Background/Purpose: Studying clinical effectiveness of belimumab treatment in real world clinical practice of Systemic Lupus Erythematosus (SLE) is relevant in assessing external validity of randomized controlled trials.

Methods: Retrospective chart review in 14 sites, including 58 patients. Primary objective: change in overall clinical manifestations assessed by a 6-point scale similar to PGA. Secondary objectives: change in SELENA SLEDAI; number of flares by mSS Flare index; steroid dose; other drugs and evaluation of health economic parameters, all assessed 6 months before and 6 (n: 58), 12 (n: 52) & & 18 (n: 25) months after treatment with 10±1 mg/Kg of belimumab. GSK sponsored this study #201282 (OBSErve).

Results: These results evaluate the use of Belimumab in the clinical practice setting in Argentina for up to 18 months. Baseline parameters: Age 41±13 yrs; female 91%; SLE duration ≥ 5 yrs 59%; hypocomplementemia 72%; high anti-dsDNA 64%; steroid dose ≥ 7.5 mg/day 77% and SELENA SLEDAI >10, 53%. Change in overall manifestations and secondary objectives are shown below:  

*p<0.001 ° 0,001 vs baseline (Wilcoxon)

The overall rate of suspension of steroids, azathioprine and belimumab after 18 months was 31%; 42% & 24% respectively. Key health economic parameters assessed did not vary after treatment although a tendency to reduced hospital admissions was observed (15,5% 6 months before treatment vs 6,7% pooled q6month after treatment, p: 0.09).

Conclusion: More than two thirds of patients obtained ≥ 50% overall response with relevant reductions in SELENA SLEDAI, number of flares, steroid and azathioprine treatment with sustained effects through 18 months follow up. Results are consistent with randomized controlled trials and similar observational real word studies performed in US and Europe therefore supporting the use of belimumab in our clinical practice.