Introduction
Tinnitus is the subjective impression of sound without any external source. This condition can lead to unpleasant sensations and has a substantial impact on the quality of life for persons who are experiencing it [
1]. Tinnitus is considered as a separate condition in International Classification of Functioning, Disability and Health (ICF 2001) [2
p.69]. The classification of tinnitus is beneficial in the diagnosis procedure and helps find the best treatment regimen for this condition. Tinnitus is categorized into two main types: subjective and objective tinnitus. Objective tinnitus can be heard by others, in addition to the person experiencing it. It is associated with numerous causes ranging from those related to vascular problems, muscle spasms, and dysfunction of the Eustachian tube. Subjective tinnitus, on the other hand, has no connection with outward forces and can only be heard by a sufferer. Sometimes it is referred to as “head noise” [
3]. Studies show that tinnitus is quite common condition and affects 10% to 15% of the global population [
4]. Tinnitus is an annoying condition that significantly burdens the quality of life. It causes irritability, sadness, anxiousness, frustration, insomnia, difficulty focusing, and social retract [
5].
The main goal in the treatment of tinnitus is to reduce its impact. A number of therapies can be employed to manage tinnitus, including counseling, sound therapy, and the utilization of hearing aids. Hence, conducting a thorough assessment of the influence of tinnitus on patients is a crucial component of tinnitus therapy [
6]. Tinnitus questionnaires are valuable instruments for assessing the response of individuals with tinnitus to their condition. They have been utilized in various ways, both in therapeutic settings and as components of research investigations [
7]. A variety of questionnaires have been used internationally, including the Tinnitus Handicap Questionnaire (THQ) [
8], the Tinnitus Handicap Inventory (THI) [
9], and the Tinnitus Primary Function Questionnaire (TPFQ) [
10]. The TPFQ is a survey designed to assess the impact of tinnitus on various behavioral aspects, consisting of 20 items categorized into concentration, emotions, hearing, and sleep, with values ranging from 0 to 100 [
10]. The translation of tinnitus questionnaires into multiple languages necessitates psychometric validation and comparative analysis of the questionnaire outcomes across these languages. The crosscultural translations assess the influence of tinnitus on the quality of life of patients from diverse national, regional, and cultural backgrounds [
7]. However, the TPFQ is unavailable in Central Kurdish, a language spoken by millions worldwide. This lack of a culturally appropriate assessment tool hinders the accurate assessment of tinnitus burden and the provision of effective treatment for individuals in Central Kurdish communities. Developing a Central Kurdish version of the TPFQ (TPFQ-CK) will bridge this gap, enabling healthcare professionals to effectively assess tinnitus and provide culturally competent care to Kurdish individuals. The TPFQ was translated into Central Kurdish by the cross-cultural adaptation and translation method suggested by Beaton, et al. [
11].
This study aimed to assess the reliability and validity of the TPFQ-CK. Initially, the TPFQ was translated from English to the Central Kurdish language, yielding the TPFQ-CK. Then, an additional evaluation was performed to determine the reliability and validity of the TPFQ-CK.
Discussion
The successful cross-cultural adaptation of the TPFQ is a crucial step in enhancing the questionnaire’s utility and applicability in diverse linguistic and cultural settings. This study aimed to modify the TPFQ to suit different cultural and linguistic environments while maintaining its psychometric properties [
11]. The adaptation process involved meticulous translation, back-translation, and expert evaluation. This meticulous technique aims to ensure that the questionnaire maintains semantic, idiomatic, and conceptual similarity across different languages. The findings of our study demonstrate that the adapted questionnaire maintains its language and cultural suitability [
19].
The study modified the TPFQ to suit Kurdistan cultural context and assessed TPFQ-CK’s reliability and validity, demonstrating its effectiveness in evaluating subjective tinnitus outcomes in Kurdish-speaking people in Iraq.
In assessing reliability, we observed that the TPFQ-CK had outstanding reliability and showed good item-total correlations. The internal consistency, as demonstrated by Cronbach’s α, indicated that the questionnaire items are coherent and measure a common construct consistently across the sample. The Cronbach α coefficient for the total score of the TPFQ-CK was 0.933, suggesting that the TPFQ-CK consistently yields comparable results within the same context. The Cronbach’s α of the original TPFQ (0.89) was little lower than it. The Cronbach’s α subscale values for concentration, emotion, hearing, and sleep were all greater than 0.9, which is higher than the original TPFQ values of 0.86, 0.9, 0.9, and 0.93 [
10].
