Emulating a target trial in case-control designs: an application to statins and colorectal cancer

Tiotropium Initiation and Dementia Risk in Chronic Obstructive Pulmonary Disease

Importance

Long-acting muscarinic antagonists (LAMAs), such as tiotropium, are inhaled anticholinergic bronchodilators. However, there is limited clinical evidence examining whether LAMAs may have clinically meaningful central anticholinergic effects, such as increased dementia risk.

Objective

To determine the association between tiotropium initiation and dementia risk in older adults with chronic obstructive pulmonary disease (COPD).

Design, Setting, and Participants

This population-based, active-comparator, new-user cohort study used linkable administrative databases from Ontario, Canada, with a target trial emulation framework. The cohort included new users of tiotropium monotherapy or a long-acting β2-agonist plus inhaled corticosteroid (LABA-ICS) who were 66 years or older with COPD and without dementia, from September 4, 2004, to February 29, 2012. The follow-up period was up to 10 years from treatment initiation. Analyses were conducted from May 13, 2024, to March 6, 2025.

Exposures

Tiotropium monotherapy initiators were compared with LABA-ICS initiators. The primary analysis used an intention-to-treat exposure definition.

Main Outcomes and Measures

Incident dementia was determined using a validated algorithm. A 1-year lag time was implemented to mitigate reverse causality and to account for disease latency. Cause-specific hazard ratios (HRs) with death as a competing risk were obtained from Cox models with propensity score fine stratification weights. Weighted incidence rate differences (IRDs) per 1000 person-years were calculated.

Results

Among 30 960 tiotropium monotherapy initiators and 19 530 LABA-ICS initiators, the mean (SD) age was 75.1 (6.7) years and 46.7% were female. Over a median (IQR) follow-up period of 7.59 (3.91-10.0) years from treatment initiation, tiotropium monotherapy vs LABA-ICS initiation was associated with a small increase in dementia risk per 1000 person-years (incidence rates, 29.6 [95% CI, 28.8-30.4] vs 27.4 [95% CI, 26.4-28.3]; IRD, 2.3 [95% CI, 1.0-3.5]; HR, 1.09 [95% CI, 1.04-1.14]). The secondary as-treated analysis showed no significant association per 1000 person-years (incidence rates, 24.1 [95% CI, 22.2-26.0] vs 21.4 [95% CI, 18.5-24.3]; IRD, 2.7 [95% CI, -0.8 to 6.1]; HR, 1.11 [95% CI, 0.93-1.32]).

Conclusions and Relevance

In this cohort study, among older adults with COPD, the small absolute rate increase in incident dementia associated with tiotropium monotherapy vs LABA-ICS was of questionable clinical importance, particularly when weighed against the established clinical benefits of tiotropium.

Methodologies for the Emulation of Biomarker-Guided Trials Using Observational Data: A Systematic Review

Background: Target trial emulation involves the application of design principles from randomised controlled trials (RCTs) to observational data, and is particularly useful in situations where an RCT would be unfeasible. Biomarker-guided trials, which incorporate biomarkers within their design to either guide treatment and/or determine eligibility, are often unfeasible in practice due to sample size requirements or ethical concerns. Here, we undertake a systematic review of methodologies used in target trial emulations, comparing treatment effectiveness, critically appraising them, and considering their applicability to the emulation of biomarker-guided trials. Methods: A comprehensive search strategy was developed to identify studies reporting on methods for target trial emulation comparing the effectiveness of treatments using observational data, and applied to the following bibliographic databases: PubMed, Scopus, Web of Science, and Ovid MEDLINE. A narrative description of methods identified in the review was undertaken alongside a critique of their relative strengths and limitations. Results: We identified a total of 59 papers: 47 emulating a target trial ('application' studies), and 12 detailing methods to emulate a target trial ('methods' studies). A total of 25 papers were identified as emulating a biomarker-guided trial (42%). While all papers reported methods to adjust for baseline confounding, 40% of application papers did not specify methods to adjust for time-varying confounding. Conclusions: This systematic review has identified a range of methods used to control for baseline, time-varying, and residual/unmeasured confounding within target trial emulation and provides a guide for researchers interested in emulation of biomarker-guided trials.

Use of β-adrenoreceptor drugs and Parkinson's disease incidence in women from the French E3N cohort study

BackgroundExperimental and observational studies suggest that β-adrenoreceptor drugs (β2-agonists/β-antagonists) are associated with Parkinson's disease (PD) risk. Previous epidemiological studies may be hampered by reverse causation/confounding.ObjectiveWe examined the association of β-adrenoreceptor drugs with PD incidence, while addressing reverse causation and confounding in the E3N cohort study (2004-2018) using a new-user design.MethodsIncident β2-agonists/β-antagonists users were identified through drug claims databases. Incident PD was ascertained using multiple sources and validated by experts. Drugs-PD associations were assessed using time-varying Cox proportional hazards models adjusted for multiple confounders. Main analyses used a 5y-exposure lag to address reverse causation; sensitivity analyses used a 2y-lag or no lag. We set up a nested case-control study to compare trajectories of β2-agonists/β-antagonists prescriptions before diagnosis using logistic mixed models.ResultsAnalyses for β2-agonists were based on 81,890 women; 15,169 started using β2-agonists and 579 developed PD. PD incidence was 36% lower (hazard ratio = 0.64, 95% confidence interval = 0.41-0.98; p-trend = 0.04 for the number of claims) in users of long-acting/ultra-long-acting β2-agonists (LABAs/ultra-LABAs) compared to never users. There was no significant association for β2-agonists overall and short-acting β2-agonists. Analyses for β-antagonists were based on 75,896 women; 13,081 started using β-antagonists and 552 developed PD. PD incidence was similar in ever and never users in analyses with a 5y-lag but was higher in ever than never users in analyses with 2y-lag or no lag.ConclusionsIncident use of LABAs/ultra-LABAs is associated with lower PD incidence in women. Conversely, the association between β-antagonists and PD in women is likely due to reverse causation.

