Casemix, management, and mortality of patients rreseceiving emergency neurosurgery for traumatic brain injury in the Global Neurotrauma Outcomes Study: a prospective observational cohort study

BACKGROUND

Traumatic brain injury (TBI) is increasingly recognised as being responsible for a substantial proportion of the global burden of disease. Neurosurgical interventions are an important aspect of care for patients with TBI, but there is little epidemiological data available on this patient population. We aimed to characterise differences in casemix, management, and mortality of patients receiving emergency neurosurgery for TBI across different levels of human development.

METHODS

We did a prospective observational cohort study of consecutive patients with TBI undergoing emergency neurosurgery, in a convenience sample of hospitals identified by open invitation, through international and regional scientific societies and meetings, individual contacts, and social media. Patients receiving emergency neurosurgery for TBI in each hospital's 30-day study period were all eligible for inclusion, with the exception of patients undergoing insertion of an intracranial pressure monitor only, ventriculostomy placement only, or a procedure for drainage of a chronic subdural haematoma. The primary outcome was mortality at 14 days postoperatively (or last point of observation if the patient was discharged before this time point). Countries were stratified according to their Human Development Index (HDI)-a composite of life expectancy, education, and income measures-into very high HDI, high HDI, medium HDI, and low HDI tiers. Mixed effects logistic regression was used to examine the effect of HDI on mortality while accounting for and quantifying between-hospital and between-country variation.

FINDINGS

Our study included 1635 records from 159 hospitals in 57 countries, collected between Nov 1, 2018, and Jan 31, 2020. 328 (20%) records were from countries in the very high HDI tier, 539 (33%) from countries in the high HDI tier, 614 (38%) from countries in the medium HDI tier, and 154 (9%) from countries in the low HDI tier. The median age was 35 years (IQR 24-51), with the oldest patients in the very high HDI tier (median 54 years, IQR 34-69) and the youngest in the low HDI tier (median 28 years, IQR 20-38). The most common procedures were elevation of a depressed skull fracture in the low HDI tier (69 [45%]), evacuation of a supratentorial extradural haematoma in the medium HDI tier (189 [31%]) and high HDI tier (173 [32%]), and evacuation of a supratentorial acute subdural haematoma in the very high HDI tier (155 [47%]). Median time from injury to surgery was 13 h (IQR 6-32). Overall mortality was 18% (299 of 1635). After adjustment for casemix, the odds of mortality were greater in the medium HDI tier (odds ratio [OR] 2·84, 95% CI 1·55-5·2) and high HDI tier (2·26, 1·23-4·15), but not the low HDI tier (1·66, 0·61-4·46), relative to the very high HDI tier. There was significant between-hospital variation in mortality (median OR 2·04, 95% CI 1·17-2·49).

INTERPRETATION

Patients receiving emergency neurosurgery for TBI differed considerably in their admission characteristics and management across human development settings. Level of human development was associated with mortality. Substantial opportunities to improve care globally were identified, including reducing delays to surgery. Between-hospital variation in mortality suggests changes at an institutional level could influence outcome and comparative effectiveness research could identify best practices.

FUNDING

National Institute for Health Research Global Health Research Group.

Human Vascular Microphysiological System for in vitro Drug Screening

In vitro human tissue engineered human blood vessels (TEBV) that exhibit vasoactivity can be used to test human toxicity of pharmaceutical drug candidates prior to pre-clinical animal studies. TEBVs with 400–800 μM diameters were made by embedding human neonatal dermal fibroblasts or human bone marrow-derived mesenchymal stem cells in dense collagen gel. TEBVs were mechanically strong enough to allow endothelialization and perfusion at physiological shear stresses within 3 hours after fabrication. After 1 week of perfusion, TEBVs exhibited endothelial release of nitric oxide, phenylephrine-induced vasoconstriction, and acetylcholine-induced vasodilation, all of which were maintained up to 5 weeks in culture. Vasodilation was blocked with the addition of the nitric oxide synthase inhibitor L-N^G-Nitroarginine methyl ester (L-NAME). TEBVs elicited reversible activation to acute inflammatory stimulation by TNF-α which had a transient effect upon acetylcholine-induced relaxation, and exhibited dose-dependent vasodilation in response to caffeine and theophylline. Treatment of TEBVs with 1 μM lovastatin for three days prior to addition of Tumor necrosis factor – α (TNF-α) blocked the injury response and maintained vasodilation. These results indicate the potential to develop a rapidly-producible, endothelialized TEBV for microphysiological systems capable of producing physiological responses to both pharmaceutical and immunological stimuli.

Oestrogens as modulators of neuronal signalosomes and brain lipid homeostasis related to protection against neurodegeneration

Oestrogens trigger several pathways at the plasma membrane that exert beneficial actions against neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. Part of these actions takes place in lipid rafts, which are membrane domains with a singular protein and lipid composition. These microdomains also represent a preferential site for signalling protein complexes, or signalosomes. A plausible hypothesis is that the dynamic interaction of signalosomes with different extracellular ligands may be at the basis of neuronal maintenance against different neuropathologies. Oestrogen receptors are localised in neuronal lipid rafts, taking part of macromolecular complexes together with a voltage-dependent anion channel (VDAC), and other molecules. Oestradiol binding to its receptor at this level enhances neuroprotection against amyloid-β degeneration through the activation of different signal transduction pathways, including VDAC gating modulation. Moreover, part of the stability and functionality of signalling platforms lays on the distribution of lipid hallmarks in these microstructures, which modulate membrane physicochemical properties, thus favouring molecular interactions. Interestingly, recent findings indicate a potential role of oestrogens in the preservation of neuronal membrane physiology related to lipid homeostasis. Thus, oestrogens and docosahexaenoic acid may act synergistically to stabilise brain lipid structure by regulating neuronal lipid biosynthetic pathways, suggesting that part of the neuroprotective effects elicited by oestrogens occur through mechanisms aimed at preserving lipid homeostasis. Overall, oestrogen mechanisms of neuroprotection may occur not only by its interaction with neuronal protein targets through nongenomic and genomic mechanisms, but also through its participation in membrane architecture stabilisation via 'lipostatic' mechanisms.

1,25-Dihydroxyvitamin D3 protects HL60 cells against apoptosis but down-regulates the expression of the bcl-2 gene

Exposure of myeloid leukemia cells to analogs of vitamin D results in monocytic-like maturation of several variants of these cells. We report here that brief treatment of HL60 cells with differentiation-inducing concentrations of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) makes these cells resistant to cell death by apoptosis. Resistance was studied by using the calcium inophore A23187 and the cancer chemotherapeutic drugs 1-beta-D-arabinocytosine and etoposide. Apoptosis was detected by the characteristic morphology under light microscopic examination, presence of DNA "ladders" on agarose gel electrophoresis, DNA fragmentation by filter elution assay, and the "apoptotic index" obtained by comparison of damage to mitochondrial and nuclear genes on Southern blots. The protective effect of 1,25(OH)2D3 treatment was apparent before the phenotypic evidence of differentiation and before altered traverse of the cell cycle could be detected. Northern and Western blot analysis showed that the expression of bcl-2 proto-oncogene was rapidly reduced by 1,25(OH)2D3, which excludes the involvement of this gene in the protective effect. The rapidity of the protective effect of 1,25(OH)2D3 is consistent with the hypothesis that the activation of the monocytic differentiation program is sufficient to interfere with programs that lead to cell death by apoptosis.