Association of a Shortened Duration of Adjuvant Chemotherapy With Overall Survival Among Individuals With Stage III Colon Cancer

Target Trial Emulation: Improving the Quality of Observational Studies in Inflammatory Bowel Disease Using the Principles of Randomized Trials

The past decade has seen a substantial increase in the number of randomized controlled trials (RCTs) conducted in inflammatory bowel disease (IBD). Randomized controlled trials are the gold standard method for generating robust evidence of drug safety and efficacy but are expensive, time-consuming, and may have ethical implications. Observational studies in IBD are often used to fill the gaps in evidence but are typically hindered by significant bias. There are several approaches for making statistical inferences from observational data with some that focus on study design and others on statistical techniques. Target trial emulation is an emerging methodological process that aims to bridge this gap and improve the quality of observational studies by applying the principles of an ideal, or "target," randomized trial to routinely collected clinical data. There has been a rapid expansion of observational studies that have emulated trials over the past 5 years in other medical fields, but this has yet to be adopted in gastroenterology and IBD. The wealth of nonrandomized clinical data available through electronic health records, patient registries, and administrative health databases afford innumerable hypothesis-generating opportunities for IBD research. This review outlines the principles of target trial emulation, discusses the merits to IBD observational studies in reducing the most common biases and improving confidence in causality, and details the caveats of using this approach.

Patients with T4N0 and T1‑3N1 colon cancer and a high preoperative carcinoembryonic antigen level benefit from adjuvant chemotherapy with oxaliplatin for 6 months

A shorter duration of oxaliplatin adjuvant chemotherapy has recently emerged as a potential option for patients with high-risk stage II and low-risk stage III (T1-3N1) colon cancer (CC). The present study aimed to elucidate the risk factors for recurrence in these patient populations and to identify the appropriate indications for shortened treatment durations. The present study retrospectively analyzed 396 patients who underwent curative surgery for pathological T4N0 or stage III CC, followed by adjuvant chemotherapy, at two institutes. Overall, 234 patients with T4N0 and low-risk stage III CC were categorized into the low-risk group and 162 patients with high-risk stage III CC into the high-risk group. The 3-year relapse-free survival rate was significantly higher in the low-risk group than in the high-risk group. Multivariate Cox model analysis of the low-risk group revealed that high preoperative serum levels of carcinoembryonic antigen (CEA) and incomplete 6-month adjuvant chemotherapy with oxaliplatin were independent poor prognostic factors. The prognosis of patients in the low-risk group who had abnormal CEA levels and did not complete the 6-month adjuvant treatment with oxaliplatin was similar to that of patients in the high-risk group. However, the prognosis of patients in the low-risk group with high CEA levels improved with a 6-month adjuvant treatment with oxaliplatin to a similar level to that of all patients with low CEA levels in the low-risk group. In conclusion, the present study suggested that the duration of adjuvant chemotherapy with oxaliplatin should not be shortened in patients with high preoperative CEA levels, even in the low-risk group.

Using Trial and Observational Data to Assess Effectiveness: Trial Emulation, Transportability, Benchmarking, and Joint Analysis

Comparisons between randomized trial analyses and observational analyses that attempt to address similar research questions have generated many controversies in epidemiology and the social sciences. There has been little consensus on when such comparisons are reasonable, what their implications are for the validity of observational analyses, or whether trial and observational analyses can be integrated to address effectiveness questions. Here, we consider methods for using observational analyses to complement trial analyses when assessing treatment effectiveness. First, we review the framework for designing observational analyses that emulate target trials and present an evidence map of its recent applications. We then review approaches for estimating the average treatment effect in the target population underlying the emulation, using observational analyses of the emulation data alone and using transportability analyses to extend inferences from a trial to the target population. We explain how comparing treatment effect estimates from the emulation against those from the trial can provide evidence on whether observational analyses can be trusted to deliver valid estimates of effectiveness-a process we refer to as benchmarking-and, in some cases, allow the joint analysis of the trial and observational data. We illustrate different approaches using a simplified example of a pragmatic trial and its emulation in registry data. We conclude that synthesizing trial and observational data-in transportability, benchmarking, or joint analyses-can leverage their complementary strengths to enhance learning about comparative effectiveness, through a process combining quantitative methods and epidemiologic judgments.

