Sex as a Prognostic Factor in Systematic Reviews: Challenges and Lessons Learned

Sex is a common baseline factor collected in studies that has the potential to be a prognostic factor (PF) in several clinical areas. In recent years, research on sex as a PF has increased; however, this influx of new studies frequently shows conflicting results across the same treatment or disease state. Thus, systematic reviews (SRs) addressing sex as a PF may help us to better understand diseases and further personalize healthcare. We wrote this article to offer insights into the challenges we encountered when conducting SRs on sex as a PF and suggestions on how to overcome these obstacles, regardless of the clinical domain. When carrying out a PF SR with sex as the index factor, it is important to keep in mind the modifications that must be made in various SR stages, such as modifying the PF section of CHARMS-PF, adjusting certain sections of QUIPS and extracting data on the sex and gender terms used throughout the studies. In this paper, we provide an overview of the lessons learned from carrying out our reviews on sex as a PF in different disciplines and now call on researchers, funding agencies and journals to realize the importance of studying sex as a PF.

A Multi-Omics Approach to X-Chromosome Inactivation (XCI) Identifies Severe Xci Skewing in Female Genetic Carriers of Hemophilia

Background. Hemophilia A and B are rare X-linked bleeding disorders caused by deficiencies in factor VIII (FVIII) and factor IX (FIX) respectively. Males with hemophilia are usually hemizygous for disease-causing genetic variants in the F8 or F9 genes. Females with disease-causing variants (female genetic carriers) are usually heterozygous for a F8 or F9 causative variant. However, relative to the general population, female carriers have lower factor levels and are at risk for increased bleeding. In addition, a subset of female carriers meet the criteria for hemophilia based on their factor level. X chromosome inactivation (XCI) silences transcription of one of the two X chromosomes in female mammalian cells as a mechanism of dosage compensation. XCI is a consideration in disease in all X-linked disorders. However, the literature is conflicted as to the correlation of XCI in blood with low levels and bleeding in female genetic carriers of hemophilia. In this study, we sought to further understand low factor levels in female genetic carriers. We used a multi-omics approach to characterize XCI used RNA-seq to characterize expression of the candidate genes F8 and VWF. Methods. We performed whole blood RNA-Seq (wbRNA-Seq) for subjects (N=200) selected from the My Life, Our Future (MLOF) Research Repository. wbRNA-Seq was aligned to the reference genome (GRCh38) using Star v2.7. For all subjects, we examined F8 and VWF expression in wbRNA-Seq data. We performed XCI analyses by combining wbRNA-seq and whole genome sequence (WGS) data. XCI analyses were performed for females (N=23) with matching WGS data from the NHLBI Trans-Omic for Precision Medicine program. WGS data were aligned to GRCh38 using BWA-MEM v0.7.8. Single nucleotide variants and small insertions and deletions in WGS data were assessed using GATK HaplotypeCaller v3.7. XCI skew was determined by examining the number of wbRNA-seq reads aligning to heterozygous variants in WGS data using the program, GATK ASEReadCounter. Results. wbRNA-Seq yielded high quality data in nearly all subjects (196 subjects). RNA-seq data show F8 and VWF expression in whole blood is consistent with previous findings. Abundance of VWF and F8 transcript were not significantly correlated with factor baseline levels. XCI analysis using wbRNA-seq and WGS data identified several females with a high degree of XCI skew (6 females >= 80% XCI skew), including one female in whom the same copy of chromosome X appears to be fully silenced (100% skewed). Association of FVIII baseline levels shows that this individual has baseline levels indicative of severe disease (less than 1% FVIII activity). Females with skewing >= 80% were associated with baseline levels indicative of mild hemophilia (greater than 5% factor activity). Conclusions. In this study, we used a multi-omics approach to study XCI in female genetic carriers of hemophilia. F8 and VWF expression was not associated with baseline factor levels, suggesting whole blood F8 and VWF transcript levels do not correlate with female hemophilia disease severity. XCI analyses indicated XCI skewing likely contributes to disease severity in a subset of female genetic carriers of hemophilia. One subject with severe hemophilia unexpectedly exhibited nearly 100% XCI skewing. We speculate from the baseline factor level, F8 genotype, and sequencing data available that she carries an X-chromosome genetic variant that impacts cell viability when that X chromosome is active. We are further investigating XCI skew in a larger cohort and are assessing the mechanisms which may lead to severe XCI skewing in females with hemophilia. Disclosures Konkle: BioMarin: Consultancy; Takeda: Research Funding; CSL Behring: Consultancy; Uniquire: Research Funding; Sigilon: Consultancy, Research Funding; Pfizer: Consultancy, Research Funding; Sanofi: Consultancy, Research Funding; Spark: Consultancy, Research Funding; Roche: Consultancy; Baxalta: Research Funding. Johnsen:Octapharma: Research Funding.

