Outcomes
Primary outcome. THI score14. The comparison of the THI score change between study groups was assessed before and after treatment. The THI consists of a 25-item questionnaire to classify participants into functional, emotional, and catastrophic subscales. Each item is scored on a Likert-scale from 0 to 4 (0 = ‘no,’ 2 = ‘sometimes,’ 4 = ‘yes’), resulting in a score ranging from 0 to 100. The severity levels are considered mild between 18 and 36, moderate between 38 and 56, severe between 58 and 76, and catastrophic above 7815. The THI score is one of the most used scoring system to assess the effect of an intervention in tinnitus.
Secondary outcome. Participants impression of improvement. These outcomes were assessed by the Clinical Global Impression of Improvement (CGI-I), which consists of a 7-point Likert scale ranging from ‘very much worse’ to ‘very much improved’16and one question regarding the participant’s perceived improvement resulting in a polar yes-no response. Both outcomes were measured after treatment. These outcomes were chosen to support the THI, other questionnaires were avoided so as not to compromise participants’ retention.
Adverse events and adherence were also assessed in the final visit. The most common side effects of betahistine are nausea, dyspepsia, and headache13.