RISK-FACTORS OF STROKE AT HIGH AND LOW-ALTITUDE AREAS IN SAUDI-ARABIA

Background: The epidemiology of stroke at different geographical locat ions in the Kingdom of Saudi Arabia has not been adequately investigat ed, Methods: In this study, clinical types and risk factors of stroke were compared among patients at low-altitude (Riyadh, 620 m) and high- altitude (Al Baha >2000 m) areas using a case-control study design. On e-hundred ninety recently diagnosed cases (109 from Riyadh and 81 from Al Baha) were verified and subjects were interviewed. An equal number of age- and sex-matched controls from the corresponding areas were al so interviewed using a specific standard questionnaire. Results: The f requency of thrombotic stroke at high altitude was 93.4% as compared t o 79.3% at low altitude (P <0.05). The odds ratios (OR) for the differ ent risk factors at high and low altitudes, respectively, were: hypert ension 4.4 and 2.1; diabetes mellitus: 2.7 and 1.9; ischemic heart dis ease (IHD): 2.4 and 1.9; atrial fibrillation: 3.9 and 3.3, and smoking : 2.3 and 2.5, The mean hematocrit values were 45.3% at high altitude and 41.0% for low altitude patients (P <0.001) and its association wit h stroke at high altitude remained significant even after adjusting fo r age, gender and occupation, Conclusions: The study's finding of an i ncreased frequency of thrombotic stroke at high altitude was explained by increased hematocrit which might have caused this in conjunction w ith other factors such as hypertension and IHD, Larger studies are rec ommended for better clarification of interaction between high altitude and other established risk factors not included in this study, such a s sickle cell anemia and congenital heart diseases in young patients.