Early ASDAS Scores May Identify High-Risk Patients With SpA

Janis C. Kelly

December 05, 2016

Patients with axial spondyloarthritis (axSpA) who present with Ankylosing Spondylitis Disease Activity Scores (ASDAS) of 3 or higher at baseline are at increased risk of becoming disabled during the next 3 years, and this risk persists even in patients treated with tumor necrosis factor inhibitors (TNFis), researchers report in an article published online November 25 in the Annals of the Rheumatic Diseases.

Anna Molto, MD, PhD, from the Rheumatology Department, Groupe Hospitalier Cochin-Saint Vincent de Paul, Paris, France, and colleagues found that even in a country with wide access to biologics, better axSpA outcomes were associated with being male, having a higher degree of education, and white collar employment.

"In any case, physicians should be aware that when facing a patient with early axSpA, females with less formal education may be more at risk of persistent disease activity," the authors write.

Dr Molto told Medscape Medical News that the approach used in this study to define trajectories of disease should be readily translatable to clinical care. "Current recommendations highlight the importance of monitoring disease activity in SpA by patient-reported outcomes and [C-reactive protein]. ASDAS combines both, and is therefore an excellent tool to be used in clinical practice," Dr Molto said. ASDAS for the individual patient can be readily determined using an online calculator.

The researchers used data for 370 patients in the DESIR (Devenir des Spondyloarthrites Indifférenciées Récentes) cohort of patients with early inflammatory back pain to identify disease activity trajectories during a 3-year follow-up period, as well as both baseline characteristics and treatment and disability outcomes associated with each trajectory.

DESIR is a prospective, multicenter, longitudinal observational study of patients with early axSpA. Patients had back pain for more than 3 months but less than 3 years, and symptoms suggesting an SpA score of 5 or more on a scale of 0 to 10. All were TNFi-naive at baseline, and all fulfilled the Assessment in SpondyloArthritis Society criteria for axSpA at baseline and had at least three ASDAS values available during 3 years of follow-up.

Analysis of ASDAS scores over the course of 3 years revealed five trajectories of disease activity: persistent moderate disease activity (t1; n = 134, 36.2%), persistent inactive disease (t2; n = 66, 17.8%), changing from very high disease activity to inactive disease (t3; n = 29, 7.8%), persistent high disease activity (t4; n = 126, 34.1%), and persistent very high disease activity (t5; n = 15, 4.1%).

Study data also included age, sex, degree of education, blue collar (ie, physically demanding) vs white collar (sedentary) employment, employment status (working, on sick leave, or on permanent work disability), and days of sick leave. Multivariable multinomial regression analysis showed that patients from the t4 and t5 trajectories were five to eight times more likely to be declared work disabled during the 3-year follow-up period than those in the other three groups.

The researchers also found that initial high disease activity was more likely to become inactive in patients who were male, more highly educated, and/or had peripheral joint involvement.

The authors note that these different outcomes were apparent even though structural progression is typically slow in early axSpA.

Dr Molto told Medscape Medical News that the researchers were surprised to find that compared with the t1 "persistent moderate disease activity" group, more TNFi treatment was used by patients with t4 "persistent high disease activity" and t5 "persistent very high disease activity," as well as by those in t3, whose disease went from highly active to inactive.

Dr Molto said, "One might think that the group of patients that remained in the high disease activity trajectories were patients with more difficult access to health care. However, DESIR is a French cohort, and in France there is universal health care coverage. Furthermore, the proportion of patients who received a TNFi in those high disease categories was higher when compared to the moderate/inactive categories. Therefore, this leads to the conclusion that other factors besides access to care explain disease activity in axSpA."

Nortin M. Hadler, MD, emeritus professor of medicine and microbiology/immunology, University of North Carolina at Chapel Hill, who was not involved in the study, told Medscape Medical News that the consistency between the statistical modeling and clinical intuition, experience, and judgment are reassuring.

"Experienced clinicians are well aware that patients with persistent, high-level symptoms are more ill (a tautology) and more likely to experience functional compromise at work and at home. These models offer little for the care of the individual patients. It is possible they can be used in the design of clinical trials," said Dr Hadler, who is a member of the Spondylitis Association of America medical advisory board.

He added, "These are highly respected clinical investigators who are aware of the limitations of this analysis. As they discuss, their analysis does not allow them to parse the subjective/psychological variables that contribute to their measures of disease activity. It could be that the trajectories reflect differences in the degree to which coping is compromised."

The study authors and Dr Hadler have disclosed no relevant financial relationships.

Ann Rheum Dis. Published online November 25, 2016. Abstract

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