Study designs of evaluations included in the review
The authors did not specify any inclusion criteria regarding the study design, but did exclude case studies. Studies with a follow-up period of longer than one year were included in the review. Prospective and retrospective studies with and without a control were included.
Specific interventions included in the review
Radiotherapy was the intervention of interest. The papers included in the review examined nasopharyngeal and parotid irradiation. The authors described radiotherapy techniques in the review.
Participants included in the review
The authors did not explicitly state any inclusion criteria regarding the participants. Participants who underwent radiotherapy for nasopharyngeal carcinoma or parotid gland tumours were included in the review. Participants who also received cisplatinum were excluded from the review.
Outcomes assessed in the review
Hearing loss (dB) was assessed in the review. Studies were only included if they presented data on the frequency-dependent pure tone audiogram. They were excluded if they reported on otitis media only.
How were decisions on the relevance of primary studies made?
The authors did not state how the papers were selected for the review, or how many reviewers performed the selection.