Table 4. Specificity, sensitivity, positive and negative predictive values of observed child hand cleanliness by E. coli contamination categories.
| Hand indicators |
E. coli level In hand rinse (MPN per 100 ml) |
Number of samples in category | Number of dirty a observations | Number of clean observations | Specificity, % (95% CI) |
Sensitivity, % (95% CI) |
PPV, % (95% CI) | NPV, % (95% CI) |
|---|---|---|---|---|---|---|---|---|
|
Fingernails |
<1 | 333 | 245 | 88 | 26 (22, 32) | |||
| 1–9 | 178 | 145 | 33 | 82 (75, 87) | 37 (32, 42) | 73 (64, 80) | ||
| 10–99 | 43 | 35 | 8 | 81 (67, 92) | 13 (9, 17) | 92 (84, 96) | ||
| ≥100 | 27 | 21 | 6 | 78 (58, 91) | 8 (5, 12) | 94 (87, 98) | ||
| All≥1 | 248 | 201 | 47 | 81 (76, 86) | 45 (40, 50) | 65 (57, 73) | ||
|
Finger pads |
<1 | 333 | 77 | 256 | 77 (72, 81) | |||
| 1–9 | 178 | 47 | 131 | 26 (20, 34) | 38 (29, 47) | 66 (61, 71) | ||
| 10–99 | 43 | 14 | 29 | 33 (19, 49) | 15 (9, 25) | 90 (86, 93) | ||
| ≥100 | 27 | 11 | 16 | 41 (22, 61) | 13 (6, 21) | 94 (91, 97) | ||
| All≥1 | 248 | 72 | 176 | 29 (24, 35) | 48 (40, 57) | 59 (55, 64) | ||
|
Palms |
<1 | 333 | 84 | 249 | 75 (70, 79) | |||
| 1–9 | 178 | 46 | 132 | 26 (20, 33) | 35 (27, 44) | 65 (60, 70) | ||
| 10–99 | 43 | 14 | 29 | 33 (19, 49) | 14 (8, 23) | 90 (85, 93) | ||
| 100 | 27 | 12 | 15 | 44 (26, 65) | 13 (7, 21) | 94 (91, 97) | ||
| All≥1 | 248 | 72 | 176 | 29 (24, 35) | 46 (38, 54) | 59 (54, 63) | ||
|
Overall handsb |
<1 | 333 | 246 | 87 | 26 (22, 31) | |||
| 1–9 | 178 | 145 | 33 | 82 (75, 87) | 37 (32, 42) | 73 (64, 80) | ||
| 10–99 | 43 | 35 | 8 | 81 (67, 92) | 13 (9, 17) | 92 (84, 96) | ||
| ≥100 | 27 | 22 | 5 | 82 (62, 94) | 8 (5, 12) | 95 (88, 98) | ||
| All≥1 | 248 | 202 | 46 | 82 (76, 86) | 45 (40, 50) | 65 (57, 73) |
MPN: Most probable number; CI: Confidence interval; PPV: Positive predictive value; NPV: Negative predictive value.
aDirty defined as containing visible dirt particles or having unclean appearance.
bComposite indicator combining fingernails, finger pads and palms(i.e., any of these hand parts dirty).