GASTON: Galactic Star Formation with NIKA2 A new population of cold massive sources discovered

Understanding where and when the mass of stars is determined is one of the fundamental, mostly unsolved, questions in astronomy. Here, we present the first results of GASTON, the Galactic Star Formation with NIKA2 large programme on the IRAM 30m telescope, that aims to identify new populations of low-brightness sources to tackle the question of stellar mass determination across all masses. In this paper, we focus on the high-mass star formation part of the project, for which we map a ~ 2 deg2 region of the Galactic plane around l = 24° in both 1.2 mm and 2.0 mm continuum. Half-way through the project, we reach a sensitivity of 3.7 mJy/beam at 1.2mm. Even though larger than our target sensitivity of 2 mJy, the current sensitivity already allows the identification of a new population of cold, compact sources that remained undetected in any (sub-)mm Galactic plane survey so far. In fact, about 25% of the ~ 1600 compact sources identified in the 1.2mm GASTON image are new detections. We present a preliminary analysis of the physical properties of the GASTON sources as a function of their evolutionary stage, arguing for a potential evolution of the mass distribution of these sources with time.

Cluster cosmology with the NIKA2 SZ Large Program

The main limiting factor of cosmological analyses based on thermal Sunyaev-Zel’dovich (SZ) cluster statistics comes from the bias and systematic uncertainties that affect the estimates of the mass of galaxy clusters. High-angular resolution SZ observations at high redshift are needed to study a potential redshift or morphology dependence of both the mean pressure profile and of the mass-observable scaling relation used in SZ cosmological analyses. The NIKA2 camera is a new generation continuum instrument installed at the IRAM 30-m telescope. With a large field of view, a high angular resolution and a high-sensitivity, the NIKA2 camera has unique SZ mapping capabilities. In this paper, we present the NIKA2 SZ large program, aiming at observing a large sample of clusters at redshifts between 0.5 and 0.9, and the characterization of the first cluster oberved with NIKA2.

Mapping the gas thermodynamic properties of the massive cluster merger MOO J1142+1527 at z = 1.2

We present the results of the analysis of the very massive cluster MOO J1142+1527 at a redshift z = 1.2 based on high angular resolution NIKA2 Sunyaev-Zel’dovich (SZ) andChandraX-ray data. This multi-wavelength analysis enables us to estimate the shape of the temperature profile with unprecedented precision at this redshift and to obtain a map of the gas entropy distribution averaged along the line of sight. The comparison between the cluster morphological properties observed in the NIKA2 andChandramaps together with the analysis of the entropy map allows us to conclude that MOOJ1142+1527 is an on-going merger hosting a cool-core at the position of the X-ray peak. This work demonstrates how the addition of spatially-resolved SZ observations to low signal-to-noise X-ray data can bring valuable insights on the intracluster medium thermodynamic properties atz>1.

Observing with NIKA2Pol from the IRAM 30m telescope : Early results on the commissioning phase

The NIKA2 polarization channel at 260 GHz (1.15 mm) has been proposed primarily to observe galactic star-forming regions and probe the critical scales between 0.01-0.05 pc at which magnetic field lines may channel the matter of interstellar filaments into growing dense cores. The NIKA2 polarime-ter consists of a room temperature continuously rotating multi-mesh HWP and a cold polarizer that separates the two orthogonal polarizations onto two 260 GHz KIDs arrays. We describe in this paper the preliminary results obtained during the most recent commissioning campaign performed in December 2018. We concentrate here on the analysis of the extended sources, while the observation of compact sources is presented in a companion paper [12]. We present preliminary NIKA2 polarization maps of the Crab nebula. We find that the integrated polarization intensity flux measured by NIKA2 is consistent with expectations. In terms of polarization angle, we are still limited by systematic uncertainties that will be further investigated in the forthcoming commissioning campaigns.

Preliminary results on the instrumental polarization of NIKA2-Pol at the IRAM 30m telescope

Clarifying the role of magnetic fields in the star formation process is crucial. Observations have already shown that magnetic fields play an important role in the early stages of star formation. The high spatial resolution (∼0.01 to 0.05 pc) provided by NIKA2-Pol 1.2 mm imaging polarimetry of nearby clouds will help us clarify the geometry of the B-field within dense cores and molecular filaments as part of the IRAM 30m large program B-FUN. There are numerous challenging issues in the validation of NIKA2-Pol such as the calibration of instrumental polarization. The commissioning phase of NIKA2-Pol is underway and is helping us characterize the intensity-to-polarization “leakage” pattern of the instrument. We present a preliminary analysis of the leakage pattern and its dependence with elevation. We also present the current leakage correction made possible by the NIKA2 pipeline in polarization mode based on the NIKA2-Pol commissioning data taken in December 2018. Based on reduced Stokes I, Q, U data we find that the leakage pattern of NIKA2-Pol depends on elevation and is sensitive to the focus of the telescope.

