Poisson Distribution

泊松分布
  • 文章类型: Journal Article
    Gastric cancer is a common and deadly cancer in the world. The gold standard for the detection of gastric cancer is the histological examination by pathologists, where Gastric Histopathological Image Analysis (GHIA) contributes significant diagnostic information. The histopathological images of gastric cancer contain sufficient characterization information, which plays a crucial role in the diagnosis and treatment of gastric cancer. In order to improve the accuracy and objectivity of GHIA, Computer-Aided Diagnosis (CAD) has been widely used in histological image analysis of gastric cancer. In this review, the CAD technique on pathological images of gastric cancer is summarized. Firstly, the paper summarizes the image preprocessing methods, then introduces the methods of feature extraction, and then generalizes the existing segmentation and classification techniques. Finally, these techniques are systematically introduced and analyzed for the convenience of future researchers.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    BACKGROUND:  Systematic reviews reporting time trends in mortality following major orthopaedic surgery are few and have limitations. They reported on only a fraction (< 15%) of the available data and did not investigate potential causes of the reduction in mortality.
    METHODS:  We searched PubMed for randomized trials and observational studies, published between 1950 and 2016, reporting on mortality within 3 months of elective total hip and knee replacement (THR/TKR). Mortality risks were estimated for each 5-year interval using a Poisson regression model and presented by study design and mode of prophylaxis. To estimate the mortality reduction unrelated to anti-thrombotic use, we performed a pooled analysis of four thromboprophylaxis strategies for which data spanned five decades.
    RESULTS:  We identified 255 eligible studies, which documented 31,604 deaths among 6,293,954 patients, and found a consistent decline in mortality irrespective of study design and mode of prophylaxis. Mortality declined from 1.15% pre-1980 to 0.24% post-2000, a 78.7% relative risk reduction (95% confidence interval [CI]: 74.7-82.1%) in randomized and cohort studies. Furthermore, our data showed a 74.4% (95% CI: 68.7-79.0%) relative reduction in mortality independent of the methods of prophylaxis, thereby indicating that improvements in peri-operative care unrelated to anti-thrombotic prophylaxis played a major role in such reduction.
    CONCLUSIONS:  Mortality following elective THR/TKR has markedly declined over the past 50 years and is now low irrespective of which prophylactic agent is being used. Although anti-thrombotic prophylaxis may have contributed, other improvements in peri-operative care played a major role in the mortality reduction.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    OBJECTIVE: To evaluate the trend in presentation and postoperative outcomes of infants with hypertrophic pyloric stenosis (HPS) over the last decade.
    METHODS: This was a multicentre retrospective study in two tertiary paediatric centres between 2005 and 2015 inclusive. Participants included 626 infants who underwent a pyloromyotomy for HPS. We collected data on presentation features (age, weight, clinical signs, blood gas results, ultrasound findings) and postoperative outcomes (length of stay (LOS), complications, time to first postoperative feed).
    RESULTS: No trend was identified during the study period with regards to age, weight, biochemical findings (pH, chloride, base excess) or pre-operative ultrasound measurements. There was a downtrend in the number of palpated tumours over time, with a mean of 36% of tumours clinically palpated. Pyloric wall thickness had a moderate association with LOS in patients admitted for >8 days (correlation = 0.4752) but had a weak negative association with shorter lengths of stay (≤8 day, correlation = -0.094). Overall, median time to first feed was 7.80 h and improved yearly during the study period (hazard ratio = 1.07).
    CONCLUSIONS: Patients presenting with HPS are not being identified at an earlier age or with fewer biochemical derangements, in contrast to our initial perceptions. Subsequently, biochemical derangements can still play an important role in the diagnosis of HPS, and attention needs to be given to fluid management and electrolyte correction in all patients with HPS.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    Mass gathering events can substantially impact public safety. Analyzing patient presentation and transport rates at various mass gathering events can help inform staffing models and improve preparedness.
    A retrospective review of all patients seeking medical attention across a variety of event types at a single venue with a capacity of 68,756 from January 2010 through September 2015.
    We examined 232 events with a total of 8,260,349 attendees generating 8157 medical contacts. Rates were 10 presentations and 1.6 transports per 10,000 attendees with a non-significant trend towards increased rates in postseason National Football League games. Concerts had significantly higher rates of presentation and transport than all other event types. Presenting concern varied significantly by event type and gender, and transport rate increased predictably with age. For cold weather events, transport rates increased at colder temperatures. Overall, on-site physicians did not impact rates.
    At a single venue hosting a variety of events across a 6-year period, we demonstrated significant variations in presentation and transport rates. Weather, gender, event type, and age all play important roles. Our analysis, while representative only of our specific venue, may be useful in developing response plans and staffing models for similar mass gathering venues. (Disaster Med Public Health Preparedness. 2018;12:752-758).
