Impact of Early Versus Late Systemic Lupus Erythematosus Diagnosis on Clinical and Economic Outcomes

Abstract

Systemic lupus erythematosus (SLE) is a multisystem complex autoimmune disease that often mimics symptoms of other illnesses, which complicates the ability of healthcare providers to make the diagnosis. The objective of this study was to assess clinical outcomes, resource utilization, and costs between patients with earlier versus later SLE diagnosis. Patients aged 18-64years were identified from a large US commercial claims database between January 2000 and June 2010. Confirmed SLE diagnosis with a claims-based algorithm required either three or more claims for a visit to a rheumatologist on separate dates with an SLE diagnosis (International Classification of Diseases [ICD-9] code 710.0x), two or more claims for visits to a rheumatologist at least 60days apart with SLE diagnoses, or two or more claims for visits to rheumatologist less than 60days apart with SLE diagnoses with at least one dispensing for a typical SLE medication. SLE probable onset date was identified during the 12-month baseline period by the second claim for antinuclear antibody tests or prodromal symptoms of SLE. Patients were stratified into early or late diagnosis groups based on time between probable SLE onset and diagnosis (<6months or ≥6months, respectively). Each patient observation period began on the date of the first medical claim, with a diagnosis code for SLE that satisfied the inclusion criteria, and ended on the earliest date between health plan disenrollment and 30 June 2010. Patients in each group were propensity-score matched on age, gender, diagnosis year, region, health plan type, and comorbidities. Flare rates and resource utilization were compared post-diagnosis between groups using rate ratios. All-cause and SLE-related costs (adjusted to 2010 US dollars) per patient per month (PPPM) were calculated. There were 4,166 matched patients per group. Post-SLE diagnosis, the early diagnosis group had lower rates of mild (rate ratio [RR]0.95; 95% CI 0.93-0.96), moderate (RR0.96; 95% CI 0.94-0.99), and severe (RR0.87; 95% CI 0.82-0.93) flares compared with the late diagnosis group. The rates of hospitalizations (RR0.80; 95% CI 0.75-0.85) were lower for the early diagnosis group than the late diagnosis group. Compared with late diagnosis patients, mean all-cause inpatient costs PPPM were lower for the early diagnosis patients (US$406 vs. US$486; p=0.016). Corresponding SLE-related hospitalization costs were also lower for early compared with late diagnosis patients (US$71 vs. US$95; p=0.013). Results were consistent for other resource use and cost categories. Patients diagnosed with SLE sooner may experience lower flare rates, less healthcare utilization, and lower costs from a commercially insured population perspective. This finding needs to be further explored within the context of background SLE disease activity.