Table 3.

Rates of SLE flares, as measured by modified definition, following initiation of belimumab before and after IS use stratified by baseline SLE disease severity

	Modified definition of SLE flaresa,b
	Moderate baseline SLE		Severe baseline SLE
	Patients initiating belimumab before IS use (N = 1909)	Patients initiating belimumab after IS use (N = 3252)	Patients initiating belimumab before IS use (N = 386)	Patients initiating belimumab after IS use (N = 862)
Rate of mild flares, PPYc, mean ± SEd
6 months	4.63 ± 0.071	5.20 ± 0.058	4.91 ± 0.163	5.27 ± 0.114
12 months	4.33 ± 0.050	4.87 ± 0.041	4.56 ± 0.115	5.09 ± 0.081
24 months	4.27 ± 0.038	4.76 ± 0.031	4.40 ± 0.087	5.02 ± 0.063
Rate of moderate flares, PPYc, mean ± SEd
6 months	2.12 ± 0.048	3.51 ± 0.047	2.74 ± 0.122	4.75 ± 0.108
12 months	1.96 ± 0.033	2.87 ± 0.031	2.42 ± 0.084	3.85 ± 0.071
24 months	1.84 ± 0.025	2.56 ± 0.023	2.29 ± 0.063	3.45 ± 0.052
Rate of severe flares, PPYc, mean ± SEd
6 months	0.35 ± 0.019	0.50 ± 0.018	0.99 ± 0.073	2.07 ± 0.071
12 months	0.32 ± 0.013	0.44 ± 0.012	0.89 ± 0.051	1.71 ± 0.047
24 months	0.28 ± 0.010	0.40 ± 0.009	0.70 ± 0.035	1.48 ± 0.034

HCRU healthcare resource utilization, IS immunosuppressant, PPY per person-year, SE standard error, SLE systemic lupus erythematosus

^aSLE flare episodes were identified and classified by severity on the basis of a previously published claims-based algorithm, which considers medications of interest and HCRU associated with an SLE diagnosis or SLE-related condition flare [26]

^bThe modified definition categorized initiation of IS as filling a prescription for an immunosuppressant > 60 days after the days’ supply of the former prescription ended

^cRate of PPY is calculated as the total number of visits across all patients divided by the total person-time of observation

^dSE of the population incidence rate is calculated as √(total number of events)/(total follow-up time)