Is grip strength useful in screening to predict the severity of locomotive syndrome?

BACKGROUND: This study was conducted to investigate the relationship between grip strength and the 25-question Geriatric Locomotive Function Scale (GLFS-25) score and the diagnosis of locomotive syndrome (LS), and the usefulness of grip strength in screening for LS. METHODS: This cross-sectional study was conducted on 2251 community-dwelling residents (male, n = 1035; female, n = 1216). Subjects with GLFS-25 scores of 0-6 points, 7-15 points, 16-23 points, and 24-100 points were diagnosed with non-LS, LS-1, LS-2, and LS-3, respectively. Multivariate linear regression and multivariate logistic regression analyses were performed to assess the relationship between grip strength and the GLFS-25 score and LS after adjustment for age, sex, and body mass index. A conventional receiver operating characteristic (ROC) curve analysis was used to calculate the optimal cutoff value of grip strength for predicting the severity of LS. The discriminative ability of the model was assessed using the area under the ROC curve (AUC). RESULTS: The multivariate linear regression analysis showed that grip strength was significantly associated with the GLFS-25 score. The multivariate logistic regression analysis revealed that grip strength was significantly associated with the diagnosis of LS. The optimal cutoff values of grip strength for identifying LS-1 or more, LS-2 or more, and LS-3 or more were 36.0 kg (sensitivity 65.7%, specificity 57.1%, AUC 0.66), 35.0 kg (sensitivity 70.0%, specificity 57.5%, AUC 0.70), and 34.0 kg (sensitivity 67.2%, specificity 62.5%, AUC 0.70), respectively, in males, and 24.0 kg (sensitivity 69.1%, specificity 45.4%, AUC 0.61), 23.0 kg (sensitivity 69.5%, specificity 52.3%, AUC 0.67), and 22.0 kg (sensitivity 69.1%, specificity 61.0%, AUC 0.69) in females. CONCLUSIONS: The use of grip strength in screening to predict the severity of LS may not be clinically useful. However, the results will increase our understanding of the relationship between grip strength and the GLFS-25 scores and LS.