Survival after stroke. Risk factors and determinants in the Copenhagen Stroke Study

The eight papers included in this doctoral thesis were made during my position as a clinical research assistant at the Department of Neurology, Bispebjerg Hospital. All papers are based on the Copenhagen Stroke Study, which comprises a cohort of 1197 patients with acute stroke admitted to a single stroke unit and recruited from a well-defined area in Copenhagen, Denmark. This thesis focuses on the survival after stroke in relation to several baseline clinical characteristics and risk factors for cardiovascular disease. The thesis comes in three sections with regard to whether factors or clinical characteristics are permanent, potentially modifiable, or possible to change. The relative importance of the factors and clinical characteristics are discussed in relation to short-, intermediate-, and long-term survival after stroke. The results from the Copenhagen Stroke Study are compared to the results from other community-based or population-based studies. The two most prominent factors that determine both short- and long-term survival after stroke are age and stroke severity at onset. Advancing age and increasing severity are perceptively negatively correlated to survival. In some cases emerging therapies such as thrombolytic therapy and hypothermia may alleviate the burden of stroke severity, but this is not the case for the majority of stroke patients. The necessity to measure stroke severity with a validated stroke scale when comparing stroke patients in randomized clinical trials or population-based surveys is emphasized. For factors such as sex, and most cardiovascular risk factors further studies are necessary to clarify the relation to survival because studies disagree. Conclusions from studies of the relation between survival and alcohol intake are still debatable, mostly because of diverging definitions of the intensity of exposure. Smoking is uniformly associated with a poorer survival after stroke. Stroke unit treatment improves both short- and longterm survival regardless of stroke type, severity, age, and cardiovascular risk factor profile.