Improving risk models for patients having emergency bowel cancer surgery using linked electronic health records: a national cohort study.

BACKGROUND: Life-saving emergency major resection of colorectal cancer (CRC) is a high-risk procedure. Accurate prediction of postoperative mortality for patients undergoing this procedure is essential for both healthcare performance monitoring and preoperative risk assessment. Risk-adjustment models for CRC patients often include patient and tumour characteristics, widely available in cancer registries and audits. The authors investigated to what extent inclusion of additional physiological and surgical measures, available through linkage or additional data collection, improves accuracy of risk models. METHODS: Linked, routinely-collected data on patients undergoing emergency CRC surgery in England between December 2016 and November 2019 were used to develop a risk model for 90-day mortality. Backwards selection identified a 'selected model' of physiological and surgical measures in addition to patient and tumour characteristics. Model performance was assessed compared to a 'basic model' including only patient and tumour characteristics. Missing data was multiply imputed. RESULTS: Eight hundred forty-six of 10 578 (8.0%) patients died within 90 days of surgery. The selected model included seven preoperative physiological and surgical measures (pulse rate, systolic blood pressure, breathlessness, sodium, urea, albumin, and predicted peritoneal soiling), in addition to the 10 patient and tumour characteristics in the basic model (calendar year of surgery, age, sex, ASA grade, TNM T stage, TNM N stage, TNM M stage, cancer site, number of comorbidities, and emergency admission). The selected model had considerably better discrimination compared to the basic model (C-statistic: 0.824 versus 0.783, respectively). CONCLUSION: Linkage of disease-specific and treatment-specific datasets allowed the inclusion of physiological and surgical measures in a risk model alongside patient and tumour characteristics, which improves the accuracy of the prediction of the mortality risk for CRC patients having emergency surgery. This improvement will allow more accurate performance monitoring of healthcare providers and enhance clinical care planning.

Costs of endovascular and open repair of thoracic aortic aneurysms.

BACKGROUND: Repair of thoracic aortic aneurysms with either endovascular repair (TEVAR) or open surgical repair (OSR) represents major surgery, is costly and associated with significant complications. The aim of this study was to establish accurate costs of delivering TEVAR and OSR in a cohort of UK NHS patients suitable for open and endovascular treatment for the whole treatment pathway from admission and to discharge and 12-month follow-up. METHODS: A prospective study of UK NHS patients from 30 NHS vascular/cardiothoracic units in England aged ≥18, with distal arch/descending thoracic aortic aneurysms (CTAA) was undertaken. A multicentre prospective cost analysis of patients (recruited March 2014-July 2018, follow-up until July 2019) undergoing TEVAR or OSR was performed. Patients deemed suitable for open or endovascular repair were included in this study. A micro-costing approach was adopted. RESULTS: Some 115 patients having undergone TEVAR and 35 patients with OSR were identified. The mean (s.d.) cost of a TEVAR procedure was higher £26 536 (£9877) versus OSR £17 239 (£8043). Postoperative costs until discharge were lower for TEVAR £7484 (£7848) versus OSR £28 636 (£23 083). Therefore, total NHS costs from admission to discharge were lower for TEVAR £34 020 (£14 301), versus OSR £45 875 (£43 023). However, mean NHS costs for 12 months following the procedure were slightly higher for the TEVAR £5206 (£11 585) versus OSR £5039 (£11 994). CONCLUSIONS: Surgical procedure costs were higher for TEVAR due to device costs. Total in-hospital costs were higher for OSR due to longer hospital and critical care stay. Follow-up costs over 12 months were slightly higher for TEVAR due to hospital readmissions.

Effectiveness of GRACE risk score in patients admitted to hospital with non-ST elevation acute coronary syndrome (UKGRIS): parallel group cluster randomised controlled trial.

OBJECTIVE: To determine the effectiveness of risk stratification using the Global Registry of Acute Coronary Events (GRACE) risk score (GRS) for patients presenting to hospital with suspected non-ST elevation acute coronary syndrome. DESIGN: Parallel group cluster randomised controlled trial. SETTING: Patients presenting with suspected non-ST elevation acute coronary syndrome to 42 hospitals in England between 9 March 2017 and 30 December 2019. PARTICIPANTS: Patients aged ≥18 years with a minimum follow-up of 12 months. INTERVENTION: Hospitals were randomised (1:1) to patient management by standard care or according to the GRS and associated guidelines. MAIN OUTCOME MEASURES: Primary outcome measures were use of guideline recommended management and time to the composite of cardiovascular death, non-fatal myocardial infarction, new onset heart failure hospital admission, and readmission for cardiovascular event. Secondary measures included the duration of hospital stay, EQ-5D-5L (five domain, five level version of the EuroQoL index), and the composite endpoint components. RESULTS: 3050 participants (1440 GRS, 1610 standard care) were recruited in 38 UK clusters (20 GRS, 18 standard care). The mean age was 65.7 years (standard deviation 12), 69% were male, and the mean baseline GRACE scores were 119.5 (standard deviation 31.4) and 125.7 (34.4) for GRS and standard care, respectively. The uptake of guideline recommended processes was 77.3% for GRS and 75.3% for standard care (odds ratio 1.16, 95% confidence interval 0.70 to 1.92, P=0.56). The time to the first composite cardiac event was not significantly improved by the GRS (hazard ratio 0.89, 95% confidence interval 0.68 to 1.16, P=0.37). Baseline adjusted EQ-5D-5L utility at 12 months (difference -0.01, 95% confidence interval -0.06 to 0.04) and the duration of hospital admission within 12 months (mean 11.2 days, standard deviation 18 days v 11.8 days, 19 days) were similar for GRS and standard care. CONCLUSIONS: In adults presenting to hospital with suspected non-ST elevation acute coronary syndrome, the GRS did not improve adherence to guideline recommended management or reduce cardiovascular events at 12 months. TRIAL REGISTRATION: ISRCTN 29731761.

