How many patients with homozygous sickle cell disease who survived to the age of 60 years or more have you seen during your career?
Though the title, “Elderly Survivors with Homozygous Sickle Cell Disease,” seemed a bit incongruous to me, it sure got my attention. Prolonged survival in homozygous sickle cell disease is more common than previously thought. In 1968, a Jamaican study described 60 patients who were 30 years of age or older. In 1994 the Cooperative Study of Sickle Cell Disease in the United States estimated a median survival of 42 to 48 years. The Sickle Cell Clinic at the University of the West Indies reported in 2001 that they had treated 102 patients (64.7% women) who survived beyond their 60th birthday. Now 58 of these patients are dead (57%), 4 have emigrated, and 40 of them (39%) are still alive. In this study, the diagnosis of homozygous sickle cell disease was based on criteria that excluded sickle cell-beta° thalassemia or sickle cell-hereditary persistence of fetal hemoglobin (FHb).
None of these patients received hydroxyurea, and only two patients with renal impairment received regular transfusions. Their ages ranged from 60.2 to 85.6 years, with a slight excess of females (67%). Sickle cell-alpha+ - thalassemia was homozygous in 12% of patients, heterozygous in 39%, with a normal alpha-gene number in 46%. FHb levels were about 4.9% higher among these patients and exceeded 10% in 24% of women and 14% of men, which suggests that higher FHb levels conferred protection during childhood. Other clinical features seen in this cohort of patients with prolonged survival included an incidental presentation (40%), no bone-pain crisis (18%), bone pain decreased with age, and a history of leg ulcers (58%). Pregnancy had a benign outcome with 81% resulting in live births. In these elderly survivors, high FHb levels and possible familial clustering were consistent with genetic factors. In this group of patients, alpha-thalassemia did not promote survival. The major clinical problems emerging with age were renal impairment and declining Hb levels.
Ref. NEJM 356(6): 642-643, 2007.
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