MRI size assessment of cerebral microvasculature using diffusion-time-dependent stimulated-echo acquisition: A feasibility study in rodent.

In this study, a stimulated-echo (STE) method was employed to robustify the cerebral vessel size estimation near air-tissue, bone-tissue interfaces, and large vessels. The proposed solution is to replace the relaxation rate change from gradient-echo (GRE) with that from STE with long diffusion time after the injection of an intravascular contrast agent, superparamagnetic iron oxide nanoparticles. The corresponding diffusion length of STE is shorter than the length over which the unwanted macroscopic field inhomogeneities but is still longer than the correlation length of the fields induced by small vessels. Therefore, the unwanted field inhomogeneities are refocused, while preserving microscopic susceptibility contrast from cerebral vessels. The mean vessel diameter (dimensionless) derived from the diffusion-time-varying STE method was compared to the mean vessel diameter obtained by a conventional spin-echo (SE) and GRE combination based on Monte-Carlo proton diffusion simulations and in vivo rat experiments at 7 â€‹T. The in vivo mean vessel diameter from the MRI experiments was directly compared to available reference mouse brain vasculature obtained by a knife-edge scanning microscope (KESM), which is considered to be the gold standard. Monte-Carlo simulation revealed that SE and GRE-based MR relaxation rate changes (ΔR2 and ΔR2∗, respectively) can be enhanced using single STE-based MR relaxation rate change (ΔRSTE) by regulating diffusion time, especially for small vessels. The in vivo mean vessel diameter from the STE method demonstrated a closer agreement with that from the KESM compared to the combined SE and GRE method, especially in the olfactory bulb and cortex. This study demonstrates that STE relaxation rate changes can be used as consistent measures for assessing small cerebral microvasculature, where macroscopic field inhomogeneity is severe and signal contamination from adjacent large vessels is significant.

The robustness of T2 value as a trabecular structural index at multiple spatial resolutions of 7 Tesla MRI.

PURPOSE: To evaluate the robustness of MR transverse relaxation times of trabecular bone from spin-echo and gradient-echo acquisitions at multiple spatial resolutions of 7 T. METHODS: The effects of MRI resolutions to T2 and T2* of trabecular bone were numerically evaluated by Monte Carlo simulations. T2 , T2*, and trabecular structural indices from multislice multi-echo and UTE acquisitions were measured in defatted human distal femoral condyles on a 7 T scanner. Reference structural indices were extracted from high-resolution microcomputed tomography images. For bovine knee trabecular samples with intact bone marrow, T2 and T2* were measured by degrading spatial resolutions on a 7 T system. RESULTS: In the defatted trabecular experiment, both T2 and T2* values showed strong ( |r| > 0.80) correlations with trabecular spacing and number, at a high spatial resolution of 125 µm3 . The correlations for MR image-segmentation-derived structural indices were significantly degraded ( |r| < 0.50) at spatial resolutions of 250 and 500 µm3 . The correlations for T2* rapidly dropped ( |r| < 0.50) at a spatial resolution of 500 µm3 , whereas those for T2 remained consistently high ( |r| > 0.85). In the bovine trabecular experiments with intact marrow, low-resolution (approximately 1 mm3 , 2 minutes) T2 values did not shorten ( |r| > 0.95 with respect to approximately 0.4 mm3 , 11 minutes) and maintained consistent correlations ( |r| > 0.70) with respect to trabecular spacing (turbo spin echo, 22.5 minutes). CONCLUSION: T2 measurements of trabeculae at 7 T are robust with degrading spatial resolution and may be preferable in assessing trabecular spacing index with reduced scan time, when high-resolution 3D micro-MRI is difficult to obtain.

Meiotic pairing as an indicator of genome composition in polyploid prairie cordgrass (Spartina pectinata Link).

