History of BILAG

Origins of the BILAG Index

In the summer of 1983, the late Professor Paul Bacon (University of Birmingham) and his old friend Dr Michael Snaith (University College Hospital) discussed the unsatisfactory nature of the disease activity indices then used to assess patients with systemic lupus erythematosus (SLE). From the mid-1950s to the mid-1980s, around sixty different activity indices had appeared in the literature. All were global score indices: a patient with a particular clinical feature or blood test abnormality simply scored points, which sounds pleasingly simple but does not distinguish a feature that is improving from one that is unchanged or getting worse.

In conversations that started in Paul's rose garden in Birmingham, it was proposed that a better approach might use the principle of the physician's intention to treat. In brief, this meant a number of interested rheumatologists coming together to decide which particular groups of clinical features (or blood, urine or other investigation abnormalities) were of sufficient concern that a physician would recommend at least 20mg of steroids and/or immunosuppressive drugs. This became the Grade A (for action) assessment. Lesser but still significantly abnormal activity constituted a Grade B (for beware); a very mild set of features a Grade C (for contentment); Grade D implied the organ or system was not currently active; and Grade E that it had never been active at all.

The beauty of the system was that it provided a testable hypothesis. The original group consisted of Paul Bacon, Michael Snaith, Asad Zoma (Glasgow), Peter Maddison (then in Bath, later North Wales) and David Isenberg (UCLH). Dr, now Professor, Elaine Hay was appointed to travel to the five original BILAG centres and examine the notes of lupus patients, to determine whether a Grade A assessment had in fact been followed by the prescribed steroids or immunosuppression — validating the system and proving its reliability and sensitivity to change.

In the original publications (1988 and 1993), eight organs and systems were distinguished: constitutional, dermatological, central nervous system, musculoskeletal, cardiovascular-respiratory, vasculitis, renal and haematology. The group began meeting regularly in 1984.

Growth and the BILAG-2004 Revision

BILAG has continued to meet three times a year ever since — more than four decades later — and has expanded to around seventeen centres across the British Isles. The first major revision of the index was proposed in 2004 and, as with the original, the BILAG-2004 activity index was carefully scrutinised for its validity, reliability and sensitivity to change.

The key changes in that revision were the addition of two categories — ophthalmology and gastrointestinal — which the original index had not covered, alongside refinements to the renal section and the loss of a standalone vasculitis section, its questions redistributed among the other organs and systems. An attempt was also made to make a Grade B assessment rather harder to obtain.

The success of the BILAG system can be judged by the fact that virtually every international lupus trial now uses it, either on its own or alongside one of the better-known global score systems, the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) 2000.

Beyond the Index: Trials, Registers and Influence

BILAG's interests have expanded well beyond the development of activity indices. The group has carried out clinical trial work — notably a comparison of Azathioprine with Cyclosporine in the treatment of lupus nephritis — and other clinical studies, including the assessment of ultrasound in evaluating musculoskeletal disease. It makes considerable contributions to the British Isles Lupus Biologics Register (BILAG-BR, based at the University of Manchester), and has had important influence on NHS England policy, for example in facilitating access to Rituximab for lupus patients across the UK.

Other key contributions in this period include the development of SLE quality-of-life measurement (LupusQoL), further investigator-initiated trials including USEFUL and BEAT-LUPUS, collaborative translational research programmes such as MASTERPLANS, and innovation in disease activity capture through EASY-BILAG.

The first British Society for Rheumatology guideline on SLE, led by Caroline Gordon in 2017, marked another milestone in UK lupus care. In 2026, BILAG presents an updated BSR SLE guideline with unprecedented detail and scope, embracing a whole life-course approach to lupus management.

Following Paul Bacon's retirement, David Isenberg chaired the group from 1993 to 2019; Ed Vital (University of Leeds) is the current Chair. Under his chairmanship, BILAG remains committed to improving the care and quality of life of people with SLE, developing and promoting best practice in disease activity and outcome measurement, fostering collaborative research and innovation, steering the BILAG Biologics Register, and developing the next generation of clinical and academic lupologists. Current randomised controlled trials include FIRST (investigating first-line rituximab) and STRATIFY-LUPUS (investigating combination rituximab and belimumab with biomarker stratification).

Digital Evolution

In 2026, BILAG entered a new phase of digital transformation with the development of EasyBILAG-Digital, a next-generation platform designed to preserve the integrity of BILAG-2004 while improving usability, speed, structured assessment and data capture in both clinical practice and trials.

This digital evolution reflects the original founding philosophy: rigorous measurement, grounded in clinical intent, adapted to contemporary practice.

Explore EasyBILAG-Digital →