Chinese herbal medicine (JianPi-BuShen) and completion rate of adjuvant chemotherapy for patients with stage II and III colon cancer: A randomized clinical trial

PURPOSE

Many cancer patients express interest in using herbal medicine during chemotherapy, but little is known about its benefits and risks. This study aimed to evaluate the effects of the Chinese herbal medicine JianPi-BuShen formula (JPBS) on adjuvant chemotherapy completion in colon cancer patients.

PATIENTS AND METHODS

This multi-center, phase III, randomized, placebo-controlled trial included patients with stage II (high risk for recurrence) and stage III colon cancer following surgery, planning to receive CAPOX (capecitabine and oxaliplatin) chemotherapy. Patients were randomized 1:1 to receive either JPBS or a placebo. The primary outcome was the completion rate of planned chemotherapy cycles. Secondary outcomes included relative dose intensity (RDI), chemotherapy-induced toxicities, quality of life (measured by the Edmonton Symptom Assessment System - ESAS), adverse events (AEs), and serious AEs (SAEs). Predefined subgroup analyses were performed by age (>65/≤65) and TNM stage (II/III).

RESULTS

A total of 376 participants were analyzed, with a median age of 60.3 years; 56.9 % were male, and 67.6 % had stage III disease. Chemotherapy completion was significantly higher in the JPBS group than in the placebo group (63.0 % vs. 47.6 %, P = 0.003). Oxaliplatin RDI was also higher in the JPBS group (P = 0.049). Subgroup analyses showed JPBS significantly improved completion rates for stage II patients (73.0 % vs. 42.4 %, P = 0.001) and younger patients (66.9 % vs. 48.8 %, P = 0.004). JPBS reduced grade ≥ 2 vomiting (3.8 % vs. 6.4 %, P = 0.007) but increased grade ≥ 2 thrombocytopenia (16.2 % vs. 12.4 %, P = 0.012). Quality of life improved in stage II and younger patients.

CONCLUSION

JPBS improved chemotherapy completion rates in stage II and younger colon cancer patients without compromising tolerability. Further research is needed to explore its mechanisms and long-term effects.

De-Mystifying the Clone-Censor-Weight Method for Causal Research Using Observational Data: A Primer for Cancer Researchers

BACKGROUND

Regulators and oncology healthcare providers are increasingly interested in using observational studies of real-world data (RWD) to complement clinical evidence from randomized controlled trials for informed decision-making. To generate valid evidence, RWD studies must be carefully designed to avoid systematic biases. The clone-censor-weight (CCW) method has been proposed to address immortal time and other time-related biases.

METHODS

The objective of this manuscript is to de-mystify the CCW method for cancer researchers by describing and presenting its core components in an accessible and digestible format, using visualizations and examples from cancer-relevant studies. The CCW method has been applied in diverse settings, including investigations of the effects of surgery within a certain time after cancer diagnosis, the continuation of annual screening mammography, and chemotherapy duration on survival.

RESULTS

The method handles complex data wherein the treatment group to which an individual belongs is unknown at the start of follow-up. The three steps of the CCW method involve cloning or duplicating the patient population and assigning one clone to each treatment strategy, artificially censoring the clones when their observed data are inconsistent with the assigned strategy and weighting the cloned and censored population to address selection bias created by the artificial censoring.

CONCLUSIONS

The CCW method is a powerful tool for designing RWD studies in cancer that are free from time-related biases and successfully, to the extent possible, emulate features of a randomized clinical trial.

Overall survival after CDK4/6 inhibitor dose reduction in women with metastatic breast cancer

BACKGROUND

Breast cancer is the most common cancer in women, and the first-line treatment for patients with hormone-receptor positive/HER2-negative metastatic breast cancer is CDK4/6 inhibitor plus endocrine therapy. Understanding the impact of CDK4/6 inhibitor dose reduction, which occurs in about half of the patients, is important.

