Original articleCorrelations among clinical, radiographic, and sonographic scores for enthesitis in ankylosing spondylitis
Introduction
Inflammation of the entheses (enthesitis) is the main anatomic lesion in ankylosing spondylitis (AS) [1], [2]. The demonstration of enthesitis is crucial both to the diagnosis of AS and to the evaluation of disease activity [3]. Enthesitis cannot be convincingly demonstrated based on the clinical examination alone, as evidence of inflammation (swelling, redness, and warmth) is usually lacking and enthesitis may be difficult to distinguish from arthritis in a neighboring joint [1], [4], [5]. Inflammatory enthesitis is clinically detectable in only 10% of patients with early-stage AS and 50% of those with established AS [6]. Several indices have been developed for the clinical evaluation of enthesitis in AS. The earliest is the Mander Enthesitis Index (MEI), which evaluates 66 entheseal sites [7]. However, determining the MEI is often an exacting task. Consequently, several other indices were developed [8], [9], [10], including the Modified Mander Enthesitis Index [8], the Major Enthesitis Index in 2002 [9], the Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) in 2003 [11], and the Spondyloarthritis Research Consortium of Canada (SPARCC) [12] in 2008. None of them has achieved universal recognition [13], as each has advantages and limitations according to OMERACT Filter criteria [14]. The MASES remains the most widely used index, as it has good metrological properties and includes the main peripheral and axial entheseal sites involved in AS. The SPARCC is a new tool that evaluates only the peripheral entheses, which are easier to access for radiographic and sonographic imaging. Thus, the SPARCC may be well suited to comparisons of clinical and imaging data. Radiography remains the first-line investigation for enthesopathies, although the radiographic changes take time to develop after the onset of the inflammatory process [11]. Very few studies have focused on the radiographic evaluation of enthesitis and, to our knowledge, no radiographic enthesitis scores have been developed. Many recent studies have established that ultrasonography coupled with power Doppler imaging is useful for the early diagnosis of enthesitis [15], [16], [17]. This method provides an evaluation of disease activity at target sites and shows changes in either direction (improvement or exacerbation) in the short term. Among sonographic indices, the most widely used seem to be the Glasgow Ultrasound Enthesitis Scoring System (GUESS) [18], Sonographic Entheseal Index (SEI) [19], and Ultrasound Enthesis Score [15]. However, these indices have a few limitations. The GUESS fails to take into account some of the signs of acute enthesitis such as peritendinous edema, hypoechogenicity, and hypervascularization; whereas the SEI fails to include the Doppler imaging results [18], [19].
The objectives of our study in patients with AS were:
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to perform a clinical evaluation of enthesitis;
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to describe the distinctive radiographic and sonographic features of enthesitis;
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to look for correlations among the clinical, radiographic, and sonographic scores.
Section snippets
Methods
We prospectively studied 60 consecutive patients meeting modified New York criteria for AS [20] and seen at the rheumatology department of the M. Kassab Institute in Manouba, Tunisia. We excluded patients having a history of knee or ankle surgery, local corticosteroid injection at the study sites within the six weeks before the clinical and sonographic evaluation, or lower limb neuropathy.
Patient characteristics
We studied 60 patients, 48 (80%) men and 12 women with a mean age of 36 ± 11 years (range, 20–74 years) and a mean disease duration of 8.8 years (range, 0.5–25 years). Laboratory tests indicated systemic inflammation in 51 patients; mean ESR was 33 ± 22 (range, 2–98) and mean serum CRP was 16.9 ± 38 mg/L (range, 0–240 mg/L). Table 1 reports the AS-specific scores and the clinical, radiographic, and sonographic enthesitis scores. Table 2 shows the distribution across entheseal sites of the clinical,
Discussion
Enthesitis is now viewed as the most typical histopathological abnormality in AS [1], [4], [6], [24]. The importance of enthesitis in AS was long underestimated, because no objective assessment tools were available. Since 1987, several clinical indices have been developed for the assessment of enthesitis. At present, preference is given to concise indices, as they offer better feasibility with similar sensitivity compared to the more time-consuming indices [11], [25]. Thus, the MASES is a good
Conflict of interest statement
The authors declare no conflicts of interest.
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