Background Spondyloarthritis is a heterogeneous disease, with various and hardly predictable potential courses. Determining prognostic factors in early disease remains a difficult task.
Objectives We aimed at determining prognostic factors of a bad functional outcome at 2 years in patients with early inflammatory back pain.
Methods Data from patients included in the French multicenter DESIR cohort, i.e. suffering from inflammatory back pain (IBP) starting before 50 years of age and lasting for between 3 months and 3 years, were used in this work . A bad functional outcome was defined as an increase in BASFI superior to 75th percentile of observed progression in the cohort from inclusion visit to 24-months assessment, or a BASFI at 2 years higher than 75th percentile at this latter timepoint. Demographic, clinical, biological and radiological data collected at inclusion were compared in patients with bad functional outcome versus others, first by Chi2 test (numeric data were dichotomized according to observed median values), then by multivariate logistic regression model with stepwise selection of relevant factors.
Results 513 patients (54.4% females, mean age 34±8.8 years, 72.2% fulfilling ASAS criteria) were assessed. Of those, 130 (25.3%) fulfilled the aforementioned criteria of a bad functional outcome (with BASFI increase of at least 4 units or value at 2 years ≥36). A bad outcome was more frequently observed in “older”patients aged over 33 years at disease onset, or with educational level lower than college (both p<0.0001). Smoking patients (p<0.001) and female patients (p<0.008) also had more frequently an unfavourable course of disease. Patients not fulfilling ASAS criteria, having negative X-Rays or MRI of sacroiliac joints, with a history or active peripheral arthritis were also more prone to have poor functional outcome (all p<0.05). A high disease activity at baseline (ASDASCRP>3.5 and BASDAI>45) was also associated with a bad functional evolution (p<0.0001). Multivariate analysis revealed that not fulfilling ASAS criteria, a female sex, an age>33 years, a lower educational level, an active smoking status and a high disease activity according to BASDAI at baseline were independently associated with a bad functional outcome at 24 months follow-up (Table).
Conclusions We confirmed, in a large prospective cohort of early IBP patients, bad prognostic factors formerly described in ankylosing spondylitis, especially a low educational level, a (relatively) older age and a high disease activity at onset, and revealed that an active smoking status was also independently associated with a poor outcome. Fulfilment of ASAS criteria on the other hand was predictive of a better outcome, likely due to more consensual management of a defined disease. Female sex however, usually regarded as a protective factor in AS, was related with a (self-assessed) poorer functional outcome after 2 years of follow-up.
Dougados et al. Joint Bone Spine 2011;78(6):598-603
Disclosure of Interest : None declared