Diversity of the free helical rim flap: A case series tailoring the microsurgical technique to esthetically optimize full-thickness nasal defect reconstructions

INTRODUCTION

The free helical rim (FHR) flap offers like-with-like reconstruction for full-thickness nasal defects. A case series of nasal reconstruction using an FHR flap was presented, detailing surgical steps and refinements, as well as functional and esthetic outcomes.

METHODS AND MATERIALS

This is a retrospective cohort study of composite nasal defect reconstruction with FHR flap from August 2018 to March 2020. Descriptive data were analyzed by SPSS software.

RESULTS

Six cases were recruited, four were unilateral alar defects, one was hemi-nose, and one was ala plus tip. The average size of the defect was 2.5 × 2.8 cm2. Three FHR flaps were designed with retrograde pedicles and three with anterograde pedicles. The facial artery and veins were the recipient vessels in all cases. Vascular grafts were used in all six cases. Descending branch of the lateral circumflex femoral (DLCxF) artery and vein functioned as interposition vascular conduits in five cases. Superficial forearm vein grafts were used in one case. One patient needed flap re-exploration due to venous congestion. One patient had partial flap necrosis due to delayed infection, and one developed delayed wound dehiscence in the irradiated wound. The average follow-up was 18 months.

CONCLUSION

The FHR flap has consistent vascular anatomy. It can be raised as an anterograde or retrograde flap for a contralateral or ipsilateral inset. FHR flap can be used in extensive composite nasal defects. This case series demonstrates that interposition vascular grafts are invariably needed and the possibility of using forearm vessels as grafts instead of DLCxF artery and vein.

Early on-treatment changes in circulating tumor DNA fraction and response to enzalutamide or abiraterone in metastatic castration-resistant prostate cancer

PURPOSE

Androgen receptor pathway inhibitors (ARPI) are standard of care for treatment-naive metastatic castration-resistant prostate cancer (mCRPC), but rapid resistance is common. Early identification of resistance will improve management strategies. We investigated whether changes in circulating tumor DNA (ctDNA) fraction during ARPI treatment are linked with mCRPC clinical outcomes.

EXPERIMENTAL DESIGN

Plasma cell-free DNA was collected from 81 patients with mCRPC at baseline and after 4-weeks of first-line ARPI treatment during two prospective multi-centre observational studies (NCT02426333;NCT02471469). CtDNA fraction was calculated from somatic mutations in targeted sequencing and genome copy number profiles. Samples were classified into detected vs. undetected ctDNA. Outcome measurements were progression-free survival (PFS) and overall survival (OS). Non-durable treatment response was defined as PFS ≤ 6 months.

RESULTS

CtDNA was detected in 48/81 (59%) baseline and 29/81 (36%) 4-week samples. CtDNA fraction for samples with detected ctDNA was lower at 4-weeks vs. baseline (median 5.0% vs. 14.5%, P=0.017). PFS and OS was shortest for patients with persistent ctDNA at 4 weeks (univariate hazard ratio 4.79 (95%CI, 2.62-8.77) and 5.49 (95%CI, 2.76-10.91), respectively), independent of clinical prognostic factors. For patients exhibiting change from detected to undetected ctDNA by 4-weeks, there was no significant PFS difference versus patients with baseline undetected ctDNA. CtDNA change had a positive predictive value of 88% and negative predictive value of 92% for identifying non-durable responses.

CONCLUSIONS

Early changes in ctDNA% are strongly linked to duration of first-line ARPI treatment benefit and survival in mCRPC and may inform early therapy switches or treatment intensification.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

On-treatment plasma ctDNA fraction and treatment outcomes in metastatic castration-resistant prostate cancer

5051

Background: Androgen receptor pathway inhibitors (ARPI) are standard of care for treatment-naive metastatic castration-resistant prostate cancer (mCRPC), but primary or rapidly acquired resistance is common. Early identification of resistant disease is critical for improving management strategies. We investigated whether on-treatment changes in plasma ctDNA fraction (ctDNA%; the proportion of cell-free DNA that is tumor-derived) associate with ARPI treatment outcomes. Methods: We collected serial plasma cell-free DNA from 81 patients with mCRPC: at baseline and following 4 weeks of treatment during two prospective multi-center observational studies (NCT02426333; NCT02471469). CtDNA% was calculated by integrating deep targeted and shallow whole-genome sequencing. Samples were dichotomized at above and below 1%, and designated as high or low ctDNA%, respectively. Outcome measurements were radiographic and/or clinical progression-free survival (rcPFS) and overall survival (OS). Non-durable responses were defined as rcPFS < 6 months, excluding patients with PSA progression alone (n = 3) or treatment cessation for toxicity (n = 4). Results: Median follow-up was 27.4 months (IQR 17.7-34.9). CtDNA% was high in 47/81 (58%) patients at baseline and 29/81 (36%) patients at 4 weeks. The median ctDNA% for patients with high ctDNA was 15.0% (IQR 4.9-43.8%) at baseline and 5.0% (IQR 2.0-20.6%) at 4 weeks. High baseline ctDNA% was prognostic for rcPFS and OS (Table). RcPFS and OS was shortest for patients that retained high ctDNA% at 4 weeks. However, patients converting from high to low ctDNA% at 4 weeks did not experience different outcomes to patients with low ctDNA at both timepoints. ctDNA% associations with rcPFS and OS were independent of established clinical prognostic factors. 23/27 (85%) patients experiencing non-durable responses had high ctDNA% at baseline and 4 weeks. Only 3/47 patients (6%) experiencing durable responses had high ctDNA% at both timepoints. Sensitivity and specificity for predicting non-durable response was 85% and 94%, respectively. Conclusions: Early changes in ctDNA% are strongly linked to duration of first-line ARPI treatment benefit in mCRPC and may have utility for informing clinical trials testing early therapy switches in patients unlikely to experience durable disease responses. Clinical trial information: NCT02426333; NCT02471469. [Table: see text]

OP0012 INTERFERON-α MEDIATED THERAPEUTIC RESISTANCE IN EARLY RA IMPLICATES EPIGENETIC REPROGRAMMING

Background

An interferon gene signature (IGS) is present in approximately 50% of early, treatment naive rheumatoid arthritis (eRA) patients. We previously demonstrated it negatively impacts on initial disease outcomes.

Objectives

To 1) reproduce previous findings demonstrating the harmful effects of the IGS on early RA clinical outcomes, 2) identify which IFN class is responsible for the IGS and 3) seek evidence that IFN-α exposure contributes to harmful epigenetic footprint at disease onset.

