Factors associated with persistent symptoms after COVID-19 infection: a longitudinal study on an Italian cohort of patients discharged from hospital

Background: Although the acute phase of the COVID-19 pandemic has subsided, long COVID remains a significant and ongoing public health concern. Persistent symptoms continue to affect a substantial proportion of COVID-19 survivors, increasing healthcare burden. Objective: This study aims to identify the determinants of long-term symptom trajectories following COVID-19 infection. Methods: We conducted a prospective cohort study of 1666 adults discharged after hospitalisation for COVID-19 in Tuscany, Italy. The presence of mental confusion, exertional dyspnoea, fatigue, and insomnia was assessed at 1, 3, 6, 9, and 12 months post-discharge. The mean hospital stay was 13.6 (±12) days and 131 patients required intensive care unit admissions. Latent growth curve models were used to examine the baseline prevalence and longitudinal trajectories of each symptom, and to identify demographic and clinical factors associated with symptom persistence. Results: Fatigue was the most common persistent symptom at baseline, followed by exertional dyspnoea, insomnia, and mental confusion. Female sex was consistently associated with both baseline presence and persistence of all symptoms. Older age was linked to baseline mental confusion and to persistent dyspnoea and fatigue. Markers of greater acute severity (ICU admission, longer hospital stay, higher WHO score) were associated with symptom improvement over time. Pre-existing coronary heart disease and cancer independently predicted persistent dyspnoea and fatigue, whereas hypertension appeared protective. Conclusions: Persistent symptoms are common after COVID-19 and vary by sex, age, comorbidities, and acute disease features. Symptoms may persist up to 12 months post-hospitalisation, underscoring the need for long-term follow-up and targeted interventions.