Numerical scoring for the Classic BILAG index.
OBJECTIVE
To develop an additive numerical scoring scheme for the Classic BILAG index.


METHODS
SLE patients were recruited into this multi-centre cross-sectional study. At every assessment, data were collected on disease activity and therapy. Logistic regression was used to model an increase in therapy, as an indicator of active disease, by the Classic BILAG score in eight systems. As both indicate inactivity, scores of D and E were set to 0 and used as the baseline in the fitted model. The coefficients from the fitted model were used to determine the numerical values for Grades A, B and C. Different scoring schemes were then compared using receiver operating characteristic (ROC) curves. Validation analysis was performed using assessments from a single centre.


RESULTS
There were 1510 assessments from 369 SLE patients. The currently used coding scheme (A = 9, B = 3, C = 1 and D/E = 0) did not fit the data well. The regression model suggested three possible numerical scoring schemes: (i) A = 11, B = 6, C = 1 and D/E = 0; (ii) A = 12, B = 6, C = 1 and D/E = 0; and (iii) A = 11, B = 7, C = 1 and D/E = 0. These schemes produced comparable ROC curves. Based on this, A = 12, B = 6, C = 1 and D/E = 0 seemed a reasonable and practical choice. The validation analysis suggested that although the A = 12, B = 6, C = 1 and D/E = 0 coding is still reasonable, a scheme with slightly less weighting for B, such as A = 12, B = 5, C = 1 and D/E = 0, may be more appropriate.


CONCLUSIONS
A reasonable additive numerical scoring scheme based on treatment decision for the Classic BILAG index is A = 12, B = 5, C = 1, D = 0 and E = 0.
Cresswell
Lynne
L
MRC Biostatistics Unit, University of Cambridge, Cambridge, UK.
Yee
Chee-Seng
CS
Farewell
Vernon
V
Rahman
Anisur
A
Teh
Lee-Suan
LS
Griffiths
Bridget
B
Bruce
Ian N
IN
Ahmad
Yasmeen
Y
Prabu
Athiveeraramapandian
A
Akil
Mohammed
M
McHugh
Neil
N
Toescu
Veronica
V
D'Cruz
David
D
Khamashta
Munther A
MA
Maddison
Peter
P
Isenberg
David A
DA
Gordon
Caroline
C
D000328:Adult; D018501:Antirheumatic Agents / Q000008:administration & dosage; D004334:Drug Administration Schedule; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis* / Q000188:drug therapy; D008297:Male; D008875:Middle Aged; D012720:Severity of Illness Index; D016896:Treatment Outcome
D018501:Antirheumatic Agents; D007166:Immunosuppressive Agents