Contrasting principal stratum and hypothetical strategy estimands in multi-period crossover trials with incomplete data.

Complete case analyses of complete crossover designs provide an opportunity to make comparisons based on patients who can tolerate all treatments. It is argued that this provides a means of estimating a principal stratum strategy estimand, something which is difficult to do in parallel group trials. While some trial users will consider this a relevant aim, others may be interested in hypothetical strategy estimands, that is, the effect that would be found if all patients completed the trial. Whether these estimands differ importantly is a question of interest to the different users of the trial results. This paper derives the difference between principal stratum strategy and hypothetical strategy estimands, where the former is estimated by a complete-case analysis of the crossover design, and a model for the dropout process is assumed. Complete crossover designs, that is, those where all treatments appear in all sequences, and which compare t treatments over p periods with respect to a continuous outcome are considered. Numerical results are presented for Williams designs with four and six periods. Results from a trial of obstructive sleep apnoea-hypopnoea (TOMADO) are also used for illustration. The results demonstrate that the percentage difference between the estimands is modest, exceeding 5% only when the trial has been severely affected by dropouts or if the within-subject correlation is low.

Linkage of multiple electronic health record datasets using a 'spine linkage' approach compared with all 'pairwise linkages'.

BACKGROUND: Methods for linking records between two datasets are well established. However, guidance is needed for linking more than two datasets. Using all 'pairwise linkages'-linking each dataset to every other dataset-is the most inclusive, but resource-intensive, approach. The 'spine' approach links each dataset to a designated 'spine dataset', reducing the number of linkages, but potentially reducing linkage quality. METHODS: We compared the pairwise and spine linkage approaches using real-world data on patients undergoing emergency bowel cancer surgery between 31 October 2013 and 30 April 2018. We linked an administrative hospital dataset (Hospital Episode Statistics; HES) capturing patients admitted to hospitals in England, and two clinical datasets comprising patients diagnosed with bowel cancer and patients undergoing emergency bowel surgery. RESULTS: The spine linkage approach, with HES as the spine dataset, created an analysis cohort of 15 826 patients, equating to 98.3% of the 16 100 patients identified using the pairwise linkage approach. There were no systematic differences in patient characteristics between these analysis cohorts. Associations of patient and tumour characteristics with mortality, complications and length of stay were not sensitive to the linkage approach. When eligibility criteria were applied before linkage, spine linkage included 14 509 patients (90.0% compared with pairwise linkage). CONCLUSION: Spine linkage can be used as an efficient alternative to pairwise linkage if case ascertainment in the spine dataset and data quality of linkage variables are high. These aspects should be systematically evaluated in the nominated spine dataset before spine linkage is used to create the analysis cohort.

Multicenter Randomized Trial of Intermittently Scanned Continuous Glucose Monitoring Versus Self-Monitoring of Blood Glucose in Individuals With Type 2 Diabetes and Recent-Onset Acute Myocardial Infarction: Results of the LIBERATES Trial.

OBJECTIVE: To analyze the impact of modern glucose-monitoring strategies on glycemic and patient-related outcomes in individuals with type 2 diabetes (T2D) and recent myocardial infarction (MI) and assess cost effectiveness. RESEARCH DESIGN AND METHODS: LIBERATES was a multicenter two-arm randomized trial comparing self-monitoring of blood glucose (SMBG) with intermittently scanned continuous glucose monitoring (isCGM), also known as flash CGM, in individuals with T2D and recent MI, treated with insulin and/or a sulphonylurea before hospital admission. The primary outcome measure was time in range (TIR) (glucose 3.9-10 mmol/L/day) on days 76-90 post-randomization. Secondary and exploratory outcomes included time in hypoglycemia, hemoglobin A1c (HbA1c), clinical outcome, quality of life (QOL), and cost effectiveness. RESULTS: Of 141 participants randomly assigned (median age 63 years; interquartile range 53, 70), 73% of whom were men, isCGM was associated with increased TIR by 17 min/day (95% credible interval -105 to +153 min/day), with 59% probability of benefit. Users of isCGM showed lower hypoglycemic exposure (<3.9 mmol/L) at days 76-90 (-80 min/day; 95% CI -118, -43), also evident at days 16-30 (-28 min/day; 95% CI -92, 2). Compared with baseline, HbA1c showed similar reductions of 7 mmol/mol at 3 months in both study arms. Combined glycemic emergencies and mortality occurred in four isCGM and seven SMBG study participants. QOL measures marginally favored isCGM, and the intervention proved to be cost effective. CONCLUSIONS: Compared with SMBG, isCGM in T2D individuals with MI marginally increases TIR and significantly reduces hypoglycemic exposure while equally improving HbA1c, explaining its cost effectiveness. Studies are required to understand whether these glycemic differences translate into longer-term clinical benefit.