Bleeding severity in patients with rare bleeding disorders: real-life data from the RBiN study

Patients with hereditary rare bleeding disorders (RBDs) present with diverse hemorrhagic symptoms. Correlation between factor activity levels and clinical bleeding severity is poor for most RBDs. Threshold factor activity levels have been previously described in relation to bleeding severity but have not yet been validated. The Rare Bleeding Disorders in the Netherlands (RBiN) study is a nationwide cross-sectional study of patients registered in all 6 Dutch Haemophilia Treatment Centers with a known RBD and who are age 1 to 99 years. Bleeding scores were determined, and laboratory and clinical data were extracted from patient files. In all, 263 patients were included, of whom 202 (77%) attended the scheduled study visit. The median International Society of Thrombosis and Haemostasis (ISTH) bleeding assessment tool (BAT) score was 9. Correlations between baseline factor activity levels and ISTH BAT scores were strong for deficiencies in factor II (FII) (r = –0.792) and FX (r = –0.838) and were moderate for deficiencies of fibrinogen (r = –0.683), FV (r = –0.623), FVII (r = –0.516), FXIII (r = –0.516), and α2-antiplasmin (r = –0.594). There was no correlation for FXI deficiency (r = –0.218). The RBD BAT identified more women (94% vs 83%) and children (100% vs 71%) with an RBD than the ISTH BAT did. Importantly, 48% of patients had more severe bleeding than predicted for their baseline factor activity level. In addition, 34% of patients were predicted to be asymptomatic, but they actually had grade 2 (31%) or 3 (3%) bleeding. Bleeding severity in patients with RBDs is more pronounced than previously anticipated. The previously determined threshold factor activity levels to ensure no (spontaneous) bleeding in patients with an RBD are inaccurate. This trial was registered at www.clinicaltrials.gov as #NCT03347591.

Source apportionment of atmospheric mercury in the remote marine atmosphere: Mace Head GAW station, Irish western coast

We examined recent atmospheric mercury concentrations measured with a high temporal resolution of 15 min at Mace Head, a GAW station on the western coast of Ireland. We attributed a direct contribution of 34 % (0.44 ng m−3) to primary sources. Additionally, a steep decline (0.05 ng yr−1) in mercury concentrations was observed between 2013 and 2018. Using a stereo algorithm we reconstructed 99.9 % of the atmospheric mercury. A conservative analysis demonstrated no decrease in total gaseous mercury (TGM) associated with atmospheric species typically used as tracers for oceanic emissions. The results show that the atmospheric mercury mass is mainly loaded in a baseline factor with an ongoing decline. Moreover, we exploit temporal variation and wind pattern effects in the measured atmospheric species; the results show that the diurnal variation and seasonality in TGM observed in Mace Head are closely related to other species linked to primary sources and can be explained by transport from continental areas.

