Confidence in the diagnosis of early spondylarthropathy: a prospective follow-up of 270 early arthritis patients

OBJECTIVE: To study the confidence of office-based rheumatologists (OBR) and a college of 5 experts in their diagnosis of spondylarthropathy (SpA) for early arthritis after more than 2 years of follow-up; to determine whether at that time the degree of confidence was improved by the fulfilment of the ESSG criteria. METHODS: 270 patients with early-onset (< 1 year) arthritis were prospectively followed-up for 29+/-11 months. At the final examination, OBR and the college of 5 experts rated their confidence in the diagnosis of SpA on a 0-10 analogue scale and on a 1-4 Likert scale, respectively. RESULTS: After 29+/-11 months OBR had classified 56 patients (21%) as SpA, while a collegial diagnosis of probable (N = 32) or certain SpA (N = 14) was made for 46 patients (17%). At the final examination OBR confidence in their diagnosis (gold standard) was only 6.7+/-2.4 for all 56 cases of SpA. The cumulative fulfilment of ESSG criteria for SpA after 29+/-11 months correlated with the confidence of OBR and the experts in SpA, but improved only slightly the final confidence of OBR (7.1+/-2.3 versus 6.7+/-2.4 for all 56 SpA). Similarly, OBR confidence for the 18/56 SpA patients positive for HLA-B27 was only 7.1+/-2.0. Only 21 of these 56 patients were considered as SpA at baseline, although 37/56 (66%) had fulfilled ESSG criteria since thefirst examination. CONCLUSION: This study indicates a probable lack of consensus on the nosology of early SpA and the limited help provided by the ESSG criteria to differentiate early SpA from otherforms of arthritis at baseline.