The existence of neopolyploidy in prairie cordgrass (Spartina pectinata Link) has been documented. The neohexaploid was discovered coexisting with tetraploids in central Illinois, and has been reported to exhibit competitiveness in the natural environment. It is hypothesized that the natural tetraploid cytotype produced the hexaploid cytotype via production of unreduced gametes. Meiosis I chromosome pairing was observed in tetraploid (2n = 4x = 40), hexaploid (2n = 6x = 60), and octoploid (2n = 8x = 80) accessions and the percentage of meiotic abnormality was determined. Significant differences in meiotic abnormality exist between tetraploid, hexaploid, and octoploid cytotypes. An elevated incidence of abnormal, predominantly trivalent pairing in the neohexaploid suggests that it may possess homologous chromosomes in sets of three, in contrast to the tetraploid and octoploid cytotypes, which likely possess homologous chromosomes in sets of two. Abnormal chromosome pairing in the hexaploid may result in unequal allocation of chromosomes to daughter cells during later stages of meiosis. Chromosome pairing patterns in tetraploid, hexaploid, and octoploid cytotypes indicate genome compositions of AABB, AAABBB, and AABBA'A'B'B', respectively.

Assessment of the potential for gene flow from transgenic maize (Zea mays L.) to eastern gamagrass (Tripsacum dactyloides L.).

Eastern gamagrass (Tripsacum dactyloides L.) belongs to the same tribe of the Poaceae family as maize (Zea mays L.) and grows naturally in the same region where maize is commercially produced in the USA. Although no evidence exists of gene flow from maize to eastern gamagrass in nature, experimental crosses between the two species were produced using specific techniques. As part of environmental risk assessment, the possibility of transgene flow from maize to eastern gamagrass populations in nature was evaluated with the objectives: (1) to assess the seeds of eastern gamagrass populations naturally growing near commercial maize fields for the presence of a transgenic glyphosate-tolerance gene (cp4 epsps) that would indicate cross-pollination between the two species, and (2) to evaluate the possibility of interspecific hybridization between transgenic maize used as male parent and eastern gamagrass used as female parent. A total of 46,643 seeds from 54 eastern gamagrass populations collected in proximity of maize fields in Illinois, USA were planted in a field in 2014 and 2015. Emerged seedlings were treated with glyphosate herbicide and assessed for survival. An additional 48,000 seeds from the same 54 eastern gamagrass populations were tested for the presence of the cp4 epsps transgene markers using TaqMan® PCR method. The results from these trials showed that no seedlings survived the herbicide treatment and no seed indicated presence of the herbicide tolerant cp4 epsps transgene, even though these eastern gamagrass populations were exposed to glyphosate-tolerant maize pollen for years. Furthermore, no interspecific hybrid seeds were produced from 135 hand-pollination attempts involving 1529 eastern gamagrass spikelets exposed to maize pollen. Together, these results indicate that there is no evidence of gene flow from maize to eastern gamagrass in natural habitats. The outcome of this study should be taken in consideration when assessing for environmental risks regarding the consequence of gene flow from transgenic maize to its wild relatives.

Volumetric analysis of the cerebellum in patients with progressive supranuclear palsy.

BACKGROUND AND PURPOSE: Although early cerebellar symptoms are one of the exclusive criteria in the diagnosis of progressive supranuclear palsy (PSP), cerebellar involvement in PSP is evident both clinically and pathologically. However, structural analysis focusing on the cerebellum has not been previously studied in patients with PSP. We aimed to evaluate cerebellar involvement in PSP using a magnetic resonance imaging-based segmental volumetric analysis. METHODS: We retrospectively enrolled 48 patients with PSP composed of 25 patients with PSP-Richardson's syndrome (RS) and 23 patients with pure akinesia with gait freezing, 39 patients with Parkinson's disease (PD) and 34 healthy controls. Data on both the whole and segmented cerebellar volumes were analyzed using a fully automated procedure. RESULTS: A general linear model showed that whole cerebellar volume in patients with PSP was significantly smaller compared with that of patients with PD or controls after controlling for age, sex and intracranial volume (P = 0.34). In addition, patients with PSP exhibited decreased regional volume in the crus I, lobule VIIIa and lobule VIIIb, which play roles as secondary representations of motor tasks, compared with patients with PD or controls. In subgroup analysis of PSP, volume loss in the whole and segmental cerebellum was more pronounced in patients with PSP-RS than in those with pure akinesia with gait freezing, PD or control subjects. CONCLUSION: These data demonstrate that cerebellar atrophy is evident in patients with PSP and is especially prominent in the PSP-RS group. These findings increase understanding of the clinicopathological basis of cerebellar involvement in PSP.

