An international perspective on illness identity in adults with congenital heart disease: Associations with patient characteristics, national culture and well-being

Background: Illness identity refers to the degree to which a severe health condition is integrated into a person's sense of identity. Patients with congenital heart disease (CHD) vary in how they relate their CHD to their identity, which has implications for mental health, quality of life, and perceived health. This study explored inter-country variation in illness identity, and examined associations with patient characteristics and patient-reported outcomes in a large, international sample. Methods: This study utilized data from the APPROACH-IS-II project which included 8415 patients from 32 countries (collected between 2019 and 2022). Patients completed questionnaires on patient characteristics (i.e., age, sex, marital status, employment, education, ethnicity, NYHA class, and CHD complexity), illness identity, and patient-reported outcomes (i.e., depressive symptoms, anxiety, quality of life, self-perceived [mental and physical] health). National culture was included using Hofstede's cultural dimensions. Data were analyzed using multivariable generalized linear mixed models. Results: Inter-country variation was observed in the illness identity dimensions. Patient characteristics (i.e., sex, age, marital status, employment, education, NYHA class, and CHD complexity) and national culture were related to differences in how patients related their CHD to their identity. Acceptance and enrichment were related to better well-being, quality of life, and self-perceived health, while engulfment and rejection were associated with worse patient-reported outcomes. Conclusions: Personal and contextual factors were associated with differences in the illness identity dimensions. Moreover, the present study substantiated the unique value of illness identity dimensions in explaining individual differences in well-being, quality of life, and self-perceived health in this population.