Prevalence of subclinical enthesopathy in patients with spondyloarthropathy: an ultrasound study.

Background: Ultrasound has demonstrated to be a highly sensitive tool in the evaluation of entheses in spondyloarthropathy (SpA) patients and improves the ability of clinical examination to detect enthesopathy.

Objectives: The objectives of the study were to determine the prevalence of subclinical enthesopathy in SpA patients and to evaluate the reliability of ultrasound in the detection of abnormal findings indicative of enthesopathy.

Methods: Six hundred lower-limb entheses were assessed in 60 SpA patients without known history of entheseal involvement. Sixty rheumatoid arthritis patients and 30 control subjects were included as control groups. Clinical examination and ultrasound were consecutively performed at each of the entheses to detect signs indicative of enthesopathy. Images from 20 SpA patients were stored and afterward evaluated to determine the reliability of abnormal ultrasound findings.

Results: Ultrasound detected a high prevalence of enthesopathy in SpA patients with respect to both rheumatoid arthritis patients and control subjects (P < 0.001 for both comparisons). In SpA patients, clinical examination detected enthesopathy in 56 (9.3%) of 600 entheses. In the remainder 544 clinically asymptomatic entheses (90.7%) (not painful and not swollen), ultrasound detected in 331 (60.8%) at least 1 ultrasound sign of enthesopathy. The intrareader and interreader agreement for all ultrasound abnormal findings was good to excellent.

Conclusion: The present study demonstrates a higher sensitivity of ultrasound with respect to physical examination in the detection of signs indicative of enthesopathy in SpA patients with an adequate interreader and intrareader reliability. Further study is needed about the prognostic value of the ultrasound findings for predicting clinical onset of entheseal involvement.