Emulating a Target Trial of Shorter Compared to Longer Course of Antibiotic Therapy for Gram-Negative Bacteremia.

BACKGROUND: Despite the availability of antimicrobial therapies, gram-negative bacteremia remains a significant cause of morbidity and mortality on a global level. Recent randomized controlled trials support shorter antibiotic treatment duration for individuals with uncomplicated gram-negative bacteremia. The target trial framework using the cloning approach utilizes real-world data but eliminates the issue of immortal time bias seen in observational studies by emulating the analysis of randomized trials with full adherence. METHOD: A hypothetical target trial allocating individuals with gram-negative bacteremia to either short antibiotic treatment duration (5-7 days) or longer antibiotic treatment duration (8-14 days) was specified and emulated using the cloning, censoring, and weighting approach. The primary outcome was 90-day all-cause mortality. Secondary outcome was a composite endpoint of clinical and microbiological relapse. The emulated trial included individuals from four hospitals in Copenhagen from 2018 through 2021. RESULTS: In sum, 1040 individuals were included. The median age of the cohort was 76 years, the majority were male (54%), had community-acquired gram-negative bacteremia (86%), urinary tract infection as the source of the infection (78%), and Escherichia coli as the pathogen of the infection (73%). The adjusted 90-day risk difference in all-cause mortality was 1.3% (95% confidence interval [CI]: -.7, 3.3), and the risk ratio was 1.12 (95% CI: .89, 1.37). The adjusted 90-day risk difference in relapse was 0.7% (95% CI: -2.3, 3.8), and the risk ratio was 1.07 (95% CI: .71, 1.45). CONCLUSIONS: We found comparative outcomes for shorter treatment duration compared to longer treatment duration in patients with gram-negative bacteremia.

Identifying Veterans Who Benefit From Nirmatrelvir-Ritonavir: A Target Trial Emulation.

BACKGROUND: Nirmatrelvir-ritonavir is recommended for persons at risk for severe coronavirus disease 2019 (COVID-19) but remains underutilized. Information on which eligible groups are likely to benefit from treatment is needed. METHODS: We conducted a target trial emulation study in the Veterans Health Administration comparing nirmatrelvir-ritonavir treated versus matched untreated veterans at risk for severe COVID-19 who tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from April 2022 through March 2023. We measured incidence of any hospitalization or all-cause mortality at 30 days. Outcomes were measured for the entire cohort, as well as among subgroups defined by 30-day risk of death or hospitalization, estimated using an ensemble risk prediction model. RESULTS: Participants were 87% male with median age 66 years and 16% unvaccinated. Compared with matched untreated participants, those treated with nirmatrelvir-ritonavir (n = 24 205) had a lower 30-day risk for hospitalization (1.80% vs 2.30%; risk difference [RD], -0.50% points [95% confidence interval {CI}: -.69 to -.35]) and death (0.11% vs 0.30%; RD, -0.20 [95% CI: -.24 to -.13]). The greatest reductions in combined hospitalization or death were observed in the highest risk quartile (RD -2.85 [95% CI: -3.94 to -1.76]), immunocompromised persons (RD -1.91 [95% CI: -3.09 to -.74]), and persons aged ≥75 years (RD -1.16 [95% CI: -1.73 to -.59]). No reductions were observed in the 2 lowest risk quartiles or persons younger than 65 years. CONCLUSIONS: Nirmatrelvir-ritonavir was effective in reducing 30-day hospitalization and death in older veterans, those at highest predicted risk for severe outcomes, and immunocompromised groups. Benefit was not observed in younger veterans or groups at lower predicted risk for hospitalization and death.

Sustained Hypothetical Interventions on Midlife Alcohol Consumption in Relation to All-Cause and Cancer Mortality: The Australian Longitudinal Study on Women's Health.

