Rescaling quality of life values from discrete choice experiments for use as QALYs: a cautionary tale

Background  

Researchers are increasingly investigating the potential for ordinal tasks such as ranking and discrete choice experiments to estimate QALY health state values. However, the assumptions of random utility theory, which underpin the statistical models used to provide these estimates, have received insufficient attention. In particular, the assumptions made about the decisions between living states and the death state are not satisfied, at least for some people. Estimated values are likely to be incorrectly anchored with respect to death (zero) in such circumstances.     

Radiographic comparison of grit-blasted hydroxyaptite and arc-deposited hydroxyapatite acetabular components. A four-year follow-up study

High rates of aseptic loosening have been reported for microstructured hydroxyapatite-coated acetabular components. A macrostructured component surface (arc-deposition) not only improves resistance to shear forces experienced by the acetabular component and increases initial stability, but also provides channels for bone ingrowth. The purpose of this investigation was to radiographically compare a series of grit-blasted (microstructured) and arc-deposited (macrostructured) hydroxyapatite-coated acetabular components. A minimum 4-year retrospective radiographic analysis of acetabular components was performed on a total of 50 total hip arthroplasties. At 4 years, arc-deposited components were associated with fewer radiolucent lines in all Charnley zones, particularly Charnley zone III. While the 4-year results for arc-deposited hydroxyapatite acetabular components are superior to their microstructured predecessors, long-term results are still unknown.     

A biomechanical comparison of Schuhli nuts or cement augmented screws for plating of humeral fractures

Schuhli locking nuts can be used in poor quality cortical bone to enhance fixation stability as an alternative to cement augmented screws. This study compared the fixation strength and stability of plate constructs using Schuhli locking nuts with standard screws and cement augmented screws for fixation of simulated humeral shaft fractures in a test model with osteoporosis. The constructs were tested in axial compression, 4-point bending, and torsion to determine fixation stability. The humeri were cycled in torsion (4.5 Nm) for 1000 cycles to simulate upper extremity use during the early postoperative period and retested for stability. The Schuhli locking nuts and cement augmented screws had significantly greater fixation stability than the standard screws before (range, 6-14 times greater) and after cycling in torsional loading (range, 3-3.6 times greater). Although cement augmented screws and Schuhli augmentation showed increased fixation stability compared with the standard screws in axial and 4-point bending before cycling (range, 1.3-1.4 times greater), this was not significant. Compared with Schuhli fixation, cement augmented screws showed no significant difference in fixation stability in all loading modes before and after cycling. Schuhli locking nuts offer the stability of cement augmentation while avoiding its potential adverse effects on fracture healing with extravasation and thermal necrosis.     

A potential danger of bedclothes covering the face

Investigations of infants dying unexpectedly have reported up to 28% being found completely under bedding. No detailed physiological studies looking at the possibilities of asphyxia in this situation are available. The aim was to determine the potential for asphyxia under different types and thicknesses of bedding. A mechanical model of a 3-month-old infant's respiratory system was used. Bedding was positioned over the head in a supine position, and inspired carbon dioxide recorded. With a fixed respiratory rate and tidal volume, carbon dioxide accumulation increased with increasing layers of blankets. Up to 8.3% inspired carbon dioxide was recorded with more than four layers of blankets. A cotton sheet between the face and blankets reduced the accumulation by half. An infant found dead under bedding may have been exposed to an asphyxial stress. Suffocation from rebreathing trapped, expired gases can be a cause of death in this situation.     

四种中国产牙膏磨损性的评价

目的：观察4种中国产牙膏对人牙本质的磨损性。方法：将新鲜拔除的人健康恒牙包埋于环氧树脂块中，表面磨平。开一牙本质窗并在刷牙机上刷1000次，以Talysurf2表面测量仪测量牙本质磨损程度。结果：多数中国产牙膏具有较高的磨损性。结论：长期使用有潜在的导致牙齿磨损的可能性。     

A comparative study of oral health knowledge,attitude and behaviour of first and final year dental students of Udaipur city,Rajasthan, India

Abstract: Objective: To assess and compare differences in oral health knowledge, attitudes and behaviour among first and final year dental students in Udaipur city, Rajasthan, India. Materials and methods: In a cross‐sectional study, 182 first year students (59 males and 123 females) and 157 final year students (75 males and 82 females) of the two dental colleges in Udaipur city; Rajasthan, were surveyed using a self‐administered structured questionnaire including 37 multiple choice questions pretested through a pilot survey. The data was analysed using the spss version 10.0. The mean percentage scores, standard deviation and frequency distribution were calculated. The Student’s t‐test and anova test were used as test of significance. The linear regression analysis were used to assess the relation of knowledge, attitude and behaviour. Results: The mean % score for oral health knowledge, attitude and behaviour were significantly higher in final year students compared to first year students (P < 0.001). The linear regression analysis showed a statistically significant linear relationship of attitude with the knowledge (P < 0.001) and behaviour with the attitude (P < 0.001) of the students. Conclusion: Besides the positive changes revealed in the oral health knowledge, attitude and behaviour, among the students from first to final year of dental studies, preventive behaviour among the students could still be improved.     

