Turkish Adaptation of the CTS-6 Evaluation Tool: A Validation and Reliability Study

Overview

The purpose of this study is to develop the Turkish version of the CTS-6 Evaluation Tool and to comprehensively assess its validity and reliability in the Turkish population. The CTS-6 Evaluation Tool is a widely used and reliable instrument for the assessment of diagnosis and symptom severity in patients with carpal tunnel syndrome. In this study, the CTS-6 will undergo translation and cultural adaptation to ensure linguistic and cultural appropriateness for the Turkish population. The goal is to produce a valid, reliable, and practical tool that can be used efficiently in clinical settings. The adapted version is intended to be applicable across multiple medical specialties involved in the diagnosis and management of carpal tunnel syndrome in Turkey. The results are expected to provide a trustworthy Turkish version of the CTS-6 suitable for both clinical practice and research purposes.

A) STUDY RATİONALE: The most common peripheral neuropathy is median nerve neuropathy, and the most frequent site of entrapment of the median nerve is the carpal tunnel at the wrist. Local ischemia caused by mechanical compression of the nerve leads to demyelination of the nerve fibers, resulting in paresthesia, pain, and motor dysfunction. Paresthesias are initially more pronounced at night and later become noticeable during the day. In advanced cases, motor functions may be affected. Carpal tunnel syndrome (CTS) is more common in women, but the male-to-female ratio varies between studies. It is most commonly seen in individuals aged 50-54. The etiology and pathophysiology of CTS are multifactorial. Its etiology may include idiopathic causes (most common), anatomical causes, genetics, trauma, obesity, space-occupying lesions in the wrist, connective tissue diseases, hypermobility, metabolic and endocrine diseases, pregnancy, lactation, and menopause. Despite its prevalence and well-known clinical presentation, the best diagnostic strategy for CTS remains unclear. Clinical history and physical examination remain indispensable for diagnosis, but their diagnostic accuracy varies. Therefore, there is no standard definition for diagnosis, but clinicians use a combination of specific symptoms indicative of the syndrome. Although clinical diagnostic criteria vary considerably in the literature, the main symptoms that can be seen in CTS patients are: nocturnal paresthesias causing the patient to awaking from sleep, shaking wringing or trick movements of hands that relief symptoms symptoms, pain and or paresthesias evoked by hand grip or use of force with hand Sensory symptoms in digits 1,2,3 or parth of the 4th digit, or any combination thereof. The sensitivity and specificity of diagnostic tests for CTS vary in the literature. Commonly used diagnostic tests/signs in the literature are Tinel's sign, Phalen's test, reverse Phalen's test, carpal tunnel compression test, and Flick's sign. The current gold standard diagnostic method for CTS is electrophysiological examination. The method frequently used in electrophysiological examination for CTS diagnosis is nerve conduction studies (NCS). NCS provides quantitative data, offering additional diagnostic certainty beyond clinical impression. The diagnosis of CTS is usually based on history and physical examination, and NCS is performed as a complement to clinical findings. NCS is valuable for confirming the diagnosis. Electrophysiological examination are used as an objective marker for confirming mononeuropathy. Electrophysiological examination are valid and reproducible for confirming CTS with high sensitivity (\>85%) and specificity (95%). When NCS is not tolerated or informative, ultrasonography (USG) can detect pathology and easily localize the structure. Unlike functional studies, USG provides valuable anatomical data about tissues. USG is widely used in the diagnosis of CTS. Multiple studies have shown that USG has high sensitivity and specificity in diagnosing KTS. A 2019 study by Wang et al. showed that USG had 89% sensitivity and 72% specificity for diagnosing KTS. In 2015, Fowler et al. found that USG had a sensitivity of 91% and a specificity of 94% for diagnosing CTS. In light of all this information, clinical signs and symptoms, diagnostic tests, NCS, and the use of USG are commonly seen in the literature for diagnosing CTS. CTS remains the most commonly diagnosed compression neuropathy in the upper extremity. This diagnosis is made by a wide range of healthcare professionals, from primary care physicians to specialists and surgeons. However, the importance attributed to history and physical examination findings during the diagnostic process varies significantly both within the same specialty and between different disciplines. The lack of a clear consensus on which clinical criteria are best for diagnosing CTS can lead to differences and errors in requesting and interpreting diagnostic tests, as well as in treatment recommendations and practices. Although the reasons why clinicians use different criteria in the