No randomized controlled trial has evaluated the effect of long-term alcohol interventions on mortality. Results reported in existing observational studies may be subject to selection bias and time-varying confounding. Using data from the Australian Longitudinal Study on Women's Health 1946-1951 birth cohort, collected regularly from 1996-2016, we estimated all-cause and cancer mortality had women been assigned various alcohol interventions (in categories ranging from 0 to >30 g/day ethanol, or reduced to ≤20 g/day if higher) at baseline, and had they maintained these levels of consumption. The cumulative risks for all-cause and cancer mortality were 5.6% (10,118 women followed for 20 years) and 2.9% (18 years), respectively. For all-cause and cancer mortality, baseline ethanol up to 30 g/day showed lower risk and >30 g/day showed higher risk relative to abstention. Had women sustainedly followed the interventions, a similar relationship was observed for all-cause mortality. However, the negative association observed for intakes ≤30 g/day and positive association for intakes >30 g/day was not evident for cancer mortality. Our findings suggest that all-cause mortality could have been lower than observed if this cohort of women had consumed some alcohol (no more than 30 g/day) rather than no consumption, but cancer mortality might not.

Effect of Different Durations of Treatment With Antihypertensive Drugs With Anticholinergic Effects on the Risk of Dementia: A Target Trial Emulation Study.

Studying the effect of duration of treatment on prognostic outcomes using real-world data is challenging because only people who survive for a long time can receive a treatment for a long time. Specifying a target trial helps overcome such challenge. We aimed to estimate the effect of different durations of treatment with antihypertensive drugs with anticholinergic properties (AC AHT) on the risk of vascular dementia and Alzheimer's disease by emulating a target trial using the UK CPRD GOLD database (2001-2017). Comparing treatment for 3-6 years versus ≤3 years yielded null results for both types of dementia. Comparing a longer duration of treatment, >6 years versus ≤3 years, yielded a 10-year risk ratio of 0.69 (95% CI, 0.54-0.90) for vascular dementia and 0.91 (95% CI, 0.77-1.10) for Alzheimer's disease. For illustration, we performed an analysis that failed to emulate a target trial by assigning exposure categories using post-baseline information, obtaining implausible beneficial estimates. Our findings indicate a modest benefit of longer duration of treatment with AC AHT on vascular dementia and highlight the value of the target trial emulation to avoid selection bias in the evaluation of the effect of different durations of treatment.

How much could anemia-related interventions reduce the HIV disparity in adverse birth outcomes?

Women and other people of childbearing potential living with HIV (WLHIV) have a higher risk of adverse birth outcomes than those without HIV (WWHIV). A higher risk of anemia in WLHIV could partially explain this disparity. Using a birth outcomes surveillance study in Botswana, we emulated target trials corresponding to currently available or feasible interventions on anemia. The first target trial evaluated two interventions: initiate multiple micronutrient supplementation (MMS), and MMS or iron and folic acid supplementation by 24 weeks gestation. The remaining target trials evaluated the interventions: eliminate anemia before pregnancy; and jointly eliminate anemia before pregnancy and initiate MMS. We estimated the observed disparity in adverse birth outcomes between WLHIV and WWHIV and compared the observed disparity measure (ODM) to the counterfactual disparity measure (CDM) under each intervention. Of 137,499 individuals (22% WLHIV), the observed risk of any adverse birth outcome was 26.0% in WWHIV and 34.5% in WLHIV (ODM, 8.5% [95% CI, 7.9-9.1%]). CDMs (95% CIs) ranged from 6.6% (4.8-8.4%) for the intervention to eliminate anemia and initiate MMS to 8.4% (7.7-9.1%) for the intervention to eliminate anemia only. Preventing anemia and expanding MMS may reduce HIV disparities in birth outcomes, but interventions with greater impact should be identified.

Non-benzodiazepine Hypnotics and Police-Reported Motor Vehicle Crash Risk among Older Adults: A Sequential Target Trial Emulation.

