Starkey Research & Clinical Blog

The Tinnitus Functional Index (TFI): A New and Improved way to Evaluate Tinnitus

Meikle, M.B., Henry, J.A., Griest, S.E., Stewart, B.J., Abrams, H.B., McArdle, R., Myers, P.J., Newman, C.W., Sandridge, S., Turk, D.C., Folmer, R.L., Frederick, E.J., House, J.W., Jacobson, G.P., Kinney, S.E., Martin, W.H., Nagler, S.M., Reich, G.E., Searchfield, G., Sweetow, R. & Vernon, J.A. (2012). The Tinnitus Functional Index:  Development of a new clinical measure for chronic, intrusive tinnitus. Ear & Hearing 33(2), 153-176.

This editorial discusses the clinical implications of an independent research study and does not represent the opinions of the original authors.

The practice of clinical audiology can arguably be described as having two primary goals: the diagnosis of auditory and vestibular disorders, followed by verifiable, effective treatment and rehabilitation. There are well established, objective diagnostic tests for hearing and vestibular disorders and their treatment methods can be verified with objective and subjective tools. The evaluation and treatment of tinnitus, though equally important, is more complicated. There are test protocols for matching perceived tinnitus characteristics, but the impact of tinnitus on the individual must be measured subjectively with self-assessment questionnaires.  There are several published questionnaires to evaluate tinnitus severity and the impact it has on an individual’s activities, emotions and relationships. However, most of these questionnaires were not designed specifically to measure the effect of tinnitus treatments (Kamalski et al., 2010), so their value as follow-up measures is unknown.

Tinnitus affects as many as 50 million Americans and can have disabling effects including: sleep interference, difficulty concentrating and attending, anxiety, frustration and depression (for review see Tyler & Baker, 1983; Stouffer & Tyler, 1990; Axelsson, 1992; Meikle 1992; Dobie, 2004b). There are numerous methods of treatment available, including hearing aids, tinnitus maskers, tinnitus retraining therapy, biofeedback, counseling and others. Because there is currently no standard assessment tool to evaluate tinnitus treatment outcomes, the effectiveness of tinnitus treatment methods is difficult to verify and compare. The Tinnitus Functional Index (TFI) was developed as a collaborative effort among researchers and clinicians to develop a validated, standard questionnaire that can be used clinically for intake assessments and follow-up measurements and in the laboratory as a way of comparing treatment efficacy and identifying subject characteristics.

The developers of the TFI aimed for this inventory to be used in three ways:

1. As an intake evaluation tool to identify individual differences in tinnitus patients.
2. As a reliable and valid measurement of multiple domains of tinnitus severity.
3. As an outcome measure to assess treatment-related change in tinnitus.

The study, supported by a grant from the Tinnitus Research Consortium (TRC), had three stages. The first stage involved consultation with 21 tinnitus experts, including audiologists, otologists and hearing researchers. The panel of experts evaluated 175 items from nine previously published tinnitus questionnaires and judged them based on their relevance to 10 tinnitus negative impact domains as well as their expected responsiveness, or ability to measure treatment-related improvement. After analyzing the content validity, relevance and potential responsiveness of the 175 items (Haynes et al., 1995), 43 items were selected for the first questionnaire prototype. The TRC initially required that 10 domains of negative tinnitus impact be covered by the TFI but this expert panel added three additional domains so that the first prototype of the TFI covered 13 domains of tinnitus impact. The TRC also recommended avoiding overly negative items (such as those referring to suicidal thoughts or feeling victimized or helpless), items referring to hearing loss without mentioning tinnitus and items referring to more than one subtopic. Each domain had at least three or four items, based on recommendations for achieving adequate reliability (Fabrigar et al., 1999; Moran et al., 2001).  Each questionnaire item probed respondents for a rating on a scale of 0 to 10, based on how they experienced their tinnitus “over the past week”. For example, a typical question read, “Over the past week, how easy was it for you to cope with your tinnitus?” with potential responses from 0 being “very easy to cope” and 10 being “impossible to cope”.