Statin Use and Risk of Intracerebral Hemorrhage in Chinese Population: A Target Trial Emulation Study

BACKGROUND AND OBJECTIVES

Statins have been shown to prevent major vascular events in a wide range of individuals. However, their potential mechanisms-such as impairing fibrinogen cleavage and reducing thrombin generation-raise concerns on increased risk of intracerebral hemorrhage (ICH). Given the inconsistent findings of previous trials and observational studies, this study aims to assess the effect of statins on ICH risk in Chinese population.

METHODS

Within the framework of target trial emulation, we used data from the Yinzhou Regional Health Care Database covering the years 2011-2020. The study included patients aged 50 years or older with no history of ICH and statin use. After applying inclusion and exclusion criteria, patients were categorized as statin initiators or noninitiators based on their initial treatment regimen during the 1-month enrollment period. Using the sequential trial approach, 60 target trials were emulated each month from 2011 to 2015. Propensity score (PS) matching was applied to balance characteristics between statin initiators and noninitiators within each emulated trial, and these trials were then stacked together into a single data set. Cox proportional hazards models were used to estimate the effects of statin on ICH risk, ICH-related mortality, and all-cause mortality.

RESULTS

A total of 53,413 statin initiators and 35,033,455 noninitiators from 60 emulated trials were included in the analysis. Statin initiators were generally older (mean age 65 vs 63 years), less likely to be male (45.5% vs 50.5%), and more likely to have a history of hypertension (69.0% vs 14.1%). After PS matching, all characteristics between the 2 groups were well balanced. With a median follow-up of 6.7 (interquartile range 5.6-8.1) years, the hazard ratio (HR) of ICH for statin initiators compared with noninitiators was 1.18 (95% CI 1.03-1.35). The HRs of ICH-related mortality and all-cause mortality were 1.16 (95% CI 0.91-1.46) and 0.92 (95% CI 0.88-0.97), respectively. Results remained consistent across various subgroup and sensitivity analyses.

DISCUSSION

Statin use may increase the risk of ICH in Chinese patients without history of ICH. However, the findings of this study may be limited by residual confounding, particularly the lack of cholesterol-related measurements.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that in Chinese populations, initiation of statins may increase the risk of ICH.

Invited commentary: target trial emulation-a call for more widespread use

Causal inference methods intended for use with observational data have been widely available for decades, but barriers to their widespread adoption exist. These likely include lack of familiarity with several methodological techniques often used in combination in these investigations, such as inverse probability of treatment weighting and g-estimation, and the intensity of computational effort needed to employ these techniques. Even with these methods, critical design flaws undermine the ability to make valid causal inference in some studies. Identification of the need to explicitly pair study design elements with these causal inference methods led to development of a methodological approach recently termed target trial emulation. This approach requires that investigators define a hypothetical randomized trial, emulate that hypothetical protocol in assembling the cohort and defining study elements, and then conduct an analysis that attempts to mirror random treatment assignment. In the accompanying article by Heindel et al (Am J Epidemiol. 2025;194(3):651-658), the authors successfully emulate a target trial of systemic heparin during arteriovenous fistula creation on short-term endpoints by utilizing data from 2 existing randomized trials with key confounders available. Target trial emulation provides a framework with which to promote valid inference and generate high-quality contributions to the literature, and its use should be expanded.

A Structural Description of Biases That Generate Immortal Time

Immortal time may arise in survival analyses when individuals are assigned to treatment strategies based on post-eligibility information or selected based on post-assignment eligibility criteria. Selection based on eligibility criteria applied after treatment assignment results in immortal time when the analysis starts the follow-up at assignment. Misclassification of assignment to treatment strategies based on treatment received after eligibility results in immortal time when the treatment strategies are not distinguishable at the start of follow-up. Target trial emulation prevents the introduction of immortal time by explicitly specifying eligibility and assignment to the treatment strategies, and by synchronizing them at the start of follow-up. We summarize analytic approaches that prevent immortal time when longitudinal data are available to emulate the target trial from the time of treatment assignment. The term "immortal time bias" suggests that the source of the bias is the immortal time, but it is selection or misclassification that generates the immortal time, leading to bias.

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.

Later-age neutering causes lower risk of early-onset urinary incontinence than early neutering-a VetCompass target trial emulation study

There is growing evidence supporting clinically important associations between age at neutering in bitches and subsequent urinary incontinence (UI), although much of this evidence to date is considered weak. Target trial emulation is an innovative approach in causal inference that has gained substantial attention in recent years, aiming to simulate a hypothetical randomised controlled trial by leveraging observational data. Using anonymised veterinary clinical data from the VetCompass Programme, this study applied the target trial emulation framework to determine whether later-age neutering (≥ 7 to ≤ 18 months) causes decreased odds of early-onset UI (diagnosed < 8.5 years) compared to early-age neutering (3 to < 7 months). The study included bitches in the VetCompass database born from January 1, 2010, to December 31, 2012, and neutered between 3 and 18 months old. Bitches were retrospectively confirmed from the electronic health records as neutered early or later. The primary outcome was a diagnosis of early-onset UI. Informed from a directed acyclic graph, data on the following covariates were extracted: breed, insurance status, co-morbidities and veterinary group. Inverse probability of treatment weighting was used to adjust for confounding, with inverse probability of censoring weighting accounting for censored bitches. The emulated trial included 612 early-age neutered bitches and 888 later-age neutered bitches. A pooled logistic regression outcome model identified bitches neutered later at 0.80 times the odds (95% CI 0.54 to 0.97) of early-onset UI compared with bitches neutered early. The findings show that later-age neutering causes reduced odds of early-onset UI diagnosis compared with early-age neutering. Decision-making on the age of neutering should be carefully considered, with preference given to delaying neutering until after 7 months of age unless other major reasons justify earlier surgery. The study is one of the first to demonstrate successful application of the target trial framework to veterinary observational data.

