Studies with an enthesis index as a method of clinical assessment in ankylosing spondylitis

Abstract

The histopathological characteristic of ankylosing spondylitis (AS) is the presence of chronic enthesitis. Our aim was to develop a clinical measurement of the severity of tenderness over entheses. The scoring system was based on the patients' response to palpation over entheses easily accessible to examination. The enthesis index (EI) correlated with pain (r=0.67, p<0.01) and stiffness (r=0.46, p<0.05) scores. A single, blind, crossover study was conducted to determine the sensitivity of the index to change in clinical state associated with non-steroidal antirheumatic drug therapy and to record the interobserver variability. the index showed significantly lower scores after one week's drug treatment (p<0.05). The EI is a convenient, non-invasive measure of disease severity in patients with AS. Potential applications include the assessment of enthesitis in other polyarthritides and a means of distinguishing clinically between severity of enthesitis and synovitis in different types of polyarthritis.