Debris disks around stars in the NIKA2 era

The new NIKA2 camera at the IRAM 30m radiotelescope was used to observe three known debris disks in order to constrain the SED of their dust emission in the millimeter wavelength domain. We have found that the spectral index between the two NIKA2 bands (1mm and 2mm) is consistent with the Rayleigh-Jeans regime (λ-2), unlike the steeper spectra (λ-3) measured in the submillimeter-wavelength domain for two of the three disks - around the stars Vega and HD107146. We provide a succesful proof of concept to model this spectral inversion in using two populations of dust grains, those smaller and those larger than a grain radius a0 of 0.5mm. This is obtained in breaking the slope of the size distribution and the functional form of the absorption coefficient of the standard model. The third disk - around the star HR8799 - does not exhibit this spectral inversion but is also the youngest.

Impact of cirrhosis in patients undergoing laparoscopic liver resection in a nationwide multicentre survey

BACKGROUND

The aim was to analyse the impact of cirrhosis on short-term outcomes after laparoscopic liver resection (LLR) in a multicentre national cohort study.

METHODS

This retrospective study included all patients undergoing LLR in 27 centres between 2000 and 2017. Cirrhosis was defined as F4 fibrosis on pathological examination. Short-term outcomes of patients with and without liver cirrhosis were compared after propensity score matching by centre volume, demographic and tumour characteristics, and extent of resection.

RESULTS

Among 3150 patients included, LLR was performed in 774 patients with (24·6 per cent) and 2376 (75·4 per cent) without cirrhosis. Severe complication and mortality rates in patients with cirrhosis were 10·6 and 2·6 per cent respectively. Posthepatectomy liver failure (PHLF) developed in 3·6 per cent of patients with cirrhosis and was the major cause of death (11 of 20 patients). After matching, patients with cirrhosis tended to have higher rates of severe complications (odds ratio (OR) 1·74, 95 per cent c.i. 0·92 to 3·41; P = 0·096) and PHLF (OR 7·13, 0·91 to 323·10; P = 0·068) than those without cirrhosis. They also had a higher risk of death (OR 5·13, 1·08 to 48·61; P = 0·039). Rates of cardiorespiratory complications (P = 0·338), bile leakage (P = 0·286) and reoperation (P = 0·352) were similar in the two groups. Patients with cirrhosis had a longer hospital stay than those without (11 versus 8 days; P = 0·018). Centre expertise was an independent protective factor against PHLF in patients with cirrhosis (OR 0·33, 0·14 to 0·76; P = 0·010).

CONCLUSION

Underlying cirrhosis remains an independent risk factor for impaired outcomes in patients undergoing LLR, even in expert centres.

NIKA2 mapping and cross-instrument SED extraction of extended sources with Scanamorphos

The steps taken to tailor to NIKA2 observations the Scanamorphos algorithm (initially developed to subtract low-frequency noise from Herschel on-the-fly observations) are described, focussing on the consequences of the different instrument architecture and observation strategy. The method, making the most extensive use of the redundancy built in the multi-scan coverage with large arrays of a given region of the sky, is applicable to extended sources, while the pipeline is so far optimized for compact sources. An example of application is given. A related tool to build consistent broadband SEDs from 60 microns to 2 mm, combining Herschel and NIKA2 data, has also been developed. Its main task is to process the data least affected by low-frequency noise and coverage limitations (i.e. the Herschel data) through the same transfer function as the NIKA2 data, simulating the same scan geometry and applying the same noise and atmospheric signal as extracted from the 1mm and 2mm data.

The NIKA polarimeter on science targets: Crab nebula observations at 150 GHz and dual-band polarization images of Orion Molecular Cloud OMC-1

We present here the polarization system of the NIKA camera and give a summary of the main results obtained and performed studies on Orion and the Crab nebula. The polarization system was equipped with a room temperature continuously rotating multi-mesh half wave plate and a grid polarizer facing the NIKA cryostat window. NIKA even though less sensitive than NIKA2 had polarization capability in both 1 and 2 millimiter bands. NIKA polarization observations demonstrated the ability of such a technology in detecting the polarization of different targets, compact and extended sources like the Crab nebula and Orion Molecular Cloud region OMC-1. These measurements together with the developed techniques to deal with systematics, opened the way to the current observations of NIKA2 in polarization that will provide important advances in the studies of galactic and extra-galactic emission and magnetic fields.