Non-benzodiazepine hypnotics ( "Z-drugs") are prescribed for insomnia, but might increase risk of motor vehicle crash (MVC) among older adults through prolonged drowsiness and delayed reaction times. We estimated the effect of initiating Z-drug treatment on the 12-week risk of MVC in a sequential target trial emulation. After linking New Jersey driver licensing and police-reported MVC data to Medicare claims, we emulated a new target trial each week (July 1, 2007 - October 7, 2017) in which Medicare fee-for-service beneficiaries were classified as Z-drug-treated or untreated at baseline and followed for an MVC. We used inverse probability of treatment and censoring weighted pooled logistic regression models to estimate risk ratios (RR) and risk differences with 95% bootstrap confidence limits (CLs). There were 257,554 person-trials, of which 103,371 were Z-drug-treated and 154,183 untreated, giving rise to 976 and 1,249 MVCs, respectively. The intention-to-treat RR was 1.06 (95%CLs 0.95, 1.16). For the per-protocol estimand, there were 800 MVCs and 1,241 MVCs among treated and untreated person-trials, respectively, suggesting a reduced MVC risk (RR 0.83 [95%CLs 0.74, 0.92]) with sustained Z-drug treatment. Z-drugs should be prescribed to older patients judiciously but not withheld entirely over concerns about MVC risk.

Evaluating recommendation-based dietary and physical activity strategies for prostate cancer prevention: a target trial emulation in the Health Professionals Follow-up Study.

The 2018 World Cancer Research Fund/American Institute for Cancer Research recommends sustained strategies of physical activity and diet for cancer prevention, but evidence for long-term prostate cancer risk is limited. Using observational data from 27,859 men in the Health Professionals Follow-up Study, we emulated a target trial of recommendation-based physical activity and dietary strategies and 26-year risks of prostate cancer, adjusting for risk factors via the parametric g-formula. Compared with no intervention, limiting sugar-sweetened beverages showed a 0.4% (0.0-0.9%) lower risk of lethal (metastatic or fatal) disease and 0.5% (0.1-0.9%) lower risk of fatal disease. Restricting consumption of processed foods showed a 0.4-0.9% higher risk of all prostate cancer outcomes. Estimated risk differences for clinically significant disease were close to null for strategies involving fruits and non-starchy vegetables, whole grains and legumes, red meat, and processed meat, as well as under a joint strategy of physical activity and diet. Compared with a "low adherence" strategy, maintaining recommended physical activity levels showed a 0.4% (0.1-0.8%) lower risk of lethal and 0.5% (0.2-0.8%) lower risk of fatal disease. Adhering to specific components of current physical activity and dietary recommendations may help to prevent lethal and fatal prostate cancer over 26 years.

Antipsychotic drugs in first-episode psychosis: a target trial emulation in the FEP-CAUSAL Collaboration.

Good adherence to antipsychotic therapy helps prevent relapses in first-episode psychosis (FEP). We used data from the FEP-CAUSAL Collaboration, an international consortium of observational cohorts, to emulate a target trial comparing antipsychotics, with treatment discontinuation as the primary outcome. Other outcomes included all-cause hospitalization. We benchmarked our results to estimates from the European First Episode Schizophrenia Trial, a randomized trial conducted in the 2000s. We included 1097 patients with a psychotic disorder and less than 2 years since psychosis onset. Inverse-probability weighting was used to control for confounding. The estimated 12-month risks of discontinuation for aripiprazole, first-generation agents, olanzapine, paliperidone, quetiapine, and risperidone were 61.5% (95% CI, 52.5-70.6), 73.5% (95% CI, 60.5-84.9), 76.8% (95% CI, 67.2-85.3), 58.4% (95% CI, 40.4-77.4), 76.5% (95% CI, 62.1-88.5), and 74.4% (95% CI, 67.0-81.2), respectively. Compared with aripiprazole, the 12-month risk differences were -15.3% (95% CI, -30.0 to 0.0) for olanzapine, -12.8% (95% CI, -25.7 to -1.0) for risperidone, and 3.0% (95% CI, -21.5 to 30.8) for paliperidone. The 12-month risks of hospitalization were similar between agents. Our estimates support use of aripiprazole and paliperidone as first-line therapies for FEP. Benchmarking yielded similar results for discontinuation and absolute risks of hospitalization as in the original trial, suggesting that data from the FEP-CAUSAL Collaboration sufficed to remove confounding for these clinical questions. This article is part of a Special Collection on Mental Health.