The utility of intra-operative frozen section for the evaluation of microscopic extrathyroidal extension in papillary thyroid carcinoma.

OBJECTIVES: This study was designed to evaluate the usefulness of intra-operative frozen section for the evaluation of microscopic extrathyroidal extension (ETE) in papillary thyroid carcinoma (PTC). DESIGN: Retrospective cohort study. SETTING: Dong-A University Medical Center, Busan, Korea. PARTICIPANTS: Three hundred and sixty-four patients who underwent thyroid surgery from January 2000 to December 2010 with PTC confined to one unilateral lobe as diagnosed using preoperative ultrasonography were enrolled. MAIN OUTCOME MEASURES: The patients who had microscopic ETE on frozen section were classified into "group A," and those who did not have microscopic ETE on frozen section were classified into "group B." Clinicopathologic factors including age, gender, size of the tumour, extent of operation, ETE, multifocality, bilaterality, lymph node metastasis and recurrence were compared between the two groups. RESULTS: Of the 364 patients enrolled, ETE was confirmed in 100 patients (group A, 27.5%) on frozen biopsy. The nodule size in group A (0.94±0.87 cm) was larger than that in group B (0.86±0.79 cm) (P=.042). In group A, 15 patients (15%) showed multifocality and 11 patients (14.47%) showed bilaterality. In group B, 37 patients (14.02%) showed multifocality and seven patients (43.35%) showed bilaterality. They did not differ significantly between the two groups (P=.811, P=.182). There was a higher frequency of lymph node metastases in group A (52/86, 60.47%) than in group B (7/16, 43.75%, P=.214). Recurrence was observed in only two patients who had received thyroid lobectomy as the initial surgery in group A. CONCLUSIONS: Intra-operative frozen biopsy can be a useful method for identifying the microscopic ETE. During the surgery, it can also help the surgeon to decide the optimal extent of surgery and the need for central compartment neck dissection in PTC patients.

UTE-ΔR2 -ΔR2 * combined MR whole-brain angiogram using dual-contrast superparamagnetic iron oxide nanoparticles.

The ability to visualize whole-brain vasculature is important for quantitative in vivo investigation of vascular malfunctions in cerebral small vessel diseases, including cancer, stroke and neurodegeneration. Transverse relaxation-based ΔR2 and ΔR2 * MR angiography (MRA) provides improved vessel-tissue contrast in animal deep brain with the aid of intravascular contrast agents; however, it is susceptible to orientation dependence, air-tissue interface artifacts and vessel size overestimation. Dual-mode MRA acquisition with superparamagnetic iron oxide nanoparticles (SPION) provides a unique opportunity to systematically compare and synergistically combine both longitudinal (R1 ) and transverse (ΔR2 and ΔR2 *) relaxation-based MRA. Through Monte Carlo (MC) simulation and MRA experiments in normal and tumor-bearing animals with intravascular SPION, we show that ultrashort TE (UTE) MRA acquires well-defined vascularization on the brain surface, minimizing air-tissue artifacts, and combined ΔR2 and ΔR2 * MRA simultaneously improves the sensitivity to intracortical penetrating vessels and reduces vessel size overestimation. Consequently, UTE-ΔR2 -ΔR2 * combined MRA complements the shortcomings of individual angiograms and provides a strategy to synergistically merge longitudinal and transverse relaxation effects to generate more robust in vivo whole-brain micro-MRA. Copyright © 2016 John Wiley & Sons, Ltd.