NIKA: a mm camera for Sunyaev-Zel’dovich science in clusters of galaxies

Clusters of galaxies, the largest bound objects in the Universe, constitute a cosmological probe of choice, which is sensitive to both dark matter and dark energy. Within this framework, the Sunyaev-Zel’dovich (SZ) effect has opened a new window for the detection of clusters of galaxies and for the characterization of their physical properties such as mass, pressure and temperature. NIKA, a KID-based dual band camera installed at the IRAM 30-m telescope, was particularly well adapted in terms of frequency, angular resolution, field-of-view and sensitivity, for the mapping of the thermal and kinetic SZ effect in high-redshift clusters. In this paper, we present the NIKA cluster sample and a review of the main results obtained via the measurement of the SZ effect on those clusters: reconstruction of the cluster radial pressure profile, mass, temperature and velocity.

A low-mass galaxy cluster as a test-case study for the NIKA2 SZ Large Program

High-resolution mapping of the hot gas in galaxy clusters is a key tool for cluster-based cosmological analyses. Taking advantage of the NIKA2 millimeter camera operated at the IRAM 30-m telescope, the NIKA2 SZ Large Program seeks to get a high-resolution follow-up of 45 galaxy clusters covering a wide mass range at high redshift in order to re-calibrate some of the tools needed for the cosmological exploitation of SZ surveys. We present the second cluster analysis of this program, targeting one of the faintest sources of the sample in order to tackle the difficulties in data reduction for such faint, low-SNR clusters. In this study, the main challenge is the precise estimation of the contamination by sub-millimetric point sources, which greatly affects the tSZ map of the cluster. We account for this contamination by performing a joint fit of the SZ signal and of the flux density of the compact sources. A prior knowledge of these fluxes is given by the adjustment of the SED of each source using data from both NIKA2 and the Herschel satellite. The first results are very promising and demonstrate the possibility to estimate thermodynamic properties with NIKA2, even in a compact cluster heavily contaminated by point sources.

Presence of anesthesiologists and nurses in the operating room: Liability of surgeons and health care facilities

The presence of an anesthesiologist and certified registered nurse anesthesiologist in the operating room remains a topic of discussion in many facilities. This article provides an overview on the legislation and recommendations on this topic and recounts some of the related jurisprudence. The opinions of various actors, surgeons, anesthesiologists, anesthesiology-intensive care physicians, certified registered nurse anesthesiologists, care-facility directors and insurance companies are included. Based on these elements, we attempt to answer the question of presence of competence in anesthesiology in the operating room.

Multicentre study of perioperative versus adjuvant chemotherapy for resectable colorectal liver metastases

Background

It is not known whether perioperative chemotherapy, compared with adjuvant chemotherapy alone, improves disease‐free survival (DFS) in patients with upfront resectable colorectal liver metastases (CLM). The aim of this study was to estimate the impact of neoadjuvant 5‐fluorouracil, leucovorin and oxaliplatin (FOLFOX) on DFS in patients with upfront resectable CLM.

Methods

Consecutive patients who presented with up to five resectable CLM at two Japanese and two French centres in 2008–2015 were included in the study. Both French institutions favoured perioperative FOLFOX, whereas the two Japanese groups systematically preferred upfront surgery plus adjuvant chemotherapy. Inverse probability of treatment weighting (IPTW) and Cox regression multivariable models were used to adjust for confounding. The primary outcome was DFS.

Results

Some 300 patients were included: 151 received perioperative chemotherapy and 149 had upfront surgery plus adjuvant chemotherapy. The weighted 3‐year DFS rate was 33·5 per cent after perioperative chemotherapy compared with 27·1 per cent after upfront surgery plus adjuvant chemotherapy (hazard ratio (HR) 0·85, 95 per cent c.i. 0·62 to 1·16; P = 0·318). For the subgroup of 165 patients who received adjuvant FOLFOX successfully (for at least 3 months), the adjusted effect of neoadjuvant chemotherapy was not significant (HR 1·19, 0·74 to 1·90; P = 0·476). No significant effect of neoadjuvant chemotherapy was observed in multivariable regression analysis.

