Reassessing critical maternal antibody threshold in RhD alloimmunization: a 16-year retrospective cohort study

OBJECTIVE

To determine the critical maternal antibody threshold for specialist referral in cases of RhD alloimmunization.

METHODS

This was a retrospective cohort study, covering a 16-year period at the national tertiary fetal medicine center for management of alloimmunization. Data concerning RhD alloimmunized pregnant women were extracted from an institutional database and maternal anti-D antibody levels were cross-checked with the national reference laboratory. Fetal hemoglobin (Hb) levels were determined only at the first intrauterine transfusion (IUT) and were compared with the pretransfusion maternal anti-D antibody level (IU/mL). Sensitivity, specificity and positive and negative predictive values of maternal antibody thresholds for detecting moderate to severe (Hb ≤ 0.64MoM) fetal anemia were calculated.

RESULTS

Between 1996 and 2011, 66 women underwent a first IUT for RhD alloimmunization at our institution. The highest serum anti-D antibody level was extracted for 208 RhD alloimmunized women who did not require IUT during the last 10 years of the study period. The traditional maternal antibody threshold of > 15 IU/mL failed to detect 20% of cases of moderate to severe fetal anemia. The ≥ 4 IU/mL threshold had 100% sensitivity but a 45% false-positive rate. The optimal anti-D antibody threshold for specialist referral in our population was ≥ 6 IU/mL; at this level, no case of moderate to severe anemia was missed and specificity was 61%. Use of this threshold would have eliminated 10% of referrals to our fetal medicine unit without compromising fetal outcomes.

CONCLUSIONS

Setting the critical maternal RhD antibody level at >15 IU/mL does not provide sufficient sensitivity. The lower threshold of ≥ 4 IU/mL, though sensitive, is associated with a 45% false-positive rate. In our population, a threshold of ≥ 6 IU/mL minimizes false-positive referrals while maintaining 100% sensitivity for moderate to severe fetal anemia.

Sonographic discrimination between benign and malignant adnexal masses in premenopause

PURPOSE

The aim of this study was to assess the diagnostic value of sonographic pattern recognition by experts, a standardized morphological scoring system, the risk malignancy index (RMI) and CA 125 assay for the preoperative assessment of ovarian lesions in premenopausal patients.

MATERIAL AND METHODS

Diagnostic work-up of 1320 patients who underwent surgical exploration due to an adnexal mass at a tertiary referral center were included. We assessed the discriminative value of pattern recognition, a sonographic morphological scoring system, RMI and CA 125 by calculating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and Cohen's kappa for each diagnostic approach while using histopathology as the reference standard.

RESULTS

Pattern recognition showed the highest discriminative power with an observed kappa of 0.53. Sensitivity and specificity yielded 0.76 and 0.97 respectively. Combining pattern recognition with CA 125 serum measurement in the context of a triage system diminished the diagnostic value (kappa: 0.24; sensitivity: 0.29 specificity: 0.97). For the RMI we observed a sensitivity of 0.54 and a specificity of 0.96 and estimated kappa value yielded 0.37. Omitting the CA 125 assay and using a morphological sonographic assessment system increased the kappa value to 0.45 with sensitivity and specificity observed at 0.61 and 0.97 respectively.

CONCLUSION

Expert pattern recognition was found to be the method with the highest discriminative power in assessing an adnexal mass during premenopause. Additional assessment of serum CA 125 diminished the diagnostic accuracy. Standardized morphological sonographic assessment resulted in a moderate diagnostic accuracy. Supplementing the morphological sonographic assessment with CA 125 by using the RMI algorithm did not improve the diagnostic value.

A correlation between severe haemolytic disease of the fetus and newborn and maternal ABO blood group

OBJECTIVE

To analyse anti-D quantification levels and frequency of intrauterine transfusion (IUT), per maternal ABO blood group.

BACKGROUND

Maternally derived red cell allo-antibodies can target fetal red cell antigens in utero leading to haemolytic disease and fetal anaemia. When a clinically significant allo-antibody is formed the priority is ascertaining the risk to the fetus and maternal ABO blood groups are not considered relevant.

MATERIALS AND METHODS

This was a 10-year retrospective, observational study carried out on women referred for anti-D quantification (n = 1106), and women whose fetuses required an IUT to treat fetal anaemia (n = 62) due to anti-D, in the Republic of Ireland.