During the second stage of the study, TFI Prototype 1 was tested on 326 tinnitus patients at five independent clinical sites.  The goals for the second stage were to determine the responsiveness of items or their ability to reflect changes in tinnitus status, to evaluate the 13 tinnitus impact domains and to determine the TFI’s ability to scale tinnitus severity. The questionnaire was administered at the initial intake assessment, after 3 months and after 6 months.  In addition to completing the TFI, at the initial encounter the subjects completed a brief tinnitus history questionnaire, The Tinnitus Handicap Inventory (THI; Newman et al., 1996) and the Beck Depression Inventory-Primary Care (BDEI-PC; Beck et al., 1997).  The TFI was re-administered to 65 subjects after 3 months and again to 42 subjects after 6 months.

The researchers found that subjects had very few problems responding to the 43 selected items and that most questionnaires were fully completed. There were no floor or ceiling effects, indicating that there were no items for which responses clustered at either end of the scale, reducing the potential responsiveness of the item.  The TFI had very high convergent validity, which means it agreed well with other published scales of tinnitus severity, such as the THI.  There were large effect sizes, demonstrating that the Prototype 1 items had good responsiveness for treatment-related change and supporting use of the TFI as an outcome measure. Factor analysis of the 13 initial tinnitus impact domains yielded 8 clearly structured domains, which were retained for the second prototype.

The third stage of the study involved development and evaluation of TFI Prototype 2, which was modified based on validity and reliability measurements from the first prototype. Prototype 2 included the 30 best-functioning items from the first version, categorized according to 8 tinnitus impact domains. It was administered to 347 new participants at the initial assessment. Follow-up data were obtained from 155 participants after 3 months and from 85 participants after 6-months. Encouragingly, the results from clinical evaluation of Prototype 2 again showed good performance for all of the validity and reliability measurements, supporting its use for scaling tinnitus severity.

The best performing items from Prototype 2 were used to create the final version of the TFI, which contains 25 items in 8 domains or sub-scales: Intrusive, Sense of Control, Cognitive, Sleep, Auditory, Relaxation, Quality of Life and Emotional. Seven of the domains contain 3 items and the Quality of Life domain contains 4 items.

When used during the initial assessment, the TFI categorizes tinnitus severity according to five levels: not a problem, a small problem, a moderate problem, a big problem or a very big problem.  As a screening tool, this allows a clinician to determine the overall severity of the tinnitus to help formulate a treatment plan and consider whether referrals to other clinical professionals are needed. For example, an individual who scores in the “not a problem” level may require only brief reassurance and counseling and may be asked to follow-up only if symptoms progress. In contrast, an individual who scores in the “big problem” or “very big problem” categories will likely need referrals for additional diagnostic and therapeutic services right away.

The developers of the TFI acknowledge that their study is preliminary and more research is needed to determine the TFI’s value as an outcome measurement tool. However, based on their analyses they recommend that a change in TFI score of 13 should be considered meaningful. In other words, a decrease of 13 or more indicates an improvement based on treatment recommendations or an increase in 13 or more indicates a significant exacerbation of symptoms.

Most tinnitus self-report questionnaires were designed to assess tinnitus impact but do not specifically measure treatment outcomes. The Tinnitus Handicap Inventory (THI; Newman et al., 1996), however, has shown some promise as an initial evaluation tool and as a way to measure treatment outcome.  After formulation of the final version of the TFI, the effect sizes of the TFI were compared to the THI. Overall, the TFI had greater responsiveness, indicating that it could potentially yield statistically significant differences with fewer subjects than the THI would require. Evaluation of subs-scale domains yielded some differences between the TFI and THI, primarily related to the “Catastrophic” subscale of the THI. Most of these items were not included in the TFI, based on the TRC’s recommendations to avoid questions dealing with negative ideation. The TRC recommended against inclusion of items relating to despair inability to escape tinnitus and fear of having a terrible disease, because they may suggest to people with mild tinnitus that they will eventually have these concerns, creating feelings of negativity before treatment has started.  Because these items on the THI correlated only moderately with the more neutrally worded items on the TFI, the authors suggested that the THI Catastrophic subscale might measure a different severity domain than the TFI and may be useful in combination with the THI as an outcome measure.

