Assessing methods for dealing with treatment switching in randomised controlled trials: a simulation study

<p>Abstract</p> <p>Background</p> <p>We investigate methods used to analyse the results of clinical trials with survival outcomes in which some patients switch from their allocated treatment to another trial treatment. These included simple methods which are commonly used in medical literature and may be subject to selection bias if patients switching are not typical of the population as a whole. Methods which attempt to adjust the estimated treatment effect, either through adjustment to the hazard ratio or via accelerated failure time models, were also considered. A simulation study was conducted to assess the performance of each method in a number of different scenarios.</p> <p>Results</p> <p>16 different scenarios were identified which differed by the proportion of patients switching, underlying prognosis of switchers and the size of true treatment effect. 1000 datasets were simulated for each of these and all methods applied. Selection bias was observed in simple methods when the difference in survival between switchers and non-switchers were large. A number of methods, particularly the AFT method of Branson and Whitehead were found to give less biased estimates of the true treatment effect in these situations.</p> <p>Conclusions</p> <p>Simple methods are often not appropriate to deal with treatment switching. Alternative approaches such as the Branson & Whitehead method to adjust for switching should be considered.</p

A phase-I trial of pre-operative, margin intensive, stereotactic body radiation therapy for pancreatic cancer: the 'SPARC' trial protocol.

BACKGROUND: Standard therapy for borderline-resectable pancreatic cancer in the UK is surgery with adjuvant chemotherapy, but rates of resection with clear margins are unsatisfactory and overall survival remains poor. Meta-analysis of single-arm studies shows the potential of neo-adjuvant chemo-radiotherapy but the relative radio-resistance of pancreatic cancer means the efficacy of conventional dose schedules is limited. Stereotactic radiotherapy achieves sufficient accuracy and precision to enable pre-operative margin-intensive dose escalation with the goal of increasing rates of clear resection margins and local disease control. METHODS/DESIGN: SPARC is a "rolling-six" design single-arm study to establish the maximum tolerated dose for margin-intensive stereotactic radiotherapy before resection of pancreatic cancer at high risk of positive resection margins. Eligible patients will have histologically or cytologically proven pancreatic cancer defined as borderline-resectable per National Comprehensive Cancer Network criteria or operable tumour in contact with vessels increasing the risk of positive margin. Up to 24 patients will be recruited from up to 5 treating centres and a 'rolling-six' design is utilised to minimise delays and facilitate ongoing recruitment during dose-escalation. Radiotherapy will be delivered in 5 daily fractions and surgery, if appropriate, will take place 5-6 weeks after radiotherapy. The margin-intense radiotherapy concept includes a systematic method to define the target volume for a simultaneous integrated boost in the region of tumour-vessel infiltration, and up to 4 radiotherapy dose levels will be investigated. Maximum tolerated dose is defined as the highest dose at which no more than 1 of 6 patients or 0 of 3 patients experience a dose limiting toxicity. Secondary endpoints include resection rate, resection margin status, response rate, overall survival and progression free survival at 12 and 24 months. Translational work will involve exploratory analyses of the cytological and humoral immunological responses to stereotactic radiotherapy in pancreatic cancer. Radiotherapy quality assurance of target definition and radiotherapy planning is enforced with pre-trial test cases and on-trial review. Recruitment began in April 2015. DISCUSSION: This prospective multi-centre study aims to establish the maximum tolerated dose of pre-operative margin-intensified stereotactic radiotherapy in pancreatic cancer at high risk of positive resection margins with a view to subsequent definitive comparison with other neoadjuvant treatment options

Risk prediction models in perioperative medicine: methodological considerations

Purpose of Review: Risk prediction models hold enormous potential for assessing surgical risk in a standardized, objective manner. Despite the vast number of risk prediction models developed, they have not lived up to their potential. The aim of this paper is to provide an overview of the methodological issues that should be considered when developing and validating a risk prediction model to ensure a useful, accurate model. Recent Findings: Systematic reviews examining the methodological and reporting quality of these models have found widespread deficiencies that limit their usefulness. Summary: Risk prediction modelling is a growing field that is gaining huge interest in the era of personalized medicine. Although there are no shortcuts and many challenges are faced when developing and validating accurate, useful prediction models, these challenges are surmountable, if the abundant methodological and practical guidance available is used correctly and efficiently

