[Evaluation of performance of BASDAI (Bath Ankylosing Spondylitis Disease Activity Index) in a Brazilian cohort of 1,492 patients with spondyloarthritis: data from the Brazilian Registry of Spondyloarthritides (RBE)].

Objective: To analyze the results of the application of the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in a large series of Brazilian patients with the diagnosis of SpA and establish its correlations with specific variables into the group.

Methods: A common protocol of investigation was prospectively applied to 1492 Brazilian patients classified as SpA according to the European Spondyoarthropathies Study Group (ESSG), attended at 29 referral centers of Rheumatology in Brazil. Clinical and demographic variables, and disease indices (BASDAI, Basfi, Basri, Mases, ASQol) were applicated. The total values of BASDAI were compared to the presence of the different variables.

Results: The mean score of BASDAI was 4.20 ± 2.38. The mean scores of BASDAI were higher in patients with the combined (axial + peripheral + entheseal) (4.54 ± 2.38) clinical presentation, compared to the pure axial (3.78 ± 2.27) or pure peripheral (4.00 ± 2.38) clinical presentations (p<0.001). BASDAI also presented higher scores associated with the female gender (p<0.001) and patients who did not practice exercises (p < 0.001). Regarding the axial component, higher values of BASDAI were significantly associated with inflammatory low back pain (p<0.049), alternating buttock pain (p<0.001), cervical pain (p<0.001) and hip involvement (p<0.001). There was also statistical association between BASDAI scores and the peripheral involvement, related to the lower (p=0.004) and upper limbs (p=0.025). The presence of enthesitis was also associated to higher scores of BASDAI (p=0.040). Positive HLA-B27 and the presence of cutaneous psoriasis, inflammatory bowel disease, uveitis and urethritis were not correlated with the mean scores of BASDAI. Lower scores of BASDAI were associated with the use of biologic agents (p<0.001).

Conclusion: In this heterogeneous Brazilian series of SpA patients, BASDAI was able to demonstrate "disease activity" in patients with axial as well as peripheral disease.