Designing target trials using electronic health records: A case study of second-line disease-modifying anti-rheumatic drugs and cardiovascular disease outcomes in patients with rheumatoid arthritis

BACKGROUND

Emulation of the "target trial" (TT), a hypothetical pragmatic randomized controlled trial (RCT), using observational data can be used to mitigate issues commonly encountered in comparative effectiveness research (CER) when randomized trials are not logistically, ethically, or financially feasible. However, cardiovascular (CV) health research has been slow to adopt TT emulation. Here, we demonstrate the design and analysis of a TT emulation using electronic health records to study the comparative effectiveness of the addition of a disease-modifying anti-rheumatic drug (DMARD) to a regimen of methotrexate on CV events among rheumatoid arthritis (RA) patients.

METHODS

We used data from an electronic medical records-based cohort of RA patients from Northwestern Medicine to emulate the TT. Follow-up began 3 months after initial prescription of MTX (2000-2020) and included all available follow-up through June 30, 2020. Weighted pooled logistic regression was used to estimate differences in CVD risk and survival. Cloning was used to handle immortal time bias and weights to improve baseline and time-varying covariate imbalance.

RESULTS

We identified 659 eligible people with RA with average follow-up of 46 months and 31 MACE events. The month 24 adjusted risk difference for MACE comparing initiation vs non-initiation of a DMARD was -1.47% (95% confidence interval [CI]: -4.74, 1.95%), and the marginal hazard ratio (HR) was 0.72 (95% CI: 0.71, 1.23). In analyses subject to immortal time bias, the HR was 0.62 (95% CI: 0.29-1.44).

CONCLUSION

In this sample, we did not observe evidence of differences in risk of MACE, a finding that is compatible with previously published meta-analyses of RCTs. Thoughtful application of the TT framework provides opportunities to conduct CER in observational data. Benchmarking results of observational analyses to previously published RCTs can lend credibility to interpretation.

Making causal inferences from transactional data: A narrative review of opportunities and challenges when implementing the target trial framework

The target trial framework has emerged as a powerful tool for addressing causal questions in clinical practice and in public health. In the healthcare sector, where decision-making is increasingly data-driven, transactional databases, such as electronic health records (EHR) and insurance claims, present an untapped potential for answering complex causal questions. This narrative review explores the potential of the integration of the target trial framework with real-world data to enhance healthcare decision-making processes. We outline essential elements of the target trial framework, and identify pertinent challenges in data quality, privacy concerns, and methodological limitations, proposing solutions to overcome these obstacles and optimize the framework's application.

Patients on vitamin K treatment: is switching to direct-acting oral anticoagulation cost-effective? A target trial on a prospective cohort

AIMS

Direct-acting oral anticoagulants (DOACs) have, to a substantial degree, replaced vitamin K antagonists (VKA) as treatments for stroke prevention in atrial fibrillation (AF) patients. However, evidence on the real-world causal effects of switching patients from VKA to DOAC is lacking. We aimed to assess the empirical incremental cost-effectiveness of switching patients to DOAC compared with maintaining VKA treatment.

METHODS

The target trial approach was applied to the prospective observational Swiss-AF cohort, which enrolled 2415 AF patients from 2014 to 2017. Clinical data, healthcare resource utilisation and EQ-5D-based utilities representing quality of life were collected in yearly follow-ups. Health insurance claims were available for 1024 patients (42.4%). Overall survival, quality-of-life, costs from the Swiss statutory health insurance perspective and cost-effectiveness were estimated by emulating a target trial in which patients were randomly assigned to switch to DOAC or maintain VKA treatment.

RESULTS

228 patients switching from VKA to DOAC compared with 563 patients maintaining VKA treatment had no overall survival advantage over a 5-year observation period (HR 0.99, 95% CI 0.45, 1.55). The estimated gain in quality-adjusted life years (QALYs) was 0.003 over the 5-year period at an incremental costs of CHF 23 033 (€ 20 940). The estimated incremental cost-effectiveness ratio was CHF 425 852 (€ 387 138) per QALY gained.

CONCLUSIONS

Applying a causal inference method to real-world data, we could not demonstrate switching to DOACs to be cost-effective for AF patients with at least 1 year of VKA treatment. Our estimates align with results from a previous randomised trial.

Real-World Cost-Effectiveness of Pulmonary Vein Isolation for Atrial Fibrillation: A Target Trial Approach

OBJECTIVES

Randomized controlled trials of pulmonary vein isolation (PVI) for treating atrial fibrillation (AF) have proven the procedure's efficacy. Studies assessing its empirical cost-effectiveness outside randomized trial settings are lacking. We aimed to evaluate the effectiveness and cost-effectiveness of PVI versus medical therapy for AF.

METHODS

We followed a target trial approach using the Swiss-AF cohort, a prospective observational cohort study that enrolled patients with AF between 2014 and 2017. Resource utilization and cost information were collected through claims data. Quality of life was measured with EQ-5D-3L utilities. We estimated incremental cost-effectiveness ratios (ICERs) from the perspective of the Swiss statutory health insurance system.

RESULTS

Patients undergoing PVI compared with medical therapy had a 5-year overall survival advantage with a hazard ratio of 0.75 (95% CI 0.46-1.21; P = .69) and a 19.8% SD improvement in quality of life (95% CI 15.5-22.9; P < .001), at an incremental cost of 29 604 Swiss francs (CHF) (95% CI 16 354-42 855; P < .001). The estimated ICER was CHF 158 612 per quality-adjusted life-year (QALY) gained within a 5-year time horizon. Assuming similar health effects and costs over 5 additional years changed the ICER to CHF 82 195 per QALY gained. Results were robust to the sensitivity analyses performed.

CONCLUSIONS

Our results show that PVI might be a cost-effective intervention within the Swiss healthcare context in a 10-year time horizon, but unlikely to be so at 5 years, if a willingness-to-pay threshold of CHF 100 000 per QALY gained is assumed. Given data availability, we find target trial designs are a valuable tool for assessing the cost-effectiveness of healthcare interventions outside of randomized controlled trial settings.

Comparative Risks of Infection With Belimumab Versus Oral Immunosuppressants in Patients With Nonrenal Systemic Lupus Erythematosus

OBJECTIVE

We investigated the comparative risk of infection with belimumab versus oral immunosuppressants for the treatment of systemic lupus erythematosus (SLE).