diagnosis of CTS are not fully understood, it is thought that this is at least partly due to electrophysiological tests being considered the "gold standard" for diagnosis. In most cases, the results of these tests take precedence over clinical evaluations. Although some studies suggest that the role of electrophysiological tests in predicting treatment outcomes is limited, to our knowledge, no study to date has directly measured the extent to which electrophysiological tests contribute to diagnosis when considering carpal tunnel syndrome. Standardizing clinical criteria for CTS diagnosis is an important step in evaluating the role of electrophysiological tests. In this context, the recently defined and validated CTS-6 Evaluation Tool enables the prediction of CTS likelihood based on the presence or absence of six items recorded during history and physical examination and weighted according to their diagnostic importance. In a study aiming to evaluate the sensitivity, specificity, and inter-observer reliability of the CTS-6 Evaluation Tool, it was demonstrated that when this scale was applied by medical assistants in an upper extremity clinic, it provided high sensitivity and specificity along with a meaningful level of inter-observer reliability. These data were noted to be potentially instructive for the development of CTS screening programs and future research to be conducted in primary care settings. CTS poses significant diagnostic challenges, particularly in resource-limited settings. In such settings, reliable tools such as the CTS-6 Evaluation Tool are promising. The latest guidelines on CTS management published by the American Academy of Orthopaedic Surgeons (AAOS) in 2024 state: "Strong evidence suggests that CTS-6 can be used to diagnose carpal tunnel syndrome, in lieu of routine use of Ultrasonography or NCV/EMG" The CTS-6 Evaluation Tool, based on six findings assessed in the history and physical examination, is used to predict the likelihood of CTS. The CTS-6 Evaluation Tool has been shown to be a reliable diagnostic screening tool. Furthermore, it has been demonstrated that it can be applied consistently and reliably among users with different levels of education. In recent years, the CTS-6 Evaluation Tool has become a noteworthy tool in the diagnosis of CTS due to its ability to combine scores obtained from clinical signs and symptoms with diagnostic tests using mathematical probability ratios. The investigators plan to conduct a validity and reliability study of the Turkish version of the CTS-6 Evaluation Tool, which is expected to gain increasing importance in the diagnosis of CTS in the literature. B) STUDY OBJECTİVES: In this study, the investigators aim to develop the Turkish version of the CTS-6 Evaluation Tool and to evaluate the validity and reliability of this version. C) STUDY POPULATİON AND PARTİCİPANT GROUPS: Study Design and Sample Size: This cross-sectional study has been designed to assess the Turkish version of the CTS-6 Evaluation Tool. Sample size was determined based on power analysis and commonly recommended guidelines for cross-cultural adaptation studies, which suggest including 5-10 participants per item on the scale. Given that the CTS-6 consists of six items, a minimum of 30 participants would be required. However, considering similar studies in the literature and to ensure sufficient statistical power, validity, and reliability, three separate participant groups were created. Statistical Analyses: Data will be analyzed using the Statistical Package for the Social Sciences version 31.0 for Windows (IBM Corp., Armonk, NY, USA) and Jamovi version 2.4.11. Categorical variables will be presented as frequencies (n) and percentages (%), and numerical variables as mean ± standard deviation (SD) and median (interquartile range \[IQR\]), as appropriate. The Kolmogorov-Smirnov test and inspection of histograms and Q-Q plots will be used to assess the normality of continuous variables. Participants will be categorized into three groups: (1) patients with clinically diagnosed carpal tunnel syndrome (CTS), (2) patients with similar symptoms but without CTS (non CTS symptomatic group), and (3) healthy controls. Groups will be matched on age and sex. Between group comparisons of demographic and clinical characteristics will be performed using the chi square test or Fisher's exact test for categorical variables, and one way analysis of variance (ANOVA) or the Kruskal-Wallis test for continuous variables, depending on distributional assumptions. When global tests are statistically significant, Bonferroni corrected post hoc tests (for ANOVA) or Dunn's test with Bonferroni adjustment (for Kruskal-Wallis) will be used for pairwise comparisons. A two tailed significance level of α = 0.05 will be adopted for all analyses. Construct validity (factor analysis): Construct validity of the Turkish CTS 6 will be evaluated using exploratory factor analysis (EFA). The suitability of the data for factor analysis will be assessed with the Kaiser-Meyer-Olkin (KMO) measure of sampling adequacy and Bartlett's test of sphericity. A KMO