Generalized Species Sampling Priors with Latent Beta reinforcements

Many popular Bayesian nonparametric priors can be characterized in terms of exchangeable species sampling sequences. However, in some applications, exchangeability may not be appropriate. We introduce a {novel and probabilistically coherent family of non-exchangeable species sampling sequences characterized by a tractable predictive probability function with weights driven by a sequence of independent Beta random variables. We compare their theoretical clustering properties with those of the Dirichlet Process and the two parameters Poisson-Dirichlet process. The proposed construction provides a complete characterization of the joint process, differently from existing work. We then propose the use of such process as prior distribution in a hierarchical Bayes modeling framework, and we describe a Markov Chain Monte Carlo sampler for posterior inference. We evaluate the performance of the prior and the robustness of the resulting inference in a simulation study, providing a comparison with popular Dirichlet Processes mixtures and Hidden Markov Models. Finally, we develop an application to the detection of chromosomal aberrations in breast cancer by leveraging array CGH data.Comment: For correspondence purposes, Edoardo M. Airoldi's email is [email protected]; Federico Bassetti's email is [email protected]; Michele Guindani's email is [email protected] ; Fabrizo Leisen's email is [email protected]. To appear in the Journal of the American Statistical Associatio

Survey of doctors’ perception of professional values

Background New challenges in the medical field of the third millennium emphasise the "humanization of medicine" leading to a redefinition of doctors’ values, limits and roles. The study aims to assess whether there are different personality dimensions of physicians in relation to their perception of professional values and public expectations. Methods A questionnaire on the perception of professional values and the opinion on work in the medical field, work relationships and public expectations was administered to 374 doctors attending Continuing Medical Education courses. Results Two personality dimensions were identified: the first dimension (which we termed "Performance Attainment") is associated preeminently with values of competence, advocacy, confidentiality, spirit of enquiry, integrity, responsibility and commitment; the second dimension (which we called “Personal Involvement”) focuses on concern and compassion. The doctors that have more difficulty accepting judgements on their activity are those who think that “Performance attainment” is less important (β = 6.01; p-value = 0.007). Instead, the doctors who believe “public expectation of the health system” is not high enough, tend to think that “Performance Attainment” is more important (β = -6.08; p-value = 0.024). The less importance is given to the values of "Personal Involvement", the less is the doctor’s perception of having a leading role in respect to other health professionals (β = -2.37; p-value = 0.018). Conclusions Our results demonstrate that there are two different attitudes in terms of recognition and selection of the essential values to better practice the medical profession. Whether the doctors attach more importance to one dimension or the other, they do not differ in our analysis for how they answered the questions about relationships with patients, colleagues or family commitments in the questionnaire, even if they work in different areas. This suggests that in our research there is no single personal attitude that characterizes “a good doctor”

Effectiveness and costs of implementation strategies to reduce acid suppressive drug prescriptions: a systematic review

<p>Abstract</p> <p>Background</p> <p>Evaluation of evidence for the effectiveness of implementation strategies aimed at reducing prescriptions for the use of acid suppressive drugs (ASD).</p> <p>Methods</p> <p>A systematic review of intervention studies with a design according to research quality criteria and outcomes related to the effect of reduction of ASD medication retrieved from Medline, Embase and the Cochrane Library. Outcome measures were the strategy of intervention, quality of methodology and results of treatment to differences of ASD prescriptions and costs.</p> <p>Results</p> <p>The intervention varied from a single passive method to multiple active interactions with GPs. Reports of study quality had shortcomings on subjects of data-analysis. Not all outcomes were calculated but if so rction of prescriptions varied from 8% up to 40% and the cost effectiveness was in some cases negative and in others positive. Few studies demonstrated good effects from the interventions to reduce ASD.</p> <p>Conclusion</p> <p>Poor quality of some studies is limiting the evidence for effective interventions. Also it is difficult to compare cost-effectiveness between studies. However, RCT studies demonstrate that active interventions are required to reduce ASD volume. Larger multi-intervention studies are necessary to evaluate the most successful intervention instruments.</p

Maximizing the general success of cecal intubation during propofol sedation in a multi-endoscopist academic centre

<p>Abstract</p> <p>Background</p> <p>Achieving the target of 95% colonoscopy completion rate at centres conducting colorectal screening programs is an important issue. Large centres and teaching hospitals employing endoscopists with different levels of training and expertise risk achieving worse results. Deep sedation with propofol in routine colonoscopy could maximize the results of cecal intubation.</p> <p>Methods</p> <p>The present study on the experience of a single centre focused on estimating the overall completion rate of colonoscopies performed under routine propofol sedation at a large teaching hospital with many operators involved, and on assessing the factors that influence the success rate of the procedure and how to improve this performance, analyzing the aspects relating to using of deep sedation. Twenty-one endoscopists, classified by their level of specialization in colonoscopic practice, performed 1381 colonoscopies under deep sedation. All actions needed for the anaesthesiologist to restore adequate oxygenation or hemodynamics, even for transient changes, were recorded.</p> <p>Results</p> <p>The "crude" overall completion rate was 93.3%. This finding shows that with routine deep sedation, the colonoscopy completion rate nears, but still does not reach, the target performance for colonoscopic screening programs, at centers where colonoscopists of difference experience are employed in such programs.</p> <p>Factors interfering with cecal intubation were: inadequate colon cleansing, endoscopists' expertise in colonoscopic practice, patients' body weight under 60 kg or age over 71 years, and the need for active intervention by the anaesthesiologist. The most favourable situation - a patient less than 71 years old with a body weight over 60 kg, an adequate bowel preparation, a "highly experienced specialist" performing the test, and no need for active anaesthesiological intervention during the procedure - coincided with a 98.8% probability of the colonoscopy being completed.</p> <p>Conclusions</p> <p>With routine deep sedation, the colonoscopy completion rate nears the target performance for colonoscopic screening programs, at centers where colonoscopists of difference experience are employed in such programs. Organizing the daily workload to prevent negative factors affecting the success rate from occurring in combination may enable up to 85% of incomplete procedures to be converted into successful colonoscopies.</p