METHODS

Using observational data from a US multicenter electronic health record database, we identified patients with SLE but without lupus nephritis who initiated belimumab, azathioprine, methotrexate, or mycophenolate between 2011 and 2021. We designed and emulated hypothetical target trials to estimate the cumulative incidence and hazard ratios (HRs) of serious infection and hospitalization for serious infection comparing belimumab versus each oral immunosuppressant. We used propensity score overlap weighting to balance baseline covariates and adjusted for adherence to treatment group using inverse probability of treatment weighting. We also assessed the control outcome of traumatic injury.

RESULTS

Among 21,481 patients, we compared 2841 and 6343 initiators of belimumab and azathioprine, 2642 and 8242 initiators of belimumab and methotrexate, and 2813 and 8407 initiators of belimumab and mycophenolate, respectively. After propensity score overlap weighting, all covariates were balanced in each comparison. The mean age of the cohort was 45 years, and 94% were women. Compared with azathioprine and mycophenolate, belimumab was associated with lower risks of both serious infection (HR 0.82; 95% confidence interval [CI] 0.72-0.92 and HR 0.69; 95% CI 0.61-0.78) and hospitalization for infection (HR 0.73; 95% CI 0.57-0.94 and HR 0.56 95% CI 0.43-0.71). The risk of infection was also lower for belimumab compared with methotrexate (HR 0.86; 95% CI 0.76-0.97). There were no differences in traumatic injury risks across treatment groups.

CONCLUSION

Belimumab was associated with lower risks of serious infection than with oral immunosuppressants. This finding should inform risk/benefit considerations for SLE treatment.

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.

Parkinson's disease diagnosis codes are insufficiently accurate for electronic health record research and differ by race

BACKGROUND

There are no evidence-based guidelines for data cleaning of electronic health record (EHR) databases in Parkinson's disease (PD). Previous filtering criteria have primarily used the 9th International Statistical Classification of Diseases and Related Health Problems (ICD) with variable accuracy for true PD cases. Prior studies have not excluded atypical or drug-induced parkinsonism, and little is known about differences in accuracy by race.

OBJECTIVE

To determine if excluding parkinsonism diagnoses improves accuracy of ICD-9 and -10 PD diagnosis codes.

METHODS

We included ≥2 instances of an ICD-9 and/or -10 code for PD. We removed any records with at least one code indicating atypical or drug-induced parkinsonism first in all races, and then in Non-Hispanic White and Black patients. We manually reviewed 100 randomly selected charts per group before and after filtering, and performed a test of proportion (null hypothesis 0.5) for confirmed PD.

RESULTS

5633 records had ≥2 instances of a PD code. 2833 remained after filtering. The rate of true PD cases was low before and after filtering to remove parkinsonism codes (0.55 vs. 0.51, p = 0.84). Accuracy was lowest in Black patients before filtering (0.48, p = 0.69), but filtering had a greater (though modest) impact on accuracy (0.68, p < 0.001).

CONCLUSIONS

There was inadequate accuracy of PD diagnosis codes in the largest study of ICD-9 and -10 codes. Accuracy was lowest in Black patients but improved the most with removing other parkinsonism codes. This highlights the limitations of using current real-world EHR data in PD research and need for further study.

Statin use and risk of colorectal cancer in patients with inflammatory bowel disease

Background

Statin use has been linked to a reduced risk of advanced colorectal adenomas, but its association with colorectal cancer (CRC) in patients with inflammatory bowel disease (IBD) - a high risk population for CRC - remains inconclusive.

Methods

From a nationwide IBD cohort in Sweden, we identified 5273 statin users and 5273 non-statin users (1:1 propensity score matching) from July 2006 to December 2018. Statin use was defined as the first filled prescription for ≥30 cumulative defined daily doses and followed until December 2019. Primary outcome was incident CRC. Secondary outcomes were CRC-related mortality and all-cause mortality. Cox regression estimated adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs).

Findings

During a median follow-up of 5.6 years, 70 statin users (incidence rate (IR): 21.2 per 10,000 person-years) versus 90 non-statin users (IR: 29.2) were diagnosed with incident CRC (rate difference (RD), -8.0 (95% CIs: -15.8 to -0.2 per 10,000 person-years); aHR = 0.76 (95% CIs: 0.61 to 0.96)). The benefit for incident CRC was duration-dependent in a nested case-control design: as compared to short-term use (30 days to <1 year), the adjusted odd ratios were 0.59 (0.25 to 1.43) for 1 to <2 years of use, 0.46 (0.21 to 0.98) for 2 to <5 years of use, and 0.38 (0.16 to 0.86) for ≥5 years of use (Pfor tread = 0.016). Compared with non-statin users, statin users also had a decreased risk for CRC-related mortality (IR: 6.0 vs. 11.9; RD, -5.9 (-10.5 to -1.2); aHR, 0.56 (0.37 to 0.83)) and all-cause mortality (IR: 156.4 vs. 231.4; RD, -75.0 (-96.6 to -53.4); aHR, 0.63 (0.57 to 0.69)).

Interpretation

Statin use was associated with a lower risk of incident CRC, CRC-related mortality, and all-cause mortality. The benefit for incident CRC was duration-dependent, with a significantly lower risk after ≥2 years of statin use.

Funding

This research was supported by Forte (i.e., the Swedish Research Council for Health, Working Life and Welfare).

Implementation of the trial emulation approach in medical research: a scoping review

BACKGROUND

When conducting randomised controlled trials is impractical, an alternative is to carry out an observational study. However, making valid causal inferences from observational data is challenging because of the risk of several statistical biases. In 2016 Hernán and Robins put forward the 'target trial framework' as a guide to best design and analyse observational studies whilst preventing the most common biases. This framework consists of (1) clearly defining a causal question about an intervention, (2) specifying the protocol of the hypothetical trial, and (3) explaining how the observational data will be used to emulate it.