Methods

In a large multicentre inception cohort (n=190) of eRA patients (RA-MAP TACERA) whole blood transcriptome, IGS (MxA, IFI44L, OAS1, ISG15, IFI6) and circulating interferons (IFN)-α, -β, -γ and -λ was examined at baseline and 6 months in conjunction with disease activity and clinical characteristics. A separate eRA cohort of paired methylome and transcriptome from CD4 T and CD19 B cells (n=41 for each) was used to explore any epigenetic influence of the IGS.

Results

The baseline IGS reproducibly and significantly negatively impacts on 6-month clinical outcomes. In the high IGS cohort there was increased DAS-28 (p=0.025) and reduced probability of achieving a good EULAR response (p=0.034) at 6-months. In addition, the IGS in eRA is shown for the first time to predominantly reflect raised circulating IFN-α protein, not other classes of IFN and examination of whole blood upstream nucleic acid sensors expression suggest a RNA trigger. Both the IGS and IFN-α significantly fell in parallel at 6 months (p<0.0001), whereas other classes of IFN remained statistically static. There was a significant association with IFN-α and RF titre but not ACPA. Comparison of CD4 T and CD19 B cells between IGS high and low eRA patients demonstrated differentially methylated CPG sites and altered transcript expression of disease relevant genes e.g. PARP9, STAT1, EPTSI1 which was similarly, and persistently, altered 6 months in the separate TACERA cohort. Differentially methylated CPGs implicated altered transcription factor binding in B cells (GATA3, ETSI, NFATC2, EZH2) and T cells (p300, HIF1α) which cumulatively suggested IFN-α induced epigenetic changes promoting increased, and sustained, lymphocyte activation, proliferation and loss of anergy in the IGS high cohort.

Conclusion

We validate that the IGS is a robust prognostic biomarker in eRA predicting poor therapeutic response. Its persistent harmful effects may be driven via epigenetic modifications. These data have relevance for other IFN-α states, such as COVID-19, but also provide a rationale for the initial therapeutic targeting of IFN-α signalling, such as with JAKi, at disease onset in stratified eRA subsets.

References

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Acknowledgements

JDI is a National Institute for Health Research (NIHR) Senior Investigator. The authors acknowledge the support of TACERA Principal Investigators from all contributing NHS sites and the members of the TACERA Study Steering and Data Monitoring Committee. Additional acknowledgements include patient volunteers and administrative support from Ben Hargreaves. Newcastle researchers received infrastructural support via the Versus Arthritis Research into Inflammatory Arthritis Centre (Ref 22072), funding from The Medical Research Council; Academy of Medical Sciences; British Society of Rheumatology; The Wellcome Trust; JGW Patterson Foundation; Immune-Mediated Inflammatory Disease Biobank in the UK (IMID-Bio-UK), ANR and RTCure. This work was supported by the NIHR Newcastle Biomedical Research Centre at Newcastle Hospitals Foundation Trust and Newcastle University; views expressed are the authors’ and not necessarily those of the National Health Service, the National Institute of Health Research or the Department of Health.

Disclosure of Interests

Faye Cooles Speakers bureau: Astrazeneca: December 2021, Jessica Tarn: None declared, Dennis Lendrem: None declared, Najib Naamane: None declared, Alice Lin: None declared, Ben Millar: None declared, Nicola Maney: None declared, Nishanthi Thalayasingam: None declared, Vincent Bondet: None declared, Darragh Duffy: None declared, Michael Barnes: None declared, Graham Smith: None declared, Sandra Ng: None declared, David Watson: None declared, Rafael Henkin: None declared, Andrew Cope: None declared, Louise Reynard: None declared, Arthur Pratt: None declared, RA-MAP Consortium: None declared, John Isaacs Speakers bureau: speaker/consulting fees from AbbVie, Gilead, Roche and UCB., Grant/research support from: JDI discloses research grants from Pfizer, Janssen and GSK.

The curious case of missing heartbeats

Paroxysmal atrioventricular block (AVB) is a poorly defined and easily missed bradyarrhythmia, which can potentially lead to sudden cardiac death. It is under-recognised due to its abrupt onset and unpredictability. We describe a case that had paroxysmal AVB post-coronary angioplasty and highlight the mechanism as well as the management of this rare condition.

New developments in defecatory studies based on biomechatronics

Introduction

Defecation is a complex process that is difficult to study and analyze directly. In anorectal disease conditions, the defecation process may be disturbed, resulting in symptoms including fecal incontinence and constipation. Current state-of-the-art technology measures various aspects of anorectal function but detailed analysis is impossible because they are stand-alone tests rather than an integrated multi-dimensional test.

Objectives

The need for physiologically-relevant and easy-to-use diagnostic tests for identifying underlying mechanisms is substantial. We aimed to advance the field with integrated technology for anorectal function assessment.

Methods

We developed a simulated stool named Fecobionics that integrates several tests to assess defecation pressures, dimensions, shape, orientation and bending during evacuation. A novelty is that pressures are measured in axial direction, i.e. in the direction of the trajectory. Using this novel tool, we present new analytical methods to calculate physiologically relevant parameters during expulsion in normal human subjects.

Results

Data are reported from 28 human subjects with progressively more advanced versions of Fecobionics. A new concept utilizes the rear-front pressure (preload-afterload) diagram for computation of novel defecation indices. Fecobionics obtained physiological data that cannot be obtained with current state-of-the-art technologies.

Conclusion

Fecobionics measures well known parameters such as expulsion time and pressures as well as new metrics including defecation indices. The study suggests that Fecobionics is effective in evaluation of key defecatory parameters and well positioned as an integrated technology for assessment of anorectal function and dysfunction.

846 Pre-clinical validation of a FLT3L-fusion protein for dendritic cell expansion and anti-tumor efficacy

Background

The ligand for the receptor tyrosine kinase FMS-like tyrosine kinase 3 (FLT3) plays an importantrole in hematopoiesis. FLT3 signaling is required for the differentiation andexpansion of dendritic cells. In the context of cancer immunity, the conventional dendritic cellsubtype 1 (cDC1) are required for the generation of tumor-specific T cell responses in mousepreclinical models. In human tumors cDC1 are often underrepresented in thetumor microenvironment, supporting the hypothesis that therapeutically increasing their number via FLT3 pathway stimulation has the potential to promote T cell-mediated anti-tumor efficacy.

