Importance:  Determining the long-term efficacy of interventions is crucial for healthcare and was the purpose of this study.

Objectives: Tinnitus is often disabling and can result in a significant economic burden. Identifying tinnitus interventions with stable long-term positive effects can improve healthcare outcomes. Due to the lack of research focused on outcomes longer than 1-year post-intervention, the current study was undertaken to investigate long-term outcomes over a 6-year period following Internet-based cognitive behavior therapy (ICBT) for tinnitus.

Design: A repeated-measured study design with 6-time points was selected to assess the 6year long-term outcome of ICBT. Assessment of tinnitus distress and associated difficulties regarding anxiety, depression, insomnia, cognitive failures, satisfaction with life, and hearing disability was conducted. Given a delayed intervention group design, the control group had also received the intervention at the 6-year follow-up. There was no active control condition.

Setting: This was an online study where participants undertook an internet-based

intervention.

Participants: Participants were those with significant tinnitus who undertook an online tinnitus intervention. Participants from the original trial were invited to partake (N=138) at 1, 4, 5 and 6 years follow-up, and of those 49 (35.5%) completed the 6-year post-intervention assessment.  

Intervention: A guided ICBT intervention consisting of 21 modules was presented over 8 weeks.

Main outcome measures: Reduction in tinnitus distress was the primary outcome together with measuring the secondary outcomes of reductions in anxiety, depression, insomnia, cognitive failures, hyperacusis, hearing disability and increases with satisfaction with life.

Results: Undertaking ICBT for tinnitus led to significant improvements with little variability over the 6-year period with large within-group effect sizes e.g., Cohen’s d = 1.00 (0.80 to 1.32) at 6-years post-intervention. Small effects were found on measures of anxiety, depression, insomnia, satisfaction with life, and hyperacusis.  At 6-year follow-up clinical significance was obtained by n= 19/49 participants (39%), using the Reliable Change Index (RCI) criterion of a 23.86 points (confidence interval 7.96 to 39.76) score improvement and 27/49 participants (55%) when using the minimal clinically important difference (MCID) of 14 points (confidence interval 1.9 to 29.9). When looking at post-treatment results, durability of treatment effects were present for tinnitus distress and measures of anxiety, depression, insomnia, satisfaction with life, but not for auditory related effect of hearing disability and hyperacusis.

Conclusions and relevance: The results are of importance for health-care services and have the potential to reduce healthcare costs caused by tinnitus over 6 years.  The results are significant in indicating ICBT can improve accessibility to evidence-based care and reduce resources required to deliver clinical care.

Trial registration: clinicaltrials.gov: NCT02370810 on 5/03/2015