Accurate Exchange-Correlation Energies for the Warm Dense Electron Gas.

The density matrix quantum Monte Carlo (DMQMC) method is used to sample exact-on-average N-body density matrices for uniform electron gas systems of up to 10^{124} matrix elements via a stochastic solution of the Bloch equation. The results of these calculations resolve a current debate over the accuracy of the data used to parametrize finite-temperature density functionals. Exchange-correlation energies calculated using the real-space restricted path-integral formalism and the k-space configuration path-integral formalism disagree by up to ∼10% at certain reduced temperatures T/T_{F}≤0.5 and densities r_{s}≤1. Our calculations confirm the accuracy of the configuration path-integral Monte Carlo results available at high density and bridge the gap to lower densities, providing trustworthy data in the regime typical of planetary interiors and solids subject to laser irradiation. We demonstrate that the DMQMC method can calculate free energies directly and present exact free energies for T/T_{F}≥1 and r_{s}≤2.

Diet-induced obesity reduces the production of influenza vaccine-induced antibodies via impaired macrophage function.

Obesity is a metabolic disease characterized by low-level chronic inflammation. Obese individuals are susceptible to infection by viruses, and vaccination against these pathogens is less effective than in nonobese individuals. Here, we sought to explore the immunological environment in a mouse model of obesity induced by a high-fat diet (HFD). HFD treatment increased the body weight and epididymal fat mass. The proportion of activated B cells, T cells, and macrophages was similar between mice in the HFD group and the regular-fat diet (RFD) group. The Th1 cell subpopulation in the HFD group was increased, whereas the proportion of Treg cells was reduced compared with the RFD group. Moreover, T-cell proliferation and cytokine production did not differ between the groups when cells were stimulated with anti-CD3 and anti-CD28 antibodies in vitro. In macrophages, phagocytic activity was higher in mice fed an HFD than in those fed an RFD, but expression levels of CD86 and MHC class II antigens were similar. When macrophages were cultured in vitro, the proportion of CD86-expressing macrophages was lower in those isolated from mice in the HFD group than in those isolated from the RFD group. Furthermore, lipopolysaccharide-induced interleukin 6 (IL-6) and tumor necrosis factor alpha secretions were significantly reduced in macrophages isolated from the HFD group. In addition, influenza vaccine-induced antibodies in the HFD group diminished more rapidly than in the RFD group. These results suggest that poor functionality of macrophages during obesity might contribute to a reduction in vaccine efficacy.

Sub-zero cold tolerance of Spartina pectinata (prairie cordgrass) and Miscanthus × giganteus: candidate bioenergy crops for cool temperate climates.

Miscanthus × giganteus grown in cool temperate regions of North America and Europe can exhibit severe mortality in the year after planting, and poor frost tolerance of leaves. Spartina pectinata (prairie cordgrass), a productive C4 perennial grass native to North America, has been suggested as an alternative biofuel feedstock for colder regions; however, its cold tolerance relative to M. × giganteus is uncertain. Here, we compare the cold tolerance thresholds for winter-dormant rhizomes and spring/summer leaves of M. × giganteus and three accessions of S. pectinata. All genotypes were planted at a field site in Ontario, Canada. In November and February, the temperatures corresponding to 50% rhizome mortality (LT(50)) were near -24°C for S. pectinata and -4°C for M. × giganteus. In late April, the LT50 of rhizomes rose to -10°C for S. pectinata but remained near -4°C for M. × giganteus. Twenty percent of the M. × giganteus rhizomes collected in late April were dead while S. pectinata rhizomes showed no signs of winter injury. Photosynthesis and electrolyte leakage measurements in spring and summer demonstrate that S. pectinata leaves have greater frost tolerance in the field. For example, S. pectinata leaves remained viable above -9°C while the mortality threshold was near -5°C for M. × giganteus. These results indicate M. × giganteus will be unsuitable for production in continental interiors of cool-temperate climate zones unless freezing and frost tolerance are improved. By contrast, S. pectinata has the freezing and frost tolerance required for a higher-latitude bioenergy crop.

