RESUMO
BACKGROUND: Previous studies on low blood pressure in patients with homozygous sickle cell (SS) disease have sought new hypotheses on the mechanism of low blood pressure but have not analyzed the role of known determinants such as weight. METHODS: Blood pressure has been measured by an automated oscillometric method in 220 patients with SS disease, 144 with sickle cell-hemoglobin C disease (both groups aged, 9.5 to 18.5 years) and 122 control subjects with a normal hemoglobin genotype (aged 16.0 to 18.5 years) participating in a cohort study from birth. RESULTS: Significant age-related increases in systolic and mean arterial pressure occurred in sickle cell-hemoglobin C disease but not in SS disease. Further analyses were confined to a subgroup of 51 patients with SS, 41 patients with sickle cell-hemoglobin C, and 97 subjects with normal hemoglobin, aged 16.0 to 18.5 years in whom simultaneous measurements of height, weight, arm circumference, and hematologic test results were also available. Crude analyses showed significantly lower systolic, diastolic, and mean arterial pressure in SS disease compared with control subjects with normal hemoglobin, but further analysis showed the systolic difference to be confined to males and all differences disappeared after adjustment for weight. No differences occurred in sickle cell-hemoglobin C disease. CONCLUSIONS: These results suggest that the lower blood pressure in SS disease is attributable to low weight and that no further mechanisms need be postulated.