The Aplastic Crisis in HbSS: Observations from the Jamaican Birth Cohort.

In order to document the prevalence, clinical features, hematology and outcome of the aplastic crisis in homozygous sickle cell disease (HbSS), a cohort study has been conducted from birth. Newborn screening of 100 000 deliveries at the main government maternity hospital, Kingston, Jamaica between 1973 and 1981 detected 311 cases of HbSS who have been followed at the Medical Research Council Laboratories at the University of the West Indies, Kingston, Jamaica. Clinically defined aplastic crises occurred in 118 (38%) patients at a median age of 7.5 years (range 0.5-23.0 years). All but one event seroconverted to parvovirus B19, the exception being a 9.3 year male with classic aplasia but subsequent IgG did not exceed 3 IU. Defined by zero reticulocyte counts, 94 patients presented with a median hemoglobin of 3.7 g/dL (range 18-87 g/L) representing a median fall from steady state levels of 3.8 g/dL. Clear epidemic peaks occurred at 1979-1980, 1984-1986, and 1990-1993 and the admission rate and use of blood cultures fell with each epidemic, reflecting increased familiarity with the complication. Symptoms were usually nonspecific and all but 7 were transfused. No patient had a recurrence and two died from aplasia (one with remote rural residence and the other following an incorrect diagnosis). Of those seroconverting to parvovirus B19, 68% manifested aplasia and 24% had no hematologic change. Correctly diagnosed and managed, the aplastic crisis is essentially benign. (230 words).