Jamaican sickle cell disease: lessons from a cohort study

ABSTRACT

The Jamaican Cohort Study of sickle cell disease recruited all cases among 100 000 consecutive non-operative deliveries at the Government Maternity Hospital (Victoria Jubilee) between June 1973 and December 1981. There were 315 babies with homozygous sickle cell (SS) disease of whom 311 were followed from birth with active tracing of defaults. During this period, prophylactic penicillin and pneumococcal vaccine were introduced for the prevention of pneumonococcal septicaemia, and parental education in the early detection of acute splenic sequestration was shown to reduce mortality from this complication by 90 percent. To assess changes in survival consequent on these measures, 315 children were divided into three equal groups of 105 children born between 25/6/73 and 27/12/75 (30 months), 28/12/75 and 2/1/79 (36 months), and 3/1/79 and 28/12/81 (36 months). Mortality was assessed by survival curve analysis using the product limit method. Survival was examined from birth to the 15th birthday, and survival curves for each third compared using the log rank test for trend. There were 61 deaths (54 autopsies) before 15 years of age, 28 in the first third, 17 in the second third, and 16 in the last third, the log rank test for trend being of borderline statistical significance (p=0.05). Septicaemia or meningitis accounted for 8, 1 and 5 deaths in the three groups, respectively, and pneumococcal sepsis for 4, 1 and 1 of these deaths. Acute splenic sequestration accounted for 5, 2 and 1 deaths and the interventions (against pneumococcal sepsis and acute splenic sequestration) were assessed by combining these for anlaysis. Together they showed a significant decline in mortality during the study (test for trend, p=0.02). No change was observed in the numbers with acute chest syndrome. Early diagnosis and simple prophylactic measures significantly reduce deaths associated with SS disease.(AU)