Methods

GS-3583 is a fusion protein composed of the extracellular domain (ECD) of human FLT3 ligand(FLT3L) combined with a modified fragment crystallizable (Fc) region of human IgG4. GS-3583was designed to induce cDC1 expansion and subsequently promote tumor-reactive T cell priming, activation and recruitment into the tumor microenvironment. To evaluate the therapeutic efficacy of FLT3 stimulation in vivo, a mouse surrogate mGS-3583was designed using the ECD of mouse FLT3L fused to an engineered mouse IgG2a Fc withattenuated binding to mouse FcgRs.

Results mGS-3583 bound to recombinant mouse FLT3 with an estimated affinity of 15 nM, and to mouse FLT3-expressing cells with an EC50 of 0.15 nM. In vivo, mGS-3583 showed single agent dose-dependent tumor growth inhibition (TGI) in tumors that correlated with peripheral and intratumoral cDC1 expansion. In tumors with no initial immune infiltration, mGS-3583 led to an influx of T cells into the tumors. In addition to single agent efficacy, mGS-3583 combined effectively with programmed cell death protein (ligand)-1 (PD(L)-1) pathway blockade.

Conclusions

In vivo expansion of dendritic cells can convert uninflamed (cold) tumors to immunologically active (hot) tumors and initiate productive anti-tumor immune responses. These findings support the development GS-3583 as a promising candidate for cancer immunotherapy.

106 Stentolith As an Uncommon Complication of Loss to Follow Up After Endoscopic Biliary Stenting

Introduction

Endoscopic biliary stenting is a common procedure, with indications from malignant obstruction to benign stone disease. We discuss a patient who re-presented after endoscopic stenting having been lost to follow up, with a large ‘stentolith’ requiring open CBD exploration.

Case Presentation

A 56-year-old female presented in 2013 with obstructive jaundice and a 2-week history of abdominal pain. She was a smoker, but otherwise had no past medical, surgical, or relevant family history. After initial workup, ERCP with sphincterotomy and pigtail stent placement was performed with interval laparoscopic cholecystectomy in 2014. Post-operative follow up was not arranged, and the patient subsequently re-presented in 2020 with fatigue. MRCP confirmed a proximal CBD stone and linear artefact. Open exploration facilitated removal of the stone-stent complex.

Discussion

Complications of stenting include cholangitis, stent occlusion and migration [2]. Stenting for failed biliary stone extraction is considered a temporary measure, with removal or exchange at three months (1). However, patients may be lost to follow up and return with non-specific symptoms. A rare cause is de novo formation of a gallstone calculus encasing the stent, a phenomenon termed “stentolith” [4]. Proposed pathophysiology is through promotion of bacterial proliferation by the stent, with biofilm formation and calcium bilirubinate precipitation [6]. Variation in formation has been described, with plastic stents developing circumferential stones [12-25], due to potential space between the wall and stent.

Conclusions

This highlights the importance of robust inter-disciplinary working; careful patient follows up and implementation of a mandatory registry at all hospitals for stented patients.

Intrauterine immunizations trigger antigen-specific mucosal and systemic immunity in pigs and passive protection in suckling piglets

We assessed whether vaccines administered to the uterus at breeding can lead to sufficient colostral antibodies to protect suckling piglets against Porcine Endemic Diarrhea Virus (PEDV). An antigen from Lawsonia intracellularis, a disease that impacts weanling intestinal health, was also included because we have extensive knowledge on the pig immune response to this antigen. Gilts were mock-bred at 2nd estrus with killed sperm including an intrauterine (i.u.) vaccine comprised of recombinant (r) PEDV Spike protein (rPEDVS1) and L. intracellularis flagellin (rFliC) formulated with poly I:C, host defense peptide, and polyphosphazene (TriAdj). Gilts returned to estrus within 3 weeks and they were inseminated with killed sperm (3rd estrus) or live sperm (4th estrus) with rPEDVS1-TriAdj vaccine. They also received an i.m. injection of rFliC-TriAdj at 3rd and 4th estrus to establish whether i.u. vaccination primes systemic immunity without inducing mucosal tolerance. Control gilts were administered semen alone at 2nd estrus which allowed us to compare litter weights and sizes to industry standards. Colostrum from gilts challenged with low dose PEDV plus alum was used as positive reference samples for neutralizing antibodies and passive protection. Thirteen weeks later, the i.u.-vaccinated gilts showed significant PEDVS1-specific serum, colostral, and uterine antibody titers and colostral PEDVS1-neutralizing antibodies but poor cell-mediated immunity. Piglets born to i.u. vaccinated gilts received partial passive protection from PEDV infection 3 days after birth but eventually succumbed to the disease. Immunization by the i.u./i.m. route triggered significant anti-FliC cell-mediated immunity and colostral FliC antibodies that remained high in weaned piglet serum. This trial and a repeat trial wherein gilts were immunized at 1st estrus without semen and at 2nd estrus with live semen showed that intrauterine immunization did not impact fertility, number of live births or piglet growth kinetics. Further optimization is needed to promote robust passive protection in suckling offspring.

P–385 The relationship between systemic oestradiol and vaginal microbiota composition in miscarriage and normal pregnancy

Study question

Is there an association between serum oestradiol, vaginal microbial composition and pregnancy outcome in the early first trimester?

Summary answer

In women with a vaginal microbiome deplete of Lactobacillus species at the time of Pregnancy of Uncertain Viability (IPUV), higher serum oestradiol associates with livebirth.

What is known already

During pregnancy, oestradiol mediates vaginal mucosal properties and increases glycogen deposition in epithelial cells which is thought to support colonisation of Lactobacillus species. Low levels of Lactobacillus associates with adverse outcomes such as miscarriage and preterm birth. The direct relationship between systemic oestradiol and the vaginal microbiome has never been studied in pregnancy. However studies have shown a positive correlation between serum oestrone, vaginal glycogen and Lactobacillus abundance in menopausal women.

Study design, size, duration

This was a prospective cohort study where one-hundred women were recruited in early pregnancy at the time of IPUV and donated paired blood and vaginal samples. 40 women had an eventual miscarriage, 58 had a livebirth and two pregnancies were terminated. All 100 women donated one paired serum and vaginal sample at this time point, and 22 women with Lactobacillus depletion at the time of IPUV donated further longitudinal vaginal samples.

