| Grade | CK20 | |||||
| Negative | Weak | Moderate | Strong | Total | ||
| Grade I | N | 4 | 2 | 2 | 0 | 8 |
| % | 50.00 | 25.00 | 25.00 | 0.00 | 100.00 | |
| Grade II | N | 16 | 15 | 58 | 22 | 111 |
| % | 14.41 | 13.51 | 52.25 | 19.82 | 100.00 | |
| Grade III | N | 4 | 2 | 11 | 24 | 41 |
| % | 9.76 | 4.88 | 26.83 | 58.54 | 100.00 | |
| Grade IV | N | 2 | 0 | 0 | 0 | 2 |
| % | 100.00 | 0.00 | 0.00 | 0.00 | 100.00 | |
| Total | N | 26 | 19 | 71 | 46 | 162 |
| % | 16.05 | 11.73 | 43.83 | 28.40 | 100.00 | |
| Chi-square | X2 | 39.017 | ||||
| P-value | <0.001* | |||||