[Arterial blood pressure in homozygote patients with drepanocytosis]. / Pression artérielle chez les patients drépanocytaires homozygotes.

BACKGROUND: Relative hypotension has been reported in sickle cell patients. The aim of this study was to compare blood pressure in patients with SS disease and subjects with normal hemoglobin genotype AA and to assess whether the same clinical, biological and socio-demographic variables are associated to the mean arterial pressure in patients with sickle cell disease and normal subjects. METHOD: Blood pressure was measured with a standardized automated oscillometric method in 88 SS patients et 88 AA control subjects seen in the University Hospital of Pointe-à-Pitre (Guadeloupe). A multiple linear regression analysis for mean arterial pressure was done including type of hemoglobin (forced variable), age, sex, body mass index, pulse rate, hemoglobin concentration and interaction terms between type of hemoglobin and other variables. A regression was also fitted separately for each population. A downward stepwise strategy was used to simplify the models. RESULTS: The two groups were similar for age, height and gender ratio and pulse rate. Mean arterial pressure was significantly lower in sickle cell patients (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, pulse rate and an interaction between type of hemoglobin and age (global F = 22.04, adjusted R2 = 42%). The separate models indicated that sex was associated with mean arterial pressure only in patients with sickle cell disease and that age and hemoglobin concentration was associated with mean arterial pressure only in normal subjects. CONCLUSION: Blood pressure determinants are not similar in the two populations. The effect of age, especially, is not the same in patients with sickle cell disease and in normal subjects. These results confirm that specific patho-physiological models should be defined in sickle cell disease.

[Natural history of sickle cell anemia]. / Histoire naturelle de la drépanocytose.

Sickle-cell anaemia is characterized by three categories of clinical signs: anaemia, vaso-occlusive phenomena and infective complications, which are described here according to age. The natural history of the disease can be divided into four periods: the neonatal period which is asymptomatic but important to organize an effective protection; the first 5 years of life are characterized by a high risk of mortality, a high level of morbidity due to severe infections, episodes of acute anaemia and painful crises typical of that age-group; the life of older children and adolescents is dotted with painful crises; it is in this period that degenerative tissue pathology begins; in adulthood, the acute episodes are less frequent, but multiple complications develop. Some of them (cerebral vascular accidents or lung diseases) may be fatal, while others are the source of chronic and disabling lesions, notably ocular, orthopaedic and renal lesions, which affect the functional prognosis. Pregnancy remains a high risk. There is, therefore, a striking contrast between the basic physiopathological mechanism (polymerization of haemoglobin S) and the various clinical manifestations which depend on the type of haemoglobin, on the social and sanitary conditions in each country and on other reasons which remain to be elucidated.