RESUMO
Neck pain, dizziness, difficulty supporting the head for an extended period, and impaired movement are all symptoms of cervical spine instability, which may produce cervical spondylolisthesis in patients who have more severe symptoms. To avoid problems and consequences, early detection of cervical spine instability is required. A previous study created a Thai-language version of a cervical spine instability screening tool, named the CSI-TH, and evaluated its content validity. However, other characteristics of the CSI-TH still needed to be evaluated. The objective of the current study was to assess the rater reliability and convergent validity of the CSI-TH. A total of 160 participants with nonspecific chronic neck pain were included in the study. The Neck Disability Index Thai version (NDI-TH), the Visual Analog Scale Thai version (VAS-TH), and the Modified STarT Back Screening Tool Thai version (mSBST-TH) were used to evaluate the convergent validity of the CSI-TH. To determine inter- and intra-rater reliabilities, novice and experienced physical therapists were involved. The results showed that rater reliabilities were excellent: the intra-rater reliability was 0.992 (95% CI = 0.989 ± 0.994), and the inter-rater reliability was 0.987 (95% CI = 0.983 ± 0.991). The convergent validities of the VAS-TH, NDI-TH, and mSBST-TH when compared with the CSI-TH were 0.5446, 0.5545, and 0.5136, respectively (p < 0.01). The CSI-TH was developed for use by physical therapists and is reliable. It can be used by physical therapists, whether they are experienced or novices, and has an acceptable correlation to other neck-related questionnaires. The CSI-TH is concise, suitable for clinical use, and lower-priced when compared to the gold standard in diagnosis for patients with cervical spine instability.