value ≥0.60 and a statistically significant Bartlett's test (p \< 0.05) will be considered acceptable. Principal component analysis with direct oblimin rotation will be used for factor extraction, given the potential correlation among items. Factors with eigenvalues greater than 1 will be retained, and the scree plot will also be inspected to determine the number of factors. Items with factor loadings below 0.40 or with cross loadings differing by less than 0.10 will be considered for removal or further scrutiny. The percentage of total variance explained by the factor solution will be reported. Internal consistency reliability: Internal consistency reliability of the CTS 6 total score will be assessed using Cronbach's alpha and McDonald's ω coefficients. Values of 0.70-0.95 will be interpreted as indicating acceptable to excellent internal consistency. Corrected item-total correlations will be calculated to evaluate the contribution of each item to the overall scale; values ≥0.30 will be considered adequate. Cronbach's alpha if item deleted will also be examined to identify items that might weaken the internal consistency. Test-retest reliability: Test-retest reliability will be evaluated in a subsample of clinically stable participants who complete the CTS 6 twice with an interval of approximately 7-14 days. Stability will be determined based on the absence of any change in clinical status or treatment between assessments. For the CTS 6 total score, the intraclass correlation coefficient (ICC) and its 95% confidence intervals (CI) will be calculated using a two way mixed effects model with absolute agreement definition \[ICC(3,1)\]. ICC values will be interpreted as follows: \<0.50, poor; 0.50-0.75, moderate; 0.75-0.90, good; and \>0.90, excellent reliability. Spearman's rank correlation coefficient between test and retest scores will also be reported. In addition, Bland-Altman plots will be constructed to visually assess the agreement between test and retest scores and to identify any systematic bias. Known groups validity: Known groups validity will be examined by comparing CTS 6 total scores across the three predefined groups (Group Diagnosed with CTS Based on Defined Criteria, Group Presenting with CTS-like Symptoms, and Healthy Control Group). Convergent validity: Convergent validity will be assessed by examining the association between the CTS 6 total score and other clinical measures. Specifically, Spearman's correlation coefficients will be calculated between the CTS 6 total score and the Boston Carpal Tunnel Questionnaire (BCTQ) subscales (symptom severity and functional status), as well as visual analog scale (VAS) scores for pain or numbness (e.g., at rest, during activity, and at night), if available. Correlations ≥0.50 will be interpreted as strong, 0.30-0.49 as moderate, and 0.10-0.29 as weak. Where electrodiagnostic parameters are available (e.g., distal motor latency, sensory conduction velocity of the median nerve), their correlations with CTS 6 scores will also be explored. Accounting for potential dropouts, each group will include 42 participants, resulting in a total sample size of 126 individuals. The study population will consist of individuals aged 18-60 years who present to the Physical Medicine and Rehabilitation Outpatient Clinic at İstanbul University, İstanbul Faculty of Medicine, Esnaf Hospital. Participants will be categorized into three groups: healthy controls, individuals presenting with CTS-like symptoms, and patients diagnosed with CTS based on clinical and electrophysiological evaluations. All participants will receive detailed information about the study, provide informed consent, and have demographic data (age, height, weight, etc.) recorded. Participant Group Classification: Participants will be assigned to one of three groups based on clinical findings and electrophysiological assessments: Healthy Control Group: Participants with no history of CTS, no clinical symptoms, and no pathological findings on physical or electrophysiological examinations. This group will serve as the comparison group. Group Presenting with CTS-like Symptoms: Participants exhibiting symptoms similar to CTS, but whose diagnosis is not confirmed by electrophysiological evaluation. Group Diagnosed with CTS Based on Defined Criteria: Participants with a confirmed CTS diagnosis based on both clinical findings and electrophysiological evaluations. This grouping allows for the assessment of both clinically suspected cases identified through clinical evaluation and CTS cases confirmed via clinical and electrophysiological testing. Additionally, it facilitates comparative analyses with healthy individuals. D) SUBJECT SAFETY AND RELİABİLİTY: No significant issues are anticipated regarding participant safety or reliability during the study assessment process. E) STUDY PROTOCOL: The original version of the CTS-6 Evaluation Tool will be independently translated into Turkish by two experts. Subsequently, the two experts will collaborate to produce a single Turkish version. This Turkish version will then be back-translated into English by