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Latour CD, Su IH, Delgado M, Pate V, Poole C, Edwards JK, Stürmer T, Lund JL, Funk MJ. Hazard Ratios and Alternative Effect Measures: An Applied Illustration. Pharmacoepidemiol Drug Saf 2024; 33:e5885. [PMID: 39212064 DOI: 10.1002/pds.5885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 06/28/2024] [Accepted: 07/16/2024] [Indexed: 09/04/2024]
Abstract
PURPOSE Although the limitations of hazard ratios (HRs) for quantifying treatment effects in right-censored data have been widely discussed, HRs are still preferentially reported over other, more interpretable effect measures. This may stem from the fact that there are few applied examples that directly contrast the HR and its interpretation with alternative effect measures. METHODS We analyzed data from two randomized clinical trials comparing panitumumab plus standard-of-care chemotherapy (SOCC) with SOCC alone as first- and second-line treatment for metastatic colorectal cancer. We report the effect of treatment with panitumumab on progression-free survival (PFS) using a Cox proportional hazards model to estimate the HR and the Kaplan-Meier estimator of cumulative incidence (risk). Further analyses included examining the cumulative incidence curves; kernel-smoothed, non-parametric hazards curves; fitting the Cox model with a continuous time variable; and estimating restricted mean survival as well as median survival. RESULTS The HR was 0.82 (95% confidence interval [CI]: 0.71, 0.93), while the risk ratio (or relative risk [i.e., ratio of the cumulative incidence among the treated versus comparator]) was 0.99 (95% CI: 0.96, 1.02). These two measures suggest apparently different conclusions: either a treatment benefit or no effect. Through subsequent analyses, we demonstrated that, while the cumulative incidence of the outcome was similar by the end of follow-up regardless of treatment, the panitumumab treated group experienced longer PFS than those randomized to SOCC. Substantial nonproportional hazards were evident with panitumumab treatment reducing the hazard of progression/mortality during the first ~1.75 years but associated with an increased hazard of progress/mortality thereafter. DISCUSSION This example underscores the difficulties in interpreting HRs, particularly in the setting of qualitative violations of proportional hazards, and the value of quantifying treatment effects via multiple effect measures.
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Affiliation(s)
- Chase D Latour
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Cecil G. Sheps Center for Health Services Research, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - I-Hsuan Su
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Megan Delgado
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Virginia Pate
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Charles Poole
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jessie K Edwards
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Carolina Population Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Til Stürmer
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jennifer L Lund
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Michele Jonsson Funk
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Lee Y, Reese PP, Tran AH, Schaubel DE. Prognostic score-based methods for estimating center effects based on survival probability: Application to post-kidney transplant survival. Stat Med 2024; 43:3036-3050. [PMID: 38780593 DOI: 10.1002/sim.10092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 03/25/2024] [Accepted: 04/16/2024] [Indexed: 05/25/2024]
Abstract
In evaluating the performance of different facilities or centers on survival outcomes, the standardized mortality ratio (SMR), which compares the observed to expected mortality has been widely used, particularly in the evaluation of kidney transplant centers. Despite its utility, the SMR may exaggerate center effects in settings where survival probability is relatively high. An example is one-year graft survival among U.S. kidney transplant recipients. We propose a novel approach to estimate center effects in terms of differences in survival probability (ie, each center versus a reference population). An essential component of the method is a prognostic score weighting technique, which permits accurately evaluating centers without necessarily specifying a correct survival model. Advantages of our approach over existing facility-profiling methods include a metric based on survival probability (greater clinical relevance than ratios of counts/rates); direct standardization (valid to compare between centers, unlike indirect standardization based methods, such as the SMR); and less reliance on correct model specification (since the assumed model is used to generate risk classes as opposed to fitted-value based 'expected' counts). We establish the asymptotic properties of the proposed weighted estimator and evaluate its finite-sample performance under a diverse set of simulation settings. The method is then applied to evaluate U.S. kidney transplant centers with respect to graft survival probability.
