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Table 3 Model area under the curve (AUC) compared to the area under a random and non-informative receiver operating characteristic (ROC) curve (AUC = 0.5)

From: Evaluation of the performance of register data as indicators for dairy herds with high lameness prevalence

Indicator Predefined cut-offs Optimized cut-offs
Se (%) [95% CI] Sp (%) [95% CI] DPRa PPV [95% CI] NPV [95% CI] Se (%) [95% CI] Sp (%) [95% CI] DPR PPV [95% CI] NPV [95% CI] AUC(P)
Cow mortalityb 40 [12;74] 67 [47;83] 0.07 29 [8;58] 77 [56;91] 100 [69;100] 67 [47;83] 0.67 39 [20;59] 100 [77;100] 0.76 (0.001)
BMSCCc 40 [12;74] 77 [58;90] 0.13 36 [11;69] 79 [60;92] 70 [35;93] 67 [47;83] 0.47 41 [18;67] 87 [66;97] 0.73 (0.01)
Lean cowsd 40 [12;74] 83 [65;94] 0.23 44 [14;79] 81 [63;93] 90 [56;100] 20 [8;39] 0.10 27 [13;46] 86 [42;100] 0.53 (0.82)
SD age 1st calvinge 40 [12;74] 60 [41;77] 0 25 [7;52] 75 [53;90] 80 [44;98] 23 [10;42] 0.03 26 [12;45] 78 [40;97] 0.50 (0.95)
  1. Sensitivity (Se), specificity (Sp) and predictive values (positive predictive values = PPV, negative predictive values = NPV) with 95% confidence intervals for indicators assessed at optimised and predefined cut-offs for the identification of high lameness prevalences (≥ 16%)
  2. aDPR = Differential positive rates = Se + Sp –1 as a measure of test Se and Sp strength in combination
  3. bAnnual mean cow mortality rate
  4. cBulk milk somatic cell count × 1000 cells/mL
  5. dProportion of lean cows at slaughter out of total number slaughtered per herd (%)
  6. eStandard deviation (SD)