Mediation of the total effect of cystic fibrosis-related diabetes on mortality: A UK Cystic Fibrosis Registry cohort study.

AIM: To investigate whether the effect of cystic fibrosis-related diabetes (CFRD) on the composite outcome of mortality or transplant could act through lung function, pulmonary exacerbations and/or nutritional status. METHODS: A retrospective cohort of adult cystic fibrosis (CF) patients who had not been diagnosed with CFRD were identified from the UK Cystic Fibrosis Registry (n = 2750). Rate of death or transplant was compared between patients who did and did not develop CFRD (with insulin use) during follow-up using Poisson regression, separately by sex. Causal mediation methods were used to investigate whether lung function, pulmonary exacerbations and nutritional status lie on the causal pathway between insulin-treated CFRD and mortality/transplant. RESULTS: At all ages, the mortality/transplant rate was higher in both men and women diagnosed with CFRD. Pulmonary exacerbations were the strongest mediator of the effect of CFRD on mortality/transplant, with an estimated 15% [95% CI: 7%, 28%] of the effect at 2 years post-CFRD diagnosis attributed to exacerbations, growing to 24% [95% CI: 9%, 46%] at 4 years post-diagnosis. Neither lung function nor nutritional status were found to be significant mediators of this effect. Estimates were similar but with wider confidence intervals in a cohort that additionally included people with CFRD but not using insulin. CONCLUSION: There is evidence that pulmonary exacerbations mediate the effect of CFRD on mortality but, as they are estimated to mediate less than one-quarter of the total effect, the mechanism through which CFRD influences survival may involve other factors.

Impact of changes to the interscreening interval and faecal immunochemical test threshold in the national bowel cancer screening programme in England: results from the FIT pilot study.

INTRODUCTION: The NHS Bowel Cancer Screening Programme (BCSP) faces endoscopy capacity challenges from the COVID-19 pandemic and plans to lower the screening starting age. This may necessitate modifying the interscreening interval or threshold. METHODS: We analysed data from the English Faecal Immunochemical Testing (FIT) pilot, comprising 27,238 individuals aged 59-75, screened for colorectal cancer (CRC) using FIT. We estimated screening sensitivity to CRC, adenomas, advanced adenomas (AA) and mean sojourn time of each pathology by faecal haemoglobin (f-Hb) thresholds, then predicted the detection of these abnormalities by interscreening interval and f-Hb threshold. RESULTS: Current 2-yearly screening with a f-Hb threshold of 120 µg/g was estimated to generate 16,092 colonoscopies, prevent 186 CRCs, detect 1142 CRCs, 7086 adenomas and 4259 AAs per 100,000 screened over 15 years. A higher threshold at 180 µg/g would reduce required colonoscopies to 11,500, prevent 131 CRCs, detect 1077 CRCs, 4961 adenomas and 3184 AAs. A longer interscreening interval of 3 years would reduce required colonoscopies to 10,283, prevent 126 and detect 909 CRCs, 4796 adenomas and 2986 AAs. CONCLUSION: Increasing the f-Hb threshold was estimated to be more efficient than increasing the interscreening interval regarding overall colonoscopies per screen-benefited cancer. Increasing the interval was more efficient regarding colonoscopies per cancer prevented.

Time-varying Comparison of All-cause Mortality After Liver Transplantation Between Recipients With and Without Hepatocellular Carcinoma: A Population-based Cohort Study Using the United Kingdom Liver Transplant Registry.

BACKGROUND: Accurately identifying time-varying differences in the hazard of all-cause mortality after liver transplantation (LT) between recipients with and without hepatocellular carcinoma (HCC) may inform patient selection and organ allocation policies as well as post-LT surveillance protocols. METHODS: A UK population-based study was carried out using 9586 LT recipients. The time-varying association between HCC and post-LT all-cause mortality was estimated using an adjusted flexible parametric model (FPM) and expressed as hazard ratios (HRs). Differences in this association by transplant year were then investigated. Non-cancer-specific mortality was compared between HCC and non-HCC recipients using an adjusted subdistribution hazard model. RESULTS: The HR comparing HCC recipients with non-HCC recipients was below one immediately after LT (1-mo HR = 0.76; 95% confidence interval [CI], 0.59-0.99; P = 0.044). The HR then increased sharply to a maximum at 1.3 y (HR = 2.07; 95% CI, 1.70-2.52; P < 0.001) before decreasing. The hazard of death was significantly higher in HCC recipients than in non-HCC recipients between 4 mo and 7.4 y post-LT. There were no notable differences in the association between HCC and the post-LT hazard of death by transplant year. The estimated non-cancer-specific subdistribution HR for HCC was 0.93 (95% CI, 0.80-1.09; P = 0.390) and not found to vary over time. CONCLUSIONS: FPMs can provide a more precise comparison of post-LT hazards of mortality between HCC and non-HCC patients. The results provide further evidence that some HCC patients have extra-hepatic spread at the time of LT, which has implications for optimal post-LT surveillance protocols.

