Frequency, severity and costs of flares increase with disease severity in newly diagnosed systemic lupus erythematosus: a real-world cohort study, United States, 2004–2015

OBJECTIVE: To evaluate frequency, severity and costs of flares in US patients with newly diagnosed SLE. METHODS: Adults diagnosed with SLE between January 2005 and December 2014 were identified from US commercial claims data linked to electronic medical records. Disease and flare severity during 1 year after diagnosis were classified as mild, moderate or severe using a claims-based algorithm. Study outcomes included frequency and severity of flares stratified by disease severity during the 1-year post-diagnosis period and all-cause healthcare costs of flares by severity at 30, 60 and 90 days after flare. RESULTS: Among 2227 patients, 26.3%, 51.0% and 22.7% had mild, moderate and severe SLE, respectively. The overall annual flare rate was 3.5 and increased with disease severity: 2.2, 3.7 and 4.2, respectively, for mild, moderate and severe SLE (p<0.0001). Patients with severe SLE had a higher annual severe flare rate (0.6) compared with moderate (0.1) or mild SLE (0; p<0.0001). Mean total all-cause costs at 30, 60 and 90 days after flare were $16 856, $22 252 and $27 468, respectively, for severe flares (mild flares: $1672, $2639 and $3312; moderate flares: $3831, $6225, $8582; (p<0.0001, all time points)). Inpatient costs were the primary driver of the increased cost of severe flares. CONCLUSIONS: Flare frequency and severity in newly diagnosed patients with SLE increase with disease severity. After a flare, healthcare costs increase over the following 90 days by disease severity. Preventing flares or reducing flare rates and duration may improve outcomes and reduce healthcare costs.