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Affiliation(s)
- Youjin Lee
- Department of Biostatistics, Brown University, Providence, Rhode Island
| | - Peter P Reese
- Department of Biostatistics, Epidemiology & Informatics, University of Pennsylvania, Philadelphia, Pennsylvania
- Department of Medicine, Renal-Electrolyte and Hypertension Division, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Amelia H Tran
- Department of Biostatistics, Epidemiology & Informatics, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Douglas E Schaubel
- Department of Biostatistics, Epidemiology & Informatics, University of Pennsylvania, Philadelphia, Pennsylvania
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3
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Brnabic AJM, Curtis SE, Johnston JA, Lo A, Zagar AJ, Lipkovich I, Kadziola Z, Murray MH, Ryan T. Incidence of type 2 diabetes, cardiovascular disease and chronic kidney disease in patients with multiple sclerosis initiating disease-modifying therapies: Retrospective cohort study using a frequentist model averaging statistical framework. PLoS One 2024; 19:e0300708. [PMID: 38517926 PMCID: PMC10959335 DOI: 10.1371/journal.pone.0300708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 03/04/2024] [Indexed: 03/24/2024] Open
Abstract
Researchers are increasingly using insights derived from large-scale, electronic healthcare data to inform drug development and provide human validation of novel treatment pathways and aid in drug repurposing/repositioning. The objective of this study was to determine whether treatment of patients with multiple sclerosis with dimethyl fumarate, an activator of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway, results in a change in incidence of type 2 diabetes and its complications. This retrospective cohort study used administrative claims data to derive four cohorts of adults with multiple sclerosis initiating dimethyl fumarate, teriflunomide, glatiramer acetate or fingolimod between January 2013 and December 2018. A causal inference frequentist model averaging framework based on machine learning was used to compare the time to first occurrence of a composite endpoint of type 2 diabetes, cardiovascular disease or chronic kidney disease, as well as each individual outcome, across the four treatment cohorts. There was a statistically significantly lower risk of incidence for dimethyl fumarate versus teriflunomide for the composite endpoint (restricted hazard ratio [95% confidence interval] 0.70 [0.55, 0.90]) and type 2 diabetes (0.65 [0.49, 0.98]), myocardial infarction (0.59 [0.35, 0.97]) and chronic kidney disease (0.52 [0.28, 0.86]). No differences for other individual outcomes or for dimethyl fumarate versus the other two cohorts were observed. This study effectively demonstrated the use of an innovative statistical methodology to test a clinical hypothesis using real-world data to perform early target validation for drug discovery. Although there was a trend among patients treated with dimethyl fumarate towards a decreased incidence of type 2 diabetes, cardiovascular disease and chronic kidney disease relative to other disease-modifying therapies-which was statistically significant for the comparison with teriflunomide-this study did not definitively support the hypothesis that Nrf2 activation provided additional metabolic disease benefit in patients with multiple sclerosis.
