Abstract Background In adult congenital heart disease (ACHD), social deprivation is associated with adverse health outcomes, such as increased inpatient admissions and major adverse cardiovascular events (1). Research studies on this topic often rely on patients engaging with surveys, and the characteristics of non-respondents in relation to social deprivation remain unknown. Purpose We assessed the association between social deprivation and response to a research survey in the ACHD population. Methods We included all individuals in the UK who were invited to participate in the APPROACH-IS II study (2), which assessed patient-reported outcomes in ACHD. A validated index of relative deprivation was derived from household postcodes, based on the 2019 Index of Multiple Deprivation (IMD) scores for geographic units in England (3). A lower IMD decile indicates a greater degree of deprivation. We compared patient engagement rates between 2 centres utilising different recruitment approaches: a Southern centre (South) relying on recruitment during mainly telephone or video consultations, and a Northern centre (North) recruiting patients during face-to-face clinic appointment, with the help of an ACHD clinical and research nurse specialist. Results In total, 593 patients were asked to take part in APPROACH-IS II in the UK: 324 patients from the Southern centre and 269 patients from the Northern centre, of whom 130(40.1%) and 209(77.7%) responded, respectively (p<0.0001). In the South, patients approached were homogeneously spread amongst IMD deciles (6.0[4.0-9.0]) and respondents were significantly less deprived (higher IMD decile) than non-respondents (7.0[5.0-9.0] vs 6.0[4.0-8.0], p=0.02). Indeed, the response rate in areas of higher deprivation (IMD decile<=4) was significantly lower than in the least deprived areas (IMD >=8) (31.3% vs 47.0%, p=0.03). In the North, the distribution of deprivation in patients was skewed towards lower IMD deciles, with a significantly higher proportion of patients from areas of higher deprivation (Figure A, 26 vs 99(30.6%) in the South, p<0.0001). There was no difference in IMD decile between respondents and non-respondents in the North (Figure B, 5.0[2.0-7.0] vs 4.0[2.0-7.0], p=0.26). When comparing patients living in the most deprived areas (IMD <=4), there was a large and significant difference in response rate between centres (p<0.0001). Conclusions In our population, deprivation appears to have a significant impact on the likelihood of patients engaging with clinical research. An enhanced approach, involving face-to-face contact and the involvement of a dedicated clinical nurse specialist, can improve recruitment to research studies and abolish the effect of socioeconomic status on patient engagement.Figure 1A and B