MILAN – Most people with recent-onset chronic back pain who are referred to a rheumatologist and then diagnosed with definite axial spondyloarthritis (axSpA) maintain that diagnosis over the next 2 years, but for those with residual diagnostic uncertainty for axSpA, particular characteristics may help to identify those who will or will not go on to receive a definite diagnosis, according to presentations given at the annual European Congress of Rheumatology.
Although a rheumatologist’s early axSpA diagnosis is reliable, new research also presented at the meeting reveals that the axSpA clinical phenotype presentation has great heterogeneity around the world, adding to the challenge.
These findings also dovetail with the consensus of an expert panel from the Assessment of SpondyloArthritis international Society (ASAS) that determined early axSpA should be defined by a duration of axial symptoms of less than 2 years, a move that should make research studies of early disease more consistent.
Diagnosis at first sight
To help in overcoming the long diagnostic delay typically encountered by patients with axSpA, researchers involved in the longitudinal Spondyloarthritis Caught Early (SPACE) cohort have sought to measure the prevalence of axSpA and the reliability of an early diagnosis in patients with chronic back pain (CBP). SPACE researcher Mary Lucy Marques, MD, a rheumatologist at Coimbra (Portugal) Hospital and University Center, and PhD student at Leiden (the Netherlands) University Medical Center, presented the main results of the study, which included patients younger than 45 years with CBP of unknown origin lasting 3 months to 2 years.
Patients referred to rheumatologists were judged at each visit for the presence or absence of axSpA, and the baseline judgment was reviewed after 2 years to assess its reliability. Baseline diagnostic judgments remained rather stable, and definite axSpA was present in one-third of the patients referred to the rheumatologist (175 out of 555 patients; 32%). After 2 years, the number of patients with definite axSpA diagnosis changed to 165, due to 5% of the definite diagnoses being refuted and 8% gaining a definite axSpA diagnosis. Among the features related to axSpA, the presence (or absence) of imaging-detected sacroiliitis at baseline was the best discriminator for a definite diagnosis at 2 years.
In commenting on these findings, Alexandre Sepriano, MD, PhD, assistant professor of rheumatology, NOVA Medical School, Lisbon, Portugal, who was not involved in the study, said: “These data show that the key is likely the referral of the ‘right patients’ to tertiary care centers. The [ASAS] has developed referral criteria that can be used for this purpose. According to these, patients with chronic low back pain starting before 45 years of age should be referred to a rheumatologist if at least one additional SpA feature is present.
Dr. Alexandre Sepriano
“It should be acknowledged that axSpA is not a disease of males only. In fact, there is a 1:1 ratio between males and females in the full spectrum of the disease. Also, although imaging findings are important, not all patients will have these. Similarly, not all patients with imaging abnormalities will have the disease, and their sole presence without other SpA features does not suffice for diagnosis.”