Evaluation of Handgrip Strength Asymmetry to Assess Sarcopenia in Older Patients with Chronic Low Back Pain: A Retrospective Cross-Sectional Study

Background: Handgrip strength (HGS) is a crucial measurement for diagnosing sarcopenia, and HGS asymmetry indicates functional impairment and correlates with adverse health outcomes. Although chronic low back pain (CLBP) often coexists with sarcopenia in older people, the association between HGS asymmetry and sarcopenia in that population has not been investigated. Objectives: This study examines the association between HGS asymmetry and sarcopenia in older patients with CLBP and explores differences in the proportion of sarcopenia and severe sarcopenia according to the severity of HGS asymmetry. Design: A retrospective observational study. Setting: The study included patients who visited the outpatient department for pain management at a university hospital. Participants: Ambulatory patients 65 years and older with CLBP assessed for sarcopenia per the Asian Working Group for Sarcopenia (AWGS) 2019 protocol were enrolled. Measurements: HGS asymmetry was categorized into three groups (< 10%, 10-20%, and > 20%) based on the difference between the hands. Results: A total of 575 CLBP patients aged 65-90 years was analyzed. In females, physical performance scores declined as HGS asymmetry severity increased (p < 0.001), alongside a proportional rise in the proportion of sarcopenia (p = 0.006) and severe sarcopenia (p = 0.002). Conversely, males showed no such association. Moreover, patients with low HGS (meeting the AWGS 2019 criteria) had a higher proportion of sarcopenia (p = 0.019) and severe sarcopenia (p = 0.017) as HGS asymmetry severity increased. The multivariable analysis identified > 20% HGS asymmetry as an independent predictor of sarcopenia (adjusted odds ratio (OR) 3.296, 95% confidence interval (CI) 1.595-6.811, p = 0.001) and severe sarcopenia (adjusted OR 3.092, 95% CI 1.467-6.517, p = 0.003) exclusively in females. Conclusions: Severe HGS asymmetry was associated with poor physical performance and a higher proportion of sarcopenia in older female patients with CLBP.