The present study examines the concept of illness identity, the degree to which a chronic illness is integrated into one's identity, in adults with a chronic illness by validating a new self-report questionnaire, the Illness Identity Questionnaire (IIQ). Self-report questionnaires on illness identity, psychological, and physical functioning were assessed in two samples: adults with congenital heart disease (22-78 year old; n = 276) and with multisystem connective tissue disorders (systemic lupus erythematosus or systemic sclerosis; 17-81 year old; n = 241). The IIQ could differentiate four illness identity states (i.e., engulfment, rejection, acceptance, and enrichment) in both samples, based on exploratory and confirmatory factor analysis. All four subscales proved to be reliable. Rejection and engulfment were related to maladaptive psychological and physical functioning, whereas acceptance and enrichment were related to adaptive psychological and physical functioning. The present findings underscore the importance of the concept of illness identity. The IIQ, a self-report questionnaire, is introduced to measure four different illness identity states in adults with a chronic illness.

This large-scale, international study found that overall QOL in adults with CHD was generally good. Variation in QOL was related to patient characteristics but not country-specific characteristics. Hence, patients at risk for poorer QOL can be identified using uniform criteria. General principles for designing interventions to improve QOL can be developed.

ClinicalTrials.gov: NCT02150603.

This study found that adolescents with CHD have a good QOL, one that is better than that of control subjects from the general population. A stronger SOC and better perceived physical health are potential resources for better QOL in patients.

This international collaboration allowed us to determine that PROs in ConHD vary as a function of patient-related factors as well as the countries in which patients live.

Evidence was obtained for reciprocal pathways between SOC and the domains of perceived health, although the predominant direction of effects was found to be from SOC to perceived health. Hence, improving SOC has the potential to enhance future perceived health of adolescents with CHD.

Caring for adolescents with congenital heart disease requires attention to physical health but also to psychosocial functioning. Identifying how such psychosocial variables influence one another over time is important for designing health care strategies. The present study examined how depressive symptoms, loneliness, paternal and maternal support, and quality of life predicted one another. A total of 429 mid- to late adolescents with congenital heart disease (53.4 % boys) participated in a three-wave longitudinal study. Cross-lagged analyses indicated that depressive symptoms and loneliness mutually reinforced one another over time and led to relative decreases in quality of life. Paternal- and not so much maternal-support predicted relative decreases in depressive symptoms and loneliness and relative increases in quality of life. Maternal and paternal support, in turn, were negatively predicted by previous levels of adolescent depressive symptoms. In sum, important temporal sequences were uncovered potentially providing information for prevention and intervention targeting psychosocial functioning in adolescents with congenital heart disease.

This work was funded by KU Leuven and European Network of Endometriosis (ENE), supported by the European Commission (Public Health Executive Agency). No competing interests are declared.