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    To determine possible differences in serious adverse effects among the 10 currently approved biological and targeted synthetic DMARDs (b/ts-DMARDs) for RA.
    Systematic review in bibliographic databases, trial registries and websites of regulatory agencies identified randomized trials of approved b/ts-DMARDs for RA. Network meta-analyses using mixed-effects Poisson regression models were conducted to calculate rate ratios for serious adverse events (SAEs) and deaths between each of the 10 drugs and control (i.e. no b/ts-DMARD treatment), based on subjects experiencing an event in relation to person-years. Confidence in the estimates was assessed by applying the Grading of Recommendations Assessment, Development and Evaluation approach (GRADE).
    A total of 117 trials (47 615 patients) were included. SAEs were more common with certolizumab compared with abatacept (rate ratio = 1.58, 95% CI: 1.18, 2.14), adalimumab (1.36, 95% CI: 1.02, 1.81), etanercept (1.60, 95% CI: 1.18, 2.17), golimumab (1.45, 95% CI: 1.00, 2.08), rituximab (1.63, 95% CI: 1.16, 2.30), tofacitinib (1.44, 95% CI: 1.03, 2.02) and control (1.45, 95% CI: 1.13, 1.87); and tocilizumab compared with abatacept (1.30, 95% CI: 1.03, 1.65), etanercept (1.31, 95% CI: 1.04, 1.67) and rituximab (1.34, 95% CI: 1.01, 1.78). No other comparisons were statistically significant. Accounting for study duration confirmed our findings for up to 6 months\' treatment but not for longer-term treatment (6-24 months). No differences in mortality between b/ts-DMARDs and control were found. Based on the GRADE approach, confidence in the estimates was low due to lack of head-to-head comparison trials and imprecision in indirect estimates.
    Despite low confidence in the estimates, our analysis found potential differences in rates of SAEs. Our data suggest caution should be taken when deciding among available drugs.
    PROSPERO CRD42014014842.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    BACKGROUND: Medial ulnar collateral ligament (UCL) injuries of the elbow that require surgical management are uncommon. There is growing evidence, however, suggesting that the incidence of UCL reconstruction (UCLR) procedures is rapidly increasing. We sought to quantify the incidence of age-related trends for UCLR from 2003 to 2014 and subsequently to project future trends through 2025. We hypothesized that as the total number of UCLRs performed increased, a disproportionate incidence among younger patients would be observed.
    METHODS: New York State\'s Statewide Planning and Research Cooperative System database was queried from 2003 to 2014 to identify individuals between 10 and 40 years old undergoing UCLR. Poisson regression was used to develop future projections for UCLR and New York State population through 2025, and incidence estimates per 100,000 people were calculated.
    RESULTS: In New York State between 2003 and 2014, there were 890 patients who underwent UCLR, with average annual incidence per 100,000 people equaling 6.3 ± 2.8 for ages 15 to 19 years, significantly greater than for all other age groups (P < .001). Projections from 2015 through 2025 suggest that incidence in 15- to 19-year-olds and 20- to 24-year-olds will continue to rapidly increase while rates for other age groups will remain relatively stable.
    CONCLUSIONS: The number of UCLRs performed between 2003 and 2014 increased by 343%, and a disproportionate trend in average annual incidence for patients between 15 and 19 years old was observed. As our review of the literature questioned outcomes in adolescent athletes after UCLR, continued attempts at preventing these injuries in the young throwing athlete remain paramount.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Comparative Study
    Calibration (estimation of model parameters) compares model outcomes with observed outcomes and explores possible model parameter values to identify the set of values that provides the best fit to the data. The goodness-of-fit (GOF) criterion quantifies the difference between model and observed outcomes. There is no consensus on the most appropriate GOF criterion, because a direct performance comparison of GOF criteria in model calibration is lacking.
    We systematically compared the performance of commonly used GOF criteria (sum of squared errors [SSE], Pearson chi-square, and a likelihood-based approach [Poisson and/or binomial deviance functions]) in the calibration of selected parameters of the MISCAN-Colon microsimulation model for colorectal cancer. The performance of each GOF criterion was assessed by comparing the 1) root mean squared prediction error (RMSPE) of the selected parameters, 2) computation time of the calibration procedure of various calibration scenarios, and 3) impact on estimated cost-effectiveness ratios.
    The likelihood-based deviance resulted in the lowest RMSPE in 4 of 6 calibration scenarios and was close to best in the other 2. The SSE had a 25 times higher RMSPE in a scenario with considerable differences in the values of observed outcomes, whereas the Pearson chi-square had a 60 times higher RMSPE in a scenario with multiple studies measuring the same outcome. In all scenarios, the SSE required the most computation time. The likelihood-based approach estimated the cost-effectiveness ratio most accurately (up to -0.15% relative difference versus 0.44% [SSE] and 13% [Pearson chi-square]).
    The likelihood-based deviance criteria lead to accurate estimation of parameters under various circumstances. These criteria are recommended for calibration in microsimulation disease models in contrast with other commonly used criteria.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Comparative Study
    OBJECTIVE: To investigate the preventive effect of antireflux surgery against esophageal adenocarcinoma (EAC) compared with medical treatment of gastroesophageal reflux disease (GERD) and to the background population.
    BACKGROUND: GERD is causally associated with EAC. Effective symptomatic treatment can be achieved with medication and antireflux surgery; however the possible preventive effect on EAC development remains unclear.
    METHODS: This systematic review identified 10 studies comparing EAC risk after antireflux surgery with nonoperated GERD patients, including 7 studies of patients with Barrett\'s esophagus, and 2 studies comparing EAC risk after antireflux surgery to the background population. A fixed-effects Poisson meta-analysis was conducted to calculate pooled incidence rate ratios (IRR) and 95% confidence intervals (CIs).
    RESULTS: The pooled IRR in patients after antireflux surgery was 0.76 (95% CI 0.42-1.39) compared with medically treated GERD patients. In patients with Barrett\'s esophagus, the corresponding IRR was 0.46 (95% CI 0.20-1.08), and 0.26 (95% CI 0.09-0.79) when restricted to publications after 2000. There was no difference in EAC risk between antireflux surgery and medical treatment in GERD patients without known Barrett\'s esophagus (IRR 0.98, 95% CI 0.72-1.33). The EAC risk remained elevated in patients after antireflux surgery compared with the background population (IRR 10.78, 95% CI 8.48-13.71). Although the clinical heterogeneity of the included studies was high, the statistical heterogeneity was low.
    CONCLUSIONS: Antireflux surgery may prevent EAC better than medical therapy in patients with Barrett\'s esophagus. The EAC risk after antireflux surgery does not seem to revert to that of the background population.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    OBJECTIVE: To explore the association between red blood cell transfusion and necrotizing enterocolitis (NEC) in a neonatal intensive care unit with liberal transfusion practices.
    METHODS: A retrospective cohort study was conducted for all infants weighing <1500 g who received at least 1 packed red blood cell transfusion between January 2008 and June 2013 in a tertiary neonatal intensive care unit. The primary outcome was NEC, defined as Bell stage II or greater. The temporal association of NEC and transfusion was assessed using multivariate Poisson regression.
    RESULTS: The study sample included 414 very low birth weight infants who received 2889 consecutive red blood cell transfusions. Twenty-four infants (5.8%) developed NEC. Four cases of NEC occurred within 48 hours of a previous transfusion event. Using multivariate Poisson regression, we did not find evidence of a temporal association between NEC and transfusion (P = .32).
    CONCLUSIONS: There was no association between NEC and red blood cell transfusion. Our results differ from previous studies and suggest that the association between NEC and transfusion may be contextual.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

  • 文章类型: Journal Article
    OBJECTIVE: The reported effects of treating cerebral cavernous malformations (CCMs) by neurosurgical excision or stereotactic radiosurgery are imprecise and vary between studies.
    METHODS: We searched Ovid Medline, EMBASE and The Cochrane Library for peer-reviewed publications of cohort studies describing outcomes of treating 20 or more patients with CCM with at least 80% completeness of follow-up. Two reviewers extracted data to quantify the incidence of a composite outcome (death, non-fatal intracranial haemorrhage, or new/worse persistent focal neurological deficit) after CCM treatment. We explored associations between summary measures of study characteristics and outcome using Poisson meta-regression analyses.
    RESULTS: We included 63 cohorts, involving 3424 patients. The incidence of the composite outcome was 6.6 (95% CI 5.7 to 7.5) per 100 person-years after neurosurgical excision (median follow-up 3.3 years) and 5.4 (95% CI 4.5 to 6.4) after stereotactic radiosurgery (median follow-up 4.1 years). After neurosurgical excision the incidence of the composite outcome increased with every per cent point increase in patients with brainstem CCM (rate ratio (RR) 1.03, 95% CI 1.01 to 1.05), and decreased with each more recent study midyear (RR 0.91, 95% CI 0.85 to 0.98) and each per cent point increase in patients presenting with haemorrhage (RR 0.98, 95% CI 0.96 to 1.00). We did not find significant associations in studies of stereotactic radiosurgery.
    CONCLUSIONS: The reported risks of CCM treatment (and the lower risks of neurosurgical excision over time, from recently bled CCMs, and for CCMs outside the brainstem) compare favourably with the risks of recurrent haemorrhage from CCM. Long-term effects, especially important for stereotactic radiosurgery, are unknown.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Sci-hub)

公众号