The complexity of post COVID-19 condition Exploring long-term health effects

The main objective of this thesis is to enhance our understanding of post COVID-19 condition by exploring its long-term health effects, focusing on symptom development and progression. We used data from the P4O2 COVID-19 cohort, which included 95 patients aged 40-65 years with persistent symptoms 3-6 months after infection.
We observed that diffusion capacity (DLCO) was below the lower limit of normal in 40.2% of the patients, with age and severe acute infection independently associated with this decrease. Fatigue was reported by 75.9% of patients at 3-6 months, decreasing to 57.1% at 12-18 months after infection. Post COVID-19 patients were grouped into 11 symptom-based clusters previously seen in an ME/CFS cohort. Three distinct trajectories were identified for fatigue and dyspnoea: decreasing, high persistent, and low persistent. Never smokers and participants in lifestyle interventions were more likely to show improvement. Similarly, moderate cases and lifestyle intervention participants had higher odds of decreasing dyspnoea compared to high persistent. We also found a decline in kidney function. The estimated glomerular filtration rate (eGFR) decreased over time from 85.3 ml/min/1.73m² during acute phase to 80.9 ml/min/1.73m² at 12-18 months after infection. Compared to controls, eGFR in post COVID-19 patients was 6.45 ml/min/1.73m² lower at 3-6 months and 10.26 ml/min/1.73m² lower at 12-18 months.
These findings underscore the diverse and persistent nature of post COVID-19 symptoms and highlight the role of demographic and physiological factors. They emphasize the importance of personalized treatment strategies that consider the unique symptom profiles and backgrounds of patients.