an expert fluent in both languages. The experts will review the back-translated version and finalize the Turkish version. This cross-sectional study will include participants aged 18-60 years who present to the Physical Medicine and Rehabilitation Outpatient Clinics at Istanbul University, Istanbul Faculty of Medicine, Esnaf Hospital, between March 1, 2026 and July 1, 2026. Three separate groups will be formed from participants who do not meet the predefined exclusion criteria: (1) a control group of healthy individuals with no clinical or electrophysiological pathology, (2) a group presenting with CTS-like symptoms but considered normal based on electrophysiological evaluation, and (3) a group diagnosed with CTS according to clinical and electrophysiological criteria. Accounting for potential dropouts, 42 participants per group will be recruited, for a total of 126 participants. All participants will receive detailed written and verbal information about the study's objectives, duration, and procedures, and written informed consent will be obtained. During the assessments, participants will complete the Boston Carpal Tunnel Questionnaire (BCTQ) to evaluate symptom severity and functional status, while the investigator will complete the CTS-6 Evaluation Tool. For reliability analysis, a test-retest method will be applied, with at least 30 participants completing the questionnaire twice, two weeks apart. The BCTQ is widely used to assess symptom severity in CTS. It consists of two scales evaluating symptom severity and functional status. The first section has 11 questions assessing symptom severity, scored on a 5-point scale (1 = least severe, 5 = most severe). The second section has 8 questions assessing functional capacity, also scored from 1 to 5, with higher scores indicating reduced function. Mean scores for symptom severity and functional capacity are calculated separately by dividing the total score by the number of items. The Turkish version of this questionnaire has previously been validated. Eligible participants will complete the CTS-6 Evaluation Tool and the BCTQ, and their clinical and electrophysiological findings will be recorded. Participants will be assigned to the appropriate group according to the order of presentation and assessments, and each participant will be numbered. All electrophysiological measurements, scale assessments, and questionnaire completions will be performed on the same day. Electrophysiological assessments will be conducted by a single evaluator using a four-channel Nihon-Kohden electromyography device (MEM-4200K, Neuropack 8, Nihon-Kohden, Tokyo, Japan) according to methods recommended by the American Association of Neuromuscular \& Electrodiagnostic Medicine. For all participants, median nerve distal motor latency (DML) and conduction velocity will be measured orthodromically from the Abductor Pollicis Brevis (APB) muscle using wrist and antecubital fossa stimulation (G1 to stimulator distance: 7 cm; G1 to G2 electrode distance: 4 cm). Median nerve sensory distal latency (DSL) and conduction velocity will be measured antidromically from the 2nd digit (G1 to stimulator: 13 cm; G1 to G2: 4 cm). Comparative antidromic studies of median-ulnar nerve sensory peak latency will be performed from the 4th digit (G1 to stimulator: 13 cm; G1 to G2: 4 cm). Ulnar nerve sensory DSL and conduction velocity will be measured antidromically from the 5th digit (G1 to stimulator: 11 cm; G1 to G2: 4 cm). Distal motor latency (DML) and conduction velocity of the ulnar nerve will be measured orthodromically from the Abductor Digiti Minimi muscle using wrist and below-elbow stimulation (approximately 3 cm distal to the medial epicondyle; G1 to stimulator: 7 cm; G1 to G2: 4 cm). All assessments will be conducted at a standard room temperature of 25 °C, maintaining hand temperature above 32 °C. F) PLANNED TESTS WITH DURATION and LABORATORY INFORMATION: Clinical Examination: Examiner: Dr. Cem Can Yücel Duration: Approx. 20 minutes Department of Physical Medicine and Rehabilitation, Istanbul University, Istanbul Faculty of Medicine, Esnaf Hospital Outpatient Clinics, Suleymaniye Takvimhane Cad., No:19, Fatih, Istanbul, Turkey Phone number: +90 506 645 1834 Email adress: yucelccan19@icloud.com Electrophysiological Examination (Nerve Conduction Studies): Examiner: Prof. Dr. Sina Arman (Esmailzadeh) Duration: Approx. 20 minutes Department of Physical Medicine and Rehabilitation, Istanbul University, Istanbul Faculty of Medicine, Esnaf Hospital Outpatient Clinics, Suleymaniye Takvimhane Cad., No:19, Fatih, Istanbul, Turkey Phone Number: +90 536 648 1111 Email adress: sinabox@gmail.com Notes: Electrophysiological evaluation will include median and ulnar nerve conduction studies according to standard AANEM protocols. All questionnaires will be self-administered by participants, and validated Turkish version will be used. This study will be conducted as a single-center study at the Department of Physical Medicine and Rehabilitation, Istanbul University, Istanbul Faculty of Medicine, Esnaf Hospital Outpatient Clinics, Istanbul, Turkey.