Associations between fat mass and multi-site pain: A 5-year longitudinal study

OBJECTIVE: Pain is common in older adults and typically involves multiple sites. Obesity is an important risk factor in the pathogenesis of pain and multi-site pain (MSP). This study aimed to examine longitudinal associations between fat mass and MSP, and to explore the potential mechanisms of any associations.

METHODS: Data from a longitudinal population-based study of older adults (n=1099) was utilized with measurements at baseline and after 2.6 and 5.1 years. At each time-point, presence/absence of pain at the neck, back, hands, shoulders, hips, knees and feet was assessed by questionnaire. Fat mass was assessed by dual energy x-ray absorptiometry and height and weight measured.

RESULTS: Participants were of mean age 63 years, mean BMI 27.9 kg/m² and 51% women. Participants reporting greater number of painful sites had greater fat mass, fat mass index (FMI) and BMI both cross-sectionally and longitudinally. In multivariable analyses, fat mass was associated with MSP (OR, 1.06 per SD; CI 1.02, 1.10) and pain at the hands, knees, hips and feet (OR=1.29 to 1.99 per SD, all P<0.05). Results were similar for FMI and BMI, although the latter was also associated with back pain (OR 1.25 per SD; 95% CI 1.02 to 1.54).

CONCLUSION: Fat mass, FMI and BMI are associated with MSP, pain at all lower limb sites and hand pain, independent of socio-demographic, physical activity and psychological factors. This suggests that both loading and systemic inflammatory factors may have an important role in the pathogenesis of fat-related MSP.