Use of expert knowledge in evaluating costs and benefits of alternative service provisions: A case study

Objectives: A treatment pathway model was developed to examine the costs and benefits of the current bowel cancer service in England and to evaluate potential alternatives in service provision. To use the pathway model, various parameters and probability distributions had to be specified. They could not all be determined from empirical evidence and, instead, expert opinion was elicited in the form of statistical quantities that gave the required information. The purpose of this study is to describe the procedures used to quantify expert opinion and note examples of good practice contained in the case study. Methods: The required information was identified and preparatory discussion with four experts refined the questions they would be asked. In individual elicitation sessions they quantified their opinions, mainly in the form of point and interval estimates for specified variables. New methods have been developed for quantifying expert opinion and these were implemented in specialized software that uses interactive graphics. This software was used to elicit opinion about quantities related to measurable covariates. Results: Assessments for thirty-four quantities were elicited and available checks supported their validity. Eight points of good practice in eliciting and using expert judgment were evident. Parameters and probability distributions needed for the pathway model were determined from the elicited assessments. Simulation results from the pathway model were used to inform policy on bowel cancer service provision. Conclusions: The study illustrates that quantifying and using expert judgment can be acceptable in real problems of practical importance. For full benefit to be gained from expert knowledge, elicitation must be conducted carefully and should be reported in detail

Efficacy of property marking as a situational crime prevention strategy

Burglary and stealing are crimes that have a significant impact and cost on its victims and society. To mitigate such crimes, property marking is a situational crime prevention strategy that attempts to prevent through dissuasion. There are many forms of property marking, yet there is limited research of its efficacy. Where there have been such studies, there has been some indications of success. Therefore, the study assessed the efficacy of property marking to reduce burglary and stealing crimes. The study undertook a quantitate approach using non-equivalent control groups to assess the geo-spatial impact of property marking when applied at a saturation level. Three housing groups were established (N878), comprising an experimental (n278), adjacent (n300) and control (n300) groups, with significance measured using a Wald Chi-square method. Results indicated that when property marking is applied at saturation levels (≥80%), both burglary and stealing crimes decreased significantly. Furthermore, that displacement for both burglary and stealing occurred in the adjacent area. Recommendations suggest that property marking should not be used in a sporadic manner; instead, targeted at an optimal saturation level. Such targeting should have the aim to target burglary and stealing hotspots and saturate these areas for property marking to work effectively

2-De­oxy-2,3-O-isopropyl­idene-2,4-di-C-methyl-β-l-arabinose

X-ray crystallography unequivocally confirmed the stereochemistry of the C atom at position 2 in the carbon scaffold of the title mol­ecule, C10H18O4. The pyran­ose ring exists in a chair conformation with the methyl group on the C atom in the 2 position in an equatorial configuration. The absolute stereochemistry was determined from the starting material. The crystal structure consists of O—H⋯O hydrogen-bonded chains of mol­ecules running parallel to the b axis

2,3-O-(S)-Benzyl­idene-2-C-methyl-d-ribono-1,4-lactone

The crystal structure of the title compound, C13H14O5, establishes (i) the (S) – rather than (R) – configuration at the acetal carbon and (ii) that both the acetal and the lactone form five- rather than six-membered rings; the absolute configuration is determined by the use of 2-C-methyl-d-ribono-1,4-lactone as the starting material. The compound consists of hydrogen-bonded chains of mol­ecules running along the a axis; there are no unusual packing features. Only classical hydrogen bonding has been considered

Randomised trial of glutamine, selenium, or both, to supplement parenteral nutrition for critically ill patients

