B42-04 Establishment of a National Testing Service for Vascular Endothelial Growth Factor D to Aid the Diagnosis of Lymphangioleiomyomatosis

Rationale Lymphangioleiomyomatosis (LAM) is a rare systemic disease affecting women of child-bearing age, which behaves as a slow-growing, metastatic neoplasm. It is predominantly associated with diffuse cystic lung disease. Vascular endothelial growth factor D (VEGF-D) is the most useful serum biomarker currently in use, with diagnostic and prognostic value in LAM. Access to testing displays considerable variation throughout Europe, with many centres referring testing to outside centres, including to centres in the United States. Here we describe the establishment of a national VEGF-D testing service in a rare lung disease referral centre in the Republic of Ireland. Methods Serum samples were collected from patients undergoing investigation for potential cystic lung disease. Serum VEGF-D concentrations were measured by enzyme-linked immunosorbent assay (ELISA). VEGF-D results from samples previously sent for testing to international referral laboratories were collated and analysed for the presence of paired samples within both cohorts. These samples were subsequently analysed to assess correlation between laboratories. Statistical analysis was performed with GraphPad Prism software. Results Serum VEGF-D results from our centre included 65 cases: 29 with known LAM, 15 with undifferentiated diffuse cystic lung disease (DCLD), 12 with other confirmed cystic lung diseases and 6 non-cystic lung disease controls. VEGF-D values within this cohort ranged from 5273 pg/ml to 108 pg/ml. As regards test precision, at a concentration of 954 pg/mL, the coefficient of variation was 11.8%. Serum VEGF-D results previously sent to a separate international referral centre included 58 cases: 28 with LAM, 13 with undifferentiated DCLD, 8 with other confirmed cystic lung disease and 9 non-cystic lung disease controls. VEGF-D values within this cohort ranged from 2592 pg/ml to < 250 pg/ml. 23 cases had paired samples analysed by both laboratories, with a p value of 0.098 on Wilcoxon matched-pairs signed rank test. Conclusions VEGF-D testing at our centre correlated with testing performed at our international referral centre. Improved access to testing, allowing faster turnaround times and reduced diagnostic wait times, is of utmost importance in contributing to LAM patient care improvement at our centre. This abstract is funded by: None