Cindy Porras

Heart and kidney diseases are among the most common long-term health problems worldwide. Many people do not realise that these conditions are closely connected. When the heart, blood vessels, or kidneys stop working properly, problems in one organ can cause problems in the others. This interaction is known as the cardiorenal connection. Three conditions play an important role in this, peripheral arterial disease (poor blood flow to the limbs, most commonly the legs), chronic kidney disease, and a type of early heart dysfunction called diastolic dysfunction. They often occur together and share many of the same risk factors, such as high blood pressure, diabetes, smoking, and ageing. The goal of this thesis was to better understand these conditions and how they affect different groups of patients. To do this, I used real-world data from electronic health records, which reflect everyday clinical practice, and modern research methods. The work focuses on three main themes: differences between women and men, factors that predict poor outcomes, and how health changes over time. A major finding of this research is that women and men often experience peripheral arterial disease differently. Women tend to report less typical symptoms, which can make the disease harder to recognise early. Men more often describe the classic symptom of pain in the legs while walking that goes away with rest. Because women’s symptoms are more varied, they are at risk of being diagnosed later. This matters, because earlier diagnosis can lead to better treatment and improved long-term outcomes. The thesis also shows that even though many factors are known to increase the risk of complications in peripheral artery disease, only a small number of prediction tools exist to help doctors identify high-risk patients. Some of these tools leave out important information, such as the patient’s sex. As a result, they may not work equally well for everyone. Another part of the thesis focused on the connection between kidney function and the heart. As kidney function gets worse, the heart can have more difficulty relaxing and filling with blood, which is an early sign of heart failure. This work showed that these changes in the heart happen gradually and are already present in people who do not yet have symptoms. This finding supports the idea that heart and kidney disease should be monitored together rather than separately. Finally, the thesis explored the strengths and limitations of using electronic health records for research. These records contain valuable information about large and diverse groups of patients, making it possible to study real-life disease patterns. However, important data are often missing, which can make it difficult, for example, to apply certain prediction tools in practice.