Defining ferritin clinical decision limits to improve diagnosis and treatment of iron deficiency: A modified Delphi study.

BACKGROUND: Iron deficiency is highly prevalent worldwide and is an issue of health inequity. Despite its high prevalence, uncertainty on the clinical applicability and evidence-base of iron-related lab test cut-offs remains. In particular, current ferritin decision limits for the diagnosis of iron deficiency may not be clinically appropriate nor scientifically grounded. METHODS: A modified Delphi study was conducted with various clinical experts who manage iron deficiency across Canada. Statements about ferritin decision limits were generated by a steering committee, then distributed to the expert panel to vote on agreement with the aim of achieving consensus and acquiring feedback on the presented statements. Consensus was reached after two rounds, which was defined as 70% of experts rating their agreement for a statement as 5 or higher on a Likert scale from 1 to 7. RESULTS: Twenty-six clinical experts across 10 different specialties took part in the study. Consensus was achieved on 28 ferritin decision limit statements in various populations (including patients with multiple comorbid conditions, pediatric patients, and pregnant patients). For example, there was consensus that a ferritin <30 µg/L rules in iron deficiency in all adult patients (age ≥ 18 years) and warrants iron replacement therapy. CONCLUSION: Consensus statements generated through this study corresponded with current evidence-based literature and guidelines. These statements provide clarity to facilitate clinical decisions around the appropriate detection and management of iron deficiency.

Coagulation test understanding and ordering by medical trainees: Novel teaching approach.

Background: Coagulation testing provides a prime opportunity to make an impact on the reduction of unnecessary laboratory test ordering, as there are clear indications for testing. Despite the prothrombin time/international normalized ratio and activated partial thromboplastin time being validated for specific clinical indications, they are frequently ordered as screening tests and often ordered together, suggesting a gap in understanding of coagulation. Methods: Based on a needs assessment, we developed an online educational module on coagulation for trainees, incorporating education on testing cost, specificity, and sensitivity. Fifty participating resident physicians and medical students completed a validated premodule quiz, postmodule quiz after completion of the module, and a latent quiz 3 to 6 months after to assess longer-term knowledge retention. Trainees provided responses regarding their subjective laboratory test-ordering practices before and after module completion. Results: The median premodule quiz score was 67% (n = 50; range, 24%-86%) with an increase of 24% to a median postmodule quiz score of 91% (n = 50; range, 64%-100%). There was evidence of sustained knowledge acquisition with a latent quiz median score of 89% (n = 40; range, 67%-100%). Trainees were more likely to consider the sensitivity, specificity, and cost of laboratory investigations before ordering them following completion of the educational module. Conclusions: Using the expertise of medical educators and incorporating trainee feedback, we employed a novel approach to the teaching of coagulation to maximize its approachability and clinical relevance. We found sustained knowledge retention regarding coagulation and appropriate coagulation test ordering, and a subjective change to trainee ordering habits following participation in our educational intervention.

Desmopressin responsiveness by age in type 1 von Willebrand disease.

BACKGROUND: Patients with type 1 von Willebrand disease (VWD) undergo a desmopressin (DDAVP) responsiveness challenge at diagnosis to assess whether DDAVP reverses their coagulation deficits. Current practice assumes DDAVP responsiveness remains constant over the lifetime. In patients with type 1 VWD, VWF-related parameters increase with age. This study explores whether DDAVP responsiveness also differs with age in this population. METHODS: We conducted a retrospective chart review of 106 patients enrolled at our center since 1990. Our primary outcome was DDAVP responsiveness at 1 hour after DDAVP challenge. Locally weighted scatterplot smoothing fit and Spearman correlation coefficients were used to study the relationship between age and DDAVP responsiveness. For female participants, we used the Kruskal-Wallis test to compare absolute and relative changes in DDAVP responsiveness at various ages. RESULTS: We had 79 patients (56 female) with type 1 VWD with at least 1 DDAVP challenge. In women with type 1 VWD, the absolute change in DDAVP responsiveness did not vary significantly with age (VWF:antigen [Ag], -0.08, P = .56; VWF:ristocetin cofactor [RCo], -0.16, P = .26; low-molecular-weight component of factor VIII [FVIII:C], -0.01, P = .93), nor did the relative change in DDAVP responsiveness (VWF:Ag, -0.03, P = .86; VWF:RCo, -0.25, P = .09; FVIII:C, -0.14, P = .34). The data plot suggested a relationship. CONCLUSION: In women with type 1 VWD, DDAVP responsiveness may vary over the life cycle. Our exploratory findings are limited by our retrospective data, cross-sectional design, and small sample. Future studies should investigate the relationship between age and DDAVP responsiveness prospectively to evaluate whether there is clinical utility in rechallenging postpubertal female patients with type 1 VWD.

