The cooperative study of sickle cell disease: review of study design and objectives.

Although sickle cell disease has been known for years and many of its manifestations have been recognized, the "natural history" or clinical course of the disease from early childhood to death is not well understood. This is largely because of the variable degree of severity, the variability of the many manifestations, and the complexity of the interaction of the disease process with other health-related events. Therefore, information obtained to date hs been largely anecdotal, retrospective in nature, and lacking statistical stature. Consequently, there are many unanswered clinical questions about this illness. Therefore, the National Heart, Lung, and Blood Institute of the National Institutes of Health has initiated a large-scale, multi-institution investigation based on an analytical and specific process, which is described. This 5-year study will provide the data base to answer existing questions and provide information to improve present medical management. Knowledge of risk factors, rates of progression, and incidence and nature of complications will directly impact on the care of sickle cell patients. In addition, this information will improve counseling related to family decisions and opportunities now available for prenatal diagnosis. Likewise, a data bank of clinical manifestations and a classification or index of severity are essential as emerging antisickling agents require clinical trials.