Rethinking Symptom Fluctuation in Multimorbidity: A Dynamic Systems Framework From Primary Care

BACKGROUND: Symptom fluctuation is a common but poorly understood feature of multimorbidity in primary care. Conventional disease-centred frameworks provide limited explanation for day-to-day variability in symptoms such as fatigue, reduced activity tolerance and dyspnoea. AIM: To propose a conceptual framework that explains symptom fluctuation in multimorbidity as a dynamic systems phenomenon. CONCEPTUAL APPROACH: Drawing on clinical observation and theoretical integration, we conceptualise symptom expression as emerging from dynamic configurations of interacting physiological systems within a shared multimorbidity state space. These configurations determine the level of physical reserve and are continuously shaped by everyday life conditions, including sleep, activity, nutrition and fluid balance. KEY INSIGHTS: This framework reframes symptom variability not as a direct output of individual diseases but as an emergent property of system-level interactions occurring near the limits of physiological stability. Small perturbations in everyday life conditions may shift system configuration and lead to disproportionate changes in symptom expression. IMPLICATIONS: Understanding symptoms as dynamic expressions of physiological system states may help clinicians interpret variability without assuming disease progression and may support care strategies focused on maintaining system stability and functional reserve. CONCLUSION: A dynamic systems perspective offers a clinically grounded reconceptualisation of symptom fluctuation in multimorbidity and provides a basis for more context-sensitive primary care.