METHODS

The aim of this scoping review was to identify and review all explicit attempts of trial emulation studies across all medical fields. Embase, Medline and Web of Science were searched for trial emulation studies published in English from database inception to February 25, 2021. The following information was extracted from studies that were deemed eligible for review: the subject area, the type of observational data that they leveraged, and the statistical methods they used to address the following biases: (A) confounding bias, (B) immortal time bias, and (C) selection bias.

RESULTS

The search resulted in 617 studies, 38 of which we deemed eligible for review. Of those 38 studies, most focused on cardiology, infectious diseases or oncology and the majority used electronic health records/electronic medical records data and cohort studies data. Different statistical methods were used to address confounding at baseline and selection bias, predominantly conditioning on the confounders (N = 18/49, 37%) and inverse probability of censoring weighting (N = 7/20, 35%) respectively. Different approaches were used to address immortal time bias, assigning individuals to treatment strategies at start of follow-up based on their data available at that specific time (N = 21, 55%), using the sequential trial emulations approach (N = 11, 29%) or the cloning approach (N = 6, 16%).

CONCLUSION

Different methods can be leveraged to address (A) confounding bias, (B) immortal time bias, and (C) selection bias. When working with observational data, and if possible, the 'target trial' framework should be used as it provides a structured conceptual approach to observational research.

Vergleich der Effektivität von multiplen dynamischen Behandlungsstrategien unter Nutzung der Target-Trial-Emulierung

Hintergrund

Therapieentscheidungen, die durch „Wenn-dann“-Algorithmen basierend auf bspw. Krankheitsverläufen oder vergangenen Therapien geregelt werden, sind dynamische Fragestellungen. Die Effektivität von dynamischen Therapiestrategien wird häufig mit Real World Data (RWD), d. h. Realdaten, untersucht. Einerseits bieten RWD ein großes Potenzial, da hiermit viele unterschiedliche in der Routineversorgung vorkommende Therapiestrategien analysiert werden können. Andererseits bergen Effektschätzer aus RWD-Analysen ein hohes Verzerrungspotenzial.

Ziel der Arbeit

Dieser Artikel beschreibt, wie dynamische Behandlungsstrategien mithilfe von RWD adäquat verglichen und damit die optimale Therapiestrategie identifiziert werden können.

Material und Methoden

Wir beschreiben, wie die Kombination aus drei Ansätzen eine kausale Interpretation der Ergebnisse erlaubt. Hierzu gehören (1) Kausaldiagramme, (2) Target-Trial-Emulierung sowie (3) statistische g‑Methoden. Der beschriebene kausale Ansatz und die genannten Begriffe und Konzepte werden erläutert und anhand eines Fallbeispiels verdeutlicht, in welchem untersucht wird, wann die antivirale Therapie bei behandlungsnaiven Patient:innen mit HIV-Infektion begonnen werden sollte.

Ergebnisse

Kausaldiagramme visualisieren kausale Prozesse, die der Datengenerierung zugrunde liegen. Sie helfen, Parameter zu identifizieren, die in der Analyse berücksichtigt werden müssen. Die Target-Trial-Emulierung simuliert eine randomisierte klinische Studie, indem alle möglichen dynamischen Strategien definiert, die Patientendaten kopiert („geklont“) und jede:r Patient:in jedem Behandlungsarm zugewiesen werden. In einer kausalen Per-Protokoll-Analyse werden alle Patient:innen, die das jeweilige Protokoll einer Behandlungsstrategie verletzen, zensiert. Durch g‑Methoden wird für informatives Zensieren adjustiert. Die erwarteten Outcomes jeder Behandlungsstrategie werden simuliert und miteinander verglichen.

Schlussfolgerung

Dynamische Behandlungsstrategien können mithilfe von RWD adäquat verglichen werden, wenn drei kausale Ansätze kombiniert werden und die erforderlichen Daten vorliegen. Diese Ansätze sind (1) Kausaldiagramme, (2) Target-Trial-Emulierung sowie (3) statistische g‑Methoden.

Exploring new frontiers in prostate cancer research: Report from the 2022 Coffey-Holden prostate cancer academy meeting

INTRODUCTION

The 2022 Coffey-Holden Prostate Cancer Academy (CHPCA) Meeting, "Exploring New Frontiers in Prostate Cancer Research," was held from June 23 to 26, 2022, at the University of California, Los Angeles, Luskin Conference Center, in Los Angeles, CA.

METHODS

The CHPCA Meeting is an annual discussion-oriented scientific conference organized by the Prostate Cancer Foundation, that focuses on emerging and next-step topics deemed critical for making the next major advances in prostate cancer research and clinical care. The 2022 CHPCA Meeting included 35 talks over 10 sessions and was attended by 73 academic investigators.

RESULTS

Major topic areas discussed at the meeting included: prostate cancer diversity and disparities, the impact of social determinants on research and patient outcomes, leveraging real-world and retrospective data, development of artificial intelligence biomarkers, androgen receptor (AR) signaling biology and new strategies for targeting AR, features of homologous recombination deficient prostate cancer, and future directions in immunotherapy and nuclear theranostics.

DISCUSSION

This article summarizes the scientific presentations from the 2022 CHPCA Meeting, with the goal that dissemination of this knowledge will contribute to furthering global prostate cancer research efforts.

