The objective of this observational study is to compare the efficacy and safety of tixocutibine and belizumab in the treatment of systemic lupus erythematosus in patients aged 18-65 years with systemic lupus erythematosus. The main question it aims to answer is: In the overall population of systemic lupus erythematosus: What is the response rate (SRI-4) of the two drugs in treating systemic lupus erythematosus? Which drug has better efficacy and safety? This study is a retrospective study. The participants will not receive any treatment.

Inclusion Criteria:

• Age range: 18 - 65 years old;
• Meets the revised SLE classification criteria of the American College of Rheumatology in 1997 or the SLE diagnostic classification criteria issued by EULAR/ACR in 2019;
• SELENA-SLEDAI score of at least 8 points (clinical symptoms of no less than 6 points, excluding positive anti-double-stranded DNA (anti-dsDNA) and low complement);
• Patients who have been using tofacitinib or belimumab for at least 12 weeks.

Exclusion Criteria:

• Having active central nervous system diseases;
• eGFR < 30 mL/min/1.73m², or undergoing hemodialysis or kidney transplantation;
• Pregnant women, or women planning to get pregnant in the near future while taking the medication, or lactating women;
• Participants who are simultaneously participating in other clinical studies;
• Patients who have received treatment with tixagrel or belimumab for less than 12 weeks.

The inclusion period is from March 1, 2021 to March 1, 2024. Patients who visited the First Affiliated Hospital of Shandong University Medical University, the Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Wuhan University People's Hospital, and the Department of Nephrology of Capital Medical University Affiliated Beijing Friendship Hospital for clinical diagnosis of systemic lupus erythematosus were included.