Association between syndesmophyte and metabolic syndrome in patients with psoriatic arthritis or ankylosing spondylitis: a cross-sectional study

OBJECTIVE: To investigate the prevalence of and factors associated with metabolic syndrome (MetS) in patients with psoriatic arthritis (PsA) or ankylosing spondylitis (AS). METHODS: This cross-sectional study included PsA or AS patients who attended Siriraj Hospital (Bangkok, Thailand) during March 2014 to October 2017. The Harmonized MetS definition was used to diagnose MetS. Demographic, clinical, and spinal radiographic data were collected. Logistic regression was used to identify factors associated with MetS. RESULTS: Among 319 patients, 153 had AS and 166 had PsA. MetS was present in 43% of PsA and 19% of AS (p < 0.001). Multiple regression analysis identified body mass index (BMI) > 23 (odds ratio [OR]: 3.7), female gender (OR range: 3.8–3.9), and the number of syndesmophytes or ankylosis [SynAnk] (OR: 1.1) were associated with MetS among PsA patients. For AS patients, BMI > 23 (OR: 9.1) and age > 40 (OR: 4.3) were associated with MetS. Disease activity index was not associated with MetS. CONCLUSIONS: MetS was significantly more prevalent in PsA than in AS. Structural change of the spine was associated with MetS in PsA. PsA patients with being female, BMI > 23 or evidence of spinal change should be informed to screen for MetS. AS patients with age > 40 or BMI > 23 should be informed to screen for MetS.