Assessing the role of lipid-lowering therapy on multi-cancer prevention: A mendelian randomization study

Background: Statin use for cancer prevention has raised wide attention but the conclusions are still controversial. Whether statins use have exact causal effects on cancer prevention remains unclear. Methods: Based on the Genome-Wide Association Studies (GWAS) datasets from the large prospective UK Biobank and other consortium databases, two-sample mendelian randomization (MR) analysis was conducted to explore the causal effects of statins use on varied site-specific cancer risks. Five MR methods were applied to investigate the causality. The stability, heterogeneity, and pleiotropy of MR results were also evaluated. Results: The atorvastatin use could increase the risk of colorectal cancer (odd ratio (OR) = 1.041, p = 0.035 by fixed-effects inverse variance weighted (IVW) method (IVW_FE), OR = 1.086, p = 0.005 by weighted median; OR = 1.101, p = 0.048 by weighted mode, respectively). According to the weighted median and weighted mode, atorvastatin could modestly decrease the risk of liver cell cancer (OR = 0.989, p = 0.049, and OR = 0.984, p = 0.004, respectively) and head and neck cancer (OR = 0.972, p = 0.020). Besides, rosuvastatin use could reduce the bile duct cancer risk by 5.2% via IVW_EF method (OR = 0.948, p = 0.031). No significant causality was determined in simvastatin use and pan-cancers via the IVW_FE or multiplicative random-effects IVW (IVW_MRE) method if applicable (p > 0.05). There was no horizontal pleiotropy observed in the MR analysis and the leave-one-out analysis proved the stability of the results. Conclusion: The causalities between statin use and cancer risk were only observed in colorectal cancer and bile duct cancer in the European ancestry population. Future works are warranted to provide more robust evidence for supporting statin repurposing for cancer prevention.

Transporting observational study results to a target population of interest using inverse odds of participation weighting

Inverse odds of participation weighting (IOPW) has been proposed to transport clinical trial findings to target populations of interest when the distribution of treatment effect modifiers differs between trial and target populations. We set out to apply IOPW to transport results from an observational study to a target population of interest. We demonstrated the feasibility of this idea with a real-world example using a nationwide electronic health record derived de-identified database from Flatiron Health. First, we conducted an observational study that carefully adjusted for confounding to estimate the treatment effect of fulvestrant plus palbociclib relative to letrozole plus palbociclib as a second-line therapy among estrogen receptor (ER)-positive, human epidermal growth factor receptor (HER2)-negative metastatic breast cancer patients. Second, we transported these findings to the broader cohort of patients who were eligible for a first-line therapy. The interpretation of the findings and validity of such studies, however, rely on the extent that causal inference assumptions are met.

Chronic metformin intake and gastric cancer: A pooled analysis within the Stomach cancer Pooling (StoP) Project

INTRODUCTION

The association between chronic use of metformin and risk of gastric cancer (GC) has been investigated with contradicting results. We aimed to study the association between chronic use of metformin and GC by using data from the Stomach cancer Pooling (StoP) Project, an epidemiological consortium of case-control studies on GC.

METHODS

Data from three studies of the StoP Project with available information on metformin intake were analyzed. Multivariable logistic regression models were used to estimate study-specific odds ratios (ORs) and 95% confidence intervals (CIs) for the association between chronic use of metformin and GC risk. Analyses were adjusted for sex, age, socioeconomic status, body mass index, smoking status, alcohol drinking status, and history of diabetes. Study-specific ORs and 95% CIs were then pooled with a random-effects model. The dose-response relationship between the duration of metformin intake and GC was assessed with a one-stage logistic model, and the duration of intake was modelled using second-order fractional polynomials.

RESULTS

The OR of GC in metformin users versus non-users was 1.01 (95% CI=0.61, 1.67). The association between metformin and GC did not change among different strata of study participants' characteristics or when restricting the analyses to those with a history of diabetes. The dose-response analysis showed a slightly reducing trend in the OR of GC and a borderline significant association with increasing duration of metformin intake.

CONCLUSIONS

The results of our study do not clearly support an association between chronic use of metformin and GC, warranting further research.

Association of Adjuvant Chemotherapy With Overall Survival Among Patients With Locally Advanced Gastric Cancer After Neoadjuvant Chemotherapy

IMPORTANCE

Neoadjuvant chemotherapy (NAC) is a standard treatment option for locally advanced gastric cancer (LAGC); however, the indications for adjuvant chemotherapy (AC) in patients with LAGC who received NAC remain controversial.

OBJECTIVE

To compare survival rates between patients with LAGC who received AC and those who did not after NAC followed by surgery.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter, international cohort study included 353 patients with LAGC undergoing curative-intent gastrectomy after NAC at 2 tertiary referral teaching hospitals in China between June 1, 2008, and December 31, 2017. To externally validate the findings in the Chinese patients, 109 patients from the US and Italy between June 1, 2006, and June 30, 2013, were reviewed. The follow-up period of the Chinese patients was completed in December 2020, and the follow-up period of the Western patients was completed between February and July 2017. Data analysis was performed from December 1, 2020, to February 28, 2021.

EXPOSURES

Patients who received AC and those who did not were propensity score matched to evaluate the association of AC with survival.

MAIN OUTCOMES AND MEASURES

Overall survival (OS), disease-free survival, and disease-specific survival.

RESULTS

Of 353 patients from China (275 [78.1%] male; mean [SD] age, 58.0 [10.7] years), 262 (74.1%) received AC and 91 (25.9%) did not. After propensity score matching, the 3-year OS was significantly higher in patients who received AC (60.1%; 95% CI, 53.1%-68.1%) than in those who did not (49.3%; 95% CI, 39.8%-61.0%) (P = .02). Lymph node ratio (LNR) was significantly associated with AC benefit (P < .001 for interaction), and a plot of the interaction between LNR and AC demonstrated that AC was associated with improved OS in patients with higher (≥9%) LNRs (3-year OS: 46.6% vs 21.7%; P < .001), but not in patients with LNRs less than 9% (3-year OS: 73.9% vs 71.3%; P = .30). When stratified by AC cycles, only those patients who completed at least 4 AC cycles exhibited a significant survival benefit in the 6-month (hazard ratio, 0.56; 95% CI, 0.33-0.96; P = .03) and 9-month landmark analysis (hazard ratio, 0.50; 95% CI, 0.27-0.94; P = .03). In the external cohort, improved OS with AC administration was also found in patients with LNRs of 9% or greater (3-year OS: 53.0% vs 26.3%; P = .04).

CONCLUSIONS AND RELEVANCE

In this cohort study, the administration of AC after NAC and resection of LAGC was associated with improved prognosis in patients with LNRs of 9% or greater. These findings suggest that LNR might be valuable in AC selection in future decision-making processes.

