No significant differences in persistence of HLA antibodies between CR⁻ and CR⁺ recipients. Longitudinal class I (A and B) and class II (C and D) HLA Ab NBG ratios were plotted over time for CR⁻ (A and C) and CR⁺ recipients (B and D). The dashed line marks the cutoff used to distinguish positive and negative results. Kaplan-Meier survival analysis was used to evaluate the persistence of new class I (E) and class II (F) antibodies, with CR⁻ and CR⁺ recipients compared using the log-rank test and associated P values reported.