1,720,998 research outputs found
Practice Patterns, Predictors of Use and Clinical Efficacy of Endoscopic Clips for Prevention of Delayed Post-polypectomy Bleeding
No full textColonoscopy reduces colorectal cancer through the removal of pre-cancerous polyps, which exposes patients to potential adverse events. Endoscopic clips are used by practitioners to prevent delayed post-polypectomy bleeding. This thesis reports the results of two studies performed with the aim of evaluating the practice patterns and clinical efficacy of prophylactic clipping during polypectomy. A meta-analysis of randomized trials showed that prophylactic clipping is not efficacious in preventing delayed bleeding during routine polypectomy, especially among polyps < 10 mm. A large retrospective cohort study then described clinical parameters associated with clip usage. We demonstrated that use of clips increased over time in a high-volume outpatient endoscopy unit. Furthermore, a high degree of variability in clipping patterns existed between endoscopists, including among polyps < 10 mm, where no efficacy exists. Taken together, these results reveal an urgent need for effective knowledge translation to eliminate this ineffective and costly practice during routine polypectomy
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
Biomarker-Guided Risk Prediction Models For The Presence Of High-Risk Polyps Among Screening-Eligible Populations In Alberta
No full textBackground: Colorectal cancer (CRC) remains a leading cause of cancer-related morbidity and mortality in Canada. Although population-based screening programs are in place, participation rates are suboptimal, and first-line tests such as the fecal immunochemical test (FIT) have limited sensitivity for detecting high-risk adenomas (HRAs), the primary precursors to most CRCs. Improved risk stratification tools are needed to identify individuals at greatest risk for HRAs and optimize screening efforts. Objectives: This thesis evaluated the utility of blood-based biomarkers and circulating microRNAs (miRNAs) in enhancing risk prediction models (RPMs) for HRAs among average-risk, screening-eligible individuals in Alberta. The objectives were to: (1) systematically review biomarker-informed RPMs for CRC or HRAs; (2) develop and validate models incorporating metabolic and tumor-associated serum biomarkers; and (3) assess the predictive performance of circulating miRNAs in individuals with a positive FIT. Methods: A systematic review identified studies that developed or validated biomarker-based RPMs at the time of colonoscopy. Two empirical studies were then conducted using clinical, demographic, and biospecimen data from participants at the Forzani & MacPhail Colon Cancer Screening Centre. The first study evaluated associations between glucose metabolism, liver function, and tumor markers with HRA risk, incorporating significant biomarkers into logistic regression-based RPMs. The second study used LASSO regression to develop a miRNA-based model among FIT-positive individuals. Model performance was assessed using AUC, bootstrap validation, calibration curves, and reclassification indices. Results: The review identified 16 studies, most of which lacked external validation or standardized reporting. In the biomarker study (n=980), glucose, c-peptide, triglycerides, and carcinoembryonic antigen (CEA) were significantly associated with HRA presence, yielding a modestly improved AUC of 0.66. In the miRNA study, eight LASSO-selected miRNAs produced a bootstrap-validated AUC of 0.80, demonstrating superior discrimination. Conclusion: Blood-based biomarkers and miRNAs can enhance RPMs for identifying HRAs. These findings support the integration of molecular markers into CRC screening programs to improve risk stratification, reduce unnecessary colonoscopies, and advance early detection. Further validation and implementation studies are needed to support clinical adoption
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
Development and internal validation of a risk prediction model for high-risk adenomas among average risk colorectal cancer screening participants
