We agree with Kami and colleagues that the incidence of malignant hematologic conditions was lower in patients 60 years of age or older than in patients age 20 to 49 years or patients age 50 to 59 years. However, we think that it is more appropriate to present these results by using a time-dependent method. The probability of developing a malignant hematologic disorder at 10 years was 12% ± 3% in patients age 20 to 49 years, 17% ± 6% in patients age 50 to 59 years, and 5% ± 3% in patients age 60 years or older. Patients 50 to 59 years of age had a significantly higher risk for developing a malignant hematologic condition at 10 years (P < 0.001) than did the younger and older age group. However, this risk was not statistically significantly lower for patients 60 years or older than for patients 20 to 47 years of age. The lower incidence in patients age 60 years or older is therefore due to the shorter observation time in this group.

The incidence and probability of developing a solid tumor at 10 years were increased in patients 60 years of age or older (16% ± 6%), compared with patients younger than 50 years of age (3% ± 1%; P < 0.001). To adjust for the inherently increased risk for solid tumors associated with older age, we compared the number of solid tumors observed after immunosuppression for aplastic anemia with the expected number of events in a general, age-adjusted population (Table).

Compared with a general population, the risk for developing a solid tumor does not increase in older patients treated with immunosuppression; these findings are in agreement with data published by Socié and colleagues, who showed that after immunosuppression the ratio of observed to expected tumors was 1.65 (95% CI, 0.67 to 3.41) (1).