | 88.3 (91.5–84.4) | 0.90 (0.94–0.86) | |
| ≥1.00 | 91.5 (96.8–82.5) | 90.9 (93.7–87.3) | 0.91 (0.95–0.88) | |
| ≥1.25 | 91.5 (96.8–82.5) | 92.4 (95.0–89.0) | 0.92 (0.96–0.88) | |
| ≥1.50 | 88.7 (95.0–79.0) | 93.8 (96.1–90.7) | 0.91 (0.95–0.87) | |
| ≥1.75 | 84.5 (92.0–74.0) | 95.6 (97.5–92.8) | 0.90 (0.94–0.86) | |
| ≥2.00 | 81.7 (89.9–70.9) | 96.2 (98.0–93.6) | 0.89 (0.94–0.84) | |
| ≥2.25 | 78.9 (87.7–67.6) | 97.9 (99.2–95.8) | 0.88 (0.93–0.84) | |
| ≥2.50 | 71.8 (81.9–59.9) | 98.5 (99.5–96.6) | 0.85 (0.91–0.80) | |
| ≥2.75 | 52.1 (64.1–39.9) | 99.1 (99.8–97.5) | 0.76 (0.82–0.70) | |
| ≥3.00 | 22.5 (34.0-13.5) | 99.7 (100–98.4) | 0.61 (0.66–0.56) | |
| Convalescent samples | ≥0.00 | 100 | 0 | |
| ≥0.25 | 71.7 (83.2–57.7) | 75.5 (81.3–68.9) | 0.74 (0.80–0.67) | |
| ≥0.50 | 69.8 (81.7–55.7) | 84.0 (88.8–78.2) | 0.77 (0.84–0.70) | |
| ≥0.75 | 69.8 (81.7–55.7) | 89.5 (93.4–84.4) | 0.80 (0.86–0.73) | |
| ≥1.00 | 66.0 (78.5–51.7) | 92.5 (95.7–87.9) | 0.79 (0.86–0.73) | |
| ≥1.25 | 66.0 (78.5–51.7) | 93.6 (96.5–89.1) | 0.80 (0.86–0.73) | |
| ≥1.50 | 66.0 (78.5–51.7) | 96.0 (98.3–92.3) | 0.81 (0.88–0.74) | |
| ≥1.75 | 64.2 (76.9–49.8) | 97.0 (98.9–93.6) | 0.81 (0.87–0.74) | |
| ≥2.00 | 62.3 (75.2–47.9) | 97.0 (98.9–93.6) | 0.80 (0.86–0.73) | |
| ≥2.25 | 60.4 (73.5–46.0) | 97.5 (99.2–94.3) | 0.80 (0.86–0.73) | |
| ≥2.50 | 50.9 (64.9–36.8) | 99.0 (99.9–96.4) | 0.75 (0.82–0.68) | |
| ≥2.75 | 35.0 (50.2–23.1) | 99.0 (99.9–96.4) | 0.67 (0.74–0.61) | |
| ≥3.00 | 9.4 (20.7–3.1) | 100 (100–98.2) | 0.55 (0.59–0.51) | |
| All samples | ≥0.00 | 100 | 0 | |
| ≥0.25 | 85.5 (91.2–78.0) | 73.4 (77.1–69.4) | 0.79 (0.83–0.76) | |
| ≥0.50 | 83.9 (89.9–76.2) | 84.1 (87.1–80.7) | 0.84 (0.88–0.80) | |
| ≥0.75 | 82.3 (88.5–74.4) | 88.9 (91.4–86.0) | 0.86 (0.89–0.82) | |
| ≥1.00 | 80.6 (87.2–72.6) | 91.5 (93.7–88.8) | 0.86 (0.90–0.82) | |
| ≥1.25 | 80.6 (87.2–72.6) | 92.8 (94.8–90.3) | 0.87 (0.90–0.83) | |
| ≥1.50 | 79.0 (85.8–70.8) | 94.6 (96.4–92.4) | 0.87 (0.91–0.83) | |
| ≥1.75 | 75.0 (82.3–66.4) | 96.1 (97.6–94.1) | 0.86 (0.90–0.82) | |
| ≥2.00 | 73.4 (80.9–64.7) | 96.5 (97.9–94.6) | 0.85 (0.89–0.81) | |
| ≥2.25 | 71.0 (78.8–62.1) | 97.8 (98.8–96.2) | 0.84 (0.88–0.80) | |
| ≥2.50 | 63.7 (72.2–54.6) | 98.7 (99.5–97.4) | 0.81 (0.86–0.77) | |
| ≥2.75 | 43.5 (52.7–34.7) | 99.3 (99.8–98.1) | 0.71 (0.76–0.67) | |
| ≥3.00 | 14.5 (22.0–8.8) | 99.9 (100–99.0) | 0.57 (0.54–0.60) |
* 95% CI: 95% confidence interval.