Participants/materials, setting, methods

Participants were recruited from an Early Pregnancy Unit and underwent transvaginal ultrasound assessment of their pregnancy. Serum samples were analysed with an immunoassay on a ROCHE COBAS E411 analyser for Oestradiol (pg/ml) and Progesterone (ng/ml). Bacterial DNA was extracted from paired vaginal swabs and sequenced using Illumina MiSeq sequencing of 16S rRNA gene amplicons.

Main results and the role of chance

Lactobacillus dominance of the vagina was associated with higher serum levels of E2 and progesterone compared to depletion (E2=398pg/ml vs 302pg/ml(p = 0.02), P4=23.1ng/ml vs 17ng/ml(p = 0.02)). E2 and P4 were positively correlated (r = 0.6, p &lt; 0.05). At species level, L. crispatus dominance associated with significantly higher levels of E2 compared to high-diversity communities (468pg/ml vs 302pg/ml(p = 0.03) but no such relationship was observed for P4. Both E2 and P4 levels were lower in women who eventually miscarried. However there was no significant difference in the vaginal bacterial composition at genera or species level at this early gestational age (P = 0.08) regardless of per vaginal bleeding. However in women with Lactobacillus depleted microbiota, livebirth was associated with significantly higher E2 levels compared to women suffering miscarriage (212pg/ml in miscarriage vs 395pg/ml in livebirth, p = 0.003) (OR = 22.4 P = 0.004). In 22 women who had Lactobacillus depletion at the time of IPUV (7 with an eventual outcome of miscarriage, and 15 with an eventual outcome of livebirth), longitudinal vaginal bacterial DNA sequencing was performed. In 7/15 women with livebirth, and higher E2 levels, the microbial composition changed to become more Lactobacillus dominant during pregnancy, whereas in those with miscarriage, only 1/7 changed to become Lactobacillus dominant.

Limitations, reasons for caution

In this study, serum oestradiol levels were compared to the local vaginal bacterial environment. The ideal would be to study local vaginal oestradiol, glycogen and the bacterial composition.

Wider implications of the findings: In contrast to previous studies in menopause where low oestrogen levels associate with the vaginal microbial composition, this study uses the high oestradiol environment of early pregnancy to study the mechanistic relationship between oestradiol and vaginal Lactobacillus abundance.

Trial registration number

NA

Hacking Trust: The Presence of Faces on Automated Teller Machines (ATMs) Affects Trustworthiness

Trustworthiness is a core concept that drives individuals’ interaction with others, as well with objects and digital interfaces. The perceived trustworthiness of strangers from the evaluation of their faces has been widely studies in social psychology; however, little is known about the possibility of transferring trustworthiness from human faces to other individuals, objects or interfaces. In this study, we explore how the perceived trustworthiness of automated teller machines (ATMs) is influenced by the presence of faces on the machines, and how the trustworthiness of the faces themselves is transferred to the machine. In our study, participants (N = 57) rated the trustworthiness of ATMs on which faces of different age, gender, and ethnicity are placed. Subsequently, the trustworthiness of the ATMs is compared to the trustworthiness ratings of faces presented on their own. Results of our works support the idea that faces’ trustworthiness can be transferred to objects on which faces are presented. Moreover, the trustworthiness of ATMs seems to be influenced by the age of presented faces, with ATMs on which children faces are presented are trusted more than the same machines when adults’ or elders’ faces are presented, but not by the ethnicity (Asian or Caucasian) or gender (male or female) of presented faces.

Tissue-specific cell-free DNA degradation quantifies circulating tumor DNA burden

Profiling of circulating tumor DNA (ctDNA) may offer a non-invasive approach to monitor disease progression. Here, we develop a quantitative method, exploiting local tissue-specific cell-free DNA (cfDNA) degradation patterns, that accurately estimates ctDNA burden independent of genomic aberrations. Nucleosome-dependent cfDNA degradation at promoters and first exon-intron junctions is strongly associated with differential transcriptional activity in tumors and blood. A quantitative model, based on just 6 regulatory regions, could accurately predict ctDNA levels in colorectal cancer patients. Strikingly, a model restricted to blood-specific regulatory regions could predict ctDNA levels across both colorectal and breast cancer patients. Using compact targeted sequencing (<25 kb) of predictive regions, we demonstrate how the approach could enable quantitative low-cost tracking of ctDNA dynamics and disease progression.

Circulating tumour DNA (ctDNA) represents a non-invasive option to monitor cancer progression. Here, the authors perform deep sequencing of plasma cell-free DNA, and find that nucleosome-dependent cfDNA degradation at 6 specific regulatory regions is predictive of ctDNA burden.

Fecobionics assessment of the effect of position on defecatory efficacy in normal subjects

BACKGROUND

Defecation is a complex process and up to 25% of the population suffer from symptoms of defecatory dysfunction. For functional testing, diagnostics, and therapy of anorectal disorders, it is important to know the optimal defecation position. is The aim of this study was to evaluate defecation pressure patterns in side lying, seated and squatting defecation positions in normal subjects using a simulated stool device called Fecobionics.

METHODS

The Fecobionics expulsion parameters were assessed in an interventional study design conducted from May 29 to December 9 2019. Subjects were invited to participate in the study through advertisement at The Chinese University of Hong Kong. The Fecobionics device consisted of a core containing pressure sensors at the front (caudal end) and rear (cranial end) and a polyester-urethane bag spanning most of the core length which also contained sensors. The Fecobionics bag was distended to 50 ml in the rectum of normal subjects (no present and past symptoms of defecatory disorders, no prior abdominal surgery, medication or chronic diseases). Studies were done in side lying (left lateral recumbent position), seated (hip flexed 90°) and squatting position (hip flexed 25°). Pressure endpoints including the rear-front pressure diagram and defecation indices were compared between positions.

RESULTS

Twelve subjects (6 females/6 males, mean age 26.3 ± 2.6 [19.0-48.0] years) were included and underwent the planned procedures. The resting anal pressure for side lying and seated positions were 33.1 ± 4.1 cmH₂O and 37.1 ± 4.0 cmH₂O (p > 0.3). The anal squeeze pressure for side lying and seated positions were 98.4 ± 6.9 cmH₂O and 142.3 ± 16.4 cmH₂O (p < 0.05). The expulsion duration for the side lying, seated and squatting positions were 108.9 ± 8.3 s, 15.0 ± 2.1 s and 16.1 ± 2.9 s, respectively (p < 0.01 between lying and the two other positions). The maximum evacuation pressure for seated and squatting were 130.1 ± 12.4 cmH2O and 134.0 ± 11.1 cmH₂O (p > 0.5). Rear-front pressure diagrams and distensibility indices demonstrated distinct differences in pressure patterns between the side lying position group and the other positions.