Value of routine echocardiography in the management of stroke.

BACKGROUND: Transthoracic echocardiography is routinely performed in patients with stroke or transient ischemic attack (TIA) to help plan secondary stroke management, but recent data evaluating its usefulness in this context are lacking. We sought to evaluate the value of echocardiography for identifying clinically actionable findings for secondary stroke prevention. METHODS: We conducted a multicentre cohort study of patients admitted to hospital with stroke or TIA between 2010 and 2015 at 2 academic hospitals in Toronto, Ontario, Canada. Clinically actionable echocardiographic findings for secondary stroke prevention included cardiac thrombus, patent foramen ovale, atrial myxoma or valvular vegetation. We identified patient characteristics associated with clinically actionable findings using logistic regression. RESULTS: Of the 1862 patients with stroke or TIA we identified, 1272 (68%) had at least 1 echocardiogram. Nearly all echocardiograms were transthoracic; 1097 (86%) were normal, 1 (0.08%) had an atrial myxoma, 2 (0.2%) had a valvular vegetation, 11 (0.9%) had a cardiac thrombus and 66 (5.2%) had a PFO. Patent foramen ovale was less likely among patients older than 60 years (adjusted odds ratio [OR] 0.34, 95% confidence interval [CI] 0.20-0.57), with prior stroke or TIA (adjusted OR 0.31, 95% CI 0.09-0.76) or with dyslipidemia (adjusted OR 0.39, 95% CI 0.15-0.84). Among the 130 patients with cryptogenic stroke who had an echocardiogram (n = 110), a PFO was detected in 19 (17%) on transthoracic echocardiogram. INTERPRETATION: Most patients with stroke or TIA had a normal echocardiogram, with few having clinically actionable findings for secondary stroke prevention. Clinically actionable findings, specifically PFO, were more common in patients with cryptogenic stroke.

REDucing Unnecessary Coagulation Testing in the Emergency Department (REDUCED).

The PT/INR (prothrombin time/international normalized ratio) and aPTT (activated partial thromboplastin time) were tests developed in the early 20th century for specific and unique indications. Despite this, they are often ordered together routinely. The objective of this study was to determine if a multimodal intervention could reduce PT/INR and aPTT testing in the emergency department (ED). This was a prospective multi-pronged quality improvement study at St. Michael's Hospital. The initiative involved stakeholder engagement, uncoupling of PT/INR and aPTT testing, teaching, and most importantly a revision to the ED order panels. After changes to order panels, weekly rates of PT/INR and aPTT testing per 100 ED patients decreased (17.2 vs 38.4, rate ratio=0.45 (95% CI 0.43-0.47), p<0.001; 16.6 vs 37.8, rate ratio=0.44 (95% CI 0.42-0.46), p<0.001, respectively). Rate of creatinine testing per 100 ED patients, our internal control, increased during the same period (54.0 vs 49.7, rate ratio=1.09 (95% CI 1.06-1.12); p<0.0001) while the weekly rate per 100 ED patients receiving blood transfusions slightly decreased (0.5 vs 0.7, rate ratio=0.66 (95% CI 0.49-0.87), p=0.0034). We found that a simple process change to order panels was associated with meaningful reductions in coagulation testing without obvious adverse effects.

