 In 1994, a research team consisting of rheumatologists, physiotherapists, and others with a special interest in Ankylosing Spondylitis, developed the index in Bath, England (hence the reason for "Bath" in the name), describing a self-administered 6-question measurement tool that later become the gold standard for measuring and evaluating AS disease activity.BASDAI is a quick and simple measure taking between 30 seconds and 2 minutes to complete.BASDAI demonstrates statistically significant (p<0.001) reliability and incorporates a reasonable scale.