The duration of treatment effect was evaluated in 10 patients with HIV-related thrombocytopenia who received an average of 10 IVIG infusions (range, 1 to 26) and 15 anti-D infusions (range, 2 to 40), retrospectively. The y-axis depicts the mean duration (days) of effect for IVIG and anti-D treatments for each patient. The anti-D effect lasted longer in 9 of the 10 patients (mean difference, 11.6 days; P = .007). The mean platelet increase after anti-D infusions was significantly higher than the mean platelet increase after IVIG treatments (P = .02; data not shown). (▵) IVIG; (▪) anti-D.