Spondyloarthritis（SpA） patients attending Nanfang Hospital of Southern Medical University will generate a large number of clinical condition scales, laboratory indicators, imaging data such as X-rays or MRIs in the course of multiple standardized follow-up visits, as well as medical specimens from some of the patients who undergo surgical treatments. The Department of Orthopaedic Surgery of Nanfang Hospital is looking forward to the future and proposes to establish a specialized cohort named "Nanfang SpA Bidirectional Specialized Disease Cohort" by simply recording the clinical and imaging data of the above patients who have attended the clinic, been treated routinely, and have been followed up in the department without any interventional research measures. The cohort is proposed to: (1) archive the disease characteristics, biochemical index data, and disease assessment scales of all SpA patients attending the Southern Hospital; (2) record the X-ray and magnetic resonance imaging data of the patients to establish the "Southern SpA Imaging Dataset". This provides strong support for subsequent SpA research projects and lays the foundation for subsequent large-scale transect studies and retrospective studies.

In this study, on the basis of not imposing randomized or interventional treatments and not generating additional examination tests on patients, the chronic disease data formed by multiple visits of SpA patients using conventional treatment regimens were used to form a bi-directional, disease-specific cohort by means of data entry alone, consisting of: one SpA condition information dataset, one SpA imaging dataset.

SpA condition information dataset: enter the disease duration, symptom characteristics, family history, comorbidities, previous medication use and efficacy of all outpatient diagnosed SpA patients; for each natural visit time point, establish BASDAI and ASDASCRP scores to assess the disease activity, assess the patient's physical functioning by BASFI scale, and EQ-5D and SF-36 scales to assess the quality of life; Recorded labs for each visit such as CRP, ESR and anti-streptococcal hemolysin O (ASO), anti-streptococcal DNAase B (ADNS). The subject group will not direct patients to lab tests that are not prescribed by the attending physician.

SpA imaging dataset: all imaging data of patients diagnosed with SpA and naturally attending our clinic were recorded, including: MRI of sacroiliac joints, MRI of hips, MRI of cervical/lumbar/thoracic spine, and orthopantomogram of pelvis, CT of sacroiliac joints, or vascular ultrasound of sacroiliac joints and lower limbs, and the imaging data were archived after preliminary SPARCC and SPARCC SSS scores were made. The subject group would not direct patients to examinations that were not prescribed by the attending physician.

Inclusion Criteria:

• 1.Attended Nanfang Hospital, Southern Medical University, 2010-2030 2.Prospective cohort study component: subjects voluntarily participate with informed consent and sign an informed consent form 3.Retrospective cohort study: (i) patients who visited the hospital from April 2010 to April 2024 (and who will not return to the hospital at a later date) were exempted from informed consent; (ii) patients who visited the hospital from May 2024 to April 2025 were required to sign an informed consent 4.10 years old ≤ age ≤ 59 years old 5.Patients with a standardized diagnosis of spondyloarthritis by the following guidelines or diagnostic criteria, i.e., meeting one of the following diagnostic criteria: (1) 2009 ASAS classification criteria for axial spondyloarthritis; (2) 2011 ASAS classification criteria for peripheral spondyloarthritis

Exclusion Criteria:

• 1. Women who are pregnant, preparing for pregnancy or breastfeeding 2.Moderate to Severe Heart Failure (New York Heart Association Class 3-4) 3.Active peptic ulcers/bleeding 4.Judged by the investigator to be unsuitable for participation in this study

Spondyloarthritis (SpA) is a group of diseases characterized by inflammation of the sacro-skeletal joints and the tendon attachment points of the spine and peripheral joints, etc. The course of SpA is characterized by gradual progression, and it is divided into three main stages, from mild to severe, namely, undifferentiated SpA (uSpA), sacroiliac arthritis, and AS. The uSpA stage is characterized by a gradual progression.In the uSpA stage, the only manifestations are fat metaplasia or inflammation of the attachment points of the sacroiliac joints, while in the sacroiliac arthritis stage, subchondral intramedullary edema of the sacroiliac joints develops, and in the AS stage, sacroiliac erosion and fusion of the joints occur.