Emulations of Oncology Trials Using Real-World Data: A Systematic Literature Review.

By evaluating published emulations of oncology RCTs studies in which both the active and comparator groups are sourced from RWD and target trial results are available for benchmarking, this systematic review aims to gain insight into factors related to emulation performance. Thirteen oncology emulation studies using various types of RWD were identified through an online database search of PubMed through 2022. Based on the ROBINS-I tool, most studies (N=8) had a serious risk of overall bias driven by risk of bias from confounding. Approximately half of the studies (N=6) fully proxied the RCT entry criteria. Of 11 RWD studies that provided sufficient detail to quantify emulation performance, the emulation HR estimate fell within the 95% CI of the trial estimate in 9 of the studies. There were no clear trends between risk of bias or degree to which the entry criteria were proxied and emulation performance. Findings may have been influenced by publication bias and researcher degrees of freedom, as only one emulation study pre-registered its protocol. Tools for comprehensively characterizing factors that affect emulation performance, including the real-world clinical context as it relates to the RCT research question, are needed to evaluate the feasibility of a RCT emulation.

Evaluating the Effectiveness of Systemic Heparin During Arteriovenous Fistula Creation by Emulating a Target Trial.

Most of the 800,000 people living with end-stage kidney disease in the United States rely on a functioning vascular access to provide life-sustaining hemodialysis, yet one-third of arteriovenous fistulas experience early failures. Determining the safety and effectiveness of systemic heparin during fistula creation could improve the quality and quantity of life for these vulnerable patients. In this paper, a pragmatic randomized trial was emulated to assess the effect of systemic heparin administration (vs. none) during radiocephalic arteriovenous fistula creation on early bleeding and thrombosis using data from two international multicenter randomized trials performed between 2014 and 2019. Marginal risks were estimated using inverse probability weighted parametric survival analysis and confidence intervals were generated with bootstrapping. A total of 914 patients were enrolled and 61% received systemic heparin; median (IQR) age was 58 (49, 67) years and 45% were on hemodialysis at enrollment. No difference in the risk of bleeding events was observed, with a risk difference (95% CI) at 14 days of -0.1% (-1.6, 1.4). The risk of access thrombosis was lower in the heparin group, with a risk of 3.7% (2.6, 4.8) after heparin and 5.3% (3.4, 7.4) without heparin at 14 days (risk ratio 0.72, 95% CI 0.50, 0.98).

Prenatal exposure to benzodiazepine and z-hypnotics and fifth-grade scholastic skills - emulating target trials using data from the Norwegian Mother, Father and Child Cohort Study.

Evidence is limited regarding the effect of prenatal benzodiazepine and z-hypnotic exposure and long-term neurodevelopment in childhood. The objective of this study was to investigate the effects of initiating benzodiazepine or z-hypnotic treatment in early, mid and late pregnancy on fifth-grade numeracy and literacy scholastic skills in children, by emulating three target trials. The trials are identical except for the timing of enrollment and the number of eligible individuals. Eligibility to the trials required a history of anxiety and/or depression prior to pregnancy. We used data from the Norwegian Mother, Father and Child Cohort Study, linked to the Medical Birth Registry of Norway, to emulate the trials. We adjusted for baseline covariates that were available at time 0 for each trial by inverse probability of treatment weighting using the propensity score. The findings of this study did not show any effect of mothers' initiation of treatment with benzodiazepines or z-hypnotics in early, mid or late pregnancy on the children's 5th grade test scores in numeracy and literacy. The study results provide reassurance for patients in need of benzodiazepines and z-hypnotics during pregnancy; however, these findings need to be interpreted with caution due to low study power in some of the analyses.

Effectiveness of intravenous methylprednisolone pulse in patients with severe microscopic polyangiitis and granulomatosis with polyangiitis.

