Client Oriented Scale of Improvement (COSI) and its relationship to several other measures of benefit and satisfaction provided by hearing aids.

Several methods for measuring the self-reported benefit and satisfaction provided by a hearing aid were compared by administering all methods to each of 98 subjects. Significant correlations between many of the measures and reasonably high test-retest correlations for two of the measures administered twice suggest that most of the measures provide valid estimates of benefit and/or satisfaction. One of the methods included is a new tool called the Client Oriented Scale of Improvement (COSI). In this method, the client effectively writes the self-report questionnaire by nominating up to five listening situations in which help with hearing is required. At the conclusion of rehabilitation, reduction in disability and the resulting ability to communicate in these specific situations is quantified. Based on correlation analysis, the COSI method is as statistically valid as the much longer, more traditional questionnaires. Other features, such as relevance, diagnostic utility, compatibility with normal interviewing techniques, and good test-retest reliability, make it particularly suitable for routine clinical use.