Association of COVID-19 vaccines ChAdOx1 and BNT162b2 with major venous, arterial, or thrombocytopenic events: A population-based cohort study of 46 million adults in England

BACKGROUND

Thromboses in unusual locations after the Coronavirus Disease 2019 (COVID-19) vaccine ChAdOx1-S have been reported, although their frequency with vaccines of different types is uncertain at a population level. The aim of this study was to estimate the population-level risks of hospitalised thrombocytopenia and major arterial and venous thromboses after COVID-19 vaccination.

METHODS AND FINDINGS

In this whole-population cohort study, we analysed linked electronic health records from adults living in England, from 8 December 2020 to 18 March 2021. We estimated incidence rates and hazard ratios (HRs) for major arterial, venous, and thrombocytopenic outcomes 1 to 28 and >28 days after first vaccination dose for ChAdOx1-S and BNT162b2 vaccines. Analyses were performed separately for ages <70 and ≥70 years and adjusted for age, age2, sex, ethnicity, and deprivation. We also prespecified adjustment for anticoagulant medication, combined oral contraceptive medication, hormone replacement therapy medication, history of pulmonary embolism or deep vein thrombosis, and history of coronavirus infection in analyses of venous thrombosis; and diabetes, hypertension, smoking, antiplatelet medication, blood pressure lowering medication, lipid lowering medication, anticoagulant medication, history of stroke, and history of myocardial infarction in analyses of arterial thromboses. We selected further covariates with backward selection. Of 46 million adults, 23 million (51%) were women; 39 million (84%) were <70; and 3.7 million (8.1%) Asian or Asian British, 1.6 million (3.5%) Black or Black British, 36 million (79%) White, 0.7 million (1.5%) mixed ethnicity, and 1.5 million (3.2%) were of another ethnicity. Approximately 21 million (46%) adults had their first vaccination between 8 December 2020 and 18 March 2021. The crude incidence rates (per 100,000 person-years) of all venous events were as follows: prevaccination, 140 [95% confidence interval (CI): 138 to 142]; ≤28 days post-ChAdOx1-S, 294 (281 to 307); >28 days post-ChAdOx1-S, 359 (338 to 382), ≤28 days post-BNT162b2-S, 241 (229 to 253); >28 days post-BNT162b2-S 277 (263 to 291). The crude incidence rates (per 100,000 person-years) of all arterial events were as follows: prevaccination, 546 (95% CI: 541 to 555); ≤28 days post-ChAdOx1-S, 1,211 (1,185 to 1,237); >28 days post-ChAdOx1-S, 1678 (1,630 to 1,726), ≤28 days post-BNT162b2-S, 1,242 (1,214 to 1,269); >28 days post-BNT162b2-S, 1,539 (1,507 to 1,572). Adjusted HRs (aHRs) 1 to 28 days after ChAdOx1-S, compared with unvaccinated rates, at ages <70 and ≥70 years, respectively, were 0.97 (95% CI: 0.90 to 1.05) and 0.58 (0.53 to 0.63) for venous thromboses, and 0.90 (0.86 to 0.95) and 0.76 (0.73 to 0.79) for arterial thromboses. Corresponding aHRs for BNT162b2 were 0.81 (0.74 to 0.88) and 0.57 (0.53 to 0.62) for venous thromboses, and 0.94 (0.90 to 0.99) and 0.72 (0.70 to 0.75) for arterial thromboses. aHRs for thrombotic events were higher at younger ages for venous thromboses after ChAdOx1-S, and for arterial thromboses after both vaccines. Rates of intracranial venous thrombosis (ICVT) and of thrombocytopenia in adults aged <70 years were higher 1 to 28 days after ChAdOx1-S (aHRs 2.27, 95% CI: 1.33 to 3.88 and 1.71, 1.35 to 2.16, respectively), but not after BNT162b2 (0.59, 0.24 to 1.45 and 1.00, 0.75 to 1.34) compared with unvaccinated. The corresponding absolute excess risks of ICVT 1 to 28 days after ChAdOx1-S were 0.9 to 3 per million, varying by age and sex. The main limitations of the study are as follows: (i) it relies on the accuracy of coded healthcare data to identify exposures, covariates, and outcomes; (ii) the use of primary reason for hospital admission to measure outcome, which improves the positive predictive value but may lead to an underestimation of incidence; and (iii) potential unmeasured confounding.

CONCLUSIONS

In this study, we observed increases in rates of ICVT and thrombocytopenia after ChAdOx1-S vaccination in adults aged <70 years that were small compared with its effect in reducing COVID-19 morbidity and mortality, although more precise estimates for adults aged <40 years are needed. For people aged ≥70 years, rates of arterial or venous thrombotic events were generally lower after either vaccine compared with unvaccinated, suggesting that either vaccine is suitable in this age group.

Identification of causal effects in case-control studies

BACKGROUND

Case-control designs are an important yet commonly misunderstood tool in the epidemiologist's arsenal for causal inference. We reconsider classical concepts, assumptions and principles and explore when the results of case-control studies can be endowed a causal interpretation.

RESULTS

We establish how, and under which conditions, various causal estimands relating to intention-to-treat or per-protocol effects can be identified based on the data that are collected under popular sampling schemes (case-base, survivor, and risk-set sampling, with or without matching). We present a concise summary of our identification results that link the estimands to the (distribution of the) available data and articulate under which conditions these links hold.

CONCLUSION

The modern epidemiologist's arsenal for causal inference is well-suited to make transparent for case-control designs what assumptions are necessary or sufficient to endow the respective study results with a causal interpretation and, in turn, help resolve or prevent misunderstanding. Our approach may inform future research on different estimands, other variations of the case-control design or settings with additional complexities.

OUP accepted manuscript

Aims

Previous studies have found high sodium intake to be associated with increased risks of cardiovascular disease (CVD) and all-cause mortality among individuals with hypertension; findings on the effect of intake among individuals without hypertension have been equivocal. We aimed to compare the risks of incident CVD and all-cause mortality among initiators of sodium-containing acetaminophen with the risk of initiators of non-sodium-containing formulations of the same drug according to the history of hypertension.