OBJECTIVES: To evaluate the effectiveness and safety of two different intravenous methylprednisolone (IVMP) pulse doses in patients with severe microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA). METHODS: We emulated a target trial using observational data from the nationwide registry in Japan. Patients with severe glomerulonephritis or diffuse alveolar haemorrhage were selected and pseudo-randomized into three groups using propensity score-based overlap weighting as follows: non-IVMP, IVMP 0.5 g/day and IVMP 1.0 g/day. The primary outcome was all-cause mortality, and the secondary outcomes were composite all-cause mortality and kidney failure, severe relapse and serious infection from 2 to 48 weeks after treatment initiation. To estimate the treatment effects, the Cox proportional hazard model and Fine-Gray subdistribution hazard model were used. RESULTS: In this emulated target trial, of 201 eligible patients (MPA, 175; GPA, 26), 6 (3%) died, 4 (2.0%) had kidney failure, 11 (5.5%) had severe relapse, and 40 (19.9%) had severe infections. Hazard ratios (HR) for IVMP 0.5 g/day and IVMP 1.0 g/day pulse groups compared with non-IVMP pulse were as follows: all-cause mortality 0.46 (95% CI: 0.07, 2.81) and 0.07 (95% CI: 0.01, 0.41), respectively; all-cause mortality/kidney failure 1.18 (95% CI: 0.26, 5.31) and 0.59 (95% CI: 0.08, 4.52), respectively; subdistribution HRs for severe relapse were 1.26 (95% CI: 0.12, 13.70) and 3.36 (95% CI: 0.49, 23.29), respectively; and for serious infection 1.88 (95% CI: 0.76, 4.65) and 0.94 (95% CI: 0.28, 3.13), respectively. CONCLUSION: IVMP 1.0 g/day pulse may improve 48-week mortality in patients with severe MPA/GPA.

Survival outcomes of primary vs interval cytoreductive surgery for International Federation of Gynecology and Obstetrics stage IV ovarian cancer: a nationwide population-based target trial emulation.

BACKGROUND: The effect of primary cytoreductive surgery vs interval cytoreductive surgery on International Federation of Gynecology and Obstetrics stage IV ovarian cancer outcomes remains uncertain and may vary depending on the stage and the location of extraperitoneal metastasis. Emulating target trials through causal assessment, combined with propensity score adjustment, has become a leading method for evaluating interventions using observational data. OBJECTIVE: This study aimed to assess the effect of primary vs interval cytoreductive surgery on progression-free and overall survival in patients with International Federation of Gynecology and Obstetrics stage IV ovarian cancer using target trial emulation. STUDY DESIGN: Using the comprehensive French national health insurance database, we emulated a target trial to explore the causal impacts of primary vs interval cytoreductive surgery on stage IV ovarian cancer prognosis (Surgery for Ovarian cancer FIGO 4: SOFI-4). The clone method with inverse probability of censoring weighting was used to adjust for informative censoring and to balance baseline characteristics between the groups. Subgroup analyses were conducted based on the stages and extraperitoneal metastasis locations. The study included patients younger than 75 years of age, in good health condition, who were diagnosed with stage IV ovarian cancer between January 1, 2014, and December 31, 2022. The primary and secondary outcomes were respectively 5-year progression-free survival and 7-year overall survival. RESULTS: Among the 2772 patients included in the study, 948 (34.2%) were classified as having stage IVA ovarian cancer and 1824 (65.8%) were classified as having stage IVB ovarian cancer at inclusion. Primary cytoreductive surgery was performed for 1182 patients (42.6%), whereas interval cytoreductive surgery was conducted for 1590 patients (57.4%). The median progression-free survival for primary cytoreductive surgery was 19.7 months (interquartile range, 19.3-20.1) as opposed to 15.7 months (interquartile range, 15.7-16.1) for those who underwent interval cytoreductive surgery. The median overall survival was 63.1 months (interquartile range, 61.7-65.4) for primary cytoreductive surgery in comparison with 55.6 months (interquartile range, 53.8-56.3) for interval cytoreductive surgery. The findings of our study indicate that primary cytoreductive surgery is associated with a 5.0-month increase in the 5-year progression-free survival (95% confidence interval, 3.8-6.2) and a 3.9-month increase in 7-year overall survival (95% confidence interval, 1.9-6.2). These survival benefits of primary over interval cytoreductive surgery were observed in both the International Federation of Gynecology and Obstetrics stage IVA and IVB subgroups. Primary cytoreductive surgery demonstrated improved progression-free survival and overall survival in patients with pleural, supradiaphragmatic, or extra-abdominal lymph node metastasis. CONCLUSION: This study advocates for the benefits of primary cytoreductive surgery over interval cytoreductive surgery for patients with stage IV ovarian cancer and suggests that extraperitoneal metastases like supradiaphragmatic or extra-abdominal lymph nodes should not automatically preclude primary cytoreductive surgery consideration in suitable patients.

