Psychometric evaluation of the self-management skills checklist across Brazil and the United States: Toward global measurement of transition readiness in sickle cell disease

Abstract Background: The transition from pediatric to adult care is a critical period of vulnerability for adolescents and young adults (AYAs) with sickle cell disease (SCD), often marked by care discontinuity and disengagement. Regular assessment of transition readiness is essential for identifying gaps in disease knowledge and supporting continuity of care. The Self-Management Skills Checklist (SMSC) is a 21-item, multi-dimensional tool developed in the United States (US) to assess self-management skills for transition readiness in AYAs with SCD, capturing both skill and knowledge domains from the perspectives of patients and proxy caregivers. However, the SMSC has not been validated outside the US, limiting its global applicability. The study aims to evaluate the psychometric properties and cross-country measurement invariance of the SMSC in the US and Brazil, a high-burden country that has implemented universal newborn screening and now sees approximately 80% of children with SCD survive into adulthood, despite peak in mortality between ages 18 and 30. Methods: The SMSC was translated into Brazilian Portuguese, underwent cognitive evaluation, and was culturally adapted. We analyzed secondary data from 398 AYAs with SCD in Brazil (n=197) and the US (n= 201). Internal consistency was evaluated using Cronbach's alpha. Confirmatory factor analysis (CFA) was performed using robust weighted least squares estimation. Competing models (unidimensional, two-factor, and reduced-item) were compared using model fit indices (CFI, TLI, RMSEA) and chi-square difference tests. Measurement invariance (configural, metric, scalar) was assessed across countries. Structural models examined associations between SMSC domains and internalizing, externalizing, and support needs variables. Missing data were imputed using random forest-based multiple imputation. All analyses were conducted on RStudio (Version 2024.04.0+735). Results: The included sample of had a mean age of 16.3 ± 2.1 years, 200 males (50.3%) / 198 (49.7%) females, the majority (72%) had HbSS or HbSβ0-thalassemia and were not on chronic transfusion therapy. The SMSC demonstrated acceptable reliability (global α= 0.75; skills α=0.64; knowledge α=0.62). CFA supported a two-factor structure (RMSEA= 0.07, CFI= 0.82, TLI= 0.80). A reduced 14-item model showed improved fit (RMSEA=0.03, CFI= 0.98, TLI= 0.98) and was selected for invariance testing. Configural and metric invariance were supported (ΔCFI 0.01), while scalar invariance was not, indicating potential cross-cultural differences in item interpretation. Exploratory models revealed cognitive, behavioral, and affective subdimensions associated with psychosocial constructs. These findings suggest that while the underlying factor structure is stable across countries, differences in intercepts may reflect cultural or contextual response variations. Discussion: This study provides evidence for the validity of a shortened, 14-item SMSC for assessing transition readiness in AYAs with SCD across diverse settings. Its strong psychometric properties support the SMSC's utility in guiding transition planning across diverse settings. However, limited cross-national consistency- particularly the lack of scalar invariance- suggests that item interpretation may differ by context. Future research is needed to assess predictive validity, test-retest reliability, and explore cultural adaptations for broader use in low- and middle-income countries.