Interaction picture density matrix quantum Monte Carlo.

The recently developed density matrix quantum Monte Carlo (DMQMC) algorithm stochastically samples the N-body thermal density matrix and hence provides access to exact properties of many-particle quantum systems at arbitrary temperatures. We demonstrate that moving to the interaction picture provides substantial benefits when applying DMQMC to interacting fermions. In this first study, we focus on a system of much recent interest: the uniform electron gas in the warm dense regime. The basis set incompleteness error at finite temperature is investigated and extrapolated via a simple Monte Carlo sampling procedure. Finally, we provide benchmark calculations for a four-electron system, comparing our results to previous work where possible.

Integrating plant morphological traits with remote-sensed multispectral imageries for accurate corn grain yield prediction.

Sustainable crop production requires adequate and efficient management practices to reduce the negative environmental impacts of excessive nitrogen (N) fertilization. Remote sensing has gained traction as a low-cost and time-efficient tool for monitoring and managing cropping systems. In this study, vegetation indices (VIs) obtained from an unmanned aerial vehicle (UAV) were used to detect corn (Zea mays L.) response to varying N rates (ranging from 0 to 208 kg N ha-1) and fertilizer application methods (liquid urea ammonium nitrate (UAN), urea side-dressing and slow-release fertilizer). Four VIs were evaluated at three different growth stages of corn (V6, R3, and physiological maturity) along with morphological traits including plant height and leaf chlorophyll content (SPAD) to determine their predictive capability for corn yield. Our results show no differences in grain yield (average 13.2 Mg ha-1) between furrow-applied slow-release fertilizer at ≥156 kg N ha-1 and 208 kg N ha-1 side-dressed urea. Early season remote-sensed VIs and morphological data collected at V6 were least effective for grain yield prediction. Moreover, multivariate grain yield prediction was more accurate than univariate. Late-season measurements at the R3 and mature growth stages using a combination of normalized difference vegetation index (NDVI) and green normalized difference vegetation index (GNDVI) in a multilinear regression model showed effective prediction for corn yield. Additionally, a combination of NDVI and normalized difference red edge index (NDRE) in a multi-exponential regression model also demonstrated good prediction capabilities.

Dynamics of thermalization and decoherence of a nanoscale system.

We study the decoherence and thermalization dynamics of a nanoscale system coupled nonperturbatively to a fully quantum-mechanical bath. The system is prepared out of equilibrium in a pure state of the complete system. We propose a random matrix model and show analytically that there are two robust temporal regimes in the approach of the system to equilibrium-an initial Gaussian decay followed by an exponential tail, consistent with numerical results on small interacting lattices [S. Genway, A. F. Ho, and D. K. K. Lee, Phys. Rev. Lett. 105, 260402 (2010)]. Furthermore, the system decays towards a Gibbs ensemble in accordance with the eigenstate thermalization hypothesis.

A K-nearest neighbors survival probability prediction method.

We introduce a nonparametric survival prediction method for right-censored data. The method generates a survival curve prediction by constructing a (weighted) Kaplan-Meier estimator using the outcomes of the K most similar training observations. Each observation has an associated set of covariates, and a metric on the covariate space is used to measure similarity between observations. We apply our method to a kidney transplantation data set to generate patient-specific distributions of graft survival and to a simulated data set in which the proportional hazards assumption is explicitly violated. We compare the performance of our method with the standard Cox model and the random survival forests method.

Porcine feasibility and safety study of a new paclitaxel-eluting biliary stent with a Pluronic-containing membrane.