CONCLUSIONS

The delay in expelling the Fecobionics device in the lying position was associated with dyssynergic pressure patterns on the device. Quantitative differences were not found between the seated and squatting position. Trial Registration http://www.clinicaltrials.gov Identifier: NCT03317938.

Cerebral venous sinus thrombosis following post-neurosurgical intracranial hypotension: A case report and systematic review of the literature

Cerebral venous sinus thrombosis (CVST) following brain surgery is a feared complication, commonly described after direct injury to the sinus. However, distant CVST occurring away from the operative area are unexpected. Yet, there is a strong physio-pathological rational supporting the role of intracranial hypotension as a risk factor of CVST. Here, we report the case of a frontal arachnoid cyst depletion followed by an extensive contralateral CVST. Given the major prognostic consequences observed in this clinical illustration, we further investigated the hypothesis of intracranial hypotension as an etiology of CVST by carrying out a systematic review of the literature.

Prevention and treatment of cancer-associated thrombosis

Cancer is a hypercoagulable state with an associated increased risk of venous thromboembolism (vte) that is further amplified in individuals who undergo chemotherapy. Compared with patients having cancer alone or vte alone, patients who develop cancer-associated vte have a significantly poorer prognosis. The risks of recurrent vte despite appropriate anticoagulation therapy and of bleeding are also higher in patients with cancer than in those without. For those reasons, the prevention and appropriate management of cancer-associated thrombosis is of paramount importance. Although low-molecular-weight heparin has been the standard of care for the prevention and treatment of cancer-associated thrombosis, direct oral anticoagulants are increasingly being adopted as an effective and safe alternative.

GW190521: A Binary Black Hole Merger with a Total Mass of 150 M_{⊙}

On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85_{-14}^{+21}  M_{⊙} and 66_{-18}^{+17}  M_{⊙} (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65  M_{⊙}. We calculate the mass of the remnant to be 142_{-16}^{+28}  M_{⊙}, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is 5.3_{-2.6}^{+2.4}  Gpc, corresponding to a redshift of 0.82_{-0.34}^{+0.28}. The inferred rate of mergers similar to GW190521 is 0.13_{-0.11}^{+0.30}  Gpc^{-3} yr^{-1}.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Abstract 44: Monitoring of ctDNA burden from noncoding DNA

Our understanding of mutations in noncoding DNA is still nascent across most cancer types. Similarly, the potential clinical utility of noncoding DNA in cancer liquid biopsy assays remains mostly unexplored. Here, we identify high-frequency noncoding mutation hotspots in whole genomes from hundreds of gastrointestinal tumors and show that these mutations can be detected in liquid biopsy samples from cancer patients. We demonstrate how profiling of noncoding mutation hotspots can significantly increase the accuracy of ctDNA burden estimation, with minimal impact on sequencing cost, when paired with existing targeted cfDNA assays. Our results suggest that targeted NGS liquid biopsy assays should target both protein-coding and noncoding mutations when estimation and monitoring of ctDNA burden is a key clinical endpoint.

Citation Format: Guo Yu, Zhong Wee Poh, Guanhua Zhu, Iain Tan, Sarah Ng, Patrick Tan, Anders Skanderup. Monitoring of ctDNA burden from noncoding DNA [abstract]. In: Proceedings of the AACR Special Conference on Advancing Precision Medicine Drug Development: Incorporation of Real-World Data and Other Novel Strategies; Jan 9-12, 2020; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_1):Abstract nr 44.

FRI0309 DAILY SELF-REPORTED FLARE PROFILES IN AXIAL SPONDYLOARTHRITIS: ASSOCIATIONS BETWEEN FLARE, SYMPTOMS AND BEHAVIOUR

Background:

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease, characterised by fluctuating periods of flare and remission. Flare is a multidimensional change of disease state; whereby flare definitions have previously been formulated using validated composite indices, or through qualitative retrospective investigation of flare states. Smartphone technologies for tracking disease symptoms provide unique, daily insights into self-reported individual flare experience, and may present an opportunity to gain a more complete understanding of flare burden and symptom patterns.

Objectives:

To assess frequency and characteristics of axSpA flares, utilising data collected in the uMotif symptom tracking app.

Methods:

Patients with axSpA attending the Royal National Hospital for Rheumatic Diseases in Bath were invited to participate. Through the uMotif app, patients were sent daily reminders to log flare, pain, fatigue, sleep, recommended exercise, mood and stress using 5-point Likert scales, in addition to optional variables such as smoking and menstrual cycle. Self-reported periods of flare were identified. For each patient reporting flare within the study period, a mean ‘flare’ and ‘non-flare’ score was calculated for each variable. Paired t-tests were conducted for each variable, to investigate which variables correlate with flare status.

Results:

Between 5th April 2018 and 8th March 2019, 174 patients consented for research and logged a mean of 99.73 (SD 99.97, range 1 - 323 days) days of data. 136/174 (78%) patients recorded at least 1 flare, with 1330 flares recorded in total. For patients reporting at least 1 flare, each flare lasted a mean of 2.20 days (SD 2.53 days, range 1 – 33 days), with a mean frequency of once every 45.19 days (SD 53.06, range 3.2 -314 days). Significant relationships were identified between flare status and uMotif scores (Table 1).

Table 1.