METHODS

This real-world cohort study is based on electronic health records from Capital Region of Denmark. All women with metastatic breast cancer initiating first-line treatment with CDK4/6 inhibitor between May 2017 and October 2022 were included.

RESULTS

A total of 546 patients were eligible for inclusion in the 12-week landmark analysis and 192 (35%) experienced dose reduction. These patients were older, had worse ECOG PS, more received prior adjuvant endocrine treatment, and more received fulvestrant as the endocrine backbone. Dose reduction was associated with reduced overall survival (39.9 vs. 54.3 months) and shorter treatment duration (18.0 vs. 26.9 months). Adjusted hazard ratio for death was 1.38 (95% CI: 1.01-1.89).

CONCLUSIONS

Dose reduction of CDK4/6 inhibitors within the first 12 weeks of treatment was associated with significantly higher mortality and shorter treatment duration. These findings contrast with previous analyses showing no effect of dose reduction, likely due to considering immortal time bias in this study.

Comparative effectiveness of treatment approaches for early invasive breast cancer

BACKGROUND

Randomized controlled trials (RCTs) suggested breast conserving therapy (BCT) and mastectomy have similar survival for early-stage breast cancer, whereas observational studies reported survival advantage for BCT. We aimed to address biases in observational studies to compare the effect of BCT and mastectomy on survival.

METHODS

We emulated a target trial using institutional cancer registry. We included adult women diagnosed with early invasive first primary breast tumors ≤ 5 cm between July 2011 and December 2017. We used cloning, censoring, and weighting to estimate risk differences (RDs) and risk ratios (RRs) for all-cause mortality and recurrence or all-cause mortality between BCT and mastectomy (reference).

RESULTS

Our study population comprised 534 observations with breast cancer. Median age was 56 years and 65 % were racial/ethnic minorities. The 8-year RD was 1.5 % (95 % confidence limits [CL]: -7.0 %, 9.8 %) and RR was 1.1 (95 % CL: 0.57, 2.2) for all-cause mortality. Results for recurrence or mortality were similar.

CONCLUSIONS

Our results suggest that target trial emulation to mitigate selection and immortal-time biases in observational studies may generate estimates that are more compatible with RCTs when comparing the effects of BCT and mastectomy on survival. Studies with longer follow-up and more events are needed to confirm our findings.

Target trial framework for determining the effect of changes in training load on injury risk using observational data: a methodological commentary

In recent years, a large focus has been placed on managing training load for injury prevention. To minimise injuries, training recommendations should be based on research that examines causal relationships between load and injury risk. While observational studies can be used to estimate causal effects, conventional methods to study the relationship between load and injury are prone to bias. The target trial framework is a valuable tool that requires researchers to emulate a hypothetical randomised trial using observational data. This framework helps to explicitly define research questions and design studies in a way that estimates causal effects. This article provides an overview of the components of the target trial framework as applied to studies on load and injury and describes various considerations that should be made in study design and analyses to minimise bias.

Optimising the use of electronic medical records for large scale research in psychiatry

The explosion and abundance of digital data could facilitate large-scale research for psychiatry and mental health. Research using so-called "real world data"-such as electronic medical/health records-can be resource-efficient, facilitate rapid hypothesis generation and testing, complement existing evidence (e.g. from trials and evidence-synthesis) and may enable a route to translate evidence into clinically effective, outcomes-driven care for patient populations that may be under-represented. However, the interpretation and processing of real-world data sources is complex because the clinically important 'signal' is often contained in both structured and unstructured (narrative or "free-text") data. Techniques for extracting meaningful information (signal) from unstructured text exist and have advanced the re-use of routinely collected clinical data, but these techniques require cautious evaluation. In this paper, we survey the opportunities, risks and progress made in the use of electronic medical record (real-world) data for psychiatric research.