Methods and results

Using The Health Improvement Network, we conducted two cohort studies among individuals with and without hypertension. We examined the relation of sodium-containing acetaminophen to the risk of each outcome during 1-year follow-up using marginal structural models with an inverse probability weighting to adjust for time-varying confounders. The outcomes were incident CVD (myocardial infarction, stroke, and heart failure) and all-cause mortality. Among individuals with hypertension (mean age: 73.4 years), 122 CVDs occurred among 4532 initiators of sodium-containing acetaminophen (1-year risk: 5.6%) and 3051 among 146 866 non-sodium-containing acetaminophen initiators (1-year risk: 4.6%). The average weighted hazard ratio (HR) was 1.59 [95% confidence interval (CI) 1.32–1.92]. Among individuals without hypertension (mean age: 71.0 years), 105 CVDs occurred among 5351 initiators of sodium-containing acetaminophen (1-year risk: 4.4%) and 2079 among 141 948 non-sodium-containing acetaminophen initiators (1-year risk: 3.7%), with an average weighted HR of 1.45 (95% CI 1.18–1.79). Results of specific CVD outcomes and all-cause mortality were similar.

Conclusion

The initiation of sodium-containing acetaminophen was associated with increased risks of CVD and all-cause mortality among individuals with or without hypertension. Our findings suggest that individuals should avoid unnecessary excessive sodium intake through sodium-containing acetaminophen use.

Long-Term Statin Use, Total Cholesterol Level, and Risk of Colorectal Cancer: A Prospective Cohort Study

INTRODUCTION

Statin use has been examined as a potential chemopreventive strategy against colorectal cancer (CRC). Previous studies have not been able to investigate this topic with adequate follow-up time or disentangle the effects of statin use and total cholesterol level. We investigated prospectively this topic.

METHODS

Eligible participants (100,300 women and 47,991 men) in the Nurses' Health Study and Health Professionals Follow-Up Study were followed for up to 24 years. Cox proportional hazards models were used to estimate hazard ratios and 95% confidence intervals.

RESULTS

We documented 2,924 incident CRC cases during follow-up. In fully adjusted analyses, longer duration of statin use was associated with higher risk of colon cancer (hazard ratios, the 95% confidence interval was 1.09, 0.95-1.25 for 1-5 years; 1.16, 0.99-1.36 for 6-10 years; 1.08, 0.81-1.44 for 11-15 years; 1.85, 1.30-2.61 for >15 years; vs never users, P = 0.004 for trend) rather than rectal cancer. The risk elevation was driven by proximal colon cancer (1.16, 0.98-1.38 for 1-5 years; 1.19, 0.98-1.45 for 6-10 years; 1.25, 0.89-1.74 for 11-15 years; 2.17, 1.46-3.24 for >15 years; vs never users, P = 0.001 for trend) rather than distal colon cancer. The results remained robust in analyses among participants with hypercholesterolemia or who never received screening. Total cholesterol level was not associated with CRC risk.

DISCUSSION

This study does not support benefit of statin use in CRC chemoprevention or any association between total cholesterol level and CRC risk. On the contrary, long-term statin use may be associated with increased colon cancer risk (driven by proximal colon cancer).

[Secondary Data for Pharmacoepidemiological Research - Making the Best of It!]

Studies using secondary data such as health care claims data are often faced with methodological challenges due to the time-dependence of key quantities or unmeasured confounding. In the present paper, we discuss approaches to avoid or suitably address various sources of potential bias. In particular, we illustrate the target trial principle, marginal structural models, and instrumental variables with examples from the "GePaRD" database. Finally, we discuss the strengths and limitations of record linkage which can sometimes be used to supply missing information.

Conducting Real-world Evidence Studies on the Clinical Outcomes of Diabetes Treatments

Real-world evidence (RWE), the understanding of treatment effectiveness in clinical practice generated from longitudinal patient-level data from the routine operation of the healthcare system, is thought to complement evidence on the efficacy of medications from randomized controlled trials (RCTs). RWE studies follow a structured approach. (1) A design layer decides on the study design, which is driven by the study question and refined by a medically informed target population, patient-informed outcomes, and biologically informed effect windows. Imagining the randomized trial we would ideally perform before designing an RWE study in its likeness reduces bias; the new-user active comparator cohort design has proven useful in many RWE studies of diabetes treatments. (2) A measurement layer transforms the longitudinal patient-level data stream into variables that identify the study population, the pre-exposure patient characteristics, the treatment, and the treatment-emergent outcomes. Working with secondary data increases the measurement complexity compared to primary data collection that we find in most RCTs. (3) An analysis layer focuses on the causal treatment effect estimation. Propensity score analyses have gained in popularity to minimize confounding in healthcare database analyses. Well-understood investigator errors, like immortal time bias, adjustment for causal intermediates, or reverse causation, should be avoided. To increase reproducibility of RWE findings, studies require full implementation transparency. This article integrates state-of-the-art knowledge on how to conduct and review RWE studies on diabetes treatments to maximize study validity and ultimately increased confidence in RWE-based decision making.

Emulating a Randomised Controlled Trial With Observational Data: An Introduction to the Target Trial Framework

Randomised controlled trials (RCTs) are often considered to be the highest quality of evidence owing to the absence of baseline confounding, the simplicity of analyses, and direct estimation of causal effects. However, observational studies can be designed to mimic RCTs and estimate causal treatment effects. In this review, we describe the target trial framework to illustrate how observational studies can successfully emulate RCTs. We focus on key design elements of RCTs and how to emulate them with observational data. These elements include 1) eligibility criteria, 2) treatment assignment and randomisation, 3) specification of "time zero", 4) outcomes, 5) follow-up, 6) causal contrasts (intention-to-treat vs per-protocol), and 7) statistical analyses. In addition, we describe the design of an example target trial created to emulate the Trial to Assess Improvement in Therapeutic Outcomes by Optimizing Platelet Inhibition With Prasugrel Thrombolysis in Myocardial Infarction (TRITON-TIMI) 38 trial and compare effect estimates. Overall, careful design of a target trial using observational data can produce causal effect estimates that are often comparable to RCTs.