Part of the study results are consistent with previous clinical analysis, such as age, sex, course of disease, leukopenia, lymphopenia, CRP, and hypoproteinemia are not risk factors for SLE complicated by IFI; SLEDAI score, the use of GCs, immunosuppressant and antibiotics are risk factors for SLE complicated by IFI. The gene discussed is CRP; the disease is systemic lupus erythematosus.