C3 and cancer: In the univariate Cox proportional hazards analysis, several factors were significantly associated with an increased risk of Salmonella infection among patients with SLE, including male sex (HR 2.55, 95% CI: 1.07–6.07, p = 0.03), lymphoproliferative disorder or cancer (HR 3.08, 95% CI: 1.06–8.94, p = 0.04), leukopenia (HR 2.67, 95% CI: 1.19–6.02, p = 0.02), lymphopenia (HR 3.98, 95% CI: 1.83–8.68, p < 0.001), decreased C3 (HR 2.48, 95% CI: 1.13–5.47, p = 0.02), proteinuria (HR 4.06, 95% CI: 1.39–11.92, p = 0.01), and hepatitis (HR 3.17, 95% CI: 1.20–8.41, p = 0.02) (Table 3).