Methods of analysis for survival outcomes with time-updated mediators, with application to longitudinal disease registry data.

Mediation analysis is a useful tool to illuminate the mechanisms through which an exposure affects an outcome but statistical challenges exist with time-to-event outcomes and longitudinal observational data. Natural direct and indirect effects cannot be identified when there are exposure-induced confounders of the mediator-outcome relationship. Previous measurements of a repeatedly-measured mediator may themselves confound the relationship between the mediator and the outcome. To overcome these obstacles, two recent methods have been proposed, one based on path-specific effects and one based on an additive hazards model and the concept of exposure splitting. We investigate these techniques, focusing on their application to observational datasets. We apply both methods to an analysis of the UK Cystic Fibrosis Registry dataset to identify how much of the relationship between onset of cystic fibrosis-related diabetes and subsequent survival acts through pulmonary function. Statistical properties of the methods are investigated using simulation. Both methods produce unbiased estimates of indirect and direct effects in scenarios consistent with their stated assumptions but, if the data are measured infrequently, estimates may be biased. Findings are used to highlight considerations in the interpretation of the observational data analysis.

Five-year results of Amaze: a randomized controlled trial of adjunct surgery for atrial fibrillation.

OBJECTIVES: The Amaze trial showed that adding atrial fibrillation (AF) surgery to cardiac operations increased return to sinus rhythm (SR) without impact on quality of life or survival at 2 years. We report outcomes to 5 years. METHODS: In a multicentre, phase III, pragmatic, double-blind, randomized controlled superiority trial, cardiac surgery patients with >3 months of AF were randomized 1:1 to adjunct AF surgery or control. Primary outcomes of 1-year SR restoration and 2-year quality-adjusted survival were already reported. This study reports on rhythm, survival, quality-adjusted survival, stroke, medication and safety to 5 years. RESULTS: Between 2009 and 2014, 352 patients were randomized. By 5 years 79 died, 58 withdrew, 34 were lost to follow-up and the remaining 182 provided data. AF surgery significantly increased the odds of remaining in SR at 5 years {odds ratio = 2.98 [95% confidence interval (CI) 1.23, 7.17], P = 0.015}. There was a non-significant decrease in stroke incidence [odds ratio = 0.605 (95% CI 0.284, 1.287), P = 0.19], but no improved survival [5-year survival: AF surgery 77.3% (95% CI 71.1%, 83.5%), controls 77.8% (95% CI 71.7%, 84.0%), P = 0.85]. Quality-adjusted survival difference was negligible (-0.03; 95% CI -0.33, 0.27, P = 0.85). The composite of survival free of stroke and AF was better in the AF surgery group [odds ratio = 2.34 (95% CI 1.03, 5.31)]. There were no other differences. CONCLUSIONS: Adjunct AF surgery confers a higher rate of SR to 5 years and a better composite outcome of survival free of stroke and AF but has no impact on overall or quality-adjusted survival or other clinical outcomes. CLINICAL TRIAL REGISTRATION NUMBER: ISRCTN82731440.

Endovascular stent grafting and open surgical replacement for chronic thoracic aortic aneurysms: a systematic review and prospective cohort study.