Acceptability of Using Real-World Data to Estimate Relative Treatment Effects in Health Technology Assessments: Barriers and Future Steps

OBJECTIVES

Evidence about the comparative effects of new treatments is typically collected in randomized controlled trials (RCTs). In some instances, RCTs are not possible, or their value is limited by an inability to capture treatment effects over the longer term or in all relevant population subgroups. In these cases, nonrandomized studies (NRS) using real-world data (RWD) are increasingly used to complement trial evidence on treatment effects for health technology assessment (HTA). However, there have been concerns over a lack of acceptability of this evidence by HTA agencies. This article aims to identify the barriers to the acceptance of NRS and steps that may facilitate increases in the acceptability of NRS in the future.

METHODS

Opinions of the authorship team based on their experience in real-world evidence research in academic, HTA, and industry settings, supported by a critical assessment of existing studies.

RESULTS

Barriers were identified that are applicable to key stakeholder groups, including HTA agencies (eg, the lack of comprehensive methodological guidelines for using RWD), evidence generators (eg, avoidable deviations from best practices), and external stakeholders (eg, data controllers providing timely access to high-quality RWD). Future steps that may facilitate future acceptability of NRS include improvements in the quality, integration, and accessibility of RWD, wider use of demonstration projects to highlight the value and applicability of nonrandomized designs, living, and more detailed HTA guidelines, and improvements in HTA infrastructure relating to RWD.

CONCLUSION

NRS can represent a crucial source of evidence on treatment effects for use in HTA when RCT evidence is limited.

Adjuvant Ovarian Function Suppression in Premenopausal Hormone Receptor-Positive Breast Cancer

Importance

Few oncology studies have assessed the effectiveness of adjuvant ovarian function suppression (OFS) in observational settings for premenopausal hormone receptor-positive breast cancer. Target trial emulation is increasingly used for estimating treatment outcomes in observational cohorts.

Objectives

To describe hormone therapy and OFS treatment patterns (aim 1), examine the association between adding OFS to tamoxifen (TAM) or aromatase inhibitor (AI) and survival (aim 2), and examine the association between duration of hormone treatment (TAM or AI) plus OFS (H-OFS) and survival (aim 3).

Design, Setting, and Participants

This population-based cohort study included all premenopausal, early-stage breast cancer diagnoses between 2010 and 2020 in Alberta, Canada. Target trial emulation was conducted. Eligibility criteria were directly modeled after the Suppression of Ovarian Function Trial (SOFT) and Tamoxifen and Exemestane Trial (TEXT). Participants were followed up for a maximum of 5 years. Data were analyzed from July 2022 through March 2023.

Exposures

For aim 2, exposures were receiving the following baseline treatments for 2 years: AI + OFS (AI-OFS), TAM + OFS (T-OFS), and TAM alone. For aim 3, exposures were a 2-year or greater and a less than 2-year duration of H-OFS.

Main Outcomes and Measures

Recurrence-free survival was the primary outcome of interest. Marginal structural Cox models with inverse probability treatment and censoring weights were used to estimate hazard ratios (HRs), adjusted for baseline and time-varying confounding variables.

Results

Among 3434 female patients with premenopausal, early-stage breast cancer diagnoses (median [IQR] age, 45 [40-48] years), 2647 individuals satisfied SOFT and TEXT eligibility criteria. There were 2260 patients who initiated TAM, 232 patients who initiated T-OFS, and 155 patients who initiated AI-OFS; 192 patients received H-OFS for 2 or more years, and 195 patients received H-OFS for less than 2 years. The 5-year recurrence risks were not significantly lower in AI-OFS vs TAM (HR, 0.76; 95% CI, 0.38-1.33) or T-OFS vs TAM (HR, 0.87; 95% CI, 0.50-1.45) groups. Patients receiving H-OFS for 2 or more years had significantly better 5-year recurrence-free survival compared with those receiving H-OFS for less than 2 years (HR, 0.69; 95% CI, 0.54-0.90).

Conclusions and Relevance

This study found no significant reductions in recurrence risk for AI-OFS and T-OFS compared with TAM alone. H-OFS duration for at least 2 years was associated with significantly improved recurrence-free survival.

