Using audiometric thresholds and word recognition in a treatment study.
OBJECTIVE
First, to examine a possible limit on significant results imposed by a progressive floor effect for hearing threshold improvement in a treatment study. This floor effect for hearing recovery suggests that if inclusion criteria are not set sufficiently high, the superiority of a treatment group may not be detectable. Second, to examine the outcomes when using two different types of criteria for significant change in a subject's word recognition score.


METHODS
Several single-number criteria (e.g., 15 percentage points) are compared with the 95% (p=0.05) criteria from the binomial critical difference table for monosyllables. Critical differences for binomial variables change depending on whether the starting value lies in the middle (near 50% correct) or at either extreme of the range of scores (0 or 100%). Different judgments of significant word recognition improvement (or decrease) using binomial versus single-value criteria are presented.


METHODS
A recent treatment study of sudden sensorineural hearing loss (n=318) is used to illustrate these effects.


CONCLUSIONS
First, there is a progressive floor effect of presenting severity that co-varies with the outcome measure hearing threshold recovery. In some designs, this may act to constrain the ability to detect a significant difference. Second, in the example data set, the use of single-value criteria for significant within-subject change in word recognition (e.g., 15 percentage points) introduced a miscategorization error rate of approximately 9% when compared with the result of the binomial 95% critical difference table.
Halpin
Chris
C
Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts 02114, USA. cfhalpin@meei.harvard.edu
Rauch
Steven D
SD
D001301:Audiometry, Pure-Tone / Q000379:methods*; D001309:Auditory Threshold / Q000187:drug effects*; D003639:Hearing Loss, Sudden / Q000188:drug therapy*; D006801:Humans; D012189:Retrospective Studies; D013063:Speech Discrimination Tests / Q000379:methods*; D013067:Speech Perception / Q000187:drug effects*; D013069:Speech Reception Threshold Test; D013256:Steroids / Q000627:therapeutic use; D016896:Treatment Outcome
D013256:Steroids