BACKGROUND: The management of chronic thoracic aortic aneurysms includes conservative management, watchful waiting, endovascular stent grafting and open surgical replacement. The Effective Treatments for Thoracic Aortic Aneurysms (ETTAA) study investigates timing and intervention choice. OBJECTIVE: To describe pre- and post-intervention management of and outcomes for chronic thoracic aortic aneurysms. DESIGN: A systematic review of intervention effects; a Delphi study of 360 case scenarios based on aneurysm size, location, age, operative risk and connective tissue disorders; and a prospective cohort study of growth, clinical outcomes, costs and quality of life. SETTING: Thirty NHS vascular/cardiothoracic units. PARTICIPANTS: Patients aged > 17 years who had existing or new aneurysms of ≥ 4 cm in diameter in the arch, descending or thoracoabdominal aorta. INTERVENTIONS: Endovascular stent grafting and open surgical replacement. MAIN OUTCOMES: Pre-intervention aneurysm growth, pre-/post-intervention survival, clinical events, readmissions and quality of life; and descriptive statistics for costs and quality-adjusted life-years over 12 months and value of information using a propensity score-matched subsample. RESULTS: The review identified five comparative cohort studies (endovascular stent grafting patients, n = 3955; open surgical replacement patients, n = 21,197). Pooled short-term all-cause mortality favoured endovascular stent grafting (odds ratio 0.71, 95% confidence interval 0.51 to 0.98; no heterogeneity). Data on survival beyond 30 days were mixed. Fewer short-term complications were reported with endovascular stent grafting. The Delphi study included 20 experts (13 centres). For patients with aneurysms of ≤ 6.0 cm in diameter, watchful waiting was preferred. For patients with aneurysms of > 6.0 cm, open surgical replacement was preferred in the arch, except for elderly or high-risk patients, and in the descending aorta if patients had connective tissue disorders. Otherwise endovascular stent grafting was preferred. Between 2014 and 2018, 886 patients were recruited (watchful waiting, n = 489; conservative management, n = 112; endovascular stent grafting, n = 150; open surgical replacement, n = 135). Pre-intervention death rate was 8.6% per patient-year; 49.6% of deaths were aneurysm related. Death rates were higher for women (hazard ratio 1.79, 95% confidence interval 1.25 to 2.57; p = 0.001) and older patients (age 61-70 years: hazard ratio 2.50, 95% confidence interval 0.76 to 5.43; age 71-80 years: hazard ratio 3.49, 95% confidence interval 1.26 to 9.66; age > 80 years: hazard ratio 7.01, 95% confidence interval 2.50 to 19.62; all compared with age < 60 years, p < 0.001) and per 1-cm increase in diameter (hazard ratio 1.90, 95% confidence interval 1.65 to 2.18; p = 0.001). The results were similar for aneurysm-related deaths. Decline per year in quality of life was greater for older patients (additional change -0.013 per decade increase in age, 95% confidence interval -0.019 to -0.007; p < 0.001) and smokers (additional change for ex-smokers compared with non-smokers 0.003, 95% confidence interval -0.026 to 0.032; additional change for current smokers compared with non-smokers -0.034, 95% confidence interval -0.057 to -0.01; p = 0.004). At the time of intervention, endovascular stent grafting patients were older (age difference 7.1 years; 95% confidence interval 4.7 to 9.5 years; p < 0.001) and more likely to be smokers (75.8% vs. 66.4%; p = 0.080), have valve disease (89.9% vs. 71.6%; p < 0.0001), have chronic obstructive pulmonary disease (21.3% vs. 13.3%; p = 0.087), be at New York Heart Association stage III/IV (22.3% vs. 16.0%; p = 0.217), have lower levels of haemoglobin (difference -6.8 g/l, 95% confidence interval -11.2 to -2.4 g/l; p = 0.003) and take statins (69.3% vs. 42.2%; p < 0.0001). Ten (6.7%) endovascular stent grafting and 15 (11.1%) open surgical replacement patients died within 30 days of the procedure (p = 0.2107). One-year overall survival was 82.5% (95% confidence interval 75.2% to 87.8%) after endovascular stent grafting and 79.3% (95% confidence interval 71.1% to 85.4%) after open surgical replacement. Variables affecting survival were aneurysm site, age, New York Heart Association stage and time waiting for procedure. For endovascular stent grafting, utility decreased slightly, by -0.017 (95% confidence interval -0.062 to 0.027), in the first 6 weeks. For open surgical replacement, there was a substantial decrease of -0.160 (95% confidence interval -0.199 to -0.121; p < 0.001) up to 6 weeks after the procedure. Over 12 months endovascular stent grafting was less costly, with higher quality-adjusted life-years. Formal economic analysis was unfeasible. LIMITATIONS: The study was limited by small numbers of patients receiving interventions and because only 53% of patients were suitable for both interventions. CONCLUSIONS: Small (4-6 cm) aneurysms require close observation. Larger (> 6 cm) aneurysms require intervention without delay. Endovascular stent grafting and open surgical replacement were successful for carefully selected patients, but cost comparisons were unfeasible. The choice of intervention is well established, but the timing of intervention remains challenging. FUTURE WORK: Further research should include an analysis of the risk factors for growth/rupture and long-term outcomes. TRIAL REGISTRATION: Current Controlled Trials ISRCTN04044627 and NCT02010892. FUNDING: This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 6. See the NIHR Journals Library website for further project information.

