Table 1.

Severity of Sensorineural Hearing Loss at Onset and at Last Evaluation by the Chang Ototoxicity Grading Scale (N = 235)

Grade	Criteria	Onset, No. (%)	Last Evaluation, No. (%)
0	≤ 20 dB at 1, 2, and 4 kHz	202 (86.0)	202 (86.0)
1a	≥ 40 dB at 6-12 kHz	10 (4.3)	3 (1.3)
1b	> 20 and < 40 dB at 4 kHz	2 (0.9)	1 (0.4)
2a	≥ 40 dB at ≥ 4 kHz	3 (1.3)	1 (0.4)
2b	> 20 and < 40 dB at < 4 kHz	12 (5.1)	9 (3.8)
3	≥ 40 dB at ≥ 2 kHz	3 (1.3)	6 (2.6)
4	≥ 40 dB at ≥ 1 kHz	3 (1.3)	13 (5.5)

NOTE. Sensorineural hearing threshold in decibel (dB) was assessed by bone conduction or air conduction with normal tympanogram. The worse ear was used when a patient had an asymmetric Chang grade.