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Table 2 Rate of L. infantum infection, percent agreement and Cohen’s kappa agreement between enzyme-linked immunosorbent assay results for serum and oral transudate samples

From: Detection of specific antibodies against Leishmania infantum in canine serum and oral transudate using an in-house ELISA

Classification (number of dogs) Number of positive dogs (%) Percent agreement (%) Cohen’s κ agreement (interpretation) 95% CI of Cohen’s κ agreement
Serum ELISA OT ELISA
Total of dogs (407) 149 (36.6) 133 (32.7) 345 (84.8) 0.66 (substantial agreement) 0.59–0.74
Sex
 Female (209) 78 (37.3) 71 (34) 174 (83.3) 0.64 (substantial agreement) 0.53–0.75
 Male (198) 71 (35.9) 62 (31.3) 171 (86.4) 0.7 (substantial agreement) 0.59–0.8
Agea
 Young (79) 17 (21.5)b 15 (19)c 69 (87.3) 0.61 (substantial agreement) 0.39–0.83
 Adult (267) 114 (42.7)b 103 (38.6)c 224 (83.9) 0.67 (substantial agreement) 0.58–0.76
Breed
 Purebred (190) 63 (33.2) 63 (33.2) 158 (83.2) 0.62 (substantial agreement) 0.5–0.74
 Mixed breed (217) 86 (39.6) 70 (32.3) 187 (86.2) 0.7 (substantial agreement) 0.6–0.8
Geographical distribution
 Asturias (47) 0 (0)d 3 (6.4)e 44 (93.6) -h -h
 Barcelona (110) 30 (27.3)d 23 (20.9)e 99 (90) 0.73 (substantial agreement) 0.58–0.88
 Cádiz (54) 9 (16.7)d 7 (13)e 48 (88.9) 0.56 (moderate agreement) 0.25–0.87
 Mallorca (94) 33 (35.1)d 28 (29.8)e 74 (79.6) 0.54 (moderate agreement) 0.36–0.72
Clinical status
 Sick (41) 41 (100)f 37 (90.2)g 37 (90.2) -h -h
 Apparently healthy (366) 108 (29.5)f 96 (26.2)g 308 (84.2) 0.61 (substantial agreement) 0.52–0.7
 Negative control (Asturias) and positive control dogs (Sick) (88) 41 (46.6) 40 (45.5) 81 (92.1) 0.84 (almost perfect agreement) 0.73–0.95
Serological status
 High positive (26) 26 (100) 26 (100) 26 (100) -h -h
 Medium positive (40) 40 (100) 34 (85) 34 (85) -h -h
 Low positive (83) 83 (100) 50 (60.2) 50 (60.2) -h -h
 Negative (258) 0 (0) 23 (8.9) 235 (91.1) -h -h
 Negative control (Asturias) and high and medium positive dogs (113) 66 (58.4) 63 (55.8) 104 (92) 0.84 (almost perfect agreement) 0.74–0.94
  1. CI confidence interval, ELISA enzyme-linked immunosorbent assay, OT oral transudate
  2. aAge was not recorded in 61 dogs
  3. bFisher’s Exact test: P = 0.001
  4. cFisher’s Exact test: P = 0.001
  5. dChi-square test: χ2 = 23.7, df = 3, P < 0.001
  6. eChi-square test: χ2 = 12.8, df = 3, P = 0.004
  7. fFisher’s Exact test: P < 0.0001
  8. gFisher’s Exact test: P < 0.0001
  9. hCohen’s kappa (κ) agreement could not be calculated in the Asturias, the seropositive sick dogs and the serological status groups because of the lack of positivity to both tests or the lack of negativity to both tests