Paired t-tests: flare vs. non-flare scores for each variable

Estimated difference^p-valueN95% CI (lower limit)95% CI (upper limit)Variable-0.870.266-2.630.88Red Painful Eyes-0.670.000*130-0.78-0.56Pain-0.570.004*25-0.94-0.20Chest Pain-0.510.005*15-0.83-0.18Hot Flushes-0.500.000*129-0.61-0.40Fatigue-0.440.1962-2.231.35Blood in Stool-0.380.000*128-0.47-0.29Mood-0.360.000*127-0.52-0.20Anti-Inflammatory Use-0.360.000*128-0.48-0.23Recommended Exercise-0.340.000*33-0.51-0.17Confidence in Self-Management-0.260.000*128-0.37-0.15Stress-0.250.17015-0.620.12Screen Time-0.190.000*130-0.26-0.12Sleep Quality-0.150.45812-0.590.28Menstrual Cycle-0.110.10322-0.250.02Eyesight0.090.1953-0.120.30Flare of Psoriasis0.050.65626-0.170.26Medication Adherence0.040.7973-0.530.61Smoking Today-0.030.48450-0.110.05Caffeine Intake

N= number of patients with both a flare and non-flare entry for each variable; CI=confidence interval

Higher variable scores indicate more positive outcomes (e.g. a higher pain score indicates less pain)

^Estimated difference between flare and non-flare entries (e.g. on average, the mean pain score of a flare entry is 0.67 [0.56– 0.78 CI] less than a non-flare entry)

*p<0.01

Conclusion:

These findings demonstrate significant relationships between a variety of patient-reported symptoms and flare, including variables that to our knowledge, have not yet been explored in axSpA. Small estimated differences were found between scores for ‘flare’ versus ‘no-flare’. Further work is needed to characterise fluctuating flare/no-flare patterns of individuals tracking daily symptoms in the uMotif app. In future research, it will be important to determine whether there is a chronological pattern of variables during the pre-flare period that can predict a flare. Greater understanding of such patterns may allow identification of the optimal timing of intervention to prevent a period of flare and improve quality of life for patients with axSpA.

Acknowledgments:

We thank UCB for funding use of the uMotif application.

Disclosure of Interests:

Rosie Barnett: None declared, Stanley Ng: None declared, Simon Jones: None declared, Matthew Young: None declared, Raj Sengupta Grant/research support from: Research grants from UCB, Pfizer, Abbvie and Novartis, Speakers bureau: Received honoraria for giving talks from Abbvie, Biogen, UCB, Novartis, Pfizer

Intracranial activity of selpercatinib (LOXO-292) in RET fusion-positive non-small cell lung cancer (NSCLC) patients on the LIBRETTO-001 trial

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Background: Patients with RET fusion-positive NSCLC have an ~50% lifetime prevalence of developing central nervous system (CNS) metastases. Selpercatinib is a highly selective oral RET inhibitor with CNS penetration. Its intracranial antitumor activity was previously demonstrated in an orthotopic RET fusion-positive preclinical model. The activity of selpercatinib in RET fusion-positive NSCLC patients with CNS metastases was evaluated as a prespecified subgroup analysis in LIBRETTO-001, a registrational phase 1/2 trial (NCT03157128). Methods: This global (89 sites, 16 countries) trial enrolled patients with advanced RET-altered solid tumors, including patients with RET fusion-positive advanced NSCLC with baseline CNS metastases. The selpercatinib recommended phase 2 dose was 160 mg twice daily, dosed orally in 28-day cycles. CNS metastases were assessed by MRI/CT scan at baseline, then every 8 weeks for 1 year, and every 12 weeks thereafter. The primary endpoint for this analysis was intracranial objective response rate (ORR, confirmed; RECIST v1.1) as assessed by independent review committee (IRC). Secondary endpoints included intracranial duration of response (DoR) by IRC. To be included in the efficacy analysis, patients were required to have adequate follow-up time (opportunity for ≥6 months follow-up from the first dose). Analyses were based on 17Jun2019 data cutoff date. Results: 79 patients with RET fusion-positive NSCLC and baseline CNS metastases were enrolled. Per IRC, 22 of 79 patients had measurable (≥10 mm) CNS disease; 14 of the 22 patients had adequate follow-up time for analysis. This efficacy-evaluable population had a median age of 64 yrs (range 43-80), ECOG PS 0/1 = 21% / 79%, and all had prior systemic therapy. 5 of the 14 patients received prior intracranial radiotherapy; all radiotherapy was completed > 2 months prior to selpercatinib. The intracranial ORR in the 14 patients was 93% (n = 13; 95% CI = 66.1 – 99.8), including 2 complete responses (14%) and 11 partial responses (79%). The median intracranial DoR was 10.1 months (95% CI = 6.7 – NE), with CNS progression events (n = 5) or death (n = 1) reported in 6 of 13 responders. The remaining responders (n = 7) were ongoing and censored. Presentation will include updated IRC data as of 16Dec2019. Conclusions: Selpercatinib had marked intracranial anti-tumor activity in RET fusion-positive NSCLC patients with CNS metastases. Tumor responses were durable, independently-confirmed, and observed in patients with prior systemic chemotherapy. Clinical trial information: NCT03157128 .

A28 RELATIVE RATES OF ULCERATIVE COLITIS TO CROHN’S DISEASE: PARALLEL EPIDEMIOLOGIES IN NEWLY VS. HIGHLY INDUSTRIALIZED COUNTRIES

Background

Inflammatory bowel disease (IBD) first presents in a population as cases of ulcerative colitis (UC) followed by cases of Crohn’s disease (CD). Newly industrialized countries (NIC) show a prallel epidemiology of IBD to highly industrialized countries (HIC) in the previous century; one marker of this is the relative incidence/prevalence rates of UC to CD, which approximates 1 over time.

Aims

Provide evidence for the UC:CD ratio as a proxy for disease penatrance in a population.

Methods

Systematic review of MedLine and Embase for studies reporting incidence or prevalence of UC and CD. Log-linear regression (by region and NIC/HIC [2019 United Nations definitions]) was used to calculate average annual percent change (AAPC) and associated 95% confidence intervals (CI). Data were plotted on an online, interactive map to show trends (link provided).

Results

We extracted data from 218 studies compising population-level data from 69 countries. We found negative AAPCs as the prevalence ratio of UC:CD significantly decreased over time in East Asia, West Asia, North Europe, and South Europe; 6/12 global regions displayed significantly decreasing incidence ratios. No AAPC was found to be significantly increasing (Table 1). When examing HIC/NIC, we found a significant effect of NIC on the UC:CD prevalence ratio after 2000 (AAPC:−3.83;95%CI:−6.28,−1.31) while HIC regions remained stable (AAPC:2.14;95%CI:−1.40,5.82). Looking at all available data, both HICs and NICs show significantly decreasing UC:CD prevalence ratios (HIC:AAPC:−3.72;95% CI:−4.46,−2.97; NIC:AAPC:−2.62;95%CI:−4.13,−1.08).

Conclusions

In some HICs (eg. Canada), the UC:CD incidence ratio was &lt;1 in the earliest available data (1966), explaining the stable AAPC in North America (AAPC:−0.24;95%CI:−1.12,0.65). However, in NICs (eg. Southern Asia), the AAPC is rapidly decreasing (AAPC:−24.68;95%CI:−37.85,−8.71) as areas like Sri Lanka rapidly fall from an incidence ratio of 7.5 (2007) to 2.8 (2012), mimicking trends in IBD epidimeology of HICs in the previous century.