Virologic suppression and mortality of patients who migrate for HIV care in the province of British Columbia, Canada, from 2003 to 2012: a retrospective cohort study.

BACKGROUND: Migration among persons living with HIV (PLWH) seeking HIV care is common; however its effect on health outcomes in resource-rich settings is not well understood. We conducted a retrospective cohort study to quantify the extent to which PLWH are migrating for care within British Columbia (BC) and its association with virologic suppression and mortality. METHODS: Eligible PLWH first initiated treatment in BC between 2003 and 2012 (N = 3653). Analyses were performed at the regional Health Authority (HA) level (N = 5). For privacy reasons, we kept the name of these HAs anonymous and we re-named these five regions as 1 to 5. PLWH were classified according to the HA where they resided and received HIV care. We calculated all-cause mortality rates, life expectancies (at age of 20 years), and in, out and net migration rates across HAs using different demographic methods. Virologic suppression (<50 copies/mL) was based on the last viral load available for each PLWH. We also calculated per-capita rates (per 100 PLWH ever on cART) for each HA by dividing the number of PLWH by the number of physicians attending this population. RESULTS: There is considerable heterogeneity in physician availability across all HAs, with per-capita rates (per 100 PLWH ever on cART) ranging from 2.2 (HA 1) to 12.7 (HA 3) based on the HA PLWH received care. We observed that in HAs 1, 4, and 5, between 4 and 10% of PLWH migrated to HA 3 (i.e. the largest urban center) to receive care, and for HA 2 this proportion increased to 21%. In HA 3, 77% of its PLWH residents remained in the same HA for their care. Migrating to a larger center for HIV care was not associated with higher rates of viral load suppression; it was significantly associated with lower mortality rates and higher life expectancies. CONCLUSIONS: A thorough understanding of the reason(s) for these significant migration rates across BC will be critical to inform resource allocation and optimize the impact of HIV treatment.

Reaction of silylene with sulfur dioxide: some gas-phase kinetic and theoretical studies.

Time-resolved kinetic studies of the reaction of silylene, SiH2, with SO2 have been carried out in the gas phase over the temperature range 297-609 K, using laser flash photolysis to generate and monitor SiH2. The second order rate coefficients at 1.3 kPa (SF6 bath gas) fitted the Arrhenius equation: log(k/cm(3) molecule(-1) s(-1)) = (-10.10 ± 0.06) + (3.46 ± 0.45 kJ mol(-1))/RT ln 10 where the uncertainties are single standard deviations. The collisional efficiency is 71% at 298 K, and in kinetic terms the reaction most resembles those of SiH2 with CH3CHO and (CH3)2CO. Quantum chemical calculations at the G3 level suggest a mechanism occurring via addition of SiH2 to one of the S=O double bonds leading to formation of the three-membered ring, thione-siloxirane which has a low energy barrier to ring expansion to yield the four-membered ring, 3-thia-2,4-dioxasiletane, the lowest energy adduct found on the potential energy (PE) surface. RRKM calculations, however, show that, if formed, this molecule would only be partially stabilised under the reaction conditions and the rate coefficients would be pressure dependent, in contrast with experimental findings. The G3 calculations reveal the complexity of possible intermediates and end products and taken together with the RRKM calculations indicate the most likely end products to be H2SiO + SO ((3)Σ(-)). The reaction is compared and contrasted with that of SiH2 + CO2.

Responsible innovation: a pilot study with the U.K. Engineering and Physical Sciences Research Council.

