1,721,435 research outputs found
Li yong lin chuang shen he ji hua jia qiang Xianggang de lin chuang guan zhi
No full textPh.D.Clinical audits aim at creating a sustainable quality improvement process, and that is achieved by continuous systematic patient outcome data tracking with consistent follow-up criteria. Previous clinical audit studies focused mainly on its application in intervention effectiveness measurement and analysis of hospital service quality. The compliance on risk preventive model formulation could also be found in some studies. Recent researches on quality improvement largely relied on data collected by the National Surgical Quality Improvement Program (ACS-NSQIP) of the American College of Surgeons. This United States-based clinical record platform that is highly acknowledged on improving patient outcome at the affiliated hospitals. Alongside the rising trend of utilising clinical audit projects in clinical governance enhancement, there is a growing importance of optimising audit programme design, application, and customisation. However, whether it is beneficial to conduct a regional-wide or a department-focused clinical audit in terms of improving surgical outcome quality is unknown. In this thesis, we examine the use of regional and departmental audit programmes – Surgical Outcomes Monitoring and Improvement Programme (SOMIP) and Post-operative Complication Monitoring Programme (PPCMP). Studying these the local programmes would reinforce our knowledge on the benefit of clinical audit programme implementation in Hong Kong. We utilise clinical audit to investigate clinical intervention efficiency and administrative phenomenon in Hong Kong. We also establish locally relevant recommendation on launching an in-house clinical audit programme.Methods and results1) Tackling surgical site infections with specific care bundle in elective hepatobiliary and pancreatic surgeryPost-operative surgical site infection (SSI) is associated with a prolonged hospital stay, and increased post-operative morbidity and mortality. A team-specific SSI care bundle was designed and implemented in the Hepato-biliary and Pancreatic (HBP) surgical team at the Department of Surgery of PWH in 2009. The bundle serves the purpose to reduce SSI in elective surgery. We evaluated the efficiency of SSI care bundle with the SOMIP clinical audit data.1,319 cases were captured in the 6 years period and there were 139 (10.5%) SSI incidence observed. Pre- and post-intervention analysis was performed with the χ² test, it suggested that surgical site infection (SSI) rate significantly dropped (21.7% vs. 8.7%, OR=0.346, 95% C.I.=0.190–0.629; p<0.001). No significant difference on SSI in the subsequent years could be observed and the rates of SSI had maintained between 7.3% and 9.3% The data confirmed a positive impact of SSI care bundle on the reduction of post-operative SSI, and such positive impact remained sustainable in subsequent years when the care bundle is applied in long-term. (Further described in Chapter III)2) The “weekend effect” in emergency general and specialty surgeryIt is believed the weekend service quality may be relatively inferior as a result of the lack of senior surgeons, less available facilities and longer waiting time. The observation of a higher mortality rate among patients admitted over the weekend compared to the weekday is known as the “weekend effect”. The effect would be different according to operative magnitudes, surgical types and the size of surgical units. This study aimed to close our knowledge gap on the presence of “weekend effect” in emergency surgery services from 2010 to 2014 at the PWH Department of Surgery. Individual analysis was conducted respectively for general surgery and specialty surgery.1,860 patients underwent emergent surgeries in the 4-year study period. 1,398 (75.2%) patients’ operations were performed on the weekdays. The overall post-operative 30-day mortality was 115 (6.2%) and 654 (35.2%) for morbidity. We then found there is a significant different between weekday and weekend mortality (p=0.033). Multivariant analysis was performed and suggested the day of operation (weekday/ weekend) was an independent variable for post-operative mortality. We found that weekends had lower mortality than the weekdays (OR=0.538, 95% C.I.=0.315–0.919; p=0.023). Analysis was further separated into general and specialty surgeries. There was a significant difference between weekday and weekend mortality in general surgery. Day of week was an independent variable for mortality and weekends had lower mortality than the weekdays (OR=0.516, 95% C.I.