Funding Agencies

None

Prospects for observing and localizing gravitational-wave transients with Advanced LIGO, Advanced Virgo and KAGRA

We present our current best estimate of the plausible observing scenarios for the Advanced LIGO, Advanced Virgo and KAGRA gravitational-wave detectors over the next several years, with the intention of providing information to facilitate planning for multi-messenger astronomy with gravitational waves. We estimate the sensitivity of the network to transient gravitational-wave signals for the third (O3), fourth (O4) and fifth observing (O5) runs, including the planned upgrades of the Advanced LIGO and Advanced Virgo detectors. We study the capability of the network to determine the sky location of the source for gravitational-wave signals from the inspiral of binary systems of compact objects, that is binary neutron star, neutron star-black hole, and binary black hole systems. The ability to localize the sources is given as a sky-area probability, luminosity distance, and comoving volume. The median sky localization area (90% credible region) is expected to be a few hundreds of square degrees for all types of binary systems during O3 with the Advanced LIGO and Virgo (HLV) network. The median sky localization area will improve to a few tens of square degrees during O4 with the Advanced LIGO, Virgo, and KAGRA (HLVK) network. During O3, the median localization volume (90% credible region) is expected to be on the order of 10 5 , 10 6 , 10 7 Mpc 3 for binary neutron star, neutron star-black hole, and binary black hole systems, respectively. The localization volume in O4 is expected to be about a factor two smaller than in O3. We predict a detection count of 1 - 1 + 12 ( 10 - 10 + 52 ) for binary neutron star mergers, of 0 - 0 + 19 ( 1 - 1 + 91 ) for neutron star-black hole mergers, and 17 - 11 + 22 ( 79 - 44 + 89 ) for binary black hole mergers in a one-calendar-year observing run of the HLV network during O3 (HLVK network during O4). We evaluate sensitivity and localization expectations for unmodeled signal searches, including the search for intermediate mass black hole binary mergers.

Search for Subsolar Mass Ultracompact Binaries in Advanced LIGO's Second Observing Run

We present a search for subsolar mass ultracompact objects in data obtained during Advanced LIGO's second observing run. In contrast to a previous search of Advanced LIGO data from the first observing run, this search includes the effects of component spin on the gravitational waveform. We identify no viable gravitational-wave candidates consistent with subsolar mass ultracompact binaries with at least one component between 0.2  M_{⊙}-1.0  M_{⊙}. We use the null result to constrain the binary merger rate of (0.2  M_{⊙}, 0.2  M_{⊙}) binaries to be less than 3.7×10^{5}  Gpc^{-3} yr^{-1} and the binary merger rate of (1.0  M_{⊙}, 1.0  M_{⊙}) binaries to be less than 5.2×10^{3}  Gpc^{-3} yr^{-1}. Subsolar mass ultracompact objects are not expected to form via known stellar evolution channels, though it has been suggested that primordial density fluctuations or particle dark matter with cooling mechanisms and/or nuclear interactions could form black holes with subsolar masses. Assuming a particular primordial black hole (PBH) formation model, we constrain a population of merging 0.2  M_{⊙} black holes to account for less than 16% of the dark matter density and a population of merging 1.0  M_{⊙} black holes to account for less than 2% of the dark matter density. We discuss how constraints on the merger rate and dark matter fraction may be extended to arbitrary black hole population models that predict subsolar mass binaries.

Effect of cold plasma on polyphenol oxidase inactivation in cloudy apple juice and on the quality parameters of the juice during storage

Direct cold plasma treatment has been investigated as an alternative non-thermal technology as a means of maintaining and improving quality of fresh cloudy apple juice. Process variables studied included type of plasma discharge, input voltage and treatment time on polyphenol oxidase (PPO) inactivation. Spark discharge plasma at 10.5 kV for 5 min was the best treatment, with near total inactivation of PPO achieved, although good PPO inactivation was also recorded using shorter treatment times. Residual activity (RA) of PPO was 16 and 27.6% after 5 and 4 min of treatment respectively. This PPO inactivation was maintained throughout the storage trials, but decreased with samples treated for a shorter time. Plasma treatment improved key quality parameters of Golden delicious cloudy apple juice, with retention of critical quality parameters during extended storage trials. Color was the most noticeable change, which was enhanced with retention of a greener color. An increase of 69 and 64% was obtained in the total phenolic content after 4 and 5 min of treatment, respectively. Therefore, cold plasma was demonstrated to be a good alternative to traditional heat treatments for enhanced quality retention of fresh cloudy apple juice and over its storage.

Tests of General Relativity with GW170817

The recent discovery by Advanced LIGO and Advanced Virgo of a gravitational wave signal from a binary neutron star inspiral has enabled tests of general relativity (GR) with this new type of source. This source, for the first time, permits tests of strong-field dynamics of compact binaries in the presence of matter. In this Letter, we place constraints on the dipole radiation and possible deviations from GR in the post-Newtonian coefficients that govern the inspiral regime. Bounds on modified dispersion of gravitational waves are obtained; in combination with information from the observed electromagnetic counterpart we can also constrain effects due to large extra dimensions. Finally, the polarization content of the gravitational wave signal is studied. The results of all tests performed here show good agreement with GR.

Female adiposity and time-to-pregnancy: a multiethnic prospective cohort

STUDY QUESTION

Are higher overall and central adiposity associated with reduced fecundability, measured by time-to-pregnancy (TTP), in Asian women?

SUMMARY ANSWER

Higher overall adiposity, but not central adiposity, was associated with longer TTP in Asian women.

WHAT IS KNOWN ALREADY

High body mass index (BMI) has been associated with a longer TTP, although the associations of body composition and distribution with TTP are less clear. There are no previous studies of TTP in Asian women, who have a relatively higher percentage of body fat and abdominal fat at relatively lower BMI.