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Affiliation(s)
- Alan J M Brnabic
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
| | - Sarah E Curtis
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
| | - Joseph A Johnston
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
| | - Albert Lo
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
| | - Anthony J Zagar
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
| | - Ilya Lipkovich
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
| | - Zbigniew Kadziola
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
| | - Megan H Murray
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
| | - Timothy Ryan
- Eli Lilly and Company, Lilly Corporate Center, Indianapolis, IN, United States of America
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Handorf EA, Smaldone M, Movva S, Mitra N. Analysis of survival data with nonproportional hazards: A comparison of propensity-score-weighted methods. Biom J 2024; 66:e202200099. [PMID: 36541715 PMCID: PMC10282107 DOI: 10.1002/bimj.202200099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 09/09/2022] [Accepted: 11/04/2022] [Indexed: 12/24/2022]
Abstract
One of the most common ways researchers compare cancer survival outcomes across treatments from observational data is using Cox regression. This model depends on its underlying assumption of proportional hazards, but in some real-world cases, such as when comparing different classes of cancer therapies, substantial violations may occur. In this situation, researchers have several alternative methods to choose from, including Cox models with time-varying hazard ratios; parametric accelerated failure time models; Kaplan-Meier curves; and pseudo-observations. It is unclear which of these models are likely to perform best in practice. To fill this gap in the literature, we perform a neutral comparison study of candidate approaches. We examine clinically meaningful outcome measures that can be computed and directly compared across each method, namely, survival probability at time T, median survival, and restricted mean survival. To adjust for differences between treatment groups, we use inverse probability of treatment weighting based on the propensity score. We conduct simulation studies under a range of scenarios, and determine the biases, coverages, and standard errors of the average treatment effects for each method. We then demonstrate the use of these approaches using two published observational studies of survival after cancer treatment. The first examines chemotherapy in sarcoma, which has a late treatment effect (i.e., similar survival initially, but after 2 years the chemotherapy group shows a benefit). The other study is a comparison of surgical techniques for kidney cancer, where survival differences are attenuated over time.
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Affiliation(s)
| | - Marc Smaldone
- Department of Surgical Oncology, Fox Chase Cancer Center, PA, USA
| | - Sujana Movva
- Department of Medicine, Memorial Sloan Kettering Cancer Center, NY, USA
| | - Nandita Mitra
- Division of Biostatistics, University of Pennsylvania Perelman School of Medicine, PA, USA
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Rytgaard HCW, Eriksson F, van der Laan MJ. Estimation of time-specific intervention effects on continuously distributed time-to-event outcomes by targeted maximum likelihood estimation. Biometrics 2023; 79:3038-3049. [PMID: 36988158 DOI: 10.1111/biom.13856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2021] [Accepted: 02/22/2023] [Indexed: 03/30/2023]
Abstract
This work considers targeted maximum likelihood estimation (TMLE) of treatment effects on absolute risk and survival probabilities in classical time-to-event settings characterized by right-censoring and competing risks. TMLE is a general methodology combining flexible ensemble learning and semiparametric efficiency theory in a two-step procedure for substitution estimation of causal parameters. We specialize and extend the continuous-time TMLE methods for competing risks settings, proposing a targeting algorithm that iteratively updates cause-specific hazards to solve the efficient influence curve equation for the target parameter. As part of the work, we further detail and implement the recently proposed highly adaptive lasso estimator for continuous-time conditional hazards with L1 -penalized Poisson regression. The resulting estimation procedure benefits from relying solely on very mild nonparametric restrictions on the statistical model, thus providing a novel tool for machine-learning-based semiparametric causal inference for continuous-time time-to-event data. We apply the methods to a publicly available dataset on follicular cell lymphoma where subjects are followed over time until disease relapse or death without relapse. The data display important time-varying effects that can be captured by the highly adaptive lasso. In our simulations that are designed to imitate the data, we compare our methods to a similar approach based on random survival forests and to the discrete-time TMLE.
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Affiliation(s)
| | - Frank Eriksson
- Section of Biostatistics, University of Copenhagen, Copenhagen, Denmark
| | - Mark J van der Laan
- Division of Biostatistics, University of California, Berkeley, California, USA
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6
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Moodie EEM. Causal inference for oncology: past developments and current challenges. Int J Biostat 2023; 19:273-281. [PMID: 36054829 DOI: 10.1515/ijb-2022-0056] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2022] [Accepted: 07/20/2022] [Indexed: 12/26/2022]
Abstract
In this paper, we review some important early developments on causal inference in medical statistics and epidemiology that were inspired by questions in oncology. We examine two classical examples from the literature and point to a current area of ongoing methodological development, namely the estimation of optimal adaptive treatment strategies. While causal approaches to analysis have become more routine in oncology research, many exciting challenges and open problems remain, particularly in the context of censored outcomes.
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Affiliation(s)
- Erica E M Moodie
