P30 The impacts of a positive BAL galactomannan in non-haematological patients

Abstract

Introduction and objectives The detection of galactomannan in bronchoalveolar lavage (BAL) fluid can assist in the diagnosis of invasive aspergillosis, but the evidence for its role outside of haemato-oncology remains incomplete. We aimed to assess how the introduction of BAL galactomannan testing in a tertiary centre, which uses standardised electronic order sets for bronchoscopic investigations, impacted on the diagnosis of fungal disease within the Trust. We also investigated how positive results were interpreted by referring teams. Methods We performed a single-centre retrospective study of adult non-haematological patients who had a positive BAL galactomannan (optimal density index [ODI]≥0.500) from November 2014 to April 2018. Demographic data, clinical details, laboratory investigations, relevant radiology and the antimicrobial history were obtained from the electronic patient record. Consultant review of final respiratory diagnosis was undertaken in all cases. Results 121 patient episodes were included in the study, of which 54 (44.6%) were under the care of respiratory physicians, 39 (32.2%) were in critical care, 19 (15.7%) were related to vasculitis and 20 (16.5%) involved recipients of solid organ transplants. In only 29 cases (24.0%) was the positive galactomannan result felt to reflect significant fungal disease in terms of invasive aspergillosis, ABPA or severe asthma with fungal sensitisation. Of 55 BAL galactomannan results with ODI 0.500–1.000, only 2 reflected fungal disease, both of which had coexistent positive serology. In 35 cases (28.9%) a positive BAL galactomannan influenced clinical decisions in terms of commencing, narrowing or continuing antifungal therapy, of which on 13 occasions antifungal therapy was commenced with the ultimate diagnosis being non-mycological: associated medication-related side-effects in this group included deranged liver function tests, rash and fever. Conclusion Requesting of BAL galactomannans for patients without clear risk factors for fungal disease resulted in significant numbers of false positive results which should influence future practice in bronchoscopy. The cut-off value for BAL galactomannan positivity in non-haematological patients may benefit from being raised to 1.000 to avoid inappropriate and potentially harmful therapy. Additional analysis of negative BAL galactomannan results will need to be performed to assess the utility of the investigation in non-haematological patients.