The Coping-Mediated Symptom Model: Extending the Theory of Unpleasant Symptoms for Sleep Disturbance and Fatigue in Cardiovascular Disease

Anxiety, sleep disturbance, and fatigue co-occur in adults with cardiovascular disease (CVD) and are associated with reduced quality of life (QOL), poor self-care, and increased healthcare use. The Theory of Unpleasant Symptoms (TOUS) organizes these symptoms well but treats psychological factors, including coping, as antecedents acting directly on symptom experience, leaving the mechanism connecting stress to symptom burden unspecified. This paper proposes the Coping-Mediated Symptom Model, an extension of TOUS that repositions appraisal-shaped coping from antecedent to mediator and incorporates the moderating structure that TOUS lacks. Drawing on Lazarus and Folkman's Stress-Appraisal-Coping framework and on empirical evidence from cardiovascular nursing, behavioral health, and psychophysiology, the model specifies perceived stress and anxiety as antecedents, coping quality as the mediator linking them to a latent sleep-fatigue symptom cluster, and perceived social support as a moderator of both the antecedent-to-coping and coping-to-symptom paths. Autonomic and hypothalamic-pituitary-adrenal pathways establish physiological plausibility. Six propositions state the model in a form estimable by structural equation modeling. Unlike prior TOUS extensions, which adapt the theory for new populations or perspectives while preserving its antecedent structure, this model modifies that structure, relocating the intervention target from symptom management to appraisal and coping.