Arthritis & Rheumatism, Volume 63,
November 2011 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Chicago, Illinois November 4-9, 2011.


Longitudinal Assessment of SLE Disease Activity: BILAG-2004, SLEDAI-2000 or Both?

Yee1,  Chee-Seng, Gordon1,  Caroline, Isenberg2,  David A., Griffiths3,  Bridget, Teh4,  Lee- Suan, Bruce5,  Ian N., Ahmad6,  Yasmeen

University of Birmingham, Birmingham, United Kingdom
Southhampton General Hospital, Southampton, United Kingdom
St. Thomas' Hospital, London, United Kingdom
Lupus Research Unit, The Rayne Institute, Kings College London School of Medicine, London, United Kingdom
MRC Biostatistics Unit, Cambridge, United Kingdom
University College London, London WC1E 6JF, United Kingdom
Freeman Hospital, Newcastle Upon Tyne, United Kingdom
Royal Blackburn Hospital, Blackburn, United Kingdom
A, Manchester, United Kingdom
The Department of Rheumatology, Betsi Cadwaladr University Health Board (West), Llandudno, LL30 1LB, UK, Wales, United Kingdom
University College London, London, United Kingdom
Sheffield Center Rheumatic Dis, Sheffield South Yorkshire, United Kingdom
Royal National Hospital for Rheumatic Diseases, Bath, United Kingdom

Background/Purpose:

This analysis was to compare the responsiveness of BILAG-2004 and SLEDAI-2000 indices and to determine if there was any added value in combining the two indices.

Methods:

This was an analysis of a longitudinal study of SLE patients where data were collected on BILAG-2004, SLEDAI-2000 and therapy at every visit. The external responsiveness of the indices was assessed by determining the relationship between change in disease activity and change in therapy between two consecutive visits. The indices were compared by assessing the main effects of the indices using logistic regression. The recently developed new methods of analysing BILAG-2004 system scores, BILAG-2004 systems tally (BST) and simplified BST (sBST), were also assessed. Receiver operating characteristics (ROC) curves analyses were used to describe the performance of these indices individually or in various combinations of the two. Sensitivity, specificity, PPV, NPV and AUC were estimated.

Results:

There were 1414 observations from 347 patients. Both indices maintained an independent relationship with change in therapy when compared. Tables 1 and 2 summarises the performance of the two indices and various combinations of the two, as dichotomous variables.

Table 1. Sensitivity, specificity, PPV, NPV and AUC of deterioration in disease activity on increase in therapy

Deterioration in scoreSensitivity % (95% CI)Specificity % (95% CI)PPV % (95% CI)NPV % (95% CI)AUC
BILAG-2004 deterioration in score53.9 (48.6, 59.1)92.8 (90.7, 94.4)68.7 (62.4, 74.3)87.3 (85.0, 89.2)0.73
SLEDAI-2000 Increase >= 147.4 (41.6, 53.2)82.4 (80.0, 84.6)44.2 (39.0, 49.5)84.2 (81.6, 86.5)0.65
SLEDAI-2000 Increase >= 328.7 (23.7, 34.2)95.4 (94.0, 96.5)64.8 (56.8, 72.0)82.0 (79.5, 84.3)0.62
BILAG-2004 deterioration in score or SLEDAI-2000 Increase >= 165.1 (59.4, 70.4)79.2 (76.5, 81.7)47.9 (43.2, 52.7)88.5 (86.1, 90.6)0.72
BILAG-2004 deterioration in score or SLEDAI-2000 Increase >= 358.3 (52.7, 63.6)90.6 (88.4, 92.4)64.5 (58.8, 69.8)88.1 (85.8, 90.0)0.74

Table 2. Sensitivity, specificity, PPV, NPV and AUC of improvement in disease activity on decrease in therapy

Improvement in scoreSensitivity % (95% CI)Specificity % (95% CI)PPV % (95% CI)NPV % (95% CI)AUC
BILAG-2004 improvements (with no deterioration)54.1 (49.4, 58.7)65.2 (62.2, 68.0)48.0 (43.6, 52.4)70.5 (66.7, 74.0)0.60
BILAG-2004 improvement to C/D (with no deterioration)52.8 (48.1, 57.3)66.1 (63.1, 68.9)48.0 (43.5, 52.5)70.2 (66.4, 73.7)0.59
SLEDAI-2000 Decrease >= 138.7 (34.7, 42.9)77.0 (74.2, 79.6)50.0 (45.1, 54.9)67.9 (64.4, 71.2)0.58
SLEDAI-2000 Decrease >= 418.8 (15.4, 22.7)90.3 (88.2, 92.1)53.5 (46.2, 60.6)65.2 (62.0, 68.3)0.55
SLEDAI-2000 Decrease >= 4 with no BILAG-2004 deterioration (similar to SRI)1.5 (0.8, 2.9)98.9 (97.9, 99.4)44.4 (23.5, 67.6)62.8 (59.8, 65.7)0.50
BILAG-2004 improvements with no SLEDAI-2000 increase >= 148.2 (43.8, 52.6)70.0 (67.2, 72.7)48.8 (44.2, 53.5)69.5 (65.9, 72.8)0.59
BILAG-2004 improvements (and no deterioration) with no SLEDAI-2000 increase >= 148.2 (43.8, 52.6)70.0 (67.2, 72.7)48.8 (44.2, 53.5)69.5 (65.9, 72.8)0.59
BILAG-2004 improvements (and no deterioration) with no SLEDAI-2000 increase >= 352.9 (48.3, 57.5)66.3 (63.3, 69.1)48.3 (43.8, 52.8)70.3 (66.6, 73.8)0.60
BILAG-2004 improvement to C/D (and no deterioration) with no SLEDAI-2000 increase >= 147.1 (42.8, 51.4)70.8 (68.0, 73.5)48.9 (44.2, 53.6)69.2 (65.7, 72.6)0.59
BILAG-2004 improvement to C/D (and no deterioration) with no SLEDAI-2000 increase >= 351.6 (47.0, 56.2)67.2 (64.2, 70.0)48.3 (43.8, 52.9)70.0 (66.3, 73.5)0.59

Both indices had better performance when analysed as non-dichotomous variables (predominantly counts or continuous variables). The AUC from ROC analysis for increase in therapy are: BILAG-2004 system scores 0.75, BST 0.83, sBST 0.81, SLEDAI-2000 variables (change in score and previous visit score) 0.76, combination of BST and SLEDAI-2000 variables 0.84, and combination of sBST and SLEDAI-2000 variables 0.83. The AUC from ROC analysis for decrease in therapy are: BILAG-2004 system scores 0.65, BST 0.66, sBST 0.65, SLEDAI-2000 variables 0.63, combination of BST and SLEDAI-2000 variables 0.67, and combination of sBST and SLEDAI-2000 variables 0.67. There was minimal improvement in the performance when SLEDAI-2000 variables were combined with BST or sBST.

Conclusion:

We recommend the use of counts or continuous variables, due to improved efficiency and performance over dichotomous variables, in clinical trials. BST and sBST appear to have better performance than SLEDAI-2000 in assessment of SLE disease activity longitudinally, especially for deterioration in disease activity. There is minimal benefit in combining the indices. These findings should be investigated further with trial data.

To cite this abstract, please use the following information:
Yee, Chee-Seng, Gordon, Caroline, Isenberg, David A., Griffiths, Bridget, Teh, Lee- Suan, Bruce, Ian N., et al; Longitudinal Assessment of SLE Disease Activity: BILAG-2004, SLEDAI-2000 or Both? [abstract]. Arthritis Rheum 2011;63 Suppl 10 :601
DOI:

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