=0.298–0.893; p=0.018). No significant difference could be observed between weekends and weekdays for morbidity in general surgeries, and morbidity and mortality in specialty surgeries. These results suggested emergency surgery services in the Department of Surgery of PWH were not affected by the “weekend effect” (i.e. mortality increases after operations conducted over the weekends). (Further described in Chapter IV)3) Exploring the effect of hospital volume on outcome of elective major hepatectomy in Hong KongSurgical techniques require years of training and practice and it is considered a crucial determinant in surgical outcomes. It is believed that a higher volume hospital provides more practice experience to surgeons than the lower volume hospitals, thus better surgical service is expected. Currently, it is an unknown in the relationship between hospital-volume and surgical outcome in Hong Kong. We focused on studying the volume-outcome relationship of elective major hepatectomy because the operation is technically demanding and variation of hospital-volume in different departments. Hospital volume categories (high-volume hospital and low-volume hospital – HVH and LVH) were defined by the volume threshold that shows a significant difference in post-operative 30-day mortality. The primary endpoints were 30-day morbidity, intra-operative blood loss, and length of in-hospital stay. We also investigated if service networking provided by the HVHs to LVHs would be beneficial to the surgical performance of the LVHs.Over the 7-year study period (June 2009 – July 2016), 2,389 patients were captured by the SOMIP and the overall post-operative 30-day mortality rate was 2.1% (51 patients). A total of 81 annual hospital-volume entries was included and the median annual hospital-volume of elective major hepatectomy was 18 (range from 1 to 170). The relationship between hospital-volume and 30-day mortality was plotted by scattered-plot and tested with χ² test, and the cutoff volume was 40 major hepatectomy cases per year (OR=2.23, 95% C.I.=1.25–3.98; p=0.005). By using this cut-off volume, high-volume hospitals had consistent mortality rates below 4%. We observed a significant difference in 30-day morbidity rate (p<0.001) and length of hospital stay (p=0.027) but no significant difference for intra-operative blood loss between the high-volume and low-volume hospitals. This means receiving elective major hepatectomy from the HVHs would give better surgical outcomes (morbidity and length of stay) than the LVHs. In addition to this, we also found there was a significant difference on the annual 30- day mortality in the service networking supported LVHs to the LVHs without this support (0% vs. 34.5%; p=0.049). (Further elaborated in Chapter V)4) Predicting risk of post-operative pneumonia after elective operations with Post-operative Pneumonia Risk Indication Score in Elective Surgery (PRISES)Post-operative pneumonia (POP) is one of the major morbidities causing an increased length of in-hospital stay and higher operative mortality. Developing a POP risk score with the risk factors for POP is beneficial to healthcare providers with easier high-risk group identification. There were some POP risk scores developed in different places but the accuracy for application in Hong Kong is questionable. This study utilised the local clinical audit data to develop an institutional POP risk score for elective surgeries – PRISES. This risk calculator was formulated and verified with different sets of internal clinical audit programme data for POP prediction accuracy.The retrospective cohort study included 5,433 elective patients aged from 18 to 100 years. 22 risk factors referenced from the SOMIP analysis were tested using multivariate logistic regression in our study. There were 10 variables found significantly related to POP and included in the PRISES (gender, American Society of Anaesthesiologist (ASA), surgical teams, pulse in surgery, surgical magnitude, operating time, steroid use, functional health dependency, presence of dyspnoea, and potassium range). The Hosmer-Lemeshow test showed that this model fit the samples (p=0.878) and the Area Under the curve of the Receiver Operating Characteristic (AUROC) showed a good fit (p=0.819, 95% C.I.= 0.782–0.856). PRISES consists of 5 cut-off points for the likelihood of POP development. PRISES was verified with another set of cohort data and the model fit (Hosmer-Lemeshow test, p=0.360, AUROC p=0.901, 95% C.I.=0.852–0.950). These results suggested individual patient could use PRISES to predict the probability of developing POP after elective operations. (Further elaborated in Chapter VI)5) Improving surgical quality in a surgical department with close to real-time monitoring system – the Post-procedure Complication Monitoring Programme (PPCMP)The surgeon-led PPCMP keeps track of the patients’ post-operative outcomes. This inhouse surgical audit programme was officially launched in 2010, aimed at cultivating higher accountability of surgeons to the operative outcomes and better quality of surgeries. The platform enables prompt responses from surgeons and department management to unanticipated events and regular service quality assurance. This study describes the setup of the PPCMP and the improvement