Conclusion

Compared with adjuvant chemotherapy, perioperative FOLFOX does not improve DFS in patients with resectable CLM, provided adjuvant chemotherapy is given successfully.

[Boston Keratoprosthesis with temporal aponeurosis graft: A solution when there seems to be no more]

PURPOSE

To report cases of patients with severe bilateral corneal blindness and recurrent refractory perforation to keratoplasty and conventional treatment, for whom Boston keratoprosthesis (KP) was a satisfactory alternative when combined with a temporalis aponeurosis graft.

DESCRIPTION OF CASES

The first patient had progressive Lyell syndrome with spontaneous corneal perforation. The second had a severe graft vs. host reaction with a persistent Seidel-positive descemetocele. Despite repeated penetrating keratoplasties, amniotic membrane (AM) transplantations, and buccal mucosal (BM) grafts, they both experienced recurrent corneal perforation. The only solution thus appeared to be Boston Type I KP surgery. One month postoperatively, the first patient had to receive a temporalis aponeurosis (TA) graft, due to thinning of the recipient graft. Six months postoperatively, his visual acuity (VA) was 1/10 without correction, and the corneal status had been stabilized. The second patient underwent KP and TA graft concurrently. Six months after surgery, VA was 2/10 uncorrected, and the local inflammation had been stabilized.

OBSERVATION

Boston type I keratoprostheses constitute an alternative in cases of severe bilateral corneal blindness with perforation refractory to conventional treatment and surgery, with satisfactory visual results.

DISCUSSION

Patients with preoperative severe ocular surface disease are at greater risk of postoperative keratolysis. For our patients with a higher risk, TA graft prevented corneal melt. TA seems to be more effective than AM or BM in preventing corneal thinning or melt.

CONCLUSION

We would recommend performing a TA graft in combination with Boston KP surgery concurrently as first line treatment in eyes with severe ocular surface inflammation.

[Late and sustained intraocular pressure elevation related to intravitreal anti-VEGF injections: Cases requiring filtering surgery (French translation of the article)]

We report cases of delayed, sustained elevated intraocular pressure (IOP) associated with repeated intravitreal anti-VEGF injections (IVI), which ultimately resulted in the need for filtering surgery. Two of the three cases demonstrated severe IOP elevation despite maximal medical treatment following unilateral IVI and required urgent filtering surgery. Optic nerve involvement was severe in all three cases. These intravitreal injections were performed for exudative age-related macular degeneration (AMD), and the patients did not show any sign of glaucoma or ocular hypertension prior to the initiation of treatment. Elevated IOP secondary to intravitreal steroids is a well-known side effect, as is immediate transient IOP elevation associated with anti-VEGF injection. Late, sustained IOP elevation after repeated injections of anti-VEGF, described approximately ten years ago, is often underestimated. Its incidence is estimated between 2.1% and 13% according to studies and increases with the number of IVI (cumulative effect). The pathophysiologic process is becoming increasingly understood, and several risk factors for this chronic IOP elevation have been identified. Most often, it is a moderate IOP elevation for which topical monotherapy is sufficient, or sometimes two, three or four medications or even selective laser trabeculoplasty (SLT). However, filtering surgery may rarely be required. Our findings illustrate a little-described phenomenon: a sudden, severe, late IOP elevation in response to anti-VEGF by an "overflow" effect, requiring urgent filtering surgery.

Late and sustained intraocular pressure elevation related to intravitreal anti-VEGF injections: Cases requiring filtering surgery

We report cases of delayed, sustained elevated intraocular pressure (IOP) associated with repeated intravitreal anti-VEGF injections (IVI), which ultimately resulted in the need for filtering surgery. Two of the three cases demonstrated severe IOP elevation despite maximal medical treatment following unilateral IVI and required urgent filtering surgery. Optic nerve involvement was severe in all three cases. These intravitreal injections were performed for exudative age-related macular degeneration (AMD), and the patients did not show any sign of glaucoma or ocular hypertension prior to the initiation of treatment. Elevated IOP secondary to intravitreal steroids is a well-known side effect, as is immediate transient IOP elevation associated with anti-VEGF injection. Late, sustained IOP elevation after repeated injections of anti-VEGF, described approximately ten years ago, is often underestimated. Its incidence is estimated between 2.1 % and 13 % according to studies and increases with the number of IVI (cumulative effect). The pathophysiologic process is becoming increasingly understood, and several risk factors for this chronic IOP elevation have been identified. Most often, it is a moderate IOP elevation for which topical monotherapy is sufficient, or sometimes two, three or four medications or even selective laser trabeculoplasty (SLT). However, filtering surgery may rarely be required. Our findings illustrate a little-described phenomenon: a sudden, severe, late IOP elevation in response to anti-VEGF by an "overflow" effect, requiring urgent filtering surgery.

