Interstitial lung disease guideline: the British Thoracic Society in collaboration with the Thoracic Society of Australia and New Zealand and the Irish Thoracic Society.

1.1 An overview of the ILD guideline Since the publication of the first BTS guidelines for diffuse lung disease nearly 10 years ago, the specialty has seen considerable change. The early discussions of the Guideline Group centred upon whether the revised document might consist of the 1999 document with minor adaptations. However, it was considered that too much change had taken place in the intervening years to justify a simple editorial approach. The last decade had seen the development of a new consensus terminology for the idiopathic interstitial pneumonias (IIP) stimulated, in part, by the identification of non-specific interstitial pneumonia (NSIP) as a discrete histological pattern with increasingly recognised clinical correlates. The better prognosis seen in fibrotic NSIP than in idiopathic pulmonary fibrosis (IPF) 5 fuelled a more intense approach to diagnosis in cases of suspected IPF. This in turn has led to a radical change in accepted diagnostic gold standards, which have become increasingly multidisciplinary and dependent equally upon the skills of pathologists, radiologists and clinicians. NSIP, as a new entity, has posed particular difficulties. With more detailed studies of outcome specific to individual IIPs, especially IPF and fibrotic NSIP, the prognostic weighting given to pulmonary function impairment has been refined, especially with regard to longitudinal functional trends. Most important, with the standardisation of terminology, it became possible to recruit patients into multicentre treatment studies. With regard to IPF in particular, the last 3 years have seen more studies of treatment than in the previous history of the speciality, yet there is no universally accepted ‘‘best current treatment’’.