Table 3.
Area under the curve (AUC), cutoff values, sensitivity and specificity percentages, likelihood ratios, and predictive values for complete blood count parameters, haptoglobin concentrations, and plasma bactericide for controls and cases of bovine respiratory disease in pre-weaned dairy calves diagnosed using parallel interpretation of thoracic ultrasound and auscultation. Only parameters with AUC ⩾0.60 were considered in the analyses.
| Hematologic parameter | Unit | AUC | Cutoff | Se (%) | Sp (%) | LR+ | LR– | PPV (%) | NPV (%) |
|---|---|---|---|---|---|---|---|---|---|
| Haptoglobin | g/L | 0.677 | 0.195 | 46.4 (39.2–53.7) | 81.6 (76.6–86.0) | 2.53 | 0.66 | 71.6 | 60.4 |
| Basophils | ×109/L | 0.599 | 0.03 | 46.9 (39.7–54.2) | 67.0 (64.3–75.3) | 1.56 | 0.76 | 61.0 | 56.9 |
| Neutrophil:lymphocyte ratio | Absolute counts | 0.583 | 1.19 | 38.7 (31.8–45.9) | 80.6 (75.5–85.0) | 1.99 | 0.76 | 66.6 | 56.8 |
| Neutrophil | ×109/L | 0.556 | 4.6 | 36.1 (29.3–43.3) | 79.9 (74.7–84.4) | 1.79 | 0.8 | 64.2 | 55.5 |
| MCHC | g/L | 0.553 | 314 | 42.3 (35.2–49.6) | 67.8 (62.1–73.3) | 1.31 | 0.85 | 56.8 | 54.0 |
| Eosinophil | ×109/L | 0.547 | 0.3 | 50.5 (43.3–57.8) | 60.8 (54.8–66.5) | 1.29 | 0.81 | 56.3 | 55.1 |
| Platelet | ×109/L | 0.541 | 430 | 52.1 (44.8–59.3) | 57.6 (51.6–63.4) | 1.23 | 0.83 | 55.1 | 54.6 |
| Monocyte | ×109/L | 0.540 | 0.6 | 43.3 (36.2–50.6) | 67.1 (61.3–72.6) | 1.32 | 0.85 | 56.9 | 54.2 |
| RBC | ×1012/L | 0.537 | 10.0 | 48.5 (41.2–55.7) | 60.1 (54.1–65.8) | 1.21 | 0.86 | 54.8 | 53.8 |
| E. coli | % CFU killed | 0.522 | 89.6 | 24.2 (18.7–30.9) | 85.2 (80.5–89.1) | 1.63 | 0.89 | 62.0 | 52.9 |
| Total leukocytes | ×109/L | 0.516 | 10.0 | 33.0 (26.4–40.1) | 76.3 (70.9–81.2) | 1.39 | 0.88 | 58.2 | 53.3 |
| Hemoglobin | g/L | 0.515 | 104 | 29.4 (23.1–36.3) | 76.0 (70.6–80.8) | 1.22 | 0.93 | 55.0 | 51.8 |
| Mean platelet volume | fL | 0.509 | 5.4 | 25.3 (19.3–32.0) | 82.7 (77.8–86.9) | 1.46 | 0.90 | 59.3 | 52.5 |
% (CFU) killed = percent E. coli colony forming units killed by plasma (plasma bactericide); CFU = colony-forming units; CI = confidence interval; LR = likelihood ratio; MCHC = mean corpuscular hemoglobin concentration; NPV = negative predictive value; PPV = positive predictive value; RBC = red blood cell; Se = sensitivity; Sp = specificity. Hematocrit, mean corpuscular hemoglobin, mean corpuscular volume, RBC distribution width, lymphocyte absolute number had AUC values <0.5. Numbers in parentheses are 95% confidence intervals.