P139 Blood tests in the diagnosis of interstitial lung disease – what’s the bleedin’ point?

Aim To evaluate the use of blood tests as part of the diagnostic pathway for patients presenting with new interstitial lung disease (ILD). Method Data for all patients discussed at a local district general hospital ILD multi-disciplinary team (MDT) meeting between 2015 and 2018 was collected by accessing patient electronic records and then analysed. Results 202 unique patients were discussed in the MDT during the data collection period. The median age of the patients was 73 years. 134 were male and the remaining 68 female. The most common diagnosis was idiopathic pulmonary fibrosis (34%). Serum rheumatoid factor levels were checked in 97 patients (48%) with 12 positive results. 6 cases had a known diagnosis of rheumatoid arthritis, with only one new diagnosis of rheumatoid arthritis. Anti-nuclear antibody levels were checked in 99 patients (49%) with 17 positive results, of these 4 had connective tissue disease related ILD, 3 of which were a new diagnosis of connective tissue disease. ANCA levels were checked in 62 patients (31%) with 14 positive results, with no results leading to either a diagnosis of vasculitis or a change in management. Conclusion Guidance from the British Thoracic Society, NICE and the American Thoracic Society recommends the use of blood tests in the investigation of interstitial lung disease but there is a lack of consensus as to what tests to perform and in whom to perform them. Our data suggests that a wide panel of routine serological testing in all patients had a poor yield in terms of identifying a diagnosis and in changing patient management. Our analysis suggests more judicious selection of blood tests may be helpful in order to avoid patients undergoing unnecessary investigations and to use resources more efficiently.