PhD defence C. (Chantal) Visser

Below is a brief summary of the dissertation:

Thrombosis is the formation of a blood clot inside a blood vessel. During the COVID-19 pandemic, we saw that both the infection and vaccination could slightly increase the risk of blood clots. In this thesis, we explored how thrombosis develops, how it affects patients, and how it can be treated and prevented. 
We studied the effects of higher doses of blood thinners in ICU COVID-19 patients and found that while they did not lower the risk of thrombosis, they might reduce the risk of dying in the hospital. In addition, we showed that people who developed thrombosis during a COVID-19 hospital stay had lower quality of life after recovery, but lasting damage of the lungs was fortunately rare.  We also looked at  COVID-19 vaccine side effects. We found that while vaccination was generally safe, it could temporarily worsen a rare blood disorder (ITP) in some patients and briefly affect the stability of blood thinning treatment.
Finally, we examined how blood thinners are used in vulnerable groups, such as patients nearing the end of life or those with cancer or heart valve replacements. We found that blood thinners were often continued right up until death, even though their benefits might decrease at that stage. We also showed that lowering the target blood thinning levels for people with mechanical heart valves could improve safety without increasing the risk of blood clots.
This thesis provides new insights to improve care for patients with thrombosis and to optimize the use of blood thinners.