Source apportionment of atmospheric mercury in the remote marine atmosphere: Mace Head GAW station, Irish west coast

We examined recent atmospheric mercury concentrations measured with a high temporal resolution of 15 min. at Mace Head, a GAW station on the west coast of Ireland. We attributed a direct contribution of 34 % (0.44 ng m−3) to primary sources. Additionally, a steep decline (0.05 ng year−1) in mercury concentrations was observed between 2013 and 2018. Using a stereo algorithm we reconstructed 99.9 % of the atmospheric mercury. A conservative analysis demonstrated no decreasing of TGM associated with atmospheric species typically used as tracers for oceanic emissions. The results show that the atmospheric mercury mass is mainly loaded in a baseline factor with an on-going decline. Moreover, we exploit temporal variation and wind pattern effects in the measured atmospheric species, the results show that the diurnal variation and seasonality in TGM observed in Mace Head is closely related to other species linked to primary sources and can be explained by transport from continental areas.

Examining the measure of student engagement in the classroom using the bifactor model: Increased validity when predicting misconduct at school

Few studies have used exploratory factor analysis (EFA) and exploratory bifactor factor analysis (EBFA) to define a baseline factor structure model checking the construct-relevant psychometric multidimensionality of student engagement. This study was conducted on a sample of 3,374 students in France, Wallonia-Brussels Federation, and Luxembourg by using EFA and EBFA, and by comparing four confirmatory factor models of student engagement in the classroom. Results indicated the relevance of a bifactor model to disentangle general and specific factors of student engagement in the classroom in relation with student misconduct at school. The study suggests that if student engagement is principally a unidimensional construct, specific latent dimensions also exist (e.g., specific boredom behaviors) that have a substantive value and must be specified to increase quality of measurement and predictive validity.

Thrombin Generation As a Promising Biomarker for the Prediction of Bleeding Phenotype in Patients with Non-Severe Hemophilia

