P24 Efficacy of age adjusted d dimers in excluding pulmonary embolism in patients with cancer

Introduction Cancer is a strong provoking factor for pulmonary embolism (PE). D-dimer levels are frequently elevated in cancer patients and its specificity decrease with age, hence resulting in frequent unwarranted CT pulmonary angiogram (CTPA). There is growing evidence on the utility of age adjusted d-dimer (AADD) in patients >50 years of age. The objective of this study is to test the efficacy of AADD in ruling out PE in cancer patients when compared to conventional d-dimer cut-off. Methods Retrospective analysis of consecutive patients undergoing CTPA within 48 hours of admission at our institution from 01/04/18 – 30/09/18. Patients Results 807 CTPAs were performed over the 6-month period. 247 patients with cancer were included in further analysis of which 69 (28%) had PE. 60/178 patients (33%) with negative CTPAs had d-dimers positive and AADD negative, whilst only 3/63 CTPAs had positive d-dimers with negative AADD. In essence, 60 patients could have avoided an unnecessary CTPA by using AADD in place of conventional d-dimer, at the expense of missing 3 sub-segmental PE. Conclusion AADD has comparable performance in cancer patients and improves the specificity while retaining sensitivity of d-dimer. It can prevent significant number of inappropriate CTPAs but can potentially miss a few sub-segmental PEs. Further studies are needed to validate its utility before its universal application. Reference Wilts, et al.Thrombosis Research 2017 Apr;152:49–51