BERLIN – Patients with nonradiographic axial spondyloarthritis should be treated as aggressively as patients with ankylosing spondylitis, as the burden of disease is comparable based on clinical disease activity measures, pain levels, and global assessment scores.
Using data from registries and randomized controlled trials, Dr. Joachim Sieper, head of the medical clinic of rheumatology at the Benjamin Franklin University Clinic, Charité Medical University Berlin, compared disease burden in the two patient groups. "The question arises as to whether patients in the earlier phase of disease have a similar level of disease activity, pain, and stiffness as later-stage patients with ankylosing spondylitis," he said at the annual European Congress of Rheumatology.
Dr. Joachim Sieper
Dr. Sieper explained that it is known that a delay exists between the onset of symptoms and the final diagnosis of ankylosing spondylitis (AS). Data from the ABILITY 1 trial showed that time to diagnosis was delayed by a mean of 7.2 years in patients with nonradiographic axial spondyloarthritis.
Even when patients have symptoms, diagnosis can take several years, suggesting that referral needs to be considered earlier in patients presenting with symptoms.
Before the onset of structural damage, a diagnosis can be made on the basis of an MRI scan that shows bone inflammation, he explained. "However, we also know that MRI can have limited sensitivity, so we might miss some patients." It is possible, however, to classify these patients on the basis of clinical findings.
According to the new ASAS (Assessment of Spondyloarthritis International Society) classification criteria for axial spondyloarthritis, patients can be divided into those who have already developed radiographic damage as seen in the sacroiliac joints on x-ray, termed AS patients, and those who do not yet have structural damage, termed nonradiographic axial spondyloarthritis (nr axSpA) patients, who require MRI or clinical parameters for diagnosis (Best Pract. Res. Clin. Rheumatol. 2012;26:135-45).
Dr. Sieper analyzed baseline disease activity data derived from spondyloarthritis registries and randomized controlled trials to determine the extent of disease burden between the two classifications of axial SpA patients.
Analysis showed that the ages of patients between the two groups were similar across the databases, at around 35-40 years, as were the levels of human leukocyte antigen-B27 (HLA-B27) positivity. The ratio of females was higher in patients with nr axSpA (around 60%) than in patients with established AS (around 25%). "This is probably because females develop structural damage later, but they still have a similar level of inflammation all the time," he pointed out.
Scores on the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) hovered at 6.3-6.5 in both groups. Pain level and patient global assessment were similar in the two groups, according to the registry data and a randomized controlled trial.
The proportion of abnormal C-reactive protein levels was higher in the AS patients than in the nr axSpA patients (68% vs. 36%-38%, depending on the trial).
"The level of total pain is comparable no matter which of the groups a patient falls into," he said.
Nor were there differences between the groups in terms of patient and physician global assessment scores. The Patient’s Global Assessment of Disease Activity on a 0-10 visual analog scale was 5.0 for AS patients and 4.9 for nr axSpA patients, according to one trial.
Dr. Sieper disclosed ties with Abbott, Merck, Pfizer, and UCB.