The Inflation Reduction Act: An Opportunity to Accelerate Confidence in Real-World Evidence in the United States.

OBJECTIVES: The Inflation Reduction Act (IRA), enacted in 2022, brings substantial reforms to the US healthcare system, particularly regarding Medicare. A key aspect includes the introduction of Medicare price negotiation. The objective of this commentary is to explore the implications of the IRA for US pharmaceutical companies, with a specific focus on the role of real-world evidence (RWE) in the context of Medicare reforms. METHODS: This commentary uses a qualitative analysis of the IRA's provisions related to healthcare and pharmaceutical regulation, focusing on how these reforms change the evidence requirements for pharmaceutical companies. It discusses the methodological aspects of generating and using RWE, including techniques such as target trial emulation and quantitative bias analysis methods to address biases inherent in RWE. RESULTS: This commentary highlights that the IRA introduces a unique approach to value assessment in the United States by evaluating drug value several years after launch, as opposed to at launch, similar to health technology assessments in other regions. It underscores the central role of RWE in comparing drug effectiveness across diverse clinical scenarios to improve the accuracy of real-world data comparisons. Furthermore, this article identifies key methodologies for managing the inherent biases in RWE, which are crucial for generating credible evidence for IRA price negotiations. CONCLUSIONS: This article underscores the importance of these methodologies in ensuring credible evidence for IRA price negotiations. It advocates for an integrated approach in evidence generation, positioning RWE as pivotal for informed pricing discussions in the US healthcare landscape.

Flexible Approaches Based on Multistate Models and Microsimulation to Perform Real-World Cost-Effectiveness Analyses: An Application to Proprotein Convertase Subtilisin-Kexin Type 9 Inhibitors.

OBJECTIVES: This study aims to show the application of flexible statistical methods in real-world cost-effectiveness analyses applied in the cardiovascular field, focusing specifically on the use of proprotein convertase subtilisin-kexin type 9 inhibitors for hyperlipidemia. METHODS: The proposed method allowed us to use an electronic health database to emulate a target trial for cost-effectiveness analysis using multistate modeling and microsimulation. We formally established the study design and provided precise definitions of the causal measures of interest while also outlining the assumptions necessary for accurately estimating these measures using the available data. Additionally, we thoroughly considered goodness-of-fit assessments and sensitivity analyses of the decision model, which are crucial to capture the complexity of individuals' healthcare pathway and to enhance the validity of this type of health economic models. RESULTS: In the disease model, the Markov assumption was found to be inadequate, and a "time-reset" timescale was implemented together with the use of a time-dependent variable to incorporate past hospitalization history. Furthermore, the microsimulation decision model demonstrated a satisfying goodness of fit, as evidenced by the consistent results obtained in the short-term horizon compared with a nonmodel-based approach. Notably, proprotein convertase subtilisin-kexin type 9 inhibitors revealed their favorable cost-effectiveness only in the long-term follow-up, with a minimum willingness to pay of 39 000 Euro/life years gained. CONCLUSIONS: The approach demonstrated its significant utility in several ways. Unlike nonmodel-based or alternative model-based methods, it enabled to (1) investigate long-term cost-effectiveness comprehensively, (2) use an appropriate disease model that aligns with the specific problem under study, and (3) conduct subgroup-specific cost-effectiveness analyses to gain more targeted insights.