Peer reviewedPublisher PD

(4R)-4-(2-Allyl-2H-1,2,3-triazol-4-yl)-1,2-O-isopropyl­idene-l-threose

X-ray crystallography unequivocally confirmed the structure of the title compound, C12H17N3O4, as (4R)-4-(2-allyl-2H-1,2,3-triazol-4-yl)-1,2-O-isopropyl­idene-l-threose. The absolute configuration was determined by the use of d-glucorono-3,6-lactone as the starting material. The crystal structure consists of hydrogen-bonded chains of mol­ecules running parallel to the a axis. There are no unusual packing features

tert-Butyl 2-de­oxy-4,5-O-isopropyl­idene-d-gluconate

The relative configuration of tert-butyl 2-de­oxy-4,5-O-iso­propyl­idene-d-gluconate, C13H24O6, an inter­mediate in the synthesis of 2-de­oxy sugars, was determined by X-ray crystallography, and the crystal structure consists of chains of O—H⋯O hydrogen-bonded mol­ecules running parallel to the a axis. There are two mol­ecules in the asymmetric unit. The absolute configuration was inferred from the use of d-erythrono­lactone as the starting material

2-O-Benzhydryl-3,4-(S)-O-benzyl­idene-d-xylono-1,4-lactone

X-ray crystallography unequivocally shows that protection of the free hydroxyl group of 3,5-O-benzyl­idene-d-xylono-1,4-lactone with diphenyl­diazo­methane proceeded smoothly to give the title compound, C25H22O5, with no accompanying epimerization. Unlike the analogously protected lyxono lactone, the isomeric xylono lactone has two mol­ecules present in the asymmetric unit (Z′ = 2). The 5-ring lactones adopt envelope conformations and the 6-ring ketals adopt chair conformations

Double reading in breast cancer screening : cohort evaluation in the CO-OPS trial

Purpose: To investigate the effect of double readings by a second radiologist on recall rates, cancer detection and characteristics of cancers detected in the National Health Service Breast Screening Program in England. Materials and Methods: In this retrospective analysis we evaluated 805,206 women through screening and diagnostic test results by extracting one year of routine data from 33 English breast screening centers. Centers used double reading of digital mammograms, with arbitration if there were discrepant reads. Information on reader decisions, with results of follow-up tests, were used to explore the effect of the second reader. The statistical tests used were the test for equality of proportions, the χ2 test for independence and the t-test. Results: The first reader recalled 4·76%, (38295/805206, 95% CI 4·71%-4·80%) of women. Two readers recalled 6·19% in total, (49857/805206, 95% CI 6·14%- 6·24%), but arbitration of discordant reads reduced recall rate to 4·08%, (32863/805206, 95% CI 4·04%-4·12%, p<0.001). 7055 cancers were detected of which 627 (8·89%, 95% CI 8·22%-9·55%, p<0.001) were detected by the second reader only. These additional cancers were more likely to be ductal carcinoma in situ, (30·5% (183/600) vs 22.0% (1344/6114), p<0.001); and additional invasive cancers were smaller (mean 14·2mm vs 16·7mm, p<0.001), had fewer involved nodes, and were likely to be lower grade. Conclusion: Double reading with arbitration reduces recall and increases cancer detection compared to single reading. Cancers detected only by the second reader were smaller, lower grade, and had less nodal involvement

(S)-3-Dimethyl­amino-2-{(4S,5R)-5-[(R)-2,2-dimethyl-1,3-dioxolan-4-yl]-2,2-dimethyl-1,3-dioxolan-4-yl}-2-hydroxy­propanoic acid

The Kiliani reaction on 1-de­oxy-(N,N-dimethyl­amino)-d-fructose, itself readily available from reaction of dimethyl­amine and d-glucose, proceeded to give access to the title β-sugar amino acid, C15H27NO7. X-ray crystallography determined the stereochemistry at the newly formed chiral center. There are two mol­ecules in the asymmetric unit; they are related by a pseudo-twofold rotation axis and have very similar geometries, differing only in the conformation of one of the acetonide rings. All the acetonide rings adopt envelope conformations; the flap atom is oxygen in three of the rings, but carbon in one of them. There are two strong hydrogen bonds between the two independent mol­ecules, and further weak hydrogen bonds link the mol­ecules to form infinite chains running parallel to the a axis