Risk prediction models in perioperative medicine: methodological considerations

Identifying individuals who are at increased risk of mortality or major morbidity following surgical procedures is an important challenge in patient management. Multivariable risk prediction models (e.g., EuroSCORE, POSSUM, and the STS Risk Calculator) have been developed to help surgeons calculate a patient’s risk of mortality using a combination of risk factors. These prediction models have transformed preoperative risk assessment. Studies evaluating the performance of risk prediction models in this and other areas of medicine have, however, been characterized by poor design, methodological conduct, and reporting. We discuss the main methodological considerations behind risk prediction models and critically discuss issues in their design, validation, and transparency

A systematic review and meta-analysis of patient data from the West Africa (2013–16) Ebola virus disease epidemic

BACKGROUND:Over 28 000 individuals were infected with Ebola virus during the West Africa (2013-2016) epidemic, yet there has been criticism of the lack of robust clinical descriptions of Ebola virus disease (EVD) illness from that outbreak. OBJECTIVES:To perform a meta-analysis of published data from the epidemic to describe the clinical presentation, evolution of disease, and predictors of mortality in individuals with EVD. To assess the quality and utility of published data for clinical and public health decision-making. DATA SOURCES:Primary articles available in PubMed and published between January 2014 and May 2017. ELIGIBILITY:Studies that sequentially enrolled individuals hospitalized for EVD and that reported acute clinical outcomes. METHODS:We performed meta-analyses using random-effect models and assessed heterogeneity using the I2 method. We assessed data representativeness by comparing meta-analysis estimates with WHO aggregate data. We examined data utility by examining the availability and compatibility of data sets. RESULTS:In all, 3653 articles were screened and 34 articles were included, representing 16 independent cohorts of patients (18 overlapping cohorts) and at least 6168 individuals. The pooled estimate for case fatality rate was 51% (95% CI 46%-56%). However, pooling of estimates for clinical presentation, progression, and predictors of mortality in individuals with EVD were hampered by significant heterogeneity, and inadequate data on clinical progression. Our assessment of data quality found that heterogeneity was largely unexplained, and data availability and compatibility were poor. CONCLUSIONS:We have quantified a missed opportunity to generate reliable estimates of the clinical manifestations of EVD during the West Africa epidemic. Clinical data standards and data capture platforms are urgently needed

A systematic review and meta-analysis of patient data from the West Africa (2013–16) Ebola virus disease epidemic

BACKGROUND:Over 28 000 individuals were infected with Ebola virus during the West Africa (2013-2016) epidemic, yet there has been criticism of the lack of robust clinical descriptions of Ebola virus disease (EVD) illness from that outbreak. OBJECTIVES:To perform a meta-analysis of published data from the epidemic to describe the clinical presentation, evolution of disease, and predictors of mortality in individuals with EVD. To assess the quality and utility of published data for clinical and public health decision-making. DATA SOURCES:Primary articles available in PubMed and published between January 2014 and May 2017. ELIGIBILITY:Studies that sequentially enrolled individuals hospitalized for EVD and that reported acute clinical outcomes. METHODS:We performed meta-analyses using random-effect models and assessed heterogeneity using the I2 method. We assessed data representativeness by comparing meta-analysis estimates with WHO aggregate data. We examined data utility by examining the availability and compatibility of data sets. RESULTS:In all, 3653 articles were screened and 34 articles were included, representing 16 independent cohorts of patients (18 overlapping cohorts) and at least 6168 individuals. The pooled estimate for case fatality rate was 51% (95% CI 46%-56%). However, pooling of estimates for clinical presentation, progression, and predictors of mortality in individuals with EVD were hampered by significant heterogeneity, and inadequate data on clinical progression. Our assessment of data quality found that heterogeneity was largely unexplained, and data availability and compatibility were poor. CONCLUSIONS:We have quantified a missed opportunity to generate reliable estimates of the clinical manifestations of EVD during the West Africa epidemic. Clinical data standards and data capture platforms are urgently needed

Effectiveness of intermittent preventive treatment with sulphadoxine-pyrimethamine for control of malaria in pregnancy in western Kenya: a hospital-based study

