The critical cutoff point of the Zurich Claudication Questionnaire and the Japanese Orthopaedic Association score indicating locomotive syndrome in patients with lumbar spinal canal stenosis

Background Locomotive syndrome (LS) is a condition of decreased mobility caused by disorders of the locomotive organs. Lumbar spinal stenosis (LSS) is a LS disorder. The Japanese Orthopaedic Association score (JOA score) and the Zurich Claudication Questionnaire (ZCQ) are international evaluation tools for LSS. However, the relationship between LS and JOA score or ZCQ is unknown. This study aimed to clarify the correlations between LS progression and the values/parameters of the JOA score or ZCQ and to determine the critical cutoff point of the JOA score or ZCQ that indicates LS progression. Methods We recruited preoperative LSS patients (n = 82). Patients' mean age was 73.4 years. The study participants were evaluated using the 25-question Geriatric Locomotive Function Scale (GLFS), JOA score, and ZCQ (which consists of symptom severity and physical function), and the patients' health-related quality of life was assessed using EuroQoL-5 dimension (EQ-5D) utility values and the EuroQoL-visual analog scale (EQ-VAS). We investigated the correlations between the 25-question GLFS and each clinical variable and evaluated the critical cutoff point of each international evaluation tool to detect LS. Results There was a statistically significant correlation between 25-question GLFS and each clinical evaluation tool. LSS patients with LS showed significantly worse scores in the evaluation tools than LSS patients without LS. Moreover, we found that critical cutoff points of 17.5 on JOA score, 3.1 on ZCQ-symptom, and 2.3 on ZCQ-function could detect LS. Conclusions A statistically significant correlation exists between the 25-question GLFS and the JOA score or ZCQ. It might be important to perform decompression surgery for LSS patients before they reach the cutoff values of the several clinical evaluation tools to avoid LS progression. Study design Clinical prospective case–control study.