Objective: We evaluated the discriminant capacity of the Lupus Low Disease Activity State (LLDAS) in post-hoc analysis of data from the BLISS-52 and BLISS-76 trials of belimumab in systemic lupus erythematosus (SLE). Methods: LLDAS attainment, discrimination between belimumab and placebo arms, and the effects in subgroups with high disease activity at recruitment were evaluated at week 52 using appropriate descriptive statistics, Ï ‡2 test and logistic regression. Results: At week 52, for belimumab 10 mg/kg, 17.0% and 19.3% of patients who achieved a Systemic Lupus Erythematosus Responder Index-4 also attained LLDAS in BLISS-52 and BLISS-76, respectively. Significantly more patients attained LLDAS on belimumab 10 mg/kg compared with placebo (12.5% vs 5.8%, OR 2.32, p=0.02 for BLISS-52; 14.4% vs 7.8%, OR 1.98, p=0.04 for BLISS-76). In a subgroup analysis, the difference in week 52 LLDAS attainment between belimumab 10 mg/kg and placebo was greater in patients who had higher disease activity at baseline, compared with the overall group. Conclusions: LLDAS was able to discriminate belimumab 10 mg/kg from placebo in the BLISS-52 and BLISS-76 trials. Our findings support the validity of LLDAS as an outcome measure in SLE clinical trials.