Abstract A randomized, controlled clinical trial established the efficacy and safety of short‐term use of hydroxyurea in adult sickle cell anemia. To examine the risks and benefits of long‐term hydroxyurea usage, patients in this trial were followed for 17.5 years during which they could start or stop hydroxyurea. The purpose of this follow‐up was to search for adverse outcomes and estimate mortality. For each outcome and for mortality, exact 95% confidence intervals were calculated, or tests were conducted at α = 0.05 level ( P ‐value &lt;0.05 for statistical significance). Although the death rate in the overall study cohort was high (43.1%; 4.4 per 100 person‐years), mortality was reduced in individuals with long‐term exposure to hydroxyurea. Survival curves demonstrated a significant reduction in deaths with long‐term exposure. Twenty‐four percent of deaths were due to pulmonary complications; 87.1% occurred in patients who never took hydroxyurea or took it for &lt;5 years. Stroke, organ dysfunction, infection, and malignancy were similar in all groups. Our results, while no longer the product of a randomized study because of the ethical concerns of withholding an efficacious treatment, suggest that long‐term use of hydroxyurea is safe and might decrease mortality. Am. J. Hematol. 2010. © 2010 Wiley‐Liss, Inc.

The risks and benefits of long‐term use of hydroxyurea in sickle cell anemia: A 17.5 year follow‐up