Blood pressure in homozygous sickle cell patients

Background: Relative hypotension has been reported in sickle cell patients. The aim of this study was to compare blood pressure in patients with SS di sease and subjects with normal hemoglobin genotype AA and to assess whether the same clinical, biological and socio-demographic variables are associat ed to the mean arterial pressure in patients with sickle cell disease and n ormal subjects. Method: Blood pressure was measured with a standardized automated oscillome tric method in 88 SS patients ct 88 AA control subjects seen in the Univers ity Hospital of Pointe-a-Pitre (Guadeloupe). A multiple linens regression a nalysis for mean arterial pressure was done including type of hemoglobin (f orced variable), age, sex body mass index, pulse rate, hemoglobin concentra tion and interaction terms between type of hemoglobin and other variables. A regression was also fitted separately for each population. A downward ste pwise strategy was used to simplify the models. Results : The two groups were similar for age, height and gender ratio and pulse rare. Mean arterial pressure was significantly lower in sickle cell p atients (81.6 mmHg in SS patients vs 89.9 mmHg in AA subjects, p < 10(-4)). The final model included type of hemoglobin, age, sex, body mass index, pu lse rate and an interaction between type of hemoglobin and age (global F = 22.04, adjusted R-2 = 42%). The separate models indicated that sex was asso ciated with mean arterial pressure only in patients with sickle cell diseas e and that age and hemoglobin concentration was associated with mean arteri al pressure only in normal subjects. Conclusion: Blood pressure determinants are not similar in the two populati ons. The effect of age, especially, is not the same in patients with sickle cell disease and in normal subjects. These results confirm that specific p atho-physiological models should be defined in sickle cell disease.