BACKGROUND  

There is no international consensus for the pathological classification of IgA nephropathy [IgAN]. A number of classifications are in use, and have their supporters. This lack of consensus is a significant disadvantage in developing systems with increasing power to predict outcome for both individuals and cohorts of patients, in making international comparisons between different outcome studies, and in refining the stratification of risk for the design of clinical intervention trials.

A proposal to develop a consensus classification came forward simultaneously from the International IgA Nephropathy Network  [chair – John Feehally (Leicester)] - an informal network of nephrologists and scientists with representation from the majority of nephrology research groups around the world active in the field of IgAN [www.igan-world.org] and from two renal pathologists: Mark Haas [Chicago], originator of one widely used classification, and  Terry Cook [London]. A questionnaire sent by Terry Cook to members of the Renal Pathology Society indicated support among renal pathologists for the development of a consensus classification. The development of the this classification will be greatly helped by the experience gained in generating the recently published revised classification of lupus glomerulonephritis (Weening et al J Am Soc Nephrol 15:241-250, 2004) since many of the pathologists involved with that project are also involved with the IgAN consensus

Steering Committee

A small steering committee has been established to oversee the organisation and development of this programme. It has been chose to represent equally pathologists and nephrologists from three continents

  Pathologists                North America  Mark Haas [Baltimore]

                                    Europe            Terry Cook [London]

                                    Asia                 Fernand Lai [Hong Kong]

  Nephrologists               North America  Daniel Cattran [Toronto]

                                    Europe             John Feehally [Leicester]

                                    Asia                 Yasuhiko Tomino [Tokyo]  

  A successful introductory meeting was held in St Louis on 31^st October 2004 attended by 25 invited nephrologists and pathologists, representing the majority of groups actively working in this field, and included representatives from North America, Europe, and Asia. This was generously supported by Johnson & Johnson. There was clear agreement from all present that achieving this consensus is an important goal with real impact on teaching, research and clinical care in this field. There was a commitment from all present to seeing this work go forward as a matter of priority.  

Attendees at St Louis Meeting  

  Nephrologists [alphabetical]

Francois Berthoux [France]  Daniel Cattran [Canada] Rosanna Coppo [Italy]    Guiseppe D'Amico [Italy]    Bob van Es [Netherlands]  

John Feehally [UK]  Ron Hogg [USA]   Stephen Hsu [Singapore]    John Knight [Australia]    Philip Li [Hong Kong]    Paolo Schena [Italy]   Yasuhiko Tomino [Japan]

  Pathologists [alphabetical]

Charles Alpers [USA] Stephen Bonsibb [USA]  Jan Bruijn [Netherlands]  Terry Cook [UK]   Vivette D'Agati [USA]  Steven Emancipator [USA]   Franco Ferrario [Italy]  Agnes Fogo [USA]    Hermann-Josef Groene [Germany]  Mark Haas [USA]     Prue Hill [Australia]   

Charles Jennette [USA]  Kensuke Joh [Japan]   Fernand Lai [Hong Kong]  Ian Roberts [UK]   Patrick Walker [USA]  Jan Weening [Netherlands]     

 At the meeting agreement was reached on the following:

Overall purpose

The group agreed that this consensus is an important goal which will have real impact on research, clinical care and teaching in this field. There was a commitment from all present to seeing this work go forward as a matter of priority.

Goals of the Consensus Group

·       To agree a consensus classification of histopathology of IgA nephropathy

·       To test reproducibility of this classification among pathologists

·       To agree clinical parameters for use in outcome studies of IgA nephropathy

·       To evaluate the value of the pathology consensus classification in combination with clinical parameters in outcome studies in large cohorts of patients with IgA nephropathy: these studies should include cohorts from many geographical and racial groups

·       The pathology consensus classification to be published once the three steps above have been completed, and thereafter should be used in all future published clinicopathological outcome reports of IgA nephropathy

Two groups were established – one consisting of all pathologists at the meeting supported by five nephrologists; the other consisting of all nephrologists at the meeting supported by three pathologists.

Progress

·       The pathology group held at meeting in San Antonio at the United States & Canada Academy of Pathology [USCAP] Meeting in March 2005. The purpose of this meeting was to summarise definitions for use in the reporting of renal biopsies with IgAN. Following the meeting a draft document has been circulated and will be published on the websites of the Renal Pathology Society and the IgA nephropathy Network in the near future to allow for general discussion.
·       The pathology group are presently organising to circulate slides of IgA biopsies to test the reproducibility of the definitions arrived at in the San Antonio meeting and to pilot a score sheet for use in the assessment of biopsies from defined cohorts of patients with IgAN.
·       The nephrologists group are agreeing the necessary clinical dataset to be collected to test the classification and establishing which groups around the world have substantial cohorts of patients with necessary data and biopsy material held.
Following the preliminary work detailed above we will hold a meeting of the consensus group in Oxford on 14-16 September 2005; we intend to invite 30 delegates. The specific aims of the meeting will be:
To finalise the definitions and score sheets to be used by the pathologists in reporting and scoring of biopsies of IgAN. This will require access to microscopes and projection facilities to allow discussion of specific morphological lesions.
To finalise the discussion of the minimum datasets of clinical parameters for use in the cohorts of patients in whom the new IgAN classification will be validated
To organise the way in which biopsies will be selected and circulated to pathologists for evaluating the classification and the way in which the data will be analysed
Organising Committee:  

Professor John Feehally, The John Walls Renal Unit, LeicesterGeneral Hospital                                        

Professor Terry Cook, Histopathology, Imperial College, London

Dr Ian Roberts, Histopathology, John Radcliffe Hospital, Oxford