S122\u2005Positive vs negative specific inhalational challenges in occupational asthma; review of 9 years of testing in a single UK centre

Abstract

Introduction and objectives Occupational causes are thought to account for 20% of the global burden of asthma.1 The gold standard test for identifying occupational asthma is a specific inhalational challenge (SIC) to the suspected occupational agent. However, there is little published data on real life outcomes of these challenges. We present the outcome of data from such challenges collected in one UK centre. Methods We performed a retrospective review of 46 consecutive SICs carried at the Occupational Lung Disease service between September 2010 and June 2019. Data was collected on demographics, occupation, OASYS score pre SIC, history of previous asthma, challenge agent tested, outcome of SIC and ongoing symptoms post SIC. Results Of the 46 SICs carried out during this period, 23 were negative, 19 were positive, 3 were equivocal and 1 test could not be completed (see figure 1). Median age of patients was 49.5yrs (IQR 42–58), 18 patients were female (39%). Fifty nine percent of SICs were carried out whilst patients were currently exposed at work. Fifty three percent of negative SICs had an OASYS score of > 2.52 i.e. positive peak flow charts for work effect. The most common occupations were food industry work 11 (23%) and healthcare 9 (20%).In the positive SIC group 16% of patients had a prior history of asthma compared to none in the negative SIC group. Almost twice as many patients with negative SICs had ongoing symptoms compared to those with positive SICs (43 vs 26%). Conclusions Our data suggests that patients with a positive SIC were more likely to have a prior history of asthma documented and even when patients have a negative SIC a high proportion have ongoing symptoms. Reference Vandenplas O, Suojalehto H, Aasen TB, Baur X, Burge PS, de Blay F, et al. Specific inhalation challenge in the diagnosis of occupational asthma: consensus statement. The European respiratory journal. 2014;43(6):1573–87.Abstract S122 Figure 1 Outcomes of studies