STUDY DESIGN, SIZE, DURATION

Prospective preconception cohort using data from 477 Asian (Chinese, Malay and Indian) women who were planning to conceive and enrolled in the Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO) study, 2015-2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Women's mean age was 30.7 years. Overall adiposity was assessed by BMI, sum of 4-site skinfold thicknesses (SFT) and total body fat percentage (TBF%, measured using air displacement plethysmography); central adiposity was assessed by waist circumference (WC), waist-to-hip ratio (WHR), waist-to-height ratio (WHtR) and A body Shape Index (ABSI). Pregnancy occurring within one year from recruitment was ascertained by ultrasonography. Those who did not conceive within one year of recruitment, were lost to follow-up, or initiated fertility treatment were censored. TTP was measured in cycles. Discrete-time proportional hazards models were used to estimate the fecundability ratio (FR) and 95% confidence interval (CI) for each anthropometric measure in association with fecundability, adjusting for confounders.

MAIN RESULTS AND THE ROLE OF CHANCE

Compared to women with a normal BMI of 18.5-22.9 kg/m2, women with higher BMI of 23-27.4 and ≥27.5 kg/m2 showed lower FR of 0.66 (95% CI 0.45, 0.97) and 0.53 (0.31, 0.89), respectively. Compared to women in the lowest quartile of SFT (25-52.9 mm), those in the highest quartile of ≥90.1 mm showed lower FR of 0.58 (95% CI 0.36, 0.95). Compared to women in the lowest quartile of TBF% (13.6-27.2%), those in the upper two quartiles of 33.0-39.7% and ≥39.8% showed lower FR of 0.56 (95% CI 0.32, 0.98) and 0.43 (0.24, 0.80), respectively. Association of high BMI with reduced fecundability was particularly evident among nulliparous women. Measures of central adiposity (WC, WHR, WHtR, ABSI) were not associated with fecundability.

LIMITATIONS REASONS FOR CAUTION

Small sample size could restrict power of analysis.The analysis was confined to planned pregnancies, which could limit generalizability of findings to non-planned pregnancies, estimated at around 44% in Singapore. Information on the date of last menstrual period for each month was not available, hence the accuracy of self-reported menstrual cycle length could not be validated, potentially introducing error into TTP estimation. Measures of exposures and covariates such as cycle length were not performed repeatedly over time; cycle length might have changed during the period before getting pregnant.

WIDER IMPLICATIONS OF THE FINDINGS

Other than using BMI as the surrogate measure of body fat, we provide additional evidence showing that higher amounts of subcutaneous fat that based on the measure of SFT at the sites of biceps, triceps, suprailiac and subscapular, and TBF% are associated with longer TTP. Achieving optimal weight and reducing total percentage body fat may be a potential intervention target to improve female fertility. The null results observed between central adiposity and TTP requires confirmation in further studies.

STUDY FUNDING/COMPETING INTEREST(S)

This research is supported by Singapore National Research Foundation under its Translational and Clinical Research Flagship Programme and administered by the Singapore Ministry of Health's National Medical Research Council, (NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/2014). Additional funding is provided by the Singapore Institute for Clinical Sciences, Agency for Science Technology and Research (A*STAR), Singapore. Y.S.C., K.M.G., F.Y. and Y.S.L. have received reimbursement to speak at conferences sponsored by companies selling nutritional products. Y.S.C., K.M.G. and S.Y.C. are part of an academic consortium that has received research funding from Abbott, Nutrition, Nestle and Danone. Other authors declared no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

Constraining the p-Mode-g-Mode Tidal Instability with GW170817

We analyze the impact of a proposed tidal instability coupling p modes and g modes within neutron stars on GW170817. This nonresonant instability transfers energy from the orbit of the binary to internal modes of the stars, accelerating the gravitational-wave driven inspiral. We model the impact of this instability on the phasing of the gravitational wave signal using three parameters per star: an overall amplitude, a saturation frequency, and a spectral index. Incorporating these additional parameters, we compute the Bayes factor (lnB_{!pg}^{pg}) comparing our p-g model to a standard one. We find that the observed signal is consistent with waveform models that neglect p-g effects, with lnB_{!pg}^{pg}=0.03_{-0.58}^{+0.70} (maximum a posteriori and 90% credible region). By injecting simulated signals that do not include p-g effects and recovering them with the p-g model, we show that there is a ≃50% probability of obtaining similar lnB_{!pg}^{pg} even when p-g effects are absent. We find that the p-g amplitude for 1.4  M_{⊙} neutron stars is constrained to less than a few tenths of the theoretical maximum, with maxima a posteriori near one-tenth this maximum and p-g saturation frequency ∼70  Hz. This suggests that there are less than a few hundred excited modes, assuming they all saturate by wave breaking. For comparison, theoretical upper bounds suggest ≲10^{3} modes saturate by wave breaking. Thus, the measured constraints only rule out extreme values of the p-g parameters. They also imply that the instability dissipates ≲10^{51}  erg over the entire inspiral, i.e., less than a few percent of the energy radiated as gravitational waves.

Critical care usage after major gastrointestinal and liver surgery: a prospective, multicentre observational study

BACKGROUND

Patient selection for critical care admission must balance patient safety with optimal resource allocation. This study aimed to determine the relationship between critical care admission, and postoperative mortality after abdominal surgery.

METHODS

This prespecified secondary analysis of a multicentre, prospective, observational study included consecutive patients enrolled in the DISCOVER study from UK and Republic of Ireland undergoing major gastrointestinal and liver surgery between October and December 2014. The primary outcome was 30-day mortality. Multivariate logistic regression was used to explore associations between critical care admission (planned and unplanned) and mortality, and inter-centre variation in critical care admission after emergency laparotomy.

RESULTS

Of 4529 patients included, 37.8% (n=1713) underwent planned critical care admissions from theatre. Some 3.1% (n=86/2816) admitted to ward-level care subsequently underwent unplanned critical care admission. Overall 30-day mortality was 2.9% (n=133/4519), and the risk-adjusted association between 30-day mortality and critical care admission was higher in unplanned [odds ratio (OR): 8.65, 95% confidence interval (CI): 3.51-19.97) than planned admissions (OR: 2.32, 95% CI: 1.43-3.85). Some 26.7% of patients (n=1210/4529) underwent emergency laparotomies. After adjustment, 49.3% (95% CI: 46.8-51.9%, P<0.001) were predicted to have planned critical care admissions, with 7% (n=10/145) of centres outside the 95% CI.

CONCLUSIONS

After risk adjustment, no 30-day survival benefit was identified for either planned or unplanned postoperative admissions to critical care within this cohort. This likely represents appropriate admission of the highest-risk patients. Planned admissions in selected, intermediate-risk patients may present a strategy to mitigate the risk of unplanned admission. Substantial inter-centre variation exists in planned critical care admissions after emergency laparotomies.