No full textBackground: High-risk adenomas (HRAs) are precursors to colorectal cancer (CRC), and removing them during colonoscopy can halt progression to CRC. The aim of this study was to develop a risk prediction model for HRAs detected at screening colonoscopy based on readily available patient information. Subsequently, we aimed to understand if biomarkers of glucose metabolism were associated with HRAs, with hopes incorporating them into a baseline risk prediction model to enhance its clinical utility. Methods: The cohort consisted of 3,035 individuals aged 50 to 74 years with no prior history of cancer who underwent a primary screening colonoscopy at a centralized colon cancer screening centre between 2008 and 2016. A multivariable logistic regression model was created using CRC risk factors identified from prior research. Model covariates were collected from a baseline questionnaire and included patient demographics (age and sex), lifestyle parameters (body mass index, alcohol, smoking, and vitamin D supplement use) and medical history (family history of CRC and diabetes). Model calibration was assessed using the c-statistic. Glucose, insulin, glycated hemoglobin A1c, and c-peptide were all measured were assessed using a case control study design from from a subset of the CCSC biorepository.conditional logistic regression was used to understand their associations with HRAs. Results: Mean participant age was 58.8 years, and 54.7% were male. A total of 249 participants with HRAs were identified (8.2%). An optimism adjusted c-statistic of 0.67 was calculated, and a specificity and negative predictive value of 97.0% and 92.4% for the detection of HRAs respectively, were achieved using 20% predicted probability as a high-risk threshold. However, a sensitivity of only 10.8% was achieved. Our model has moderate predictive ability, with strengths in being able to rule those with an absence of HRAs on screening colonoscopy. Finally, after adjustment, no meaningful associations were found between these four biomarkers of glucose metabolism and HRAs. Conclusion: Although these glucose metabolism biomarkers were not found to be associated with HRAs, the production of a simple risk prediction model can still provide benefit to the current screening programs in Alberta. Maximizing screening efficiency through improved risk prediction can enhance resource allocation. Ultimately, this model has the potential to improve patient care by reducing unnecessary colonoscopies, limiting this invasive procedure to those most likely to have significant findings
Safety and Effectiveness of Non-Steroidal Anti-Inflammatory Drugs used to Prevent Post-ERCP Pancreatitis in High-Risk Populations: An Observational Cohort Study
No full textEndoscopic retrograde cholangiopancreatography (ERCP) is a common procedure for managing disorders of the pancreatic and/or biliary system(s). Though effective, ERCP is complicated by post-ERCP pancreatitis (PEP) in 5-15% of cases. Administration of a single rectal dose of a non-steroidal anti-inflammatory drug (NSAID) at the time of ERCP reduces the risk of PEP by 30-50%. However, NSAIDs are known to have adverse effects on the kidneys after prolonged use and are often not recommended in patients 65 and older and those with chronic kidney disease (CKD). Little is currently known about the potential renal harms associated with single-dose NSAIDs in the setting of medical procedures such as ERCP. We report on relevant post-ERCP renal outcomes including acute kidney injury (AKI) and acute kidney disease (AKD) in at-risk patients who received single-dose peri-procedural NSAIDs compared to those who did not, assessing for effect modification and differences in the association stratified by higher-risk subgroups, namely (1) patients 65 years of age and older versus those less than 65 years of age (n = 5,885 and n = 5,310, respectively) and (2) patients with and without pre-existing CKD (n=757 and n=10,438, respectively). Multivariable logistic regression models were developed to adjust for clinically relevant patient- and procedure-related variables. In the analyzed cohort of 11,195 patients, there was no statistically significant association between NSAIDs and AKI (aOR 0.53 (0.22, 1.26)) or AKD (aOR 0.53 (0.25, 1.10)). There was no evidence of effect modification by age (p=0.83) or by CKD (p=0.72) in the model for AKI; likewise, there was no evidence of effect modification in the model for AKD (for either age, p=0.22, or CKD, p=0.49). In conclusion, single-dose NSAIDs around the time of ERCP were not associated with clinically relevant adverse changes in renal function in the overall population nor was there evidence of effect modification by age or CKD status, and as such there were no differences in these associations within high-risk subgroups. By demonstrating that there is no association between short term exposure to NSAIDs for ERCP and adverse renal events, we hope to inform clinical practice guidelines advising on their use
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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