Analysis of suicide in the elderly in Italy. Risk factors and prevention of suicidal behavior

The authors describe the nationwide scale of suicides among the elderly in Italy for the period 1993-2010. The data are derived from the Italian Institute for Statistics (ISTAT) and the World Health Organization (WHO). The elderly turned out to represent the highest risk category for suicide, with risk increasing with age (sui- cide rates, per 100,000, in men aged 75 or over and aged 65-74 were respectively 28.3 and 15.7 in 2007). The rates for men were three times higher than those for women. The north-east and north-west regions of Italy had the highest rates of suicide in the elderly. Education was inversely related to the risk of suicide. Hanging was the most frequent method of suicide in men, and precipita- tion in women. The reasons for suicide, as inferred from available data, were predominantly mental-physical ill- nesses. The risk factors emerging from our analysis are discussed from the preventive point of view, in relation to the Italian situation and a review of the literature

N0 Stage colon cancer: prognostic role of age in relation to tumor site.

This work investigates the prognostic role of advanced age as a risk factor for recurrence in a population of patients undergoing surgery for N0 stage colon cancer, and also evaluates whether that role is affected by tumor location. A population of 129 con- secutive patients who underwent radical surgery for N0 stage colon cancer was selected. Patients were subdi- vided into three age groups: 80. The only correlation found in the examined population between age and clinical-pathological features was be- tween advanced age (>80) and tumor location in the right side of the colon. Overall survival (OS) and dis- ease-free survival (DFS) were significantly lower in pa- tients over 80 than in the other two classes. Two mul- tivariate analyses were carried out: when tumor loca- tion was not considered, age >80 represented a neg- ative prognostic factor for risk of recurrence, regardless of the other factors examined. This role was also con- firmed when tumor location was considered. As hy- pothesized by several authors, the role of advanced age which emerges from this study is mainly due to the in- creased fragility of elderly patients caused by multiple pathophysiological factors, but it does not necessarily represent an absolute contraindication to surgery. The role played by tumor location remains contro- versial, as more and more studies show that right colon cancer (RCC) is a biological entity distinct from left colon cancer (LCC). Further studies are required to examine right and left colon cancers as two separate diseases

Choices in surgical treatment of diverticulitis

Complications after surgical treatment of diverticulitis are not very frequent, in view of the total number of patients affected by this pathology, but they do become significant in absolute terms because of the high prevalence of the disease itself. Surgeons continue to debate which option is better: Hartmann re- section or combined resection and anastomosis. Since age is a crucial factor when surgery is being considered, we evaluated the outcome of surgical treatment for di- verticulitis in patients treated in our unit over a six- month period, in view of the number of elderly patients generally admitted. Between January 2001 and June 2012, 77 patients underwent surgery for diverticular disease in the Geriatric Surgery Unit of the Department of Surgical and Gastroenterological Sciences, Univer- sity of Padova Hospital. Gastrointestinal resection and anastomosis were performed in 75 patients (97%), re- sulting in an overall complication rate of 37% and a mortality rate of 1%. This surgical strategy was chosen because, when it is performed by experienced sur- geons, it offers the same results in terms of mortality and morbidity as Hartmann resection, while presenting significant advantages as regards the patient's quality of life. Various factors such as the timing of surgery, severity of the disease defined according to the Hinchey classification, patient’s clinical condition, and sur- geon's experience and expertise can all influence the surgical choice. Several studies in the literature confirm that combined resection and anastomosis is safe and ef- ficacious, but more research is needed to confirm these data

Current practice in colonoscopy in the elderly

Colonoscopy in the elderly is a reliable practice of great diagnostic and management value. However, patient\u2019s age has long been considered to af- fect the success of the procedure, achieved when the ce- cum is intubated, there is a good view of the colon if preparation has been properly carried out, and the ex- amination does not cause excessive discomfort or complications. Substantial improvements have been made to the latter two aspects, due to more widespread use of deep sedation with propofol and cardiocircula- tory monitoring during the procedure. The aim of our work was to assess whether, in the everyday prac- tice of an open-access, digestive endoscopy teaching center, staffed by various providers delivering screen- ing for polyposis, age is still a limitation to the success of the procedure and whether appropriate measures have been taken to improve colonoscopy in geriatric pa- tients. We analysed 1480 consecutive colonoscopies, of which 319 were performed in patients aged over 73 years. The examination was significantly less success- ful in this group of patients (88.1 vs 94.4, p=0.0001), but there were no major technical or use-related com- plications connected with administration of propofol for sedation purposes, despite lower doses to the el- derly (2.2\ub11.1 mg/kg total dose, mean 151\ub172.4 mg vs 2.9\ub11.3 mg/kg total dose, mean 199\ub177.9 mg in younger patients, p<0.001). More experienced tech- nical staff were not allocated to these colonoscopies (for endoscopic or anesthesiological purposes) and, according to the results of multivariate stepwise logistic regression analysis, inadequate preparation was the main factor affecting the success of the procedure in el- derly patients (OR 5.9, 95% CI 2.25-15.72; p=0.0003). Only body weight over 60 kg facilitated it (weight 6560 kg, OR 0.46, 95% CI 0.26-0.83). In colonoscopy in the elderly, safety appears to be the primary concern and, good outcomes can be achieved, but sometimes at the expense of diagnostic accuracy. This could probably be improved through better pre- and post-procedure care, not currently differentiated between young and elderly patients