BILAG INDEX
 

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The BILAG Index

Systematic Lupus Erythematosus (SLE) is a chronic disease affecting multiple human systems. Studies of the natural history of the disease and of the effect of therapeutic intervention have been hampered by the lack of a satisfactory method of assessing disease activity. In particular there is no good way of evaluating changes in disease activity which could be used to compare studies from different centres. The British Isles Lupus Assessment Group (BILAG) have addressed this problem and devised a comprehensive scoring system for assessing both current lupus disease activity and changes in that activity since the patient was last seen. The BILAG scoring system has now been in use over three decades and has been refined to improve its sensitivity.  In 1998 it was computerised by ADS-Limathon Ltd as the BLIPS program (British Lupus Integrated Prospective System). 

SLE is a complex multi-system disease. This complexity makes it difficult to monitor. In particular, there are problems in differentiating potential reversible organ dysfunction, due to disease activity, from irreversible organ damage. There is also a problem in defining the term 'activity' which contributes to an overall poor correlation between physicians' scores when assessing patients using a semi-quantitative clinical rating scale. Since the 1980's, the British Isles Lupus Assessment Group (BILAG) has developed standardised quantitative measures of clinical disease activity in SLE, in the process defining terms, which enable physicians to communicate in a common language.

The BILAG Index is a comprehensive computerised index for measuring for measuring clinical disease activity in Systemic Lupus Erythematosus (SLE). It was developed according to the principle of the 'physicians intention to treat'. The index allocates separate alphabetic scores to each of eight organ-based systems. A numeric score and total score has been added in BLIPS though this was not originally calculated. A study in 1993 demonstrated good 'between-rater' reliability for the BILAG index for each organ based system. There was no evidence of bias between observers. The BILAG Index had good overall sensitivity (87%) and specificity (99%) when compared with the 'Gold Standard' criterion (starting or increasing disease-modifying therapy). There were high positive predictive values overall, and for each organ-based system, with the exception of the neurological system. This exception can be explained by the activities of anticoagulants and other non-immunosuppresant therapies, which were used, but not evaluated.

A BILAG assessment consists of 86 questions; some based on the patient's history, some on examination findings and others on laboratory results. The questions are grouped under eight headings:

  • General (Gen)
  • Mucocutaneous (Muc)
  • Neurological (Cns)
  • Musculoskeletal (Msk)
  • Cardiovascular and Respiratory (Car)
  • Vasculitis (Vas)
  • Renal (Ren)
  • Haematological (Hae)

Additional non-scoring categories record supporting data in BLIPS

  • Biochemical (Bio)
  • Immunological (Imm)
  • Medication (Medi)
  • Other Drugs (Drug)

Many additional laboratory results can be stored but these do not form part of the scoring system. Based on answers, which you enter, the BLIPS software will calculate a clinical score. This scoring system has been derived by considering what features of SLE usually prompt a physician to increase disease-specific therapy (steroids or immunosuppresants). 

It is not the intention of the score to dictate treatment decisions. 


References

  • Hay EM, Bacon PA, Gordon C, Isenberg DA, Maddison P, Snaith ML, Symmons DPM, Viner N, Zoma A. The BILAG index: a reliable and valid instrument for measuring clinical disease activity in systemic lupus erythematosus. Quart. J. Medicine. 1993. 86: 447-458.
  • Isenberg DA, Gordon C. From BILAG to BLIPS- Disease activity assessment in lupus: past, present and future. Lupus. 2000. 9: 651-654.

 

 

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Last modified: August 20, 2008