Validation of grip strength as a measure of frailty in rheumatoid arthritis

Abstract

Rheumatoid arthritis (RA) patients often exhibit finger/wrist joint symptoms and reduced grip strength. This study aimed to validate grip strength as a measure of frailty in RA patients. Subjects were 424 female RA patients (mean age±standard deviation, 66.8±14.5 years). Frailty was defined as a score of ≥8 points on the Kihon Checklist (KCL). Finger/wrist joint symptoms were defined based on tender or swollen joints. Associations between frailty and grip strength were determined using receiver operating characteristic (ROC) curve analysis and multivariable logistic regression analysis. There were 179 subjects with frailty (42.2%). Multivariable logistic regression analysis revealed that frailty was significantly associated with grip strength independently of finger/wrist joint symptoms. In ROC curves, cut-off scores of grip strength for frailty in subjects without and with finger/wrist joint symptoms were 17 kg (sensitivity, 62.1%; specificity, 69.0%) and 14 kg (sensitivity, 63.2%; specificity, 73.0%), respectively. The results of the present study suggest that grip strength in female RA patients is associated with frailty, with a cut-off score of 17 kg (equivalent to Cardiovascular Health Study criteria, <18 kg) when RA patients have no finger/wrist joint symptoms. However, when RA patients have finger/wrist joint symptoms, measures other than grip strength such as lower limb function should be considered.

Psychometric Properties of Frailty Instruments in Adults With Rheumatoid Arthritis: A Systematic Review

“…Frailty assessment in this scenario could be used to inform patient risk profiles for shared decision‐making about individualized treatment plans to incorporate physical therapy for strength training, osteoporosis screening, or fall prevention strategies. Establishing construct validity for the PFP models that include grip strength as a component is important in the presence of hand or wrist symptoms because weak grip strength could be attributed to RA disease rather than frailty 45 . Two investigators using PFP models in this review substituted knee strength for grip strength resulting in similar outcomes for both methods, although sensitivity analyses were not pursued suggesting this issue needs further exploration 6,10 .…”

“…Establishing construct validity for the PFP models that include grip strength as a component is important in the presence of hand or wrist symptoms because weak grip strength could be attributed to RA disease rather than frailty. 45 Two investigators using PFP models in this review substituted knee strength for grip strength resulting in similar outcomes for both methods, although sensitivity analyses were not pursued suggesting this issue needs further exploration. 6 , 10 Psychometric properties of the original Fried PFP instrument 1 have not been studied in adults with RA; the reported evidence reflects only adapted PFP instruments.…”