Peripheral giant cell granuloma: a clinical study of 77 cases from 62 patients, and literature review

OBJECTIVES: The aim of this study was to identify the principle clinical features of the peripheral giant cell granuloma (PGCG), and to recognise clinical features of PGCG that are poorly defined.
DESIGN: We reviewed retrospectivety 77 cases of PGCG from 62 patients, from our files with respect to incidence, sex, patient age, race, clinical symptoms and signs, radio-graphic features and recurrence following excision.
RESULTS AND CONCLUSIONS: Our results were largety in agreement with previous reports, although there is wide variation in the results published between series. In addition, some clinical features of PGCG are poorly defined. Little is known about the retative incidences of PGCG and central giant cell granuloma. An association between PGCG and tooth loss may exist, but is poorly defined, and not all PGCG that involve edentulous areas follow recent tooth loss. Information about PGCG recurrence after excision is limited, and does not necessarily follow incomplete excision. Despite the large number of reported cases of PGCG, clarification of some clinical features is required, and may hetp formulation and interpretation of future laboratory-based research into this poorly understood lesion.     

牙本质陶瓷粉、非胶原蛋白及其复合材料对修复性牙本质形成作用的研究

目的：观察牙本质陶瓷粉（ceramic demtin powder,CDP)、CDP与非胶原蛋白（noncollagenous proteins,NCPs）复合材料（CDP／NCPs）对修复性牙本质形成的作用。方法：牙本质粉煅烧后与人牙本质NCPs复合，用SD大鼠牙作直接盖髓实验，并用组织学方法评价修复性牙本质形成的效果。结果：术后14d，CDP组：穿髓下方可见少许成牙本质细胞。CDP／NCPs组：穿髓孔周围见成纤维细胞增殖，呈团块状包绕穿髓孔。术后28d，CDP组：穿髓下方可见少量修复性牙本质团块形成。CDP／NCPs组：可见大量修复性牙本质形成。结论：CDP／NCPs能促进大鼠牙体、牙髓组织修复。     

Hip hemi-arthroplasty for neck of femur fracture: What is the current evidence?

This editorial reviews and summarises the current evidence(meta-analyses and Cochrane reviews) relating to the use of hip hemi-arthroplasty for neck of femur fractures. Regarding the optimal surgical approach,two recent meta-analyses have found that posterior approaches are associated with: higher rates of dislocation compared to lateral and anterior approaches; and higher rates of re-operation compared to lateral approaches. Posterior approaches should therefore be avoided when performing hip hemi-arthroplasty procedures. Assessing the optimal prosthesis head component,three recent meta-analyses and one Cochrane review have found that while unipolar hemiarthroplasty can be associated with increased rates of acetabular erosion at short-term follow-up(up to 1 year),there is no significant difference between the unipolar hemi-arthroplasty and bipolar hemi-arthroplasty for surgical outcome,complication profile,functional outcome and acetabular erosion rates at longer-term follow-up(2 to 4 years). With bipolar hemi-arthroplasty being the more expensive prosthesis,unipolar hemi-arthroplasty is the recommended option. With regards to the optimal femoral stem insertion technique,three recent metaanalyses and one Cochrane Review have found that,while cemented hip hemi-arthroplasties are associated with a longer operative time compared to uncemented Hip Hemi-arthroplasties,cemented prostheses have lower rates of implant-related complications(particularly peri-prosthetic femoral fracture) and improved postoperative outcome regarding residual thigh pain and mobility. With no significant difference found between the two techniques for medical complications and mortality,cemented hip hemi-arthroplasty would appear to be the superior technique. On the topic of wound closure,one recent meta-analysis has found that,while staples can result in a quicker closure time,there is no significant difference in post-operative infections rates or wound healing outcomes when comparing staples to sutures. Therefore,either suture or staple wound closure techniques appear equally appropriate for hip hemiarthroplasty procedures.     

The complete chloroplast genome of vulnerable <Emphasis Type="Italic">Aesculus wangii</Emphasis> (<Emphasis Type="Italic">Sapindaceae</Emphasis>), a narrowly endemic tree in Yunnan,China

In this study, we assembled the complete chloroplast (cp) genome of Aesculus wangii Hu (Sapindaceae), a rare and vulnerable deciduous tree native to Southeast Yunnan of China. The cp genome of A. wangii was 155,871 bp in length and contained a pair of inverted repeat (IR, 26,390 bp) regions, which were separated by the small single copy (SSC, 18,209 bp) and the large single copy (LSC, 84,882 bp) regions. The cp genome encoded 135 genes including 84 protein-coding genes, 40 tRNA genes, and eight rRNA ribosomal genes. The overall AT content of A. wangii cp genome is 62.0%. The maximum likelihood phylogenetic analysis revealed that A. wangii is sister to maples of tribe Acereae and the Acereae-Aesculus clade is sister to all other sampled Sapindaceae. The cp genome of A. wangii will be useful for future studies on the conservation, taxonomy, and phylogeny of the genus Aesculus.