RESULTS

Relative to the overall incidence of RhD allo-immunisation by blood group, women of blood group A were more likely to require IUT compared with those who were blood group O (P = 0.002).

CONCLUSION

It is known that ABO feto-maternal compatibility can influence the incidence and level of red cell allo-antibodies in pregnancy; however, it does not account for the significantly high rate of severe haemolytic disease requiring IUT seen in blood group A women.

Single timepoint models of dynamic systems

Many interesting studies aimed at elucidating the connectivity structure of biomolecular pathways make use of abundance measurements, and employ statistical and information theoretic approaches to assess connectivities. These studies often do not address the effects of the dynamics of the underlying biological system, yet dynamics give rise to impactful issues such as timepoint selection and its effect on structure recovery. In this work, we study conditions for reliable retrieval of the connectivity structure of a dynamic system, and the impact of dynamics on structure-learning efforts. We encounter an unexpected problem not previously described in elucidating connectivity structure from dynamic systems, show how this confounds structure learning of the system and discuss possible approaches to overcome the confounding effect. Finally, we test our hypotheses on an accurate dynamic model of the IGF signalling pathway. We use two structure-learning methods at four time points to contrast the performance and robustness of those methods in terms of recovering correct connectivity.

Epidemiology of invasive pneumococcal disease and vaccine provision in a tertiary referral center

Invasive pneumococcal disease (IPD) has an all-cause mortality of 5-35 % in the developed world. Pneumococcal vaccination is recommended for at-risk groups, including those infected with human immunodeficiency virus (HIV) and those over 65 years of age. However, adherence to vaccination guidelines is low. We reviewed all cases of IPD in our tertiary referral hospital from 2006 to 2010. IPD was defined as the isolation of Streptococcus pneumoniae from a normally sterile site with a compatible clinical syndrome. Demographics, risk factors, susceptibilities, pneumococcal serotype, mortality, and vaccination status for each patient were analyzed. There were 127 IPD episodes in 122 patients. The overall case fatality rate was 21.2 %. Seventy-two percent of the patients had two or more risk factors that should have prompted pneumococcal vaccination. However, the overall pneumococcal vaccination provision was only 9 %: 64.6 % of all typed isolates were contained in the pneumococcal polysaccharides vaccine 23 (PPV23), 48.8 % in the 7-valent pneumococcal conjugate vaccine (PCV7), and 60.1 % in PCV13. All isolates were fully sensitive to penicillin and cefotaxime. Recurrent IPD was seen in 11 % of the HIV-infected patients, highlighting a particular at-risk group. IPD has a high mortality rate. There is low vaccine provision in our study, although most IPD patients had risk factors that should have prompted vaccination. HIV-positive people are particularly at risk; vaccinating those with persisting CD4 counts less than 200 cells/mm(3) and the use of "prime-boost" strategies may decrease incidence in the future. Newer models of care such as a dedicated vaccine clinic as described in this study may help increase vaccine provision and uptake.

Emerging biosignature of brain function and intervention in pediatric bipolar disorder

Pediatric bipolar disorder (PBD) is a complex illness with a chronic course, requiring multiple medications over the longitudinal course of illness, with limited recovery and high relapse rate. Beyond the placebo controlled trials of monotherapy, there is an increased need to understand how each medication influences regions of affective and cognitive circuitry function by normalization or deployment of alternative circuitry regions. Functional studies are beginning to unravel the improved function in the fronto-limbic and fronto-temporal affective circuitry, and based on the paradigm administered, also in the interfacing cognitive fronto-striato-temporo-parietal regions. Treatment studies illustrated a pattern of improvement in functional activity consistently among the affective ventrolateral and medial prefrontal regions, and variably in the cognitive dorsolateral prefrontal cortex. While there is decreased activity in amygdala with treatment for mania or depression among patients with PBD, there appears to be residual increased amygdala activity regardless of response, relative to healthy controls, suggesting a trait-like abnormality. Parallel biochemical abnormalities in magnetic resonance spectroscopic studies and fronto-limbic activity in magnetic resonance imaging studies of brain function at baseline provide maiden data on predicting outcome. This preliminary cohort of studies that probed the hypothesized circuitries underlying specific symptom constructs, coupled with futuristic paradigms and analytic methods, serve as a guidepost to generate the next generation of studies and build on the emerging biosignature towards specific treatment targets for personalized medicine in PBD.