Incidence and predictors of priapism events in sickle cell anemia: a diary-based analysis

•Men with SCA and ≥3 priapism events in the prior 12 months have an 80% chance of having a priapism episode within the following 3 months.•The sum of priapism events in 3 months predicted a major priapism event. [Display omitted] We conducted one of the first prospective studies to test the hypothesis that the clinical history of priapism underestimates priapism incidence compared with a priapism pain diary. Eligibility criteria were men with sickle cell anemia (SCA) between 18 and 40 years of age who have had at least 3 episodes of priapism in the past 12 months. Seventy-one men with SCA completed the diary for at least 3 months. The first 3 months of the priapism diary were included in the analysis. A total of 298 priapism episodes were recorded, and 80% (57 of 71) of the participants had at least 1 priapism event. Priapism severity was reported in the range of moderate to the worst imaginable pain in 81.5% (263 of 298), and a total 57 participants (80%) had a median pain rating of 6 (interquartile range: 5-8) on a scale from 1 to 10. The monthly incidence rate of priapism per participant based on history versus self-report pain diary was 2.0 (95% confidence interval, 1.9-2.1) and 1.4 (95% confidence interval, 1.2-1.6), respectively (P < .001). For participants that had a prior priapism episode, 80% had another episode during the 3-month interval follow-up. The median time to that second episode was 27.5 days. Major priapism occurred in 9.9% of episodes and was associated with the sum of all prospective priapism events. Men with SCA and at least 3 priapism episodes in the past 12 months are at significant risk for recurrent priapism in the following 3 months.