BACKGROUND AND STUDY AIM: Metal stents for malignant biliary obstruction are susceptible to occlusion by tumor ingrowth or overgrowth. Therefore, we previously reported our use of a metal stent covered with a paclitaxel-incorporated membrane giving an antitumor effect to prevent occlusion from tumor ingrowth. We have also developed a new generation of paclitaxel-eluting biliary stent using a membrane containing Pluronic F-127 for effective drug delivery. The aim of this study was to investigate the safety and efficacy of drug delivery for this newly developed stent in the biliary tract. METHODS: Metal stents were coated with paclitaxel and various concentrations of Pluronic F-127 in phosphate-buffered saline solution. Stents containing varying concentrations were placed in the bile ducts of eight pigs divided as follows: group I, 0% Pluronic + 0% paclitaxel; group II, 0% Pluronic + 10% paclitaxel; group III, 10% Pluronic + 10% paclitaxel; group IV, 20% Pluronic + 10% paclitaxel. The histology of the porcine bile duct and the amount of paclitaxel in the porcine serum were examined. The amount of paclitaxel released was also measured in vitro. RESULTS: Histologic changes in the porcine biliary epithelium were acceptable in terms of safety, based on inflammatory cell infiltration and fibrotic reaction. No significant differences in histology were observed between the groups. In the porcine serum analysis, released paclitaxel was detected for 28 days with the 10% Pluronic concentration (group III). However, released paclitaxel was observed for only 7 days in groups II and IV. In the in vitro experiments, long-lasting release of paclitaxel was also noted from the stent with 10% Pluronic. CONCLUSIONS: The new paclitaxel-eluting stent with 10% Pluronic F-127 is safe and provides enhanced local drug delivery.

A comparative study of two- versus one-lung ventilation for needlescopic bleb resection.

This prospective study was conducted to evaluate the feasibility of two-lung (TL) ventilation with low tidal volume anaesthesia compared with one-lung (OL) ventilation for needlescopic bleb resection. Patients with spontaneous pneumothorax that underwent bleb resection with a 2-mm thoracoscope were enrolled. During the operation, the tidal volume was set at 4.0 mL·kg⁻¹ in the TL group and 8.0 mL·kg⁻¹ in the OL group; the respiration rate was set at 23 and 12 breaths·min⁻¹, respectively, at the same inspiratory oxygen fraction (50%). A total of 108 patients (55 patients in the TL group and 53 in the OL group) were included in this study. Airway pressure was significantly lower in the TL group (mean ± sd 8.0 ± 3.3 versus 24.0 ± 3.9 mmHg in the OL group; p<0.001). The time from endotracheal intubation to the incision was 17.1 ± 4.0 min in the TL group and 35.3 ± 7.6 min in the OL group, which was significantly different (p<0.001). However, the operation time was not different in comparisons between the two groups. Therefore, the total anaesthesia time was significantly longer in the OL group (77.9 ± 21.6 versus 64.9 ± 14.7 min in the TL group; p = 0.002). Needlescopic bleb resection using TL ventilation anaesthesia with low tidal volume was technically feasible, cost-effective and time-saving compared with OL ventilation anaesthesia.

A numerical study on the mechanical characteristics of zinc oxide-based transparent thin film transistors.

Zinc Oxide (ZnO) based Thin Film Transistors (TFTs) have been fabricated and analyzed to investigate mechanical characteristics regarding the stress, strain and deformation of electro circuits using the Finite Element Method (FEM). As the best compromise between the stretching and bending abilities, the coating thickness of SU-8 can be as important for bendability as a neutral mechanical plane. The neutral mechanical plane in electro circuits was designed for obtaining flexibility, e.g., bendability, in a previous numerical study. After that, through experimental validation, we observed what degree of SU-8 thickness was attributable for improved mechanical stability. The results suggest that not only numerical but also experimental measurements of the deformation and SU-8 coating thickness in electro circuits are useful for enhancing structural stability.

Deformation characteristics of an organic thin film transistor.

