The Bath Ankylosing Spondylitis Activity and Function Indices (BASDAI and BASFI) and their correlation with main symptoms experienced by patients with spondyloarthritis

With the aim of assessing whether the Bath Ankylosing Spondylitis Activity and Function Indices (BASDAI and BASFI) are reliable measures of disease activity and function in patients with spondyloarthritides (SpAs), 341 patients with SpA (representing ankylosing spondylitis (14.5%), psoriatic arthritis (27.3%), enteropathic arthritis (6.3%), reactive arthritis (4.9%), and undifferentiated arthritis (46.5%) were asked to complete the BASDAI and BASFI. They were asked to report what their main problems associated with the disease were from a list of seven symptoms: fatigue, neck pain, upper back pain, lower back pain, stiffness, joint pain or swelling, and pain with pressure on joints. Correlations between the main symptoms experienced by patients with SpAs and the indices, defined by Spearman’s correlation coefficient, showed that BASDAI best correlated with neck pain [BASDAI 2 and total BASDAI score correlate strongly (p = 0.003 and 0.001, respectively), and BASDAI 1, 4, and 5 correlate moderately (p = 0.03, 0.02, and 0.01, respectively)], followed by stiffness, upper back pain, pain with pressure, lower back pain, fatigue, and joint pain. Stiffness correlated strongly with nine of ten items on BASFI (BASFI 1 showed moderate correlation, p = 0.01), followed by upper back pain (four of ten items correlated strongly, three of ten correlated moderately), neck pain (three of ten tasks correlated strongly and four of ten correlated moderately), lower back pain (one task correlated strongly, five moderately), joint pain and swelling (four tasks correlated moderately), fatigue (three tasks correlated moderately), and pain with pressure (two tasks correlated moderately). BASDAI and BASFI only partly reflect disease activity and patients’ functional capacity in SpAs. An alternate instrument is required to assess SpA disease activity and functional capacity more precisely.