OBJECTIVE To monitor the effectiveness of intermittent preventive treatment (IPT) with sulphadoxine-pyrimethamine (SP) for the control of malaria in pregnancy at delivery in the Provincial Hospital in Kisumu, Kenya, and to assess the effect of IPT in participants in a cohort study. METHODS Between June 1999 and June 2000, information on IPT and birth outcome was collected in 2302 consecutive deliveries. A group of 889 women, who were enrolled in a cohort to assess the interaction between malaria and HIV, were analysed separately because of the enrolment criteria and different access to health care. RESULTS The prevalence of placental malaria was 13.8% and of low birthweight (LBW) was 12.2%. In multivariable analysis, IPT (greater than or equal to1 dose of SP) was associated with a reduction in placental malaria and LBW [adjusted odds ratio (OR) 0.56, 95% confidence interval (CI) 0.39-0.83 and OR 0.65, 95% CI 0.45-0.95, respectively]. An adjusted mean increase in birthweight of 61 g was seen (95% CI 22-101 g) for each increment in number of SP doses (greater than or equal to2 doses grouped together). IPT was associated with a reduction in placental malaria in HIV-seronegative women (OR 0.49, 95% CI 0.28-0.86) but this was not significant among HIV-seropositive women (OR 0.45, 95% CI 0.20-1.05). A significant effect on birthweight could not be detected among participants in the HIV-cohort. CONCLUSIONS This evaluation confirms that IPT with SP is effective in reducing placental malaria and LBW. It will be important to increase coverage of IPT and to extend IPT to antenatal clinics in peri-urban and rural area

Clinical effectiveness and cost-effectiveness of cognitive behavioural therapy as an adjunct to pharmacotherapy for treatment-resistant depression in primary care: the CoBalT randomised controlled trial.

BACKGROUND: Only one-third of patients with depression respond fully to treatment with antidepressant medication. However, there is little robust evidence to guide the management of those whose symptoms are 'treatment resistant'. OBJECTIVE: The CoBalT trial examined the clinical effectiveness and cost-effectiveness of cognitive behavioural therapy (CBT) as an adjunct to usual care (including pharmacotherapy) for primary care patients with treatment-resistant depression (TRD) compared with usual care alone. DESIGN: Pragmatic, multicentre individually randomised controlled trial with follow-up at 3, 6, 9 and 12 months. A subset took part in a qualitative study investigating views and experiences of CBT, reasons for completing/not completing therapy, and usual care for TRD. SETTING: General practices in Bristol, Exeter and Glasgow, and surrounding areas. PARTICIPANTS: Patients aged 18-75 years who had TRD [on antidepressants for ≥ 6 weeks, had adhered to medication, Beck Depression Inventory, 2nd version (BDI-II) score of ≥ 14 and fulfilled the International Classification of Diseases and Related Health Problems, Tenth edition criteria for depression]. Individuals were excluded who (1) had bipolar disorder/psychosis or major alcohol/substance abuse problems; (2) were unable to complete the questionnaires; or (3) were pregnant, as were those currently receiving CBT/other psychotherapy/secondary care for depression, or who had received CBT in the past 3 years. INTERVENTIONS: Participants were randomised, using a computer-generated code, to usual care or CBT (12-18 sessions) in addition to usual care. MAIN OUTCOME MEASURES: The primary outcome was 'response', defined as ≥ 50% reduction in depressive symptoms (BDI-II score) at 6 months compared with baseline. Secondary outcomes included BDI-II score as a continuous variable, remission of symptoms (BDI-II score of &lt; 10), quality of life, anxiety and antidepressant use at 6 and 12 months. Data on health and social care use, personal costs, and time off work were collected at 6 and 12 months. Costs from these three perspectives were reported using a cost-consequence analysis. A cost-utility analysis compared health and social care costs with quality adjusted life-years. RESULTS: A total of 469 patients were randomised (intervention: n = 234; usual care: n = 235), with 422 participants (90%) and 396 (84%) followed up at 6 and 12 months. Ninety-five participants (46.1%) in the intervention group met criteria for 'response' at 6 months compared with 46 (21.6%) in the usual-care group {odds ratio [OR] 3.26 [95% confidence interval (CI) 2.10 to 5.06], p &lt; 0.001}. In repeated measures analyses using data from 6 and 12 months, the OR for 'response' was 2.89 (95% CI 2.03 to 4.10, p &lt; 0.001) and for a secondary 'remission' outcome (BDI-II score of &lt; 10) 2.74 (95% CI 1.82 to 4.13, p &lt; 0.001). The mean cost of CBT per participant was £ 910, the incremental health and social care cost £ 850, the incremental QALY gain 0.057 and incremental cost-effectiveness ratio £ 14,911. Forty participants were interviewed. Patients described CBT as challenging but helping them to manage their depression; listed social, emotional and practical reasons for not completing treatment; and described usual care as mainly taking medication. CONCLUSIONS: Among patients who have not responded to antidepressants, augmenting usual care with CBT is effective in reducing depressive symptoms, and these effects, including outcomes reflecting remission, are maintained over 12 months. The intervention was cost-effective based on the National Institute for Health and Care Excellence threshold. Patients may experience CBT as difficult but effective. Further research should evaluate long-term effectiveness, as this would have major implications for the recommended treatment of depression. TRIAL REGISTRATION: Current Controlled Trials ISRCTN38231611