Cubic spline interpolation of baseline bone age among HIV⁻ participants with hemophilia (with and without a history of inhibitors) and a group of siblings without hemophilia. A total of 158 baseline films were used in the analysis: 19 participants had hemophilia and an inhibitor, 101 participants had hemophilia without an inhibitor, and 38 were sibling control participants. Altogether, 6 participants with hemophilia and 6 siblings were excluded from the analysis because they were skeletally mature at baseline, and 3 siblings lacked bone age measurements.