of operative outcomes after introducing the programme to the Department of Surgery at the PWH.PCMP captured 39,104 patients in total and 43,273 procedure records were conducted during the 7-year-period (2010 – 2016). The 30-day morbidity and 30-day mortality decreased significantly after the first year of PPCMP implementation in 2010 (OR=0.626, p<0.001; OR=0.750, p=0.05), and plateaued in subsequent years. Decreased 30-day morbidity and mortality could be observed in all surgical teams, surgical types and surgical magnitudes. These results suggested the introduction of PPCMP could contribute to the improvement of surgical quality through ongoing patient outcome monitoring mechanisms and educational-based reviewing component. (Further described in Chapter VII)6) Accuracy of Post-procedure Complication Monitoring Programme (PPCMP) on capturing surgical outcomeRecord accuracy in clinical audit project is crucial for judgment making and broadening of its applications. Following the previous study on PPCMP setup and implementation, this study validates the accuracy of PPCMP surgical outcome records by comparing with the SOMIP standard. The hypotheses the accuracy on operative outcome archive of the PPCMP was high. This would strengthen the creditability of adopting the PPCMP audit data for various quality improvement strategies. Record concordance was defined by if the presence or absence of post-operative complication on the particular patient, was listed the same in both PPCMP and SOMIP systems. We conducted logistic regression analysis for the trend of record concordance on post-operative 30-day mortality and morbidity. We also study the characteristics of the discrepant records.A total of 9,416 patients was captured in the SOMIP (reference records) programme in the 4-year study period, and PPCMP captured 9,410 (99.9%) of them. The overall concordance rate of post-operative morbidity was 84.0% and 99.7% for 30-day mortality. In-depth studies found the discrepancy dropped from 2010 to 2011 for both morbidity (p<0.01) and mortality (p<0.05) records, and showed no significant difference in the subsequent years (2011–2014). Sub-group analysis was performed on the accuracy of capturing 30-day morbidity record characteristics. Discrepant records in morbidity were significantly higher in patients of the Colorectal surgery (OR=1.197, p<0.05) and significantly lower in Paediatric Surgery and Paediatric Urology (OR=0.579, p<0.001). In surgical types, the 30-day morbidity discrepant rate in elective operations is lower than emergency operations (OR=0.601, p<0.001). In surgical magnitude, major operations matched better with the SOMIP gold standard than the ultra-major operations (OR=0.710, p<0.001). As the overall discrepancy was low, we conclude that PPCMP recorded patient outcomes in a precise and up-to-standard manner, and is fit to be utilised for future retrospective studies. (Further elaborated in Chapter VIII)ConclusionClinical audit data has proven to be useful in multiple aspects that include retrospective studies, formulate risk prevention model and monitoring the quality of surgical care. We explored with a series of studies using clinical audit. Our results suggested a customised SSI care bundle was an effective tool to lower surgical site infection in elective HBP surgery. Followed by that, our findings discovered service quality of emergent surgeries performed over the weekends is no different from the weekdays. By using clinical audit data, we also found HA hospitals that have a higher volume of elective major hepatectomy is associated with lower 30-day post-operative morbidity and shorter length of hospital stay. This represented an effective use of clinical audit data on health services planning in different hospitals within the same public healthcare system. Then we explored the use of audit programme data to formulate a POP risk model for elective surgery (PRISES). The risk score demonstrated a good POP prediction fit in our setting. Next, we studied on the surgical outcome audit programme that is instituted in our department – PPCMP. Our researches suggested that even with the support of a regional clinical audit project – SOMIP, introducing an in-house audit programme offers multiple benefits. PPCMP supplemented with a direct enhancement of clinical service improvement climate in a surgical department, it enabled prompt responses to adverse clinical phenomena. We concluded that audit programmes, such as PPCMP and SOMIP, facilitate long-term monitoring of surgical quality. Continuous commitment in carrying out clinical audit programmes offers sustainable and efficient surgical quality assurance; strengthen clinical governance in Hong Kong.臨床審核是英國國民保健署(NHS) 管治臨床工作的關鍵部分之一。它是透過分析系統、團隊或組織的表現，將提供優質的住院管理服務。現時臨床審核被多地的醫療機關視為提高醫療質量的重要工具，它的應用亦日趨增加。在香港，香港醫院管理局(醫管局)於2008 起引進了《于衛成效監察計劃》 (SOMIP) ，通過提供年度臨床審核分析數據及質量改進建議，支持並提升公立醫院的外科服務質寰。次年，沙田威爾斯親王醫院(PWH) 的中文大學醫學外科部亦成立了該部門的臨床審核一《手術後併發症監測計劃》 (PPCMP) 。