The obtained excellent internal consistency is likely due to the cross-cultural translation, this guarantees the conceptual similarity of the original TPFQ. This is accomplished through a substantial decrease in random errors. Furthermore, the original TPFQ lacked information concerning the reliability of outcomes when the assessment was administered multiple times. The test-retest reliability confirmed the stability of the questionnaire over time. We evaluated the test-retest reliability of TPFQ-CK by employing the ICC, a statistical metric utilized to quantify the resemblance between measurements acquired from the same participants. Hence, it is more suitable to utilize the ICC for assessing test-retest reliability. Based on the Landis and Koch categorization [
20], test-retest reliability can be categorized as outstanding (ICC more than 0.8), good (ICC located between 0.6 and 0.8), fair (ICC located between 0.4 to 0.6), poor (ICC located between 0.2 to 0.4), or bad (ICC less than 0.2). The test-retest reliability of TPFQ-CK in our study was excellent, as indicated by its ICC statistic, which was extremely close to 1. This result is in line with the findings of Arefi, et al. [
21] in Persian version of TPFQ reported an ICC of 0.975.
We use the Bland-Altman plot to evaluate the agreement or concordance between the first and second assessments of TPFQ-CK. It indirectly provides information about the validity and reliability of the new method or assessor. Good agreement in the plot suggests good validity (the new method measures what it should) and reasonable reliability (consistent measurements). All of the data of difference and mean of first and second assessment of TPFQ-CK was scattered between upper 95% CI (1.2790808) and lower 95% CI (-0.198681) around the mean (0.5402) which is obtained from one-sample t-test, which indicate that the two sets of measurements or assessments are in good agreement, consistent with each other, reliable, and statistically significant.
Regarding the validity, content validity is a vital aspect of questionnaire adaptation. The expert committee, consisting of bilingual professionals in otolaryngology, audiology, psychology, and linguistics, played a pivotal role in ensuring that the adapted TPFQ preserved the content validity of the original version. The inclusion of expert perspectives helped identify and resolve any linguistic or cultural nuances that might have affected the questionnaire’s comprehensibility or relevance Arian Nahad, et al. [
22].
In order to determine a constant linear correlation between the two measures, we calculated Spearman’s rho and CCC (results closer to 1 indicated higher validity). For assessing construct validity, a Spearman’s correlation coefficient was computed by comparing the TPFQ-CK total score with THQ. A strong association of 0.895 was observed between TPFQ-CK and THQ. The overall scores of the TPFQ-CK, concentration, emotion, hearing, and sleep subscales showed a strong correlation with the THQ (r=0.895, 0.843, 0.858, 0.784, and 0.798;
p<0.001). Xin, et al. [
6] showed significant correlations between the TPFQ total score, concentration, emotion, hearing, and sleep with the THQ (r=0.73, 0.70, 0.73, 0.56, and 0.56;
p<0.001), our result is higher than that of the Chinese version of TPFQ. In addition, the ceiling and floor effects were incorporated to eliminate the potential for extreme outliers in the TPFQ-CK results.
The criterion validity was assessed by the evaluation of Lin’s concordance correlation coefficient between two measures, between the first and second evaluations of the TPFQ-CK total score, concentration, emotion, hearing, and sleep, all demonstrated a robust correlation and agreement between the two evaluations, and the CCC was 0.999 for all of them. According to Akoglu [
23] and Lin [
24], when assessing the level of agreement and consistency between two measures, an ICC and CCC value close to one indicates an extremely high level of agreement and consistency between the two measures. In our study, the ICC and CCC of the total score and factors were near one, indicating an extremely high level of agreement and consistency between the two measures.
The study sample was drawn from a specific region (Sulaymaniyah governorate, Iraq), which may limit the generalizability of the findings to other Kurdish-speaking populations. Possible cultural subtleties and differences in how tinnitus is understood may be present among individuals who speak Central Kurdish, which could impact their answers to the questionnaire.
In conclusion, the TPFQ-CK is a valid and reliable assessment tool for evaluating the influence of tinnitus on the quality of life of Central Kurdish speaking individuals with tinnitus. Our findings emphasise the necessity for additional assessments of TPFQ-CK to validate its efficacy in various clinical contexts.