The perpetual need of randomized clinical trials: challenges and uncertainties in emulating the REDUCE-AMI trial.

Trial emulations in observational data analyses can complement findings from randomized clinical trials, inform future trial designs, or generate evidence when randomized studies are not feasible due to resource constraints and ethical or practical limitations. Importantly, trial emulation designs facilitate causal inference in observational data analyses by enhancing counterfactual thinking and comparisons of real-world observations (e.g. Mendelian Randomization) to hypothetical interventions. In order to enhance credibility, trial emulations would benefit from prospective registration, publication of statistical analysis plans, and subsequent prospective benchmarking to randomized clinical trials prior to their publication. Confounding by indication, however, is the key challenge to interpreting observed intended effects of an intervention as causal in observational data analyses. We discuss the target trial emulation of the REDUCE-AMI randomized clinical trial (ClinicalTrials.gov ID NCT03278509; beta-blocker use in patients with preserved left ventricular ejection fraction after myocardial infarction) to illustrate the challenges and uncertainties of studying intended effects of interventions without randomization to account for confounding. We furthermore directly compare the findings, statistical power, and clinical interpretation of the results of the REDUCE-AMI target trial emulation to those from the simultaneously published randomized clinical trial. The complexity and subtlety of confounding by indication when studying intended effects of interventions can generally only be addressed by randomization.

Effect of statin treatment on the risk of cancer in patients with heart failure: A target trial emulation study.

PURPOSE: A recent observational study suggested statins could reduce cancer diagnosis in patients with heart failure (HF). The findings need to be validated using robust epidemiological methods. This study aimed to evaluate the effect of statin treatment on the risk of cancer in patients with HF. METHODS: We conducted two target trial emulations using primary care data from IQVIA Medical Research Database-UK (2000 to 2019) with a clone-censor-weight design. The first emulated trial addressed the treatment initiation effect: initiating within 1 year versus not initiating a statin after the HF diagnosis. The second emulated trial addressed the cumulative exposure effect: continuing a statin for ≤3 years, 3-6 years, and >6 years after initiation. The study outcomes were any incident cancer and site-specific cancer diagnoses. Weighted pooled logistic regression models were used to estimate 10-year risk ratios (RR). 95% confidence intervals (CIs) were estimated using non-parametric bootstrapping. RESULTS: The first emulated trial showed that, compared to no statin, statins did not reduce the cancer risk in patients with HF (RR, 1.05; 95% CI, 0.94-1.15). The second emulated trial showed that, compared to treatment ≤3 years, statins with longer durations did not reduce the cancer risk (3-6 years: RR, 0.94; 95% CI, 0.70-1.33. >6 years: RR, 0.97; 95% CI, 0.79-1.26). No significant risk difference was observed on any site-specific cancer diagnoses. CONCLUSIONS: The results from the target trial emulations suggest that statin treatment is not associated with cancer risk in patients with HF.

An Emulated Target Trial Case Study of Real-World Overall Survival With Second-Line Maintenance Niraparib Versus Active Surveillance in Patients With Recurrent Ovarian Cancer.

PURPOSE: This retrospective real-world study compared overall survival (OS) between patients with BRCA wild-type (BRCAwt) recurrent epithelial ovarian cancer (OC) who received niraparib second-line maintenance (2LM) versus active surveillance (AS) using target trial emulation, cloning, inverse probability of censoring weighting (IPCW) methodology to minimize immortal time bias. METHODS: Eligible patients from a United States-based, deidentified, electronic health record-derived database were diagnosed with epithelial OC (January 1, 2011-May 31, 2021), were BRCAwt, and completed second-line (2L) therapy (January 1, 2017-March 2, 2022). Patient data were cloned at index (2L last treatment date), assigned to niraparib 2LM and AS cohorts, and censored when treatment deviated from clone assignment. Follow-up was measured from index to earliest of study end (May 31, 2022), last activity, or death. Median OS (mOS) and hazard ratios were estimated from stabilized IPCW Kaplan-Meier curves and Cox regression models. RESULTS: Overall, 199 patients received niraparib 2LM, and 707 had their care managed with AS. Key characteristics were balanced across cohorts after cloning and stabilized IPCW. Median follow-up was 15.6- and 9.3-months pre-cloning. IPCW mOS was 24.1 months (95% CI: 20.9-29.5) and 18.4 months (95% CI: 15.1-22.8) in niraparib 2LM and AS cohorts, respectively (hazard ratio, 0.77; 95% CI: 0.66-0.89). CONCLUSIONS: This real-world study provides supportive evidence of an OS benefit for patients with BRCAwt recurrent OC who received 2LM niraparib monotherapy compared with those whose care was managed with AS. The analytic strategies implemented were useful in minimizing immortal time bias and measured confounding.