The Tinnitus Functional Index (TFI), like other previously published tinnitus questionnaires, shows promise as a tool to measure and classify tinnitus severity. It is easy for respondents to understand the test items and can be administered briefly at or prior to the initial appointment. An additional benefit of the TFI appears to be its validity as an outcome measure of treatment effectiveness. This is critically important for guiding clinical decisions and modifying ongoing treatment plans. It also suggests that the TFI could be useful in laboratory research as a standardized way to evaluate and compare tinnitus treatment methods or to identify subject characteristics for inclusion in treatment groups. For instance, if a treatment is expected to affect the negative emotional impact of tinnitus more than the functional impact, the TFI could be useful in identifying appropriate subject candidates who are experiencing strong emotional reactions to their tinnitus. The Tinnitus Functional Index (TFI) is one of the most systematically validated methods of assessing a patient’s reaction to their tinnitus. Ease of application and interpretation place the TFI among the most compelling assessment options for clinicians working with tinnitus patients.

If you would like to use the TFI. It is now available on a website posted by Oregon Health & Science University (OHSU). OHSU owns the copyright to the TFI and permission is required by OHSU to use the TFI. The request form takes 3 minutes to complete and allows you access to the TFI form and instructions. You will then be able to use the TFI with no fee.

http://www.ohsu.edu/xd/health/services/ent/services/tinnitus-clinic/tinnitus-functional-index.cfm

References

Axelsson, A. (1992). Conclusion to Panel Discussion on Evaluation of Tinnitus Treatments. In J.M. Aran & R. Dauman (Eds) Tinnitus 91. Proceedings of the Fourth International Tinnitus Seminar (pp. 453-455). New York, NY: Kugler Publications.

Beck, A.T., Guth, D. & Steer, R.A. (1997). Screening for major depression disorders in medical in patients with the Beck Depression Inventory for Primary Care. Behavioral Research and Therapy 35, 785-791.

Dobie, R.A. (2004b). Overview: Suffering From Tinnitus. In J.B. Snow (Ed) Tinnitus: Theory and Management (pp.1-7). Lewiston, NY: BC Decker Inc.

Fabrigar, L.R., Wegeners, D.T. & MacCallum, R.C. (1999). Evaluating the use of exploratory factor analysis in psychological research. Psychological Methods 4, 272-299.

Kamalski, D.M., Hoekstra, C.E. & VanZanten, B.G. (2010). Measuring disease-specific health-related quality of life to evaluate treatment outcomes in tinnitus patients: A systematic review. Otolaryngology Head and Neck Surgery 143, 181-185.

Meikle, M.B. (1992). Methods for Evaluation of Tinnitus Relief Procedures. In J.M. Aran & R. Dauman (Eds.) Tinnitus 91: Proceedings of the Fourth International Tinnitus Seminar (pp. 555-562). New York, NY: Kugler Publications.

Meikle, M.B., Henry, J.A., Griest, S.E., Stewart, B.J., Abrams, H.B., McArdle, R., Myers, P.J., Newman, C.W., Sandridge, S., Turk, D.C., Folmer, R.L., Frederick, E.J., House, J.W., Jacobson, G.P., Kinney, S.E., Martin, W.H., Nagler, S.M., Reich, G.E., Searchfield, G., Sweetow, R. & Vernon, J.A. (2012). The Tinnitus Functional Index:  Development of a new clinical measure for chronic, intrusive tinnitus. Ear & Hearing 33(2), 153-176.

Moran, L.A., Guyatt, G.H. & Norman, G.R. (2001). Establishing the minimal number of items for a responsive, valid, health-related quality of life instrument. Journal of Clinical Epidemiology 54, 571-579.

Newman, C.W., Jacobson, G.P. & Spitzer, J.B. (1996). Development of the Tinnitus Handicap Inventory. Archives of Otolaryngology Head and Neck Surgery 122, 143-148.

Stouffer, J.L. & Tyler, R. (1990). Characterization of tinnitus by tinnitus patients. Journal of Speech and Hearing Disorders 55, 439-453.

Tyler, R. & Baker, L.J. (1983). Difficulties experienced by tinnitus sufferers. Journal of Speech and Hearing Disorders 48, 150-154.