Effects of Physical Activity on Cardiotoxicity and Cardio respiratory Function in Cancer Survivors Undergoing Chemotherapy: A Systematic Review and Meta-Analysis

Introduction: Physical activity, as a promising complementary therapy, has shown considerable potential for reducing chemotherapy-related cardiotoxicity (CTRCT) and enhancing cardiorespiratory function (CRF). This study aimed to systematically assess the effects of physical activity on CTRCT and CRF in various cancer survivors receiving chemotherapy. Methods: A systematic review and meta-analysis was conducted. A literature search was conducted across 8 databases from inception to January 2024 and was limited to the English and Chinese languages. Statistical analysis was conducted using RevMan 5.3 and Stata 17.0 software. Results: Sixteen randomized controlled trials (RCTs) were included in the systematic review and 15 RCTs were included in the meta-analysis. Among various cancer survivors undergoing chemotherapy, physical activity markedly increased absolute oxygen uptake (VO2peak or VO2max; WMD = 292.99, 95% confidence interval [CI]:87.87 to 498.12, P = .005), with significant effects of subgroup analysis at 4 to 10 weeks (P = .02) or over 16 weeks (P < .01), moderate-to-high or high intensity training (both P < .0001), patients with breast cancer (P = .009) and reported CTRCT (P = .007); relative VO2peak or VO2max(WMD = 3.30, 95%CI: 2.02 to 4.58, P < .00001), with significant effects of subgroup analysis at 10 to 16 weeks or over 16 weeks, moderate-to-high or high intensity training, patients with breast cancer, with or without reported CTRCT and exercise during chemotherapy (all P < .01); E/A values (WMD = 0.11, 95%CI:0.03 to 0.18, P = .007) and flow-mediated dilatation (WMD = 2.71, 95%CI:1.49 to 3.94, P < .0001). Compared to the control group, physical activity had no significant improvement in E/e' values (P = .50), NT-proBNP (P = .12), hs-cTn (P = 3.83), left ventricular ejection fraction (WMD = 2.89, 95%CI: -3.28 to 9.06, P = .36) with non-significant effects being independent of exercise intensity or duration, with or without CTRCT and cancer types (all P > .05), and global longitudinal strain (WMD = 0.37, 95%CI: -0.20 to 0.94, P = .20) with non-significant effects being independent of exercise duration and cancer types(both P > .05). Conclusions: Physical activity may be an effective complementary therapy to improve CRF and CTRCT in various cancer survivors, particularly during medium to long duration and moderate-to-high and high intensity exercise with concurrent chemotherapy.

Target trial emulation: Do antimicrobials or gastrointestinal nutraceuticals prescribed at first presentation for acute diarrhoea cause a better clinical outcome in dogs under primary veterinary care in the UK?

Target trial emulation applies design principles from randomised controlled trials to the analysis of observational data for causal inference and is increasingly used within human epidemiology. Veterinary electronic clinical records represent a potentially valuable source of information to estimate real-world causal effects for companion animal species. This study employed the target trial framework to evaluate the usefulness on veterinary observational data. Acute diarrhoea in dogs was used as a clinical exemplar. Inclusion required dogs aged ≥ 3 months and < 10 years, presenting for veterinary primary care with acute diarrhoea during 2019. Treatment strategies were: 1. antimicrobial prescription compared to no antimicrobial prescription and 2. gastrointestinal nutraceutical prescription compared to no gastrointestinal nutraceutical prescription. The primary outcome was clinical resolution (defined as no revisit with ongoing diarrhoea within 30 days from the date of first presentation). Informed from a directed acyclic graph, data on the following covariates were collected: age, breed, bodyweight, insurance status, comorbidities, vomiting, reduced appetite, haematochezia, pyrexia, duration, additional treatment prescription and veterinary group. Inverse probability of treatment weighting was used to balance covariates between the treatment groups for each of the two target trials. The risk difference (RD) of 0.4% (95% CI -4.5% to 5.3%) was non-significant for clinical resolution in dogs treated with antimicrobials compared with dogs not treated with antimicrobials. The risk difference (RD) of 0.3% (95% CI -4.5% to 5.0%) was non-significant for clinical resolution in dogs treated with gastrointestinal nutraceuticals compared with dogs not treated with gastrointestinal nutraceuticals. This study successfully applied the target trial framework to veterinary observational data. The findings show that antimicrobial or gastrointestinal prescription at first presentation of acute diarrhoea in dogs causes no difference in clinical resolution. The findings support the recommendation for veterinary professionals to limit antimicrobial use for acute diarrhoea in dogs.

