The BASDAI is a validated self-reported instrument, which consists of six 10 unit horizontal Numeric Rating Scales to measure the disease activity of ankylosing spondylitis (AS) from the subject's perspective. It measures the severity of fatigue, spinal and peripheral joint pain and swelling, enthesitis, and morning stiffness (both severity and duration) over the last week. The final BASDAI scores ranges from 0 to 10, with lower scores indicating lower disease activity.

The ASAS20 response is the improvement of at least 20 % and absolute improvement of at least 1 unit on a 0 to 10 Numeric Rating Scale (NRS) in at least 3 of the 4 domains: Patient's Global Assessment of Disease Activity (PtGADA), Pain assessment (total spinal pain NRS scores), Function (Bath Ankylosing Spondylitis Functional Index (BASFI)), Inflammation (mean of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) questions 5 and 6 concerning morning stiffness intensity and duration) and absence of deterioration in the potential remaining domain.

The ASAS20 response is the improvement of at least 20 % and absolute improvement of at least 1 unit on a 0 to 10 Numeric Rating Scale (NRS) in at least 3 of the 4 domains: Patient's Global Assessment of Disease Activity (PtGADA), Pain assessment (total spinal pain NRS scores), Function (Bath Ankylosing Spondylitis Functional Index (BASFI)), Inflammation (mean of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) questions 5 and 6 concerning morning stiffness intensity and duration) and absence of deterioration in the potential remaining domain.

The ASAS20 response is the improvement of at least 20 % and absolute improvement of at least 1 unit on a 0 to 10 Numeric Rating Scale (NRS) in at least 3 of the 4 domains: Patient's Global Assessment of Disease Activity (PtGADA), Pain assessment (total spinal pain NRS scores), Function (Bath Ankylosing Spondylitis Functional Index (BASFI)), Inflammation (mean of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) questions 5 and 6 concerning morning stiffness intensity and duration) and absence of deterioration in the potential remaining domain.

The ASAS40 response is the relative improvement of at least 40 % and absolute improvement of at least 2 units on a 0 to 10 Numeric Rating Scale (NRS) in at least 3 of the 4 domains: Patient's Global Assessment of Disease Activity (PtGADA), Pain assessment (total spinal pain NRS scores), Function (Bath Ankylosing Spondylitis Functional Index (BASFI)), Inflammation (mean of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) questions 5 and 6 concerning morning stiffness intensity and duration) and no worsening at all in the remaining domain.

The ASAS40 response is the relative improvement of at least 40 % and absolute improvement of at least 2 units on a 0 to 10 Numeric Rating Scale (NRS) in at least 3 of the 4 domains: Patient's Global Assessment of Disease Activity (PtGADA), Pain assessment (total spinal pain NRS scores), Function (Bath Ankylosing Spondylitis Functional Index (BASFI)), Inflammation (mean of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) questions 5 and 6 concerning morning stiffness intensity and duration) and no worsening at all in the remaining domain.

The ASAS40 response is the relative improvement of at least 40 % and absolute improvement of at least 2 units on a 0 to 10 Numeric Rating Scale (NRS) in at least 3 of the 4 domains: Patient's Global Assessment of Disease Activity (PtGADA), Pain assessment (total spinal pain NRS scores), Function (Bath Ankylosing Spondylitis Functional Index (BASFI)), Inflammation (mean of Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) questions 5 and 6 concerning morning stiffness intensity and duration) and no worsening at all in the remaining domain.

The BASFI is a validated disease-specific instrument for assessing physical function. The BASFI comprises 10 items relating to the past week. The BASFI is the mean of the 10 scores such that the total score ranges from 0 to 10, with lower scores indicating better physical function.

The BASFI is a validated disease-specific instrument for assessing physical function. The BASFI comprises 10 items relating to the past week. The BASFI is the mean of the 10 scores such that the total score ranges from 0 to 10, with lower scores indicating better physical function.

The BASFI is a validated disease-specific instrument for assessing physical function. The BASFI comprises 10 items relating to the past week. The BASFI is the mean of the 10 scores such that the total score ranges from 0 to 10, with lower scores indicating better physical function.

Subjects will score their global assessment of their disease activity in response to the question 'how active was your spondylitis on average during the last week?' using a Numeric Rating Scale (NRS) where 0 is 'not active' and 10 is 'very active'.

Subjects will score their global assessment of their disease activity in response to the question 'how active was your spondylitis on average during the last week?' using a Numeric Rating Scale (NRS) where 0 is 'not active' and 10 is 'very active'.

Subjects will score their global assessment of their disease activity in response to the question 'how active was your spondylitis on average during the last week?' using a Numeric Rating Scale (NRS) where 0 is 'not active' and 10 is 'very active'.