Low dosage use of cyclophosphamide improves the survival of patients with systemic lupus erythematosus.

Objective: To investigate the effect of cyclophosphamide (CYC) on organ involvement and SLE patients' overall and cause-specific mortality.

Methods: Information about CYC prescription was taken from the Jiangsu Lupus database, which was set up to collect medical records from SLE patients since their first admission during 1999-2009 in Jiangsu province, China. Follow-up studies were carried out in 2010 and 2015 to check the survival status of the patients. Cox regression models were used to estimate the hazard ratio (HR) and 95% CI. Kaplan-Meier model was used to assess the effect of CYC on mortality between organ involvement and non-involvement.

Results: There were 221 deaths observed out of 2446 SLE patients. CYC users decreased overall mortality of SLE (8.4%) with adjusted HR (95% CI) of 0.74 (0.56-0.97), as compared to non-users. A decrease in overall mortality of SLE was found in the low dosage (< 600 mg) of CYC users, with adjusted HR (95% CI) of 0.54 (0.36-0.81). The protection of CYC on mortality of SLE was further observed in subgroups, such as female; SLEDAI score ≥ 15 group; and those with neuropsychiatric, renal, and hematological involvements, and low serum C3. In addition, CYC could eliminate the differences in mortality between organ involvement and non-involvement, including renal, neuropsychiatric, cardiopulmonary, gastrointestinal, and hematological involvement, but not for mucocutaneous and musculoskeletal involvement.

Conclusion: Low dosage use of CYC decreased the risk of overall mortality of SLE. CYC might improve the survival of SLE patients with renal, neuropsychiatric, cardiopulmonary, gastrointestinal, and hematological involvements. Key Points • Cyclophosphamide decreases overall mortality of SLE patients. • Decreased mortality is mainly observed from low dosage use of cyclophosphamide. • Cyclophosphamide improves the survival of SLE patients when major systems such as renal, neuropsychiatric, cardiopulmonary, gastrointestinal, and hematological are involved.