Objective: The Glasgow Benefit Plot (GBP) is a graph showing the pure-tone thresholds preoperatively and postoperatively, and is meant to visualize the possible outcome of binaural hearing for individual patients. We used our database comprising a large number of patient data to test the usefulness of the GBP.
Study design: Evaluation based on retrospective clinical data.
Setting: Tertiary referral center, University clinic.
Main outcome measures: Audiometric assessment included bilateral preoperative and postoperative evaluation using conventional audiometry. Three preoperative groups (unilateral, asymmetric, and symmetric hearing impairment) were split into 6 postoperative categories in the GBP diagram.
Results: Considering the 509 operations, including 34 bilateral operations, the total outcome was distributed as follows: 34% resulted in bilateral normal hearing, 24% unilateral normal hearing (in operated ear), 14% still unilateral hearing impairment (in operated ear), 13% symmetric hearing impairment, 10% asymmetric hearing impairment (operated ear best), 5% still asymmetric hearing impairment (nonoperated ear best). The distribution of outcomes depended in part on the bone conduction level in the operated ear and in part on the hearing status in the contralateral ear.
Conclusion: The GBP is a useful instrument that provides a means for judging the binaural hearing status. However, the outcome of stapes surgery for individual persons and for a group depends critically on the preoperative audiometric criteria for patients who are chosen for surgery. In cases of depressed bone conductions, the method does not indicate the upper limit for possible hearing improvement. A number of patients with combined hearing impairments were included in the present study population. In preoperative counseling, the GBP must be complemented with information with regard to the limitation of possible hearing improvement owing to the individual bone conduction level.