Background: Non-severe hemophilia A and B account for 50% of patients with hemophilia, in which factor level does not consistently correlate with bleeding phenotype. Clinical decision-making in regards to timely prophylaxis initiation and tailored surgical management could be informed by a biomarker that is more predictive of bleeding phenotype. We hypothesized that a global method to assess clotting potential, such as thrombin generation (TG), is more predictive of bleeding phenotype than factor level. Objectives: Determine the ability of TG, as compared to standard baseline factor activity, to differentiate bleeding phenotype severity in patients with non-severe hemophilia. Methods: Subjects were recruited from two hemophilia treatment centers (HTCs): Rady Children's Hospital San Diego (RCHSD) and Center for Inherited Blood Disorders (CIBD). Subjects were eligible for enrollment if they were at least one year of age and had a diagnosis of non-severe congenital hemophilia A or B, or were genetically confirmed or suspected female carriers. All enrolled patients or their parents completed the standardized, self-administered pediatric bleeding questionnaire (Self-PBQ) or bleeding assessment tool (Self-BAT). Clinical and laboratory information were extracted from the medical chart, including age at diagnosis, bleeding event history, past surgical history, treatment history and factor VIII or IX gene analysis. Validation of self-reported bleeding symptoms was performed using chart-derived data. Bleeding phenotype was assessed using standard calculation of the bleeding score, as defined by the respective validated self-reported tools. For the purpose of this analysis, we defined a high bleeding score as 13 or more, while a low bleeding score was defined as 12 or less. After a washout period of 5x the standard half-life of the administered factor product, blood samples were collected at time of enrollment. Platelet poor plasma was obtained according to a strict protocol to minimize pre-analytical variables. TG was measured by means of the calibrated automated thrombogram, with three different reagents: low (1 pM of tissue factor [TF]), regular (5 pM of TF) and High (20 pM of TF). The following TG parameters were evaluated: Peak TG (Peak), estimated thrombin potential (ETP) and velocity index (VI). Results: Eighty-one subjects were enrolled. The median age of our cohort was 15.6 years (IQR 21.2, range 4.9 - 59.8), with a slight female predominance (51%) due to inclusion of female carriers. The median follow-up period at the HTC was 5.3 years (IQR 7.5 years), with the majority having follow-up for at least three years. Enrolled patients had the following diagnoses: mild hemophilia A (70%), mild hemophilia B (3%), moderate hemophilia A (13%), moderate hemophilia B (3%), hemophilia A carriers with normal factor VIII levels (10%) and hemophilia B carriers with normal factor IX levels (1%). Median age at diagnosis was 8 years (IQR 26.3, range 0.1 - 56.1), which strongly correlated lower baseline factor activity (r=0.573, p-value < 0.0001). The median baseline factor activity was 21% (IQR 26, range 2 - 249). Factor exposure occurred in 46% of patients (n=37), of which 5 patients were on prophylaxis at time of enrollment. Chronic arthropathy was present in 2 patients (one with mild hemophilia A and one with moderate hemophilia A) and none of the patients had a history of an inhibitor. The majority of patients had a low bleeding score (74% vs. 26%). Baseline factor level and TG values obtained with regular reagent (5 pM of TF) showed significant correlation with bleeding score (r = -0.229 to -0.237, p-value < 0.05), while values obtained with other reagents did not show a significant correlation. Sensitivity/specificity analysis revealed the following optimal cutoff values for differentiating between bleeding severities, as obtained from TG with regular reagent: ETP (<1240 nM min), Peak (<130 nM) and VI (<23 nM/min), with analysis results as shown in Table 1. Conclusion: Even though both TG and baseline factor level had comparable correlation with bleeding severity, all TG values with 5 pM TF showed a much higher sensitivity outcome and greater ability to differentiate between bleeding severities in this population. This approach shows potential for predicting bleeding severity in patients with non-severe hemophilia and should be validated in long-term prospective studies. Disclosures Nossair: Novo Nordisk: Other: Conference - Haemophilia Acadamy; Novo Nordisk: Research Funding. Hwang:BPI: Consultancy; Bayer: Consultancy; Hema Biologics: Consultancy; Shire: Consultancy; Bioverativ: Other: PI in clinical research study. Thornburg:ATHN: Research Funding; Bayer Pharmaceuticals: Research Funding; Biomarin: Consultancy; CSL Behring: Research Funding; Bioverativ: Consultancy; Genentech: Speakers Bureau; Octapharma: Research Funding; NovoNordisk: Research Funding; Shire: Research Funding; Johns Hopkins All Children's Hospital: Research Funding; Bluebird Bio: Consultancy.

Assessing association of comorbidities with treatment choice and persistence in MS

Objective:To assess whether the presence of concomitant diseases at multiple sclerosis (MS) diagnosis is associated with the choice and the treatment persistence in an Italian MS cohort.Methods:We included newly diagnosed patients (2010–2016) followed in 20 MS centers and collected demographic and clinical data. We evaluated baseline factors related to the presence of comorbidities and the association between comorbidities and the clinical course of MS and the time to the first treatment switch.Results:The study cohort included 2,076 patients. Data on comorbidities were available for 1,877/2,076 patients (90.4%). A total of 449/1,877 (23.9%) patients had at least 1 comorbidity at MS diagnosis. Age at diagnosis (odds ratio 1.05, 95% confidence interval [CI] 1.04–1.06; p < 0.001) was the only baseline factor independently related to the presence of comorbidities. Comorbidities were not significantly associated with the choice of the first disease-modifying treatment, but were significantly associated with higher risk to switch from the first treatment due to intolerance (hazard ratio 1.42, CI 1.07–1.87; p = 0.014). Association of comorbidities with risk of switching for intolerance was significantly heterogeneous among treatments (interferon β, glatiramer acetate, natalizumab, or fingolimod; interaction test, p = 0.04).Conclusions:Comorbidities at diagnosis should be taken into account at the first treatment choice because they are associated with lower persistence on treatment.