Significant time lags between the development of novel innovations (e.g., nanotechnologies), understanding of their wider impacts, and subsequent governance (e.g., regulation) have led to repeated calls for more anticipatory and adaptive approaches that promote the responsible emergence of new technologies in democratic societies. A key challenge is implementation in a pragmatic way. Results are presented of a study with the Engineering and Physical Sciences Research Council, the largest public funder of basic innovation research in the United Kingdom who, for the first time, asked applicants to submit a risk register identifying the wider potential impacts and associated risks (environment, health, societal, and ethical) of their proposed research. This focused on nanoscience for carbon capture and utilization. Risk registers were completed conservatively, with most identified impacts concerning researchers' health associated with nanoparticle synthesis, handling, and prototype device fabrication, i.e., risks that could be identified and managed with a reasonable level of certainty. Few wider environmental impacts and no future impacts on society were identified, reflecting the often uncertain and unpredictable nature of innovation. However, some applicants addressed this by including investigators with expertise beyond engineering and nanosciences supporting integrated activities that included life cycle and real-time technology assessment, which in some cases were also framed by stakeholder and/or public engagement. Proposals underpinned by a strong commitment to responsible science and innovation promoted continuous reflexivity, embedding a suite of multidisciplinary approaches around the innovation research core to support decisions modulating the trajectory of their innovation research in real-time.

Infrared matrix isolation study of the oxidation of H2S by CrCl2O2.

The thermal and photochemical reactions between CrO2Cl2 and H2S have been investigated using matrix isolation infrared spectroscopy. Twin-jet co-deposition of the two reagents into argon matrices at 14 K followed by irradiation with light of lambda > 300 nm led to the growth of a number of new bands. These have been assigned to the HSOH-CrCl2O complex, and to SO2. These assignments were supported by deuterium isotopic substitution and high level density functional calculations. Merged-jet deposition with the reaction zone at temperatures above 125 degrees C led to substantial yields of SO2 and HCl, as well as the complex of HCl with excess parent H2S. The evidence suggests that the thermal and photochemical reactions may follow different pathways.

Matrix isolation study of the reactions of CrO2Cl2 with a series of silanes.

The reactions between CrO2Cl2 and a series of silanes have been investigated using matrix isolation infrared spectroscopy. Twin-jet codeposition of the two reagents into argon matrices at 14 K followed by irradiation with light of lambda > 300 nm led to the growth of a number of new bands. These have been assigned to the appropriate silanol species formed by oxygen insertion into the Si-H bond, strongly complexed to CrCl2O. The structures and vibrational frequencies of these complexes have been characterized by high-level theoretical calculations. These calculations also support the relative preference for the insertion reaction compared to other possible pathways. Merged-jet codeposition of SiH2Cl2 with CrO2Cl2 at 200 degrees C also led to the formation of the free silanol, HSiCl2OH.

Experimental and theoretical evidence for homogeneous catalysis in the gas-phase reaction of SiH(2) with H(2)O (and D(2)O): a combined kinetic and quantum chemical study.

Time-resolved kinetic studies of the reaction of silylene, SiH(2), with H(2)O and with D(2)O have been carried out in the gas phase at 297 K and at 345 K, using laser flash photolysis to generate and monitor SiH(2). The reaction was studied independently as a function of H(2)O (or D(2)O) and SF(6) (bath gas) pressures. At a fixed pressure of SF(6) (5 Torr), [SiH(2)] decay constants, k(obs), showed a quadratic dependence on [H(2)O] or [D(2)O]. At a fixed pressure of H(2)O or D(2)O, k(obs) values were strongly dependent on [SF(6)]. The combined rate expression is consistent with a mechanism involving the reversible formation of a vibrationally excited zwitterionic donor-acceptor complex, H(2)Si...OH(2) (or H(2)Si...OD(2)). This complex can then either be stabilized by SF(6) or it reacts with a further molecule of H(2)O (or D(2)O) in the rate-determining step. Isotope effects are in the range 1.0-1.5 and are broadly consistent with this mechanism. The mechanism is further supported by RRKM theory, which shows the association reaction to be close to its third-order region of pressure (SF(6)) dependence. Ab initio quantum calculations, carried out at the G3 level, support the existence of a hydrated zwitterion H(2)Si...(OH(2))(2), which can rearrange to hydrated silanol, with an energy barrier below the reaction energy threshold. This is the first example of a gas-phase-catalyzed silylene reaction.