The aorta is the main artery that carries oxygen-rich blood from the heart to the body. An aneurysm is a swelling or bulging in a blood vessel, which usually occurs where the wall has become weak and has lost its elastic properties, which means that it does not return to its normal shape after the blood has passed through. A thoracic aortic aneurysm, or TAA for short, is an aneurysm in the section of the aorta in the chest (www.bhf.org.uk/informationsupport/conditions/thoracic-aortic-aneurysms). The Effective Treatments for Thoracic Aortic Aneurysms (ETTAA) study aimed to investigate aneurysm growth rates, patient outcomes, quality of life and costs, including those from surgery. Surgical treatments include open heart surgery, in which the section of the aorta that contains the aneurysm is removed and replaced by a new aorta made from a synthetic material, and stent grafting, in which tubes are inserted into arteries to allow blood to flow freely, using less invasive 'keyhole' surgery. The existing research evidence was reviewed, but data comparing the effectiveness of these two approaches were sparse or of limited quality, and outdated. Between 2014 and 2018, clinical experts were surveyed and 886 NHS patients with chronic thoracic aortic aneurysms (≥ 4 cm in diameter) were observed to monitor aneurysm growth and patient outcomes. If patients were unfit or unwilling to have surgery, they had conservative management with medication and lifestyle changes. For small aneurysms, experts recommended watchful waiting, with regular monitoring, until the aneurysm grew to about 6 cm in diameter. Open surgery was preferred for larger arch aneurysms and for descending aneurysms in patients with genetic disorders. Otherwise, stent grafting was preferred. The observational study recruited 321 women and 565 men with an average age of 71 years from 30 English hospitals. A total of 489 patients underwent watchful waiting and 112 received conservative management. Without surgery, death rates were higher for women and older patients, while the risk of dying doubled for each centimetre of aneurysm diameter at baseline. Of the remaining patients, 150 underwent stent grafting and 135 had open surgery. One-year overall survival was 83% after stent grafting and 79% after open surgery but the difference could be due to chance. The factors affecting survival after stent grafting or open surgery were aneurysm location, age, breathlessness and time waiting for a procedure. Small aneurysms are low risk, so blood pressure management and smoking cessation are recommended. For larger aneurysms, it is important that surgery is not delayed, as a longer waiting time to surgery means that outcomes are poorer. Only about half of patients who had surgery were considered suitable for both stent grafting and open surgery, which limited the ability to determine the best use of NHS resources. No comparative cost-effectiveness analysis was feasible. The main cost in a stent grafting procedure was the stent graft, and the main cost in an open surgery procedure was days in an intensive care unit.

Reference Case Methods for Expert Elicitation in Health Care Decision Making.

BACKGROUND: The evidence used to inform health care decision making (HCDM) is typically uncertain. In these situations, the experience of experts is essential to help decision makers reach a decision. Structured expert elicitation (referred to as elicitation) is a quantitative process to capture experts' beliefs. There is heterogeneity in the existing elicitation methodology used in HCDM, and it is not clear if existing guidelines are appropriate for use in this context. In this article, we seek to establish reference case methods for elicitation to inform HCDM. METHODS: We collated the methods available for elicitation using reviews and critique. In addition, we conducted controlled experiments to test the accuracy of alternative methods. We determined the suitability of the methods choices for use in HCDM according to a predefined set of principles for elicitation in HCDM, which we have also generated. We determined reference case methods for elicitation in HCDM for health technology assessment (HTA). RESULTS: In almost all methods choices available for elicitation, we found a lack of empirical evidence supporting recommendations. Despite this, it is possible to define reference case methods for HTA. The reference methods include a focus on gathering experts with substantive knowledge of the quantities being elicited as opposed to those trained in probability and statistics, eliciting quantities that the expert might observe directly, and individual elicitation of beliefs, rather than solely consensus methods. It is likely that there are additional considerations for decision makers in health care outside of HTA. CONCLUSIONS: The reference case developed here allows the use of different methods, depending on the decision-making setting. Further applied examples of elicitation methods would be useful. Experimental evidence comparing methods should be generated.

Aneurysm growth, survival, and quality of life in untreated thoracic aortic aneurysms: the effective treatments for thoracic aortic aneurysms study.

AIMS: To observe, describe, and evaluate management and timing of intervention for patients with untreated thoracic aortic aneurysms. METHODS AND RESULTS: Prospective study of UK National Health Service (NHS) patients aged ≥18 years, with new/existing arch or descending thoracic aortic aneurysms of ≥4 cm diameter, followed up until death, intervention, withdrawal, or July 2019. Outcomes were aneurysm growth, survival, quality of life (using the EQ-5D-5L utility index), and hospital admissions. Between 2014 and 2018, 886 patients were recruited from 30 NHS vascular/cardiothoracic units. Maximum aneurysm diameter was in the descending aorta in 725 (82%) patients, growing at 0.2 cm (0.17-0.24) per year. Aneurysms of ≥4 cm in the arch increased by 0.07 cm (0.02-0.12) per year. Baseline diameter was related to age and comorbidities, and no clinical correlates of growth were found. During follow-up, 129 patients died, 64 from aneurysm-related events. Adjusting for age, sex, and New York Heart Association dyspnoea index, risk of death increased with aneurysm size at baseline [hazard ratio (HR): 1.88 (95% confidence interval: 1.64-2.16) per cm, P < 0.001] and with growth [HR: 2.02 (1.70-2.41) per cm, P < 0.001]. Hospital admissions increased with aneurysm size [relative risk: 1.21 (1.05-1.38) per cm, P = 0.008]. Quality of life decreased annually for each 10-year increase in age [-0.013 (-0.019 to -0.007), P < 0.001] and for current smoking [-0.043 (-0.064 to -0.023), P = 0.004]. Aneurysm size was not associated with change in quality of life. CONCLUSION: International guidelines should consider increasing monitoring intervals to 12 months for small aneurysms and increasing intervention thresholds. Individualized decisions about surveillance/intervention should consider age, sex, size, growth, patient characteristics, and surgical risk.

Developing a reference protocol for structured expert elicitation in health-care decision-making: a mixed-methods study.