The implementation of target trial emulation for causal inference: a scoping review

OBJECTIVES

We aim to investigate the implementation of Target Trial Emulation (TTE) for causal inference, involving research topics, frequently used strategies, and issues indicating the need for future improvements.

STUDY DESIGN AND SETTING

We performed a scoping review by following the Joanna Briggs Institute (JBI) guidance and Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist. A health research-focused librarian searched multiple medical databases, and two independent reviewers completed screening and extraction within covidence review management software.

RESULTS

Our search resulted in 1,240 papers, of which 96 papers were eligible for data extraction. Results show a significant increase in the use of TTE in 2018 and 2021. The study topics varied and focused primarily on cancer, cardiovascular and cerebrovascular diseases, and infectious diseases. However, not all papers specified well all three critical components for generating robust causal evidence: time-zero, random assignment simulation, and comparison strategy. Some common issues were observed from retrieved papers, and key limitations include residual confounding, limited generalizability, and a lack of reporting guidance that need to be improved.

CONCLUSION

Uneven adherence to the TTE framework exists, and future improvements are needed to progress applications using causal inference with observational data.

Reporting of Observational Studies Explicitly Aiming to Emulate Randomized Trials: A Systematic Review

Importance

Observational (nonexperimental) studies that aim to emulate a randomized trial (ie, the target trial) are increasingly informing medical and policy decision-making, but it is unclear how these studies are reported in the literature. Consistent reporting is essential for quality appraisal, evidence synthesis, and translation of evidence to policy and practice.

Objective

To assess the reporting of observational studies that explicitly aimed to emulate a target trial.

Evidence Review

We searched Medline, Embase, PsycINFO, and Web of Science for observational studies published between March 2012 and October 2022 that explicitly aimed to emulate a target trial of a health or medical intervention. Two reviewers double-screened and -extracted data on study characteristics, key predefined components of the target trial protocol and its emulation (eligibility criteria, treatment strategies, treatment assignment, outcome[s], follow-up, causal contrast[s], and analysis plan), and other items related to the target trial emulation.

Findings

A total of 200 studies that explicitly aimed to emulate a target trial were included. These studies included 26 subfields of medicine, and 168 (84%) were published from January 2020 to October 2022. The aim to emulate a target trial was explicit in 70 study titles (35%). Forty-three studies (22%) reported use of a published reporting guideline (eg, Strengthening the Reporting of Observational Studies in Epidemiology). Eighty-five studies (43%) did not describe all key items of how the target trial was emulated and 113 (57%) did not describe the protocol of the target trial and its emulation.

Conclusion and Relevance

In this systematic review of 200 studies that explicitly aimed to emulate a target trial, reporting of how the target trial was emulated was inconsistent. A reporting guideline for studies explicitly aiming to emulate a target trial may improve the reporting of the target trial protocols and other aspects of these emulation attempts.

Target Trial Emulation to Improve Causal Inference from Observational Data: What, Why, and How?

ABSTRACT

Target trial emulation has drastically improved the quality of observational studies investigating the effects of interventions. Its ability to prevent avoidable biases that have plagued many observational analyses has contributed to its recent popularity. This review explains what target trial emulation is, why it should be the standard approach for causal observational studies that investigate interventions, and how to do a target trial emulation analysis. We discuss the merits of target trial emulation compared with often used, but biased analyses, as well as potential caveats, and provide clinicians and researchers with the tools to better interpret results from observational studies investigating the effects of interventions.

