Abstract

Objective: Lumbar instability is a condition that has been extensively reported in its prevalence and its effect on patients. To date, however, a clinical screening tool for this condition has not been developed for use in Thailand. The objectives of this study were to translate and test the content validity and rater reliability of a screening tool for evaluating Thai patients with lumbar instability. Methods: The investigators selected the lumbar instability questionnaire from an original English version. Elements of the tool comprised the dominant subjective findings reported by this clinical population. The screening tool was translated into the Thai language following a process of cross-cultural adaptation. The index of item-objective congruence (IOC) was checked for content validity by 5 independent experts. Seventy-five Thai patients with chronic nonspecific low back pain were asked to report their symptoms. The interview procedure using the tool was conducted by expert and novice physical therapists, which informed the intraclass correlation coefficient (ICC) for inter- and intrarater reliability. Results: The IOC was 0.95. The interrater ICC between expert and novice physical therapists was 0.92 (95% CI = 0.88-0.95). The intrarater ICC of novice physical therapist was 0.91 (95% CI = 0.86-0.94). Conclusion: The Thai version of the screening tool for patients with lumbar instability achieved excellent content validity and interrater and intrarater reliability. This screening tool is recommended for use with Thai patients with low back pain to identify the subpopulation with lumbar instability.