Skeletal Muscle and Fat Mass Reflect Chronic Pain in Older Adult.

Objectives: The prevalence of chronic pain increases with age. It has been reported that chronic pain is associated with sarcopenia and obesity. Age-related skeletal muscle loss and fat gain are known to occur due to chronic inflammation. The aim of this study was to analyze how skeletal muscle and fat, caused by chronic inflammation due to aging, regulate the development of geriatric chronic pain. Methods: The results of skeletal muscle and fat mass, 412 participants aged ≥65 years with non-specific chronic pain lasting ≥6 months, including low back, neck, and knee pain, was compared with the control without chronic pain. Body composition threshold regulating chronic pain was calculated. Results: A significantly lower skeletal muscle mass index and higher body fat percentage were observed in patients with chronic pain than that in the control. The muscle fat ratio (MFR) was significantly lower in the chronic pain group than in the control group. When the MFR threshold related to chronic pain was calculated by sex, it was 2.984 for men and 1.867 for women. Conclusions: Evaluation of the body composition of elderly patients with non-specific chronic pain revealed that the MFR was useful as an index related to chronic pain.