An organic thin film transistor (OTFT) on a flexible substrate with electroplated electrodes has many advantages in the fabrication of low cost sensors, e-paper, smart cards, and flexible displays. In this study, we simulated the mechanical characteristics of an OTFT with various compressive stress conditions using COMSOL. An analysis model, which was limited to channel, source, and drain, was used to investigate deformation and internal stress concentrations. The channel length is 40 microm and the OTFT structure is a top-contact structure. The OTFT was fabricated using pentacene as a semiconducting layer and electroplated Ni as a gate electrode. The deformation characteristics of the fabricated OTFT were predicted in terms of strain and internal stress.

Influence of shrub willow buffers strategically integrated in an Illinois corn-soybean field on soil health and microbial community composition.

Soil serves many important ecological functions and is an integral part of our existence as a society. However, concerns for soil health are growing globally, in part due to the negative impacts of agricultural management on soil resources. The production of perennial bioenergy crops on marginal land in row-crop production systems is one solution that could improve land-use efficiency and address the sustainability of cropland management. Because the relationship between crop management and the environment is complex, more research is needed to evaluate the potential benefits perennial bioenergy crop production has on soil health, as well as other ecosystem services. In this study, shrub willow buffers were strategically integrated into a corn-soybean cropping system with the main objective of reducing nitrate-N leaching from grain crop production while producing biomass for bioenergy. Two buffer systems (defined by landscape positions) were included for comparison, one on marginal land with exposure to nitrate-N leaching from upslope grain (southern plots) and one on fertile soils with less nitrate-N leaching potential (northern plots). Evaluation of soil (chemistry, bulk density, microbial community) and shrub willow vegetation properties (fine roots, leaf litter decomposition, and nutrient uptake dynamics), showed that landscape position plays an important role in (1) the dynamics of soil chemical properties, (2) shrub willow's influence and productivity, and (3) the provision of additional ecosystem services such as reductions in nitrous oxide emissions and nitrate-N leaching. In addition, the combination of crop type and landscape position (N-grain, N-willow, S-grain, and S-willow) influenced the species composition of the soil microbial community, resulting in unique and identifiable communities. These results highlight the potential application of shrub willow buffers for ecosystem service provision and support of ecosystem processes; however, understanding the relationship between the microbial community, crop type, and landscape is important for understanding the sustainability of the design.

Associations between preoperative anaemia and hospital costs following major abdominal surgery: cohort study.

BACKGROUND: Determining the cost-effectiveness and sustainability of patient blood management programmes relies on quantifying the economic burden of preoperative anaemia. This retrospective cohort study aimed to evaluate the hospital costs attributable to preoperative anaemia in patients undergoing major abdominal surgery. METHODS: Patients who underwent major abdominal surgery between 2010 and 2018 were included. The association between preoperative patient haemoglobin (Hb) concentration and hospital costs was evaluated by curve estimation based on the least-square method. The in-hospital cost of index admission was calculated using an activity-based costing methodology. Multivariable regression analysis and propensity score matching were used to estimate the effects of Hb concentration on variables related directly to hospital costs. RESULTS: A total of 1286 patients were included. The median overall cost was US $18 476 (i.q.r.13 784-27 880), and 568 patients (44.2 per cent) had a Hb level below 13.0 g/dl. Patients with a preoperative Hb level below 9.0 g/dl had total hospital costs that were 50.6 (95 per cent c.i. 14.1 to 98.9) per cent higher than those for patients with a preoperative Hb level of 9.0-13.0 g/dl (P < 0.001), 72.5 (30.6 to 128.0) per cent higher than costs for patients with a Hb concentration of 13.1-15.0 g/dl (P < 0.001), and 62.4 (21.8 to 116.7) per cent higher than those for patients with a Hb level greater than 15.0 g/dl (P < 0.001). Multivariable general linear modelling showed that packed red blood cell (PRBC) transfusions were a principal cost driver in patients with a Hb concentration below 9.0 g/dl. CONCLUSION: Patients with the lowest Hb concentration incurred the highest hospital costs, which were strongly associated with increased PRBC transfusions. Costs and possible complications may be decreased by treating preoperative anaemia, particularly more severe anaemia.