Supplementary Table 1.

Eligibility criteria (PICOS) for systematic literature review

Criteria	Inclusion criteria	Exclusion criteria
Population	Adult patients (aged ≥18 years) with active or severe active AS Second-line patients who had inadequate response to previous treatments (e.g. conventional treatment with DMARDs, NSAIDs, and/or TNFis) Second-line patients who were intolerant to previous treatments (e.g. conventional treatment with DMARDs, NSAIDs, and/or TNFi) TNFi-naïve patients as long as they had demonstrated previous intolerance or inadequate response to conventional treatments	Children Patients with mild or early AS; if the population was mixed (i.e., mild to severe), the studies were excluded if data for active or severe active AS were not reported separately Non-radiographic axial spondyloarthritis Treatment-naïve patients Non-biologic treatments for AS (e.g. DMARDs, NSAIDs) Combinations of the therapies of interest
Intervention	Secukinumab Certolizumab pegol Etanercept Adalimumab Infliximab Golimumab Note: The interventions of interest in this review consist of all formulations or routes of administration of the listed treatments at labeled doses
Comparators	Interventions listed above Placebo
Outcomes (note that references were only limited by outcomes at full-text review stage)*	Efficacy ASAS score Proportion of patients achieving ASAS 20 response, ASAS 40 response, ASAS 70 response, or ASAS 5/6 response ASAS partial remission Proportion of patients achieving ASAS 20 or ASAS 40 response in the subgroup of patients who are TNFi-naïve, TNFi-IR, or are TNFi-intolerant Patient’s global assessment of disease activity Proportion of patients with inactive disease (ASDAS <1.3) Proportion of patients with clinically important change (defined as ASDAS improvement of ≥1.1) Proportion of patients with major improvement (defined as ASDAS improvement of ≥2.0) BASDAI score Spinal mobility assessed by BASMI [cervical rotation, maximal intermalleolar distance, lateral spinal flexion, lumbar flexion (modified Schober), tragus-to-wall distance], chest expansion, and occiput-to-wall distance BASFI score 44 tender and swollen joint count MASES Serum high-sensitivity C-reactive protein mSASSS score: proportion of patients with a relapse Patient assessment of spinal pain Health-related quality of life, including: ASQoL EQ-5D SF-36 HAQ FACIT-fatigue Safety Overall AEs Overall serious AEs Mortality Treatment-related mortality Discontinuations due to AEs Individual safety outcomes	None
Study design	Phase 2, 3, and 4 randomized, controlled, prospective clinical trials Long-term follow-up studies (e.g. open-label follow-up studies with continuation of treatments in their respective randomized group) Systematic reviews and meta-analyses†	Non-randomized clinical trials Preclinical studies Phase 1 studies Prognostic studies Retrospective studies Prospective observational studies Case reports Commentaries and letters (publication type) Consensus reports Non-systematic reviews
Language	All languages	None
Date	No limit	None

^*In line with the original review, studies were screened for outcomes only during the full-text review; at the title/abstract screening stage, any outcomes will be permitted

^†In line with the original review, systematic reviews, meta-analyses, and pooled analyses will be included at the title/abstract screening stage and used for identification of any additional primary studies not identified through the database searches, but will be excluded during the full-text review

AE: adverse event; AS: ankylosing spondylitis; ASAS: Assessment of SpondyloArthritis International Society; ASAS 20/40/70: 20%/40%/70% improvement in the ASAS response criteria; ASAS 5/6: 20% improvement in any five of the six domains in the ASAS response criteria; ASDAS: Ankylosing Spondylitis Disease Activity Score; ASQoL: Ankylosing Spondylitis Quality of Life; BASDAI: Bath Ankylosing Spondylitis Disease Activity Index; BASFI: Bath Ankylosing Spondylitis Functional Index; BASMI: Bath Ankylosing Spondylitis Metrology Index; DMARD: disease-modifying anti-rheumatic drug; EQ-5D: 5-dimensions EuroQol Questionnaire; FACIT: Functional Assessment of Chronic Illness Therapy; HAQ: Health Assessment Questionnaire; MASES: Maastricht Ankylosing Spondylitis Enthesitis Score; mSASSS: modified Stoke Ankylosing Spondylitis Spinal Score; NSAID: non-steroidal anti-inflammatory drug; PICOS: population, intervention, comparators, outcomes, and study design; SF-36: 36-item Short-Form Health Survey; TNFi: tumor necrosis factor inhibitor