BACKGROUND: Many decisions in health care aim to maximise health, requiring judgements about interventions that may have higher health effects but potentially incur additional costs (cost-effectiveness framework). The evidence used to establish cost-effectiveness is typically uncertain and it is important that this uncertainty is characterised. In situations in which evidence is uncertain, the experience of experts is essential. The process by which the beliefs of experts can be formally collected in a quantitative manner is structured expert elicitation. There is heterogeneity in the existing methodology used in health-care decision-making. A number of guidelines are available for structured expert elicitation; however, it is not clear if any of these are appropriate for health-care decision-making. OBJECTIVES: The overall aim was to establish a protocol for structured expert elicitation to inform health-care decision-making. The objectives are to (1) provide clarity on methods for collecting and using experts' judgements, (2) consider when alternative methodology may be required in particular contexts, (3) establish preferred approaches for elicitation on a range of parameters, (4) determine which elicitation methods allow experts to express uncertainty and (5) determine the usefulness of the reference protocol developed. METHODS: A mixed-methods approach was used: systemic review, targeted searches, experimental work and narrative synthesis. A review of the existing guidelines for structured expert elicitation was conducted. This identified the approaches used in existing guidelines (the 'choices') and determined if dominant approaches exist. Targeted review searches were conducted for selection of experts, level of elicitation, fitting and aggregation, assessing accuracy of judgements and heuristics and biases. To sift through the available choices, a set of principles that underpin the use of structured expert elicitation in health-care decision-making was defined using evidence generated from the targeted searches, quantities to elicit experimental evidence and consideration of constraints in health-care decision-making. These principles, including fitness for purpose and reflecting individual expert uncertainty, were applied to the set of choices to establish a reference protocol. An applied evaluation of the developed reference protocol was also undertaken. RESULTS: For many elements of structured expert elicitation, there was a lack of consistency across the existing guidelines. In almost all choices, there was a lack of empirical evidence supporting recommendations, and in some circumstances the principles are unable to provide sufficient justification for discounting particular choices. It is possible to define reference methods for health technology assessment. These include a focus on gathering experts with substantive skills, eliciting observable quantities and individual elicitation of beliefs. Additional considerations are required for decision-makers outside health technology assessment, for example at a local level, or for early technologies. Access to experts may be limited and in some circumstances group discussion may be needed to generate a distribution. LIMITATIONS: The major limitation of the work conducted here lies not in the methods employed in the current work but in the evidence available from the wider literature relating to how appropriate particular methodological choices are. CONCLUSIONS: The reference protocol is flexible in many choices. This may be a useful characteristic, as it is possible to apply this reference protocol across different settings. Further applied studies, which use the choices specified in this reference protocol, are required. FUNDING: This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 37. See the NIHR Journals Library website for further project information. This work was also funded by the Medical Research Council (reference MR/N028511/1).

BACKGROUND: Decisions in health care aim to maximise health, requiring judgements about treatments. The evidence used to make these judgements is typically uncertain. In these situations, the experience of experts is essential. Structured expert elicitation collects beliefs from experts. There are different guidelines available for structured expert elicitation; however, it is not clear if any of these be can be used in health-care decision-making, for example in considering if a treatment should be made available in the NHS. This project aimed to develop a guidance for structured expert elicitation to inform health-care decision-making. METHODS: Reviews and experimental techniques were used to gather a list of methods to conduct structured expert elicitation. The suitability of these choices in health-care decision-making was then determined by comparing these with a set of standards that support the use of structured expert elicitation in health-care decision-making. RESULTS: Different guidelines prefer different approaches to conduct structured expert elicitation. There is a lack of evidence available to determine which of these methods is most appropriate across the whole of health-care decision-making. It is possible to define reference protocol methods that could be used in a particular type of health-care decision-making, health technology assessment. This includes gathering experts with knowledge of the clinical area, asking experts about things that they observe in clinical practice and asking experts individually for their beliefs. For decision-makers working outside health technology assessment, for example at a local level, or for treatments that are not yet available to patients, these choices may not be appropriate. CONCLUSIONS: This flexibility of this guidance is a useful feature. It is possible for different decision-makers in health care to interpret the reference protocol for their own circumstances.

Including random centre effects in design, analysis and presentation of multi-centre trials.

BACKGROUND: In large multicentre trials in diverse settings, there is uncertainty about the need to adjust for centre variation in design and analysis. A key distinction is the difference between variation in outcome (independent of treatment) and variation in treatment effect. Through re-analysis of the CRASH-2 trial (2010), this study clarifies when and how to use multi-level models for multicentre studies with binary outcomes. METHODS: CRASH-2 randomised 20,127 trauma patients across 271 centres and 40 countries to either single-dose tranexamic acid or identical placebo, with all-cause death at 4 weeks the primary outcome. The trial data had a hierarchical structure, with patients nested in hospitals which in turn are nested within countries. Reanalysis of CRASH-2 trial data assessed treatment effect and both patient and centre level baseline covariates as fixed effects in logistic regression models. Random effects were included to assess where there was variation between countries, and between centres within countries, both in underlying risk of death and in treatment effect. RESULTS: In CRASH-2, there was significant variation between countries and between centres in death at 4 weeks, but absolutely no differences between countries or centres in the effect of treatment. Average treatment effect was not altered after accounting for centre and country variation in this study. CONCLUSIONS: It is important to distinguish between underlying variation in outcomes and variation in treatment effects; the former is common but the latter is not. Stratifying randomisation by centre overcomes many statistical problems and including random intercepts in analysis may increase power and decrease bias in mean and standard error estimates. TRIAL REGISTRATION: Current Controlled Trials ISRCTN86750102 , ClinicalTrials.gov NCT00375258 , and South African Clinical Trial Register DOH-27-0607-1919.

