Co-morbidities

As I mentioned previously, cardiovascular disease develops over decades. The clinical manifestations of which only become apparent in later life. Now there are numerous diseases that will affect you over your lifetime. And some, like cardiovascular disease, will develop with age. It’s important to realise that these diseases don’t develop in isolation. A number of them will have similar risk factors. Obesity, for example, is a risk factor for cardiovascular disease, type 2 diabetes. There’s also some types of liver disease. And these diseases will develop in tandem in the same body over the same time period. Developing one disease, therefore, might mean that a patient is at risk of developing other diseases.

And that maybe that the clinical manifestation of a disease causes the progression of other diseases to exacerbate. One such comorbidity for cardiovascular disease is type 2 diabetes. There are numerous studies showing the link between type 2 diabetes and cardiovascular disease. 65% of all diabetic deaths are from cardiovascular disease. And patients with type 2 diabetes have a twofold increased risk of incidents of cardiovascular disease and a two- to fourfold increase in a risk of dying of cardiovascular disease. This has led to some studies concluding that type 2 diabetes is an equivalent for cardiovascular disease. In other words, patients who develop type 2 diabetes should be treated as if they’ve already had a cardiovascular event.

Other studies have disputed this, but what’s clear is that type 2 diabetes is a big risk factor for cardiovascular disease. And while we’ve been relatively successful in tackling cardiovascular disease in recent decades, this epidemic of type 2 diabetes threatens to halt our advances. It’s worth noting at this point that type 2 diabetic patients already have an increased risk of cardiovascular disease at the moment they are diagnosed. So it isn’t just that the clinical manifestations of this disease cause a progression in cardiovascular disease, but the pre-diabetic state is affecting cardiovascular disease. The mechanisms that link type 2 diabetes and cardiovascular disease are complicated by the number of risk factors these two conditions share together.

But it’s clear that type 2 diabetes increases atherogenesis, increases plaque progression, produces a pro-inflammatory state, and increases hypertension. This is, at least in part, driven by perturbations in insulin signalling and changes in nitric oxide production in intimal endothelial vascular smooth muscle cells, as well as macrophages. There are other comorbidities for cardiovascular disease. Atrial fibrillation, for example, has been shown to be a risk factor for cardiovascular disease. And Dragin and colleagues have recently published a study in circulation that shows that a whole range of pro-inflammatory states lead to cardiovascular disease, including, but not limited to systemic autoimmune disorders, systemic vasculitis, ulcerative colitis. Other studies have shown that non-alcoholic fatty liver disease has been linked to an increased risk for cardiovascular disease.

This is a whole spectrum of liver diseases. And patients with these diseases are three times more likely to die of cardiovascular disease than they are of liver-related endpoints. The complexity of understanding the effects of these comorbidities of cardiovascular disease can be seen when we consider that these comorbidities also interact. So it’s been shown that psoriasis, a chronic inflammatory disease, also increases the risk of atrial fibrillation. So psoriasis, a chronic inflammatory disease, and atrial fibrillation both increase the risk of cardiovascular disease, but also affect each other. It’s important, therefore, to remember as I mentioned in the beginning that these diseases don’t work in isolation.

They share a number of risk factors and they’re working in the same body over the same time scale. It is therefore tricky to work out which disease is causing the progression of which.