Sarcopenic Obesity in Osteoarthritis vs Rheumatoid Arthritis

Individuals with osteoarthritis (OA) may exhibit a higher prevalence of sarcopenic obesity compared with patients with rheumatoid arthritis (RA), according to a recent study published in Rheumatology.¹

The prevalence of sarcopenia — particularly in combination with ostepenia — increases with age, and sarcopenic obesity may be underrecognized, despite its impact in patients with rheumatic diseases.

Participants included 75 patients with OA and 82 patients with RA, all evaluated for body composition and total hip bone density. 

Subjects with an appendicular muscle index (AMI) to body mass index (BMI) ratio <0.789 for men, and <0.512 for women were considered to have sarcopenia; obesity cutoffs was  ≥30% fat for men, and ≥40% fat for women. Total hip T-scores between –1 and –2.5 indicated osteopenia.

Sarcopenia was diagnosed in more patients with OA vs RA (29.3% and 17.1%; P =.068), and the incidence of sarcopenic obesity was higher in study participants with OA vs RA (29.3% vs 15.9%; P =.043). The researchers hypothesized that these differences  may be partly accounted for by OA-specific biomechanical factors leading to higher bone and muscle mass loss rather than resulting from inflammatory catabolism occurring in RA. Such a finding may contradict previously held beliefs regarding sarco-osteopenia being driven by inflammatory mediators and metabolism.

Two possible limitations were noted: widespread use of bisphosphonates in RA may confound osteopenia prevalence numbers, and the use of the AMI to BMI ratio to measure sarcopenia omits grip strength.

The researchers acknowledged a need for additional longitudinal studies to examine both causes and prevalence of sarcopenia in OA and RA, citing a clinical need of fall and fracture prevention. “Identifying individuals with OA or RA who are at risk of sarcopenia may help to inform and implement appropriate interventions that aim to improve muscle strength and reduce frailty,” they concluded.

Reference

Vlietstra L, Meredith-jones K, Stebbings S, et al. Sarcopenic obesity is more prevalent in osteoarthritis than rheumatoid arthritis: are different processes involved? Rheumatology (Oxford). 2017;56(10):1816-1818.