目標以更便於前線外科醫護人員的臨床審核小組加強外部門臨床管治。由於臨床審核所帶動的效益並不顯注，所以不少醫療服務提供者忽視了臨床審核的重要性。這種尚未有清晰了解的互動關係成為了一個研究領域。因此這論文將香港臨床審核進行全面研究，並為在香港實施有系統的臨床審核計劃提供應用和效益層面的參考作用。本論文將對現存於香港的兩個臨床審核計劃- SOMIP 及PPCMP，進行研究。研究分開為三個主體。第一，研究臨床審核所收集的數據，並對預防併發痕針對性工具進行強率分析，同時亦了解並發症和死亡率的出現模式。第三，使用臨床審核計劃數據制定手術後出現併發症的風險評分血統。第三亦是在最後，對香港中文大學外科部的臨床審核一PPCMP 進行深入研究，展示了這個個別部門外科屬隊採用的部門式的臨床審核計劃當中所以應用的結構、工作編制和接勤安排。同時亦針對審核計劃引進以後所帶動的于術表現數據變化進行了解。然後，亦針對研究這個部門式的臨床審核計劃在記銬子術數據的準確性。這將加強PWH 外科臨床審核計劃反映準確數據的可信度，並為其他機構設實臨床審核計劃提供參考基準。本論文總結了臨床審核計劃對外科手術成效及質量改進的重要性。臨床審核計劃需要透過跨團樺的協同努力來維持及實蹺，它將提供多樣化的改進工具以確保香港在外科護理標準方面能夠發揮優質服務水平。Chan, Ho Man.Thesis Ph.D. Chinese University of Hong Kong 2019.Includes bibliographical references (leaves 157-173).Abstracts also in Chinese.Title from PDF title page (viewed on 18, May, 2021).Chan, Ho Man
Hierarchical Bayes based Adaptive Sparsity in Gaussian Mixture Model
No full textGaussian Mixture Model (GMM) has been widely used in statistics for its great flexibility. However, parameter estimation for GMM with high dimensionality is a challenge because of the large number of parameters and the lack of observation data. In this paper, we propose an effective method named hierarchical Bayes based Adaptive Sparsity in Gaussian Mixture Model (ASGMM) to estimate the parameters in a GMM by incorporating a two-layer hierarchical Bayes based adaptive sparsity prior. The prior we impose on the precision matrices can encourage sparsity and hence reduce the dimensionality of the parameters to be estimated. In contrast to the l(1)-norm penalty or Laplace prior, our approach does not involve any hyperparameters that must be tuned, and the sparsity adapts to the observation data. The proposed method is achieved by three steps: first, we formulate an adaptive hierarchical Bayes model of the precision matrices in the GMM with a Jeffrey's noninformative hyperprior, which expresses scale-invariance and, more importantly, is hyperparameter-free and unbiased. Second, we perform a Cholesky decomposition on the precision matrices to impose the positive definite property. Finally, we exploit the expectation maximization (EM) algorithm to obtain the final estimated parameters in the GMM. Experimental results on synthetic and real-world datasets demonstrate that ASGMM cannot only adapt the sparsity of high-dimensional data with small estimated error, but also achieve better clustering performance comparing with several classical methods. (C) 2014 Elsevier B.V. All rights reserved
Orthogonal enhanced linear discriminant analysis for face recognition
No full textFrom the intuition that natural face images lie on or near a low-dimensional submanifold, the authors propose a novel spectral graph based dimensionality reduction method, named orthogonal enhanced linear discriminant analysis (OELDA), for face recognition. OELDA is based on enhanced LDA (ELDA), which takes into account both the discriminative structure and geometrical structure of the face space, and generates non-orthogonal basis vectors. However, a significant fact is that eliminating the dependence of basis vectors can promote more effective recognition of unseen face images. For this purpose, the authors seek to improve the ELDA scheme by imposing orthogonal constraints on the basis vectors. Experimental results on real-world face datasets show that, benefitting from orthogonality, OELDA has more locality preserving power and discriminative power than LDA and ELDA, and achieves the highest recognition rates among compared methods
Neighbourhood sensitive preserving embedding for pattern classification
No full textRecently, a large family of supervised or unsupervised manifold learning algorithms that stem from statistical or geometrical theory has been designed to solve the problem of pattern classification. In this study, consider the fact that the data are usually sampled from a low-dimensional manifold space which resides in a high-dimensional Euclidean space, the authors propose a novel two-graph-based supervised linear classification algorithm called neighbourhood sensitive preserving embedding (NSPE). Different from local linear embedding (LLE) (or neighbourhood preserving embedding (NPE)) which preserves the local neighbourhood structure with one graph, NSPE can discover both the intrinsic and discriminant structure of the data manifold by constructing two graphs, that is, the within-class graph and the between-class graph. Thus, the data are mapped into a subspace where the nearby points with the same label are close to each other, whereas the nearby points with different labels are far apart. As a classification method, besides being defined on training samples, NSPE is also defined on testing samples. Experiments carried on the real-world face databases demonstrate that the results of all two-graph-based spectral methods are comparable and better than that of one-graph-based methods
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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