Table 1– Studies that have examined ototoxicity among patients treated for drug-resistant tuberculosis and assessed hearing loss using standardised testing and classification methodology

First author [ref.]	Year of study	Country	Type of testing and classification of hearing loss	Patients n	Ototoxicity n (%)	Age range yrs	HIV-infected patients n or n/n (%)
de Jager [22]	1995–2000	The Netherlands	15 dB at two adjacent frequencies or 20 dB at one frequency. Testing frequencies 250–8000 Hz	61	11 (18.0)	10–83	Not specified
Duggal [23]	2000–2006	India	10 dB at two adjacent frequencies, 20 dB at any one frequency or loss of response at three consecutive frequencies where responses were previously obtained. Testing frequencies 250–8000 Hz	64	12 (18.8)	17–65	Not specified
Kennedy [24]	2004–2009	Ireland	Audiograms every 6 weeks. Classification based on article by Brummett and Fox [25]	13	8 (61.5)	24–82	1/7 (14.3)
Peloquin [26]	1991–1998	USA	20 dB at any frequency and 15 dB at two adjacent frequencies both assessed. Audiometry tested at 250–8000 Hz	87	32–28^# (36.8–32.2)	19–79	Not specified
Sturdy [27]	2004–2009	UK	10 dB at two adjacent frequencies, 20 dB at any one frequency or clinical symptoms of hearing loss. Frequencies not specified	50	9 (18.0)	34.6±12.8^¶	5 (10)

^#: unclear from the article; ^¶: mean±sd is presented as the age range was unavailable.