Comparative effectiveness of omalizumab, mepolizumab, and dupilumab in asthma: A target trial emulation.

BACKGROUND: Multiple mAbs are currently approved for the treatment of asthma. However, there is limited evidence on their comparative effectiveness. OBJECTIVE: Our aim was to compare the effectiveness of omalizumab, mepolizumab, and dupilumab in individuals with moderate-to-severe asthma. METHODS: We emulated a hypothetical randomized trial using electronic health records from a large US-based academic health care system. Participants aged 18 years or older with baseline IgE levels between 30 and 700 IU/mL and peripheral eosinophil counts of at least 150 cells/µL were eligible for study inclusion. The study period extended from March 2016 to August 2021. Outcomes included the incidence of asthma-related exacerbations and change in baseline FEV1 value over 12 months of follow-up. RESULTS: In all, 68 individuals receiving dupilumab, 68 receiving omalizumab, and 65 receiving mepolizumab met the inclusion criteria. Over 12 months of follow-up, 31 exacerbations occurred over 68 person years (0.46 exacerbations per person year) in the dupilumab group, 63 over 68 person years (0.93 per person year) in the omalizumab group, and 86 over 65 person years (1.32 per person year) in the mepolizumab group (adjusted incidence rate ratios: dupilumab vs mepolizumab, 0.28 [95% CI = 0.09-0.84]; dupilumab vs omalizumab, 0.36 [95% CI = 0.12-1.09]; and omalizumab vs mepolizumab, 0.78 [95% CI = 0.32-1.91]). The differences in the change in FEV1 comparing patients who received the different biologics were as follows: 0.11 L (95% CI = -0.003 to 0.222 L) for dupilumab versus mepolizumab, 0.082 L (95% CI -0.040 to 0.204 L) for dupilumab versus omalizumab, and 0.026 L (95% CI -0.083 to 0.140 L) for omalizumab versus mepolizumab. CONCLUSIONS: Among patients with asthma and eosinophil counts of at least 150 cells/µL and IgE levels of 30 to 700 kU/L, dupilumab was associated with greater improvements in exacerbation and FEV1 value than omalizumab and mepolizumab.

Target Trial Emulation and Bias Through Missing Eligibility Data: An Application to a Study of Palivizumab for the Prevention of Hospitalization Due to Infant Respiratory Illness.

Target trial emulation (TTE) applies the principles of randomized controlled trials to the causal analysis of observational data sets. One challenge that is rarely considered in TTE is the sources of bias that may arise if the variables involved in the definition of eligibility for the trial are missing. We highlight patterns of bias that might arise when estimating the causal effect of a point exposure when restricting the target trial to individuals with complete eligibility data. Simulations consider realistic scenarios where the variables affecting eligibility modify the causal effect of the exposure and are missing at random or missing not at random. We discuss means to address these patterns of bias, namely: 1) controlling for the collider bias induced by the missing data on eligibility, and 2) imputing the missing values of the eligibility variables prior to selection into the target trial. Results are compared with the results when TTE is performed ignoring the impact of missing eligibility. A study of palivizumab, a monoclonal antibody recommended for the prevention of respiratory hospital admissions due to respiratory syncytial virus in high-risk infants, is used for illustration.