P15 Lung cancer multidisciplinary meeting – does the presence of emphysema on ct imaging correlate with obstructive spirometry or transfer factor?

Abstract

<h3>Introduction and Objectives</h3> Spirometry is routinely performed prior to the lung cancer multidisciplinary meeting (MDM). However, smoking related lung disease in the setting of normal spirometry is thought to be relatively prevalent.¹ We sought to evaluate if there was any correlation between common variables used in the assessment of patient fitness. <h3>Methods</h3> We performed a retrospective chart review of all patients discussed at the MDM from 1/1/2018 – 4/11/2019 who had a transfer factor (TLCO) &lt; 80, as we would expect these patients to have the highest incidence of obstructive spirometry. We recorded three key variables; spirometry FEV1/FVC, TLCO &lt; 50 or 50–80, and presence or absence of emphysema on imaging. These variables were compared using chi² test. We subsequently stratified each patient into either treatment with curative intent or palliation. <h3>Results</h3> Of the 104 patients who had a TLCO measured, 70 (67%) had obstructive spirometry (FEV1/FVC &lt;0.7). A TLCO of &lt; 50 was recorded in 24 of the 104 patients (23%). Emphysema was reported on CT thorax in 58 patients (56%). A TLCO &lt; 50 was associated with the presence of emphysema on CT thorax (p = 0.001). There was no significant association between obstructive spirometry and TLCO &lt; 50 (p = 0.68), or between obstructive spirometry and emphysema on CT (p = 0.41). Indeed, 41% of patients with obstructive spirometry do not have emphysema on CT, while 50% of patients with non-obstructive spirometry have emphysema on CT imaging. When considering the MDM decision regarding treatment with curative intent versus best supportive palliative care, no individual variable was found to be significant (obstructive vs non-obstructive spirometry, p = 0.22; TLCO &lt; 50 vs 50–80, p = 0.31; emphysema on imaging vs none, p = 0.43). <h3>Conclusion</h3> We suggest that TLCO &lt; 50 is more predictive than obstructive spirometry at identifying patients with emphysema on CT imaging. Spirometry alone can lead to significant respiratory disease being underdiagnosed; this highlights the need for multimodality, comprehensive assessment. <h3>Reference</h3> Lowe KE, Regan EA, Anzueto A, <i>et al</i>. COPDGene® 2019: Redefining the diagnosis of chronic obstructive pulmonary disease. <i>Chronic Obstr Pulm Dis</i> 2019;<b>6</b>(5):384–399.