Stroke and HIV--causal or coincidental co-occurrence?

Stroke is responsible for a large part of the global burden of disease. Worldwide in 1990 it was the second commonest cause of mortality causing approximately 4.4 million deaths. Two-thirds of these deaths occurred in less developed countries. In South Africa in 2001 it was the fourth leading reported natural cause of mortality. HIV infection has in the wake of our pandemic become a leading cause of death and dread disease with an estimated 15% of the population being infected. A co-occurrence of these two illnesses is therefore expected. The debate rests with regard to whether or not there is a causal relationship. The first suggestion that there is an association between HIV and stroke came from autopsy and case series from the USA. These were followed by population studies to determine the risk of this association. The first of these was a study from KwaZulu-Natal (KZN) that found an HIV prevalence of 16% in a young stroke population. The prevalence of HIV in that region at that time was also 16% suggesting that there was no significant increase in the risk of stroke associated with HIV infection. In another population-based study from Baltimore USA the incidence of stroke in persons with AIDS was 0.2% per year. In this study AIDS was found to confer an adjusted relative risk of 13.7 for ischaemic stroke (IS) and 25.5 for intracerebral haemorrhage (ICH) indicating that AIDS is strongly associated with both IS and ICH. A criticism directed at this study has been that only patients meeting the Centers for Disease Control (CDC) definition of AIDS were included. In a study from Germany on 772 HIV-infected patients a prevalence of 1.2% for stroke and an annual incidence rate for IS of 216/100 000 population was reported. The prevalence was highest in young adult patients with advanced HIV infection. This latter finding has been consistently observed in studies reporting on the association between HIV and stroke. The results in this regard thus appear to be inconclusive but favour an increased stroke risk at least with advanced HIV/AIDS. (excerpt)