Probabilistic linkage without personal information successfully linked national clinical datasets.

BACKGROUND: Probabilistic linkage can link patients from different clinical databases without the need for personal information. If accurate linkage can be achieved, it would accelerate the use of linked datasets to address important clinical and public health questions. OBJECTIVE: We developed a step-by-step process for probabilistic linkage of national clinical and administrative datasets without personal information, and validated it against deterministic linkage using patient identifiers. STUDY DESIGN AND SETTING: We used electronic health records from the National Bowel Cancer Audit and Hospital Episode Statistics databases for 10,566 bowel cancer patients undergoing emergency surgery in the English National Health Service. RESULTS: Probabilistic linkage linked 81.4% of National Bowel Cancer Audit records to Hospital Episode Statistics, vs. 82.8% using deterministic linkage. No systematic differences were seen between patients that were and were not linked, and regression models for mortality and length of hospital stay according to patient and tumour characteristics were not sensitive to the linkage approach. CONCLUSION: Probabilistic linkage was successful in linking national clinical and administrative datasets for patients undergoing a major surgical procedure. It allows analysts outside highly secure data environments to undertake linkage while minimizing costs and delays, protecting data security, and maintaining linkage quality.

Systematic review of endovascular stent grafting versus open surgical repair for the elective treatment of arch/descending thoracic aortic aneurysms.

OBJECTIVE: To review comparisons of the effectiveness of endovascular stent grafting (ESG) against open surgical repair (OSR) for treatment of chronic arch or descending thoracic aortic aneurysms (TAA). DESIGN: Systematic review and meta-analysis DATA SOURCES: MEDLINE, EMBASE, CENTRAL, WHO International Clinical Trials Routine data collection, current controlled trials, clinical trials and the NIHR portfolio were searched from January 1994 to March 2020. ELIGIBILITY CRITERIA FOR SELECTIVE STUDIES: All identified studies that compared ESG and OSR, including randomised controlled trials (RCTs), quasi-randomised and non-RCTs, comparative cohort studies and case-control studies matched on main outcomes were sought. Participants had to receive elective treatments for arch/descending (TAA). Studies were excluded where other thoracic aortic conditions (eg, rupture or dissection) were reported, unless results for patients receiving elective treatment for arch/descending TAA reported separately. DATA EXTRACTION AND SYNTHESIS: Data were extracted by one reviewer and checked by another. Risk of Bias was assessed using the ROBINS-I tool. Meta-analysis was conducted using random effects. Where meta-analysis not appropriate, results were reported narratively. RESULTS: Five comparative cohort studies met inclusion criteria, reporting 3955 ESG and 21 197 OSR patients. Meta-analysis of unadjusted short-term (30 day) all-cause mortality favoured ESG (OR 0.75; 95% CI 0.55 to 1.03)). Heterogeneity identified between larger and smaller studies. Sensitivity analysis of four studies including only descending TAA showed no statistical significance (OR 0.73, 95% CI 0.45 to 1.18)), moderate heterogeneity. Meta-analysis of adjusted short-term all-cause mortality favoured ESG (OR 0.71, 95% CI 0.51 to 0.98)), no heterogeneity. Longer-term (beyond 30 days) survival from all-cause mortality favoured OSR in larger studies and ESG in smaller studies. Freedom from reintervention in the longer-term favoured OSR. Studies reporting short-term non-fatal complications suggest fewer events following ESG. CONCLUSIONS: There is limited and increasingly dated evidence on the comparison of ESG and OSR for treatment of arch/descending TAA. PROSPERO REGISTRATION NUMBER: CRD42017054565.

Power and sample size for multistate model analysis of longitudinal discrete outcomes in disease prevention trials.

For clinical trials where participants pass through a number of discrete health states resulting in longitudinal measures over time, there are several potential primary estimands for the treatment effect. Incidence or time to a particular health state are commonly used outcomes but the choice of health state may not be obvious and these estimands do not make full use of the longitudinal assessments. Multistate models have been developed for some diseases and conditions with the purpose of understanding their natural history and have been used for secondary analysis to understand mechanisms of action of treatments. There is little published on the use of multistate models as the primary analysis method and potential implications on design features, such as assessment schedules. We illustrate methods via analysis of data from a motivating example; a Phase III clinical trial of pressure ulcer prevention strategies. We clarify some of the possible estimands that might be considered and we show, via a simulation study, that under some circumstances the sample size could be reduced by half using a multistate model based analysis, without adversely affecting the power of the trial.