The Association of Oxaliplatin-Containing Adjuvant Chemotherapy Duration with Overall and Cancer-Specific Mortality in Individuals with Stage III Colon Cancer: A Population-Based Retrospective Cohort Study

PURPOSE

Few studies have examined the relationship between duration of oxaliplatin-containing adjuvant chemotherapy for stage III colon cancer and mortality in routine practice. We examined the association between treatment with 50% versus >85% of a maximal course of adjuvant therapy (eight cycles of CAPOX, twelve cycles of FOLFOX) and mortality in stage III colon cancer.

METHODS

Using linked databases, we identified Ontarians aged ≥18 years at diagnosis of stage III colon cancer between 2007 and 2019. In the primary comparison, we compared patients who received 50% or >85% of a maximal course of adjuvant therapy; in a secondary comparison, we evaluated a dose effect across patients who received FOLFOX in one-cycle increments from six to ten cycles against >85% (more than ten cycles) of a maximal course of FOLFOX. The main outcomes were overall and cancer-specific mortality. Follow-up began 270 days after adjuvant treatment initiation and terminated at the first of the outcome of interest, loss of eligibility for Ontario's Health Insurance Program, or study end. Overlap propensity score weights accounted for baseline between-group differences. We determined the hazard ratio, estimating the association between mortality and treatment. Non-inferiority was concluded in the primary comparison for either outcome if the upper limit of the two-sided 95% CI was ≤1.11, which is the margin used in the International Duration Evaluation of Adjuvant Chemotherapy Collaboration.

RESULTS

We included 3546 patients in the analysis of overall mortality; 486 (13.7%) received 50% and 3060 (86.3%) received >85% of a maximal course of therapy. Median follow-up was 5.4 years, and total follow-up was 20,510 person-years. There were 833 deaths. Treatment with 50% of a maximal course of adjuvant therapy was associated with a hazard ratio of 1.13 (95% CI 0.88 to 1.47) for overall mortality and a subdistribution hazard ratio of 1.31 (95% CI 0.91 to 1.87) for cancer-specific mortality versus >85% of a maximal course of therapy. In the secondary comparison, there was a trend toward higher overall mortality in patients treated with shorter durations of therapy, though confidence intervals overlapped considerably.

CONCLUSION

We could not conclude that treatment with 50% of a maximal course is non-inferior to >85% of a maximal course of adjuvant therapy for mortality in stage III colon cancer. Clinicians and patients engaging in decision-making around treatment duration in this context should carefully consider the trade-off between treatment effectiveness and adverse effects of treatment.

Target Trial Emulation for Transparent and Robust Estimation of Treatment Effects for Health Technology Assessment Using Real-World Data: Opportunities and Challenges

Evidence about the relative effects of new treatments is typically collected in randomised controlled trials (RCTs). In many instances, evidence from RCTs falls short of the needs of health technology assessment (HTA). For example, RCTs may not be able to capture longer-term treatment effects, or include all relevant comparators and outcomes required for HTA purposes. Information routinely collected about patients and the care they receive have been increasingly used to complement RCT evidence on treatment effects. However, such routine (or real-world) data are not collected for research purposes, so investigators have little control over the way patients are selected into the study or allocated to the different treatment groups, introducing biases for example due to selection or confounding. A promising approach to minimise common biases in non-randomised studies that use real-world data (RWD) is to apply design principles from RCTs. This approach, known as 'target trial emulation' (TTE), involves (1) developing the protocol with respect to core study design and analysis components of the hypothetical RCT that would answer the question of interest, and (2) applying this protocol to the RWD so that it mimics the data that would have been gathered for the RCT. By making the 'target trial' explicit, TTE helps avoid common design flaws and methodological pitfalls in the analysis of non-randomised studies, keeping each step transparent and accessible. It provides a coherent framework that embeds existing analytical methods to minimise confounding and helps identify potential limitations of RWD and the extent to which these affect the HTA decision. This paper provides a broad overview of TTE and discusses the opportunities and challenges of using this approach in HTA. We describe the basic principles of trial emulation, outline some areas where TTE using RWD can help complement RCT evidence in HTA, identify potential barriers to its adoption in the HTA setting and highlight some priorities for future work.