Barriers to cascade screening in people at risk of Thoracic Aortic Disease: a mixed methods evaluation from the DECIDE-TAD initiative

Background Cascade genetic and imaging screening for relatives of people with non-syndromic thoracic aortic diseases (NS-TAD) is recommended by guidelines. However, the availability and uptake of cascade screening is low. The aim of this study was to use applied health research methods to identify barriers to screening, and strategies to overcome these. Methods A cohort study using routinely collected health data evaluated barriers to imaging, genetic testing, and treatment for people with NS-TAD. Delphi consensus exercises and workshops evaluated the screening process and patient experience. Focus groups considered strategies to overcome individual and institutional barriers to uptake. A consensus exercise evaluated the evidence to support cascade screening. Results A cohort study of 33,793 patients with a TAD diagnosis between 2013 and 2018 demonstrated barriers to treatment and imaging surveillance in females, non-whites, and people from-low socioeconomic backgrounds. A survey of aortic dissection survivors and relatives in England reported that 33/70 (47%) of aortic dissection survivors who responded had undergone genetic testing, including 10/22 (45%) with a positive family history of TAD. In first- and second-degree relatives 66/150 (44%) and 32/155 (21%) of respondents were offered imaging or cascade genetic testing respectively. Only 19/70 (27%) probands and 20/155 (13%) relatives who responded reported that they were involved in shared decisions about their care. Barriers to the uptake of cascade screening included limited awareness of the disease and genetic aetiology, poor health literacy, concerns about cost-effectiveness of screening with low detection rates, requirements for life-long surveillance, and the management of uncertain test results. The consensus exercise demonstrated that the certainty of the evidence to guide cascade screening was Low or Very Low. Conclusions Barriers to the implementation of cascade screening in people at high-risk for TAD occur at multiple levels suggesting that a complex intervention is required to improve equity of access.