Graft Protection Against Cold Ischemia Preservation: An Institute George Lopez 1 and Histidine-tryptophan-ketoglutarate Solution Appraisal

Cold storage of organs in preservation solutions, such as Institute George Lopez 1 (IGL-1) or histidine-tryptophan-ketoglutarate (HTK), is a mandatory step for organ transplantation. This preservation leads to an ischemic injury that affects the outcome of the organ. This article studies the liver graft eluate after organ recovery using IGL-1 or HTK solutions. We explore the influence of the volume used for washing out the liver and the consequences in the graft preservation when both solutions are used. Livers were washed out with different volumes of HTK and IGL-1 according to manufacturers' instructions and then preserved in both solutions for 24 hours at 4°C. Tissue and eluates were collected for subsequent analyses. We measured transaminases (aspartate aminotransferase and alanine aminotransferase), histology by hematoxylin/eosin staining, and red blood cell and hemoglobin counts, respectively. After washing out and cold storage, the IGL-1 processed livers showed better preservation than those with HTK solution; however, in this latter case, an important accumulation of erythrocytes was found when compared to IGL-1. These data were consistent with the higher hemoglobin and red blood cell counts observed for IGL-1 eluates after 24 hours. The volume used for washing out the organ depends on the composition and properties of the organ preservation solutions (ie, IGL-1 and HTK); this is an important factor for the graft cold preservation. The total volume used for washing out the graft should be considered because it has a direct impact on the total cost for clinical transplantations.

Neoadjuvant chemotherapy response influences outcomes in non-colorectal, non-neuroendocrine liver metastases

BACKGROUND

Indications for surgical resection of non-colorectal, non-neuroendocrine (NCNNE) liver metastases are unclear. This study analysed the influence of response to neoadjuvant chemotherapy and the presence of extrahepatic disease (EHD) on outcomes.

METHODS

Patients who underwent hepatic resection for NCNNE liver metastases and who received neoadjuvant chemotherapy at a single centre between 1982 and 2016 were analysed retrospectively. Patients were classified as having no EHD, controlled EHD or non-controlled EHD.

RESULTS

Hepatic resection was performed in 199 patients (81·2 per cent) after partial or complete response to chemotherapy or disease stabilization, and 46 patients (18·8 per cent) after tumour progression. Patients with progressive disease after chemotherapy had worse overall survival than those without (23 versus 50·4 per cent at 5 years; P = 0·004). Median survival was 63·6 (range 31·1-94·8) months for patients without EHD, 34·8 (19·2-49·2) months for those with controlled EHD and 7·2 (1·2-13·2) months for patients with non-controlled EHD (P = 0·004). In multivariable analysis, EHD (P = 0·004), response to chemotherapy (P = 0·004) and resection margins (P = 0·002) were all independent predictors of overall survival, regardless of primary tumour site.

CONCLUSION

The prognosis of patients with NCNNE liver metastases is influenced by preoperative chemotherapy and resectability.

Surgical resection versus systemic therapy for breast cancer liver metastases: Results of a European case matched comparison

BACKGROUND

Resection of breast cancer liver metastases (BCLM) combined with systemic treatment is increasingly accepted but not offered as therapeutic option. New evidence of the additional value of surgery in these patients is scarce while prognoses without surgery remains poor.

PATIENTS AND METHODS

For this case matched analysis, all nationally registered patients with BCLM confined to the liver in the Netherlands (systemic group; N = 523) were selected and compared with patients who received systemic treatment and underwent hepatectomy (resection group; N = 139) at a hepatobiliary centre in France. Matching was based on age, decade when diagnosed, interval to metastases, maximum metastases size, single or multiple tumours, chemotherapy, hormonal or targeted therapy after diagnosis. Based on published guidelines, palliative systemic treatment strategies are similar in both European countries.

