The Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) is a 6-item instrument used to measure disease activity in participants with ankylosing spondylitis. It evaluates fatigue, spinal pain, peripheral joint pain and swelling, localized tenderness, and morning stiffness (severity and duration) over the past week. Each item is scored on a 0 to 10 scale, with higher scores indicating greater disease activity. The total BASDAI score is calculated as 0.2 × (Item 1 + Item 2 + Item 3 + Item 4 + (Item 5 + Item 6)/2) and ranges from 0 to 10. Higher scores indicate worse disease activity. A BASDAI score of 4 or higher is commonly considered to indicate high disease activity.

The Ankylosing Spondylitis Disease Activity Score based on C-reactive protein (ASDAS-CRP) is a composite index used to measure disease activity in participants with ankylosing spondylitis. It combines patient-reported items and C-reactive protein (CRP) levels into a single score. The minimum score is 0, with lower scores indicating lower disease activity and higher scores indicating worse disease activity. There is no fixed maximum value because the upper end of the scale depends on the CRP level. ASDAS-CRP disease activity states are defined as inactive disease (<1.3), moderate disease activity (1.3 to <2.1), high disease activity (2.1 to ≤3.5), and very high disease activity (>3.5). Clinically important improvement is defined as a decrease of at least 1.1 units, and major improvement is defined as a decrease of at least 2.0 units.

The Bath Ankylosing Spondylitis Metrology Index (BASMI) is an instrument used to measure axial skeletal mobility in participants with ankylosing spondylitis. The total score ranges from 0 to 10. Lower scores indicate better spinal and hip mobility, while higher scores indicate greater limitation of movement and worse axial mobility.

The Ankylosing Spondylitis Quality of Life Scale (ASQoL) is a patient-reported instrument used to measure the impact of ankylosing spondylitis on health-related quality of life. The total score ranges from 0 to 18. Lower scores indicate better quality of life, while higher scores indicate worse quality of life.

Pain due to ankylosing spondylitis measured on a 0 to 10 Visual Analogue Scale (VAS) over the past week, where 0 indicates no pain and 10 indicates the most severe pain. Higher scores indicate worse pain.

Serum C-reactive protein (CRP) level measured in blood as a laboratory marker of systemic inflammation in participants with ankylosing spondylitis. Higher CRP levels indicate greater systemic inflammation.

Number of participants who experience adverse events (AEs) or serious adverse events (SAEs), including gastrointestinal reactions, abnormal liver function, abnormal kidney function, and cardiovascular events, as identified from participant-reported symptoms, routine blood and urine tests, fecal occult blood tests, liver and kidney function tests, and electrocardiograms.

Adherence to prescribed traditional Chinese medicine and Western medicine during the 2-year follow-up period, based on participant-reported and recorded medication use.

Time from the first dose of Western medication to the permanent discontinuation of any Western medication used for ankylosing spondylitis, including non-steroidal anti-inflammatory drugs (NSAIDs) and disease-modifying antirheumatic drugs (DMARDs).

Use of non-steroidal anti-inflammatory drugs (NSAIDs) during the study period and changes over time, including NSAID type, dose, frequency, and duration, based on participant-reported and recorded medication use.