Objectives: Studies on the incidence of spondyloarthritis (SpA) are scarce. Early SpA clinics should facilitate the detection of new cases as well as to decrease the diagnosis and treatment delay. However, the workload of such clinics has not been estimated.
Methods: ESPIDEP is a pilot registry of patients with early SpA performed in Madrid, Spain. General practitioners (GPs) agreed and were trained to refer all patients under 45 with either inflammatory back pain or asymmetric arthritis of lower limbs with 3 to 24 month duration of symptoms to a specialised unit during 6 consecutive months. Case definition of SpA was based on the ESSG criteria. The success of the program was measured by: the satisfaction of the GPs regarding the referral process, the percentage of patients correctly derived according to the rheumatologist, the expected incidence of AS.
Results: From a population of 111,941, the unit attended 52 patients, of whom 43 (83%) had been derived correctly and 35 were diagnosed with SpA (49% women; mean age 33+/-8; mean duration of symptoms 11+/-6 months; 46% HLA-B27 positive). The annual estimated incidence of SpA was 62.5 cases per 100,000 (95% CI: 45-87). Only 20/35 (57%) had radiological sacroiliitis and 4 (11.8%) fulfilled the modified New York criteria for ankylosing spondylitis (annual estimated incidence 7.2 per 100,000 (IC95%: 3.1-14.1)).
Conclusions: Around 60 cases of early SpA are expected annually in an area of 100,000. A referral based upon clinical parameters seems efficient. The planning of early SpA clinics may be based upon these figures.