AS Disease Activity Associated With Decreased Total Lean Mass

Men with ankylosing spondylitis (AS) were found to have significant reductions in both total and appendicular lean mass, which appear to be related to higher disease activity and bone loss.1  Muscle loss and functional abnormalities define sarcopenia, a characteristic of chronic inflammatory diseases that is attributed to elevations in inflammatory cytokines such as tumor necrosis factor (TNF).  

Despite the fact that circulating levels of proinflammatory cytokines are elevated in AS, it has not been uniformly established that patients with AS have decreased muscle mass.2  This is in contrast to osteoporosis, which has been shown to be directly related to AS disease severity.3  Authors therefore sought to determine the prevalence of sarcopenia, cachexia, and osteoporosis in patients with AS, and to clarify the relationship between these variables and disease severity.

High Yield Data Summary

  • Men with AS had reductions in total and appendicular lean mass compared with healthy age-matched controls 

Fat-free mass index (FFMI; fat-free mass divided by height squared), fat mass percentage, and bone mineral density (BMD) were obtained using dual energy X-ray absorptiometry in 67 consecutive male patients with AS (mean age, 40.9±11.0 y) and 67 age-matched healthy control patients.  

Among patients with AS, mean disease duration was 9.3 ± 7.9 years and mean Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) was 3.7 (range 0–8.6). Thirty two patients with AS (47.8 %) were defined as having  “active disease,” as defined by a BASDAI score of ≥4. 

The mini nutritional assessment (MNA), a dietary questionnaire assessing the number of meals, food intake, fluid consumption, and autonomy of feeding was used as a subjective assessment of self-perception of health and nutrition. 

For the purposes of this study, the following definitions were made by researchers:

  • Pre-sarcopenia: low skeletal muscle mass (SMI, <7.25 kg/m2)
  • Sarcopenia: the combined presence of the 2 following criteria: SMI <7.25 kg/mand a low muscle strength (handgrip strength, <30 kg) or a low muscle performance (timed get-up-and-go test, >10 s)
  • Cachexia: body mass index (BMI) <20 kg/m2 plus 3 from the 5 following parameters: anorexia, fatigue, handgrip strength <30 kg, C-reactive protein (CRP) >5 mg/L, SMI <7.25 kg/m2

Researchers found that men with AS had statistically significant reduction in total (3 kgs) and appendicular lean mass. The prevalence of pre-sarcopenia, sarcopenia, cachexia, and osteoporosis were 50.4, 34.3, 11.9, and 16.0, respectively.   

Patients with higher BASDAI scores, lower lumbar spine and hip BMD, and T-scores were more likely to have higher prevalences of pre-sarcopenia, sarcopenia and cachexia. After binary analysis regression, BASDAI was found to be the only variable significantly associated with pre-sarcopenia.

Patients with AS on TNF inhibitor therapy were found to have higher fat mass indices and increased lumbar spine BMD and T-scores. No differences in muscle mass, muscle strength, or performance tests were found between patients taking TNF inhibitors and those who were not.

Summary and Clinical Applicability

Men with AS had reductions in total and appendicular lean mass compared with healthy age-matched controls that may be related to higher disease activity. 

“Patients with AS with important weight loss should be assessed using body composition analysis,” the authors concluded.

Limitations and Disclosures

  • No scientifically determined consensus definitions of pre-sarcopenia, sarcopenia, and cachexia exist 
  • No information on vitamin D status was assessed 

The study authors declare that they have no competing interests.


  1. El maghraoui A, Ebo’o FB, Sadni S, Majjad A, Hamza T, Mounach A. Is there a relation between pre-sarcopenia, sarcopenia, cachexia and osteoporosis in patients with ankylosing spondylitis?. BMC Musculoskelet Disord. 2016;17(1):268.
  2. Plasqui G, Boonen A, Geusens P, Kroot EJ, Starmans M, van der Linden S. Physical activity and body composition in patients with ankylosing spondylitis. Arthritis Care Res. 2012;64:101–7.
  3. Ghozlani I, Ghazi M, Nouijai A, et al. Prevalence and risk factors of osteoporosis and vertebral fractures in patients with ankylosing spondylitis. Bone. 2009;44:772–6.

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