Self-Management Ability is an Indirect Mediator of Quality of Life in Heart Transplant

Abstract

We hypothesized that self-management ability predicts quality of life (QOL) in heart transplant. A multi-center, longitudinal survey of waitlisted heart transplant candidates was conducted. Structural equation modeling explored relationships among pre-transplant self-management ability scale (SMAS-30), emotional health, and physical health and post-transplant QOL. Emotional health was measured with validated instruments to measure resilience, uncertainty of illness, affect, and mood. Pre-transplant physical health was measured with Kansas City Cardiomyopathy Questionnaire subscales of physical limitation, symptom frequency, and symptom burden. We inspected the fit of the measurement model using guidelines indicative of desirable model fit: Comparative Fit Index (CFI)≥.95, Standardized Root Mean Square Residual (SRMSR)<.08, and Root Mean Square Error of Approximation (RMSEA)≤.06. We then evaluated the fit indices of the hypothesized structural models and the paths coefficients for the selection of our final model. The direct and indirect effects were tested controlling the familywise error rate using false discovery rate controlling step-up Bonferroni. The variances in the outcome variables explained by the model were obtained using the R2 statistics. Participation rate was 48% (N=197). Median follow-up was 8 months (IQR 2.3 - 15.1) with 89 transplants, 22 deaths, and 24 delists. Post-transplant survey completion was 79%. Measurement model fit was excellent (CFI=.962; RMSEA=.057; SRMR=.06). Factor loadings were >.43 across factors. Pre-transplant self-management was highly correlated with emotional health (r=.81). Our hypothesized structural model had excellent fit (CFI=.962, RMSEA=.057; SRMR=.060). Self-management had a direct effect on emotional and physical health (r=.81 and r=.37, respectively). The direct path from self-management to QOL was not significant. However, indirect paths from self-management to post-transplant QOL with emotional or physical health as a mediator were significant (standardized coefficients=.29 and 0.10 with p=.015 and .005, respectively). Increased self-management ability is associated with increased post-transplant QOL, mediated by pre-transplant emotional and pre-transplant physical health. Future attempts to improve QOL could target self-management ability.