“…Mean preoperative and postoperative pure tone audiometry was reported in accordance with the inclusion criteria, and was therefore suitable for quantitative synthesis, in 21 studies 14,17,18,20,21,24,25,31,32,36‐39,42,45‐47,49‐52 . 10 of these studies 20,21,24,25,32,38,39,42,45,52 reported air‐bone gap (ABG) data in sufficient detail so that it could be categorized in to bins of ≤20 dB HL or ˃20 dB HL. Additionally, 14 publications 15,18,19,23,24,35,36,38,42,43,46‐48,52 reported mean pre‐ and post‐operative ABG for patients with and without cholesteatoma in sufficient detail to permit weighted averages for these subgroups to be calculated.…”