Likelihood Ratios of Cough Syncope and Malacic Cough for Large Airways Collapse A Rashed, E Bartlett, DC Watchorn Lung Division, Royal Brompton Hospital, London (United Kingdom)

<bold>Background:</bold> The associations between specific symptoms and the presence of large airways collapse (LAC) are poorly understood. Elucidation of such associations could better inform the need to investigate for this condition. <bold>Aims:</bold> to conduct exploratory analyses on the associations between LAC and (1) cough syncope and (2) malacic cough. Method: we retrospectively compared proportions of LAC protocol CT studies for which clinical information included the symptom ("cough syncope" or “malacic cough”) with those for which the clinical information did not include the symptom. Proportions were compared using Fisher’s exact test. <bold>Results:</bold> A total of 230 studies were analysed, of which a total of 45 were positive for LAC (19.5%). <table-wrap><object-id>erj;64/suppl_68/PA2107/TB1</object-id><object-id>T1</object-id><object-id>TB1</object-id><table><colgroup><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td></td><td>LAC present</td><td>LAC negative</td><td>Total</td></tr><tr><td>History of cough syncope</td><td>3</td><td>1</td><td>4</td></tr><tr><td>No history of cough syncope</td><td>42</td><td>184</td><td>226</td></tr><tr><td>Total</td><td>45</td><td>185</td><td>230</td></tr></tbody></table></table-wrap> The association between cough syncope and LAC was statistically significant (two-sided p value 0.0244) with a likelihood ratio (LR) of 12.33.(LR) of 12.33. <table-wrap><object-id>erj;64/suppl_68/PA2107/TB2</object-id><object-id>T2</object-id><object-id>TB2</object-id><table><colgroup><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td></td><td>LAC present</td><td>LAC negative</td><td>Total</td></tr><tr><td>Malacic cough</td><td>4</td><td>21</td><td>25</td></tr><tr><td>No Malacic cough</td><td>41</td><td>164</td><td>205</td></tr><tr><td>Total</td><td>45</td><td>185</td><td>230</td></tr></tbody></table></table-wrap> The association between malacic cough and LAC was not statistically significant (two-sided p value 0.79) with a LR of 0.78. <bold>Conclusion:</bold> There was a statistically significant association between cough syncope and LAC in this study sample, however the association between malacic cough and LAC was not statistically