Evaluation of Waist-Calf Circumference Ratio to Assess Sarcopenia in Older Patients with Chronic Low Back Pain: A Retrospective Observational Study.

Purpose: Chronic low back pain is prevalent among older adults, who are at a higher risk for sarcopenia. The waist-to-calf circumference ratio has emerged as a health indicator, reflecting the balance between central adiposity and muscle mass. This study examined the association between waist-to-calf circumference ratio and sarcopenia, as well as factors like muscle mass, strength, and physical performance in older patients with chronic low back pain.

Patients and methods: Ambulatory patients aged 65 years and older with chronic low back pain were included. Sarcopenia was assessed using the 2019 diagnostic criteria from the Asian Working Group for Sarcopenia. We compared demographic data, pain-related factors, comorbidities, and measurements related to sarcopenia and obesity across quartiles of the waist-to-calf circumference ratio. The prevalence of sarcopenia and severe sarcopenia was investigated, and multivariable analysis was conducted to identify independent factors associated with sarcopenia.

Results: Among 592 patients, 85 had sarcopenia (14.3%), and 71 had severe sarcopenia (11.9%). Patients with a high waist-calf circumference ratio had more comorbidities and longer pain duration. The prevalence of severe sarcopenia increased with higher quartile of waist-calf circumference ratio (Q1=7.9%, Q2=8.6%, Q3=14.8%, Q4=16.9%, P=0.006). When recommended cut-off values for the parameters used to diagnose sarcopenia were applied, the numbers of patients with low grip strength and low physical performance but not low muscle mass were greater among patients with a high waist-calf circumference ratio. Also, a high waist-calf circumference ratio was significantly associated with severe sarcopenia.

Conclusion: In older patients with chronic low back pain, a high waist-calf circumference ratio was associated with severe sarcopenia, characterized by reduced muscle strength and impaired physical performance. The waist-calf circumference ratio might serve as a useful tool for assessing sarcopenia in this population.