Predicting severe disease in the second pregnancy with RhD
antibodies
The association between severity in the first and the second pregnancy
with RhD antibodies was assessed in both subgroups. In group A, 5/11
(45%) women with moderate to severe disease in the first pregnancy with
RhD immunization developed severe disease in the second pregnancy as
compared to 1/16 women with previous no or mild disease (6%, OR 12.5,
95% CI 1.2-130.6, P =.027). In group B, this was 5/8 (63%) as
compared to 7/17 women with previous no or mild disease (41%, OR 2.4,
95% CI 0.4-13.4, P =.411).
Factors from the first immunized pregnancy possibly predicting severe
disease in the subsequent pregnancy with a RhD-positive foetus were
assessed in a multivariate prediction model per subgroup (supplemental
Table S4). In group A, the highest ADCC result in the first immunized
pregnancy remained as the only factor associated with severe disease in
the subsequent pregnancy. The predictive value of this test is
summarized in Table S5. The negative predictive value of an ADCC test
result >10% appeared most useful: if the ADCC test did not
exceed 10% in the first pregnancy, 89% (95% CI 55-98%) of subsequent
RhD-positive children will not be treated with intrauterine
transfusion(s).
In group B, no predictive factors were found in this multivariate
analysis.
DISCUSSION