Diffuse Peripheral Enthesitis in Metabolic Syndrome: A Retrospective Clinical and Power Doppler Ultrasound Study

To investigate peripheral enthesitis with power Doppler ultrasound (PDUS) in patients presenting low back pain (LBP) and metabolic syndrome (MetS) in comparison with patients with only LBP, to correlate US scores with clinical-anthropometric characteristics, and to define any relationship between enthesitis and concurrent diffuse idiopathic hyperostosis syndrome (DISH).

Sixty outpatients with LBP and MetS, evaluated with multi-site entheseal PDUS, scoring inflammatory and structural damage changes, were retrospectively analyzed. A group of 60 subjects with LBP, without MetS and evaluated with the same protocol, was analyzed as the control group.

Patients showed overweight (BMI 29.8) and low-grade inflammatory state (C-reactive protein [CRP] 0.58mg/dL, erythrosedimentation rate [ESR] 20.2mm/h). Enthesitis was demonstrated in 52 (86%) patients (17.6% entheses), and in 8 controls (13.3%) (p<.00001). PD signals (15% of patients) were associated with entheseal pain (p=.0138). US scores correlated with body mass index (BMI), pain, type 2 diabetes. In 28 (46%) patients a concurrent DISH was diagnosed, correlating with older age (p<.0001), CRP (p=.0428), ESR (p=.0069) and PDUS scores (p=.0312 inflammatory, p=.0071 structural). MetS had a strong association (OR 4.375, p=.0007) with concurrent DISH.

Diffuse peripheral enthesitis is very common in MetS. Almost half of MetS patients can have a concurrent diagnosis of DISH; they are older, with higher inflammation, and higher PDUS enthesitis scores.