The ERS guidelines for LAM: trying a rationale approach to a rare disease.

Lymphangioleiomyomatosis (LAM) is a rare lung disease which predominantly affects young women. LAM is associated with much morbidity and can lead to respiratory failure and death unless lung transplantation is performed. There are no randomised trials of treatment and no consensus on the management of LAM. In order to produce guidelines for a rare disease where little evidence exists we have adapted existing guideline methodology to evaluate what evidence and knowledge there is to produce a consensus based statement. The process of guideline development comprised forming a group of experts in LAM and related fields including pathology, radiology, tuberous sclerosis and transplantation. Questions were formulated and the available evidence formed into a series of recommendations. Consensus agreement amongst the group was reached by a series of reviews with scoring of agreement, and proposals for modifications, using Likert statistics. The recommendation strength was graded using the American College of Chest Physicians health and science policy grading system according to the quality of evidence, magnitude of benefit, strength of recommendation and strength of consensus achieved. The guidelines describe the diagnostic criteria for LAM and recommended investigations and criteria for the diagnosis and appropriate work up for the diagnosis of LAM. All aspects of management from advice for patients to lung transplantation are discussed. To demonstrate how the guidelines have dealt with different areas of practice and differing evidence levels the specific areas of hormonal therapy, pneumothorax and lung transplantation for LAM are discussed. It is hoped that these guidelines will result in standardisation of diagnostic criteria and patient management which will further improve clinical care and facilitate research and clinical trials.