RESULTS

Between 1983 and 2013, 3894 patients were screened for inclusion. Overall median follow-up was 80 months (95% CI 70-90 months). The median, 3- and 5-year overall survival of the whole population was 19 months, 29% and 19%, respectively. The resection and systemic group had median survival of 73 vs. 13 months (P < 0.001), respectively. Three and 5-year survival was 18% and 10% for the systemic group and 75% and 54% for the resection group, respectively. After matching, the resection group had a median overall survival of 82 months with a 3- and 5-year overall survival of 81% and 69%, respectively, compared with a median overall survival of 31 months in the systemic group with a 3- and 5-year overall survival of 32% and 24%, respectively (HR 0.28, 95% CI 0.15-0.52; P < 0.001).

CONCLUSIONS

For patients with BCLM, liver resection combined with systemic treatment results in improved overall survival compared to systemic treatment alone. Liver resection should be considered in selected cases.

Cross-Talk Between Sirtuin 1 and High-Mobility Box 1 in Steatotic Liver Graft Preservation

BACKGROUND

Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide +-dependent histone deacetylase that regulates various pathways involved in ischemia-reperfusion injury (IRI). Moreover, high-mobility group box 1 protein (HMGB1) has also been involved in inflammatory processes during IRI. However, the roles of both SIRT1 and HMGB1 in liver preservation is poorly understood. In this communication, we evaluated the potential relationship between SIRT1 and HMGB1 in steatotic and non-steatotic liver grafts preserved in Institute Georges Lopez solution (IGL-1) preservation solution enriched or not enriched with trimetazidine (TMZ).

METHODS

Steatotic and non-steatotic livers were preserved in IGL-1 preservation solution (24 hours, 4°C), enriched or not enriched with TMZ (10 μmol/L), and then submitted to ex vivo reperfusion (2 hours; 37°C). Liver injury (AST/ALT) and function (bile output, vascular resistance) were evaluated. SIRT1, HMGB1, autophagy parameters (beclin-1, LC3B), PPAR-γ, and heat-shock protein (HO-1, HSP70) expression were determined by means of Western blot. Also, we assessed oxidative stress, mitochondrial damage (glutamate dehydrogenase), and TNF-α levels.

RESULTS

Elevated SIRT1 and enhanced autophagy were found after reperfusion in steatotic livers preserved in IGL-1+TMZ when compared with IGL-1. However, these changes were not seen in the case of non-steatotic livers. Also, HO-1 increases in the IGL-1 + TMZ group were evident only in the case of steatotic livers, whereas HSP70 and PPAR-γ protein expression were enhanced only in non-steatotic livers. All reported changes were consistent with decreased liver injury diminution, ameliorated hepatic function, and decreased TNF-α and HMGB levels. In addition, the oxidative stress and mitochondrial damage were efficiently prevented by the IGL-1 + TMZ use.

CONCLUSIONS

SIRT1 is associated with HMGB1 decreases and increased autophagy in steatotic livers, contributing to increased tolerance to cold IRI.

Risk score to predict biliary leakage after elective liver resection

Background

Biliary leakage remains a major cause of morbidity after liver resection. Previous prognostic studies of posthepatectomy biliary leakage (PHBL) lacked power, population homogeneity, and model validation. The present study aimed to develop a risk score for predicting severe PHBL.

Methods

In this multicentre observational study, patients who underwent liver resection without hepaticojejunostomy in one of nine tertiary centres between 2012 and 2015 were randomly assigned to a development or validation cohort in a 2 : 1 ratio. A model predicting severe PHBL (International Study Group of Liver Surgery grade B/C) was developed and further validated.

Results

A total of 2218 procedures were included. PHBL of any severity and severe PHBL occurred in 141 (6·4 per cent) and 92 (4·1 per cent) patients respectively. In the development cohort (1475 patients), multivariable analysis identified blood loss of at least 500 ml, liver remnant ischaemia time 45 min or more, anatomical resection including segment VIII, transection along the right aspect of the left intersectional plane, and associating liver partition and portal vein ligation for staged hepatectomy as predictors of severe PHBL. A risk score (ranging from 0 to 5) was built using the development cohort (area under the receiver operating characteristic curve (AUROC) 0·79, 95 per cent c.i. 0·74 to 0·85) and tested successfully in the validation cohort (AUROC 0·70, 0·60 to 0·80). A score of at least 3 predicted an increase in severe PHBL (19·4 versus 2·6 per cent in the development cohort, P &lt; 0·001; 15 versus 3·1 per cent in the validation cohort, P &lt; 0·001).

Conclusion

The present risk score reliably predicts severe PHBL. It represents a multi-institutionally validated prognostic tool that can be used to identify a subset of patients at high risk of severe PHBL after elective hepatectomy.