The use of the British Isles Lupus Assessment Group (BILAG) index as a valid tool in assessing disease activity in childhood-onset systemic lupus erythematosus

Objectives. The British Isles Lupus Assessment Group (BILAG) index is a standardized systemic lupus erythematosus (SLE) disease activity assessment. The main aim of this study was to correlate the BILAG index with laboratory measures of disease activity in childhood-onset SLE with and without biopsy-proven lupus nephritis. Method. Prospective observational comparison study of the BILAG index in 21 SLE patients under 18 yr of age over a 12-month period in a tertiary referral paediatric outpatient clinic. Results. Eleven patients with lupus non-nephritis and 10 patients with lupus nephritis were reviewed. The lupus nephritis patients had significantly (P<0.001) more admissions over a similar time interval since diagnosis. The renal BILAG disease activity scores were significantly greater (P = 0.013) in the lupus nephritis group (range 1-9, median 3.0, compared with 0-3 and 1.0 in the lupus non-nephritis group). The total BILAG scores and patient visual analogue scores (VAS) were higher in the lupus nephritis groups, unlike the lower physician VAS, but these differences were not statistically significant compared with other laboratory indices of disease activity. Conclusions. The BILAG index is a useful tool in monitoring disease activity in children and adolescents with SLE. The data collected for the BILAG index can be used serially and effectively by different clinicians over time to enable recording of disease status at sequential assessments. The lower patient VAS in the lupus non-nephritis group was not significant and may reflect the patients' own perception of lethargy at times of increased disease activity.