SSB and alkaline phosphatase measurement: SLE patients with AP presented with higher SLEDAI score (21.70 ± 10.32 versus 16.17 ± 7.51, P = 0.03), more organ system involvement (5.70 ± 1.56 versus 3.96 ± 1.15, P = 0.001), higher frequence of fever (77.78% versus 39.13%, P = 0.006), hepatological and hematological disorders (82.61% versus 34.78%, P = 0.01; 100% versus 60.87%, P = 0.001), serositis (62.96% versus 26.09%, P = 0.01), elevated CRP (81.82% versus 47.62%, P = 0.02), positive anti-La antibody (33.33% versus 0, P = 0.003), and higher mortality (37.04% versus 0, P = 0.001) compared to SLE patients without AP.