In this four-site clinical trial, we evaluated whether tinnitus masking (TM) and tinnitus retraining therapy (TRT) decreased tinnitus severity more than the two control groups: an attention-control group that received tinnitus educational counseling (and hearing aids if needed; TED), and a 6-month-wait-list control (WLC) group. The authors hypothesized that, over the first 6 months of treatment, TM and TRT would decrease tinnitus severity in Veterans relative to TED and WLC, and that TED would decrease tinnitus severity relative to WLC. The authors also hypothesized that, over 18 months of treatment, TM and TRT would decrease tinnitus severity relative to TED. Treatment effectiveness was hypothesized not to be different across the four sites.
Across four Veterans affairs medical center sites, N = 148 qualifying Veterans who experienced sufficiently bothersome tinnitus were randomized into one of the four groups. The 115 Veterans assigned to TM (n = 42), TRT (n = 34), and TED (n = 39) were considered immediate-treatment subjects; they received comparable time and attention from audiologists. The 33 Veterans assigned to WLC were, after 6 months, randomized to receive delayed treatment in TM, TRT, or TED. Assessment of outcomes took place using the Tinnitus Handicap Inventory (THI) at 0, 3, 6, 12, and 18 months.
Results of a repeated measures analysis of variance using an intention-to-treat approach showed that the tinnitus severity of Veterans receiving TM, TRT, and TED significantly decreased (p < 0.05) relative to Veterans in the WLC group at 3 months (effect sizes = 0.44, 0.52, and 0.27, respectively) and at 6 months (effect sizes = 0.52, 0.56, and 0.40, respectively). Analyses comparing effectiveness of TM, TRT, and TED over 18 months revealed that the three conditions were not significantly different, but that tinnitus severity in the combined groups significantly decreased (p < 0.01) from baseline to 3 months (5.6 THI points) and from 3 to 6 months (3.7 THI points). With respect to clinically significant change, about half of Veterans who received TM (55%), TRT (59%), or TED (46%) showed strong or modest improvement on the THI by 18 months. Without treatment, the WLC group did not show significant change. Treatment effectiveness did not differ by study site.
Audiologists who provided interventions to Veterans with bothersome tinnitus in the regular clinic setting were able to significantly reduce tinnitus severity over 18 months using TM, TRT, and TED approaches. These results suggest that TM, TRT, and TED, when implemented as in this trial, will provide effectiveness that is relatively similar by 6 months and beyond.