434 research outputs found

    Regression parameter estimation with serially correlated errors

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    Statistical and image analysis methods and applications

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    Multicentre observational cohort study of NSAIDs as risk factors for postoperative adverse events in gastrointestinal surgery

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    Introduction: Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as postoperative analgesia by the Enhanced Recovery After Surgery Society. Recent studies have raised concerns that NSAID administration following colorectal anastomosis may be associated with increased risk of anastomotic leak. This multicentre study aims to determine NSAIDs' safety profile following gastrointestinal resection. Methods and analysis: This prospective, multicentre cohort study will be performed over a 2-week period utilising a collaborative methodology. Consecutive adults undergoing open or laparoscopic, elective or emergency gastrointestinal resection will be included. The primary end point will be the 30-day morbidity, assessed using the Clavien-Dindo classification. This study will be disseminated through medical student networks, with an anticipated recruitment of at least 900 patients. The study will be powered to detect a 10% increase in complication rates with NSAID use. Ethics and dissemination: Following the Research Ethics Committee Chairperson's review, a formal waiver was received. This study will be registered as a clinical audit or service evaluation at each participating hospital. Dissemination will take place through previously described novel research collaborative networks

    Developing a pathway for remote assessment of surgical wounds with partners in low- and middle-income countries: An approach for efficient trials and resilient perioperative systems

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    Background: Surgical site infection (SSI) is the most common complication of abdominal surgery, and commonly occurs after hospital discharge. When patients in low- and middle-income countries (LMICs) undergo surgery, they are three times more likely to have a SSI than patients in high-income countries. Returning to hospital for routine face-to-face follow-up is the accepted gold standard for diagnosing a SSI but can be challenging in many environments, and resource intensive for healthcare teams. Aims: The overall aim of this thesis was to develop a high-quality pathway for remote surgical wound assessment using telemedicine that can be delivered flexibly across diverse healthcare settings. First, I aimed to evaluate the feasibility and accuracy of telemedicine in the detection of SSI in existing data. Second, I aimed to explore the cross-cultural equivalence of a Wound Healing Questionnaire (WHQ) across several LMICs and make recommendations for its adaptation for use in global surgery research and practice. Third, I aimed to test the feasibility and accuracy of the adapted WHQ in diagnosis of SSI. Methods: The primary outcome of interest in this thesis was SSI reported up to 30-days after surgery using the US Centres for Disease Control criteria. First, I compared the rates of SSI using telemedicine to those with in-person review in two data sources: (A) an international cohort study of adult patients discharged from hospital before 30-days after abdominal surgery; (B) a systematic review with meta-analysis of rates of SSI detection conducted in accordance with PRIMSA guidelines (PROSPERO:192596). Second, to recommend adaptations to the WHQ outcome measure for global implementation, I conducted a mixed-methods study across seven LMICs. Qualitative data were obtained from interviews and focus groups with local researchers with deductive coding aligned to cognitive theory. Quantitative data were collected in a prospective cohort study and Rasch analysis was used to explore measurement properties of the WHQ. I triangulated these data to make recommendations for cross-cultural and cross-language adaptation. Third, I conducted a validation cohort study within a randomised trial (FALCON, NCT03700749) where consecutive patients undergoing abdominal surgery for a range of indications underwent telephone assessment with the WHQ (index test) up to 72-hours before their face-to-face assessment (reference test). I worked with Community Engagement and Involvement (CEI) partners to optimise the measurement pathway. Results: The SSI rate reported using telemedicine in the cohort data was lower than with in-person follow-up (11.1% versus 13.4%, p4 demonstrated sensitivity of 0.701 (0.610-0.792), specificity of 0.911 (0.878-0.9430), positive predictive value of 0.723 (0.633-0.814) and negative predictive value of 0.901 (0.867-0.935). Discussion: Current methods for remote detection of SSI are inadequate, missing 1 in 3 patients with infection. This thesis describes the adaptation and validation of the WHQ, demonstrating that a telephone pathway for wound assessment is feasible and moderately accurate. The adapted WHQ is now ready for global implementation in research and routine postoperative surveillance, using the co-designed toolkit to optimise local measurement processes

    Mortality and pulmonary complications in patients undergoing surgery with perioperative SARSCoV- 2 infection: an international cohort study.

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    Background The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p<0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p<0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p<0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research.pre-print450 K

    Elective surgery system strengthening: development, measurement, and validation of the surgical preparedness index across 1632 hospitals in 119 countries

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    Background The 2015 Lancet Commission on global surgery identified surgery and anaesthesia as indispensable parts of holistic health-care systems. However, COVID-19 exposed the fragility of planned surgical services around the world, which have also been neglected in pandemic recovery planning. This study aimed to develop and validate a novel index to support local elective surgical system strengthening and address growing backlogs. Methods First, we performed an international consultation through a four-stage consensus process to develop a multidomain index for hospital-level assessment (surgical preparedness index; SPI). Second, we measured surgical preparedness across a global network of hospitals in high-income countries (HICs), middle-income countries (MICs), and low-income countries (LICs) to explore the distribution of the SPI at national, subnational, and hospital levels. Finally, using COVID-19 as an example of an external system shock, we compared hospitals' SPI to their planned surgical volume ratio (SVR; ie, operations for which the decision for surgery was made before hospital admission), calculated as the ratio of the observed surgical volume over a 1-month assessment period between June 6 and Aug 5, 2021, against the expected surgical volume based on hospital administrative data from the same period in 2019 (ie, a pre-pandemic baseline). A linear mixed-effects regression model was used to determine the effect of increasing SPI score. Findings In the first phase, from a longlist of 103 candidate indicators, 23 were prioritised as core indicators of elective surgical system preparedness by 69 clinicians (23 [33%] women; 46 [67%] men; 41 from HICs, 22 from MICs, and six from LICs) from 32 countries. The multidomain SPI included 11 indicators on facilities and consumables, two on staffing, two on prioritisation, and eight on systems. Hospitals were scored from 23 (least prepared) to 115 points (most prepared). In the second phase, surgical preparedness was measured in 1632 hospitals by 4714 clinicians from 119 countries. 745 (45·6%) of 1632 hospitals were in MICs or LICs. The mean SPI score was 84·5 (95% CI 84·1–84·9), which varied between HIC (88·5 [89·0–88·0]), MIC (81·8 [82·5–81·1]), and LIC (66·8 [64·9–68·7]) settings. In the third phase, 1217 (74·6%) hospitals did not maintain their expected SVR during the COVID-19 pandemic, of which 625 (51·4%) were from HIC, 538 (44·2%) from MIC, and 54 (4·4%) from LIC settings. In the mixed-effects model, a 10-point increase in SPI corresponded to a 3·6% (95% CI 3·0–4·1; p<0·0001) increase in SVR. This was consistent in HIC (4·8% [4·1–5·5]; p<0·0001), MIC (2·8 [2·0–3·7]; p<0·0001), and LIC (3·8 [1·3–6·7%]; p<0·0001) settings. Interpretation The SPI contains 23 indicators that are globally applicable, relevant across different system stressors, vary at a subnational level, and are collectable by front-line teams. In the case study of COVID-19, a higher SPI was associated with an increased planned surgical volume ratio independent of country income status, COVID-19 burden, and hospital type. Hospitals should perform annual self-assessment of their surgical preparedness to identify areas that can be improved, create resilience in local surgical systems, and upscale capacity to address elective surgery backlogs

    Interacción de la radiación electromagnética. Segregación espectral y espacial de cultivos frente a malas hierbas todos ellos pertenecientes al género Brassica.

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    La interacción de la radiación electromagnética, denominada luz si abarca el rango visible por el ojo humano (400-700nm), da lugar a un espectro específico para cada objeto animado o inanimado. En el ámbito agrario, la reflectancia espectral de los productos agrícolas tanto en el rango visible como en el infrarrojo ha sido ampliamente estudiada (algunos ejemplos se encuentran recogidos en las referencias 1, 2, 3, 4, 9, 10 & II de la bibliografía)

    Prevalence and cumulative incidence of food hyper-sensitivity in the first 10 years of life

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    Background - Prevalence, incidence and natural history of food hypersensitivity (FHS) and its trends in an unselected cohort of older children are unclear.Methods - A birth cohort born on the Isle of Wight (UK) between 2001 and 2002 was followed up prospectively. Children were clinically examined and skin prick tested at set times and invited for food challenges when indicated. At 10 years of age, children were also invited for a blood test.Results - A total of 969 children were recruited at 12 weeks of pregnancy, and 92.9%, 88.5%, 91.6% and 85.3% were assessed at 1, 2, 3 and 10 years. Prevalence of sensitization to any allergen over 10 years was 186 of 969 (19.2%; 95% CI: 16.84–21.8) and 108 of 969 (11.2%; 95% CI: 9.31–13.29) children were sensitized to at least one predefined food allergen. Excluding wheat (due to cross-reactivity with pollen), 40 of 969 (4.1%; 95% CI: 3.19–5.32) children were sensitized to a predefined food allergen. Using food challenges and/or a good clinical history, the cumulative incidence of food hypersensitivity (FHS) in the first decade of life was 64 of 947 (6.8%, 95% CI: 5.2–8.4), while the prevalence of FHS at 10 years was 30 of 827 (3.6%, 95% CI: 2.54–5.15). The vast majority, 25 of 827 (3.0%, 95% CI: 1.8–4.2), suffered from IgE-mediated food allergy, while 5 of 827 (0.6%, 95% CI: 0.07–1.3) had non-IgE-mediated food allergy/food intolerance.Conclusions - By the age of 10 years, 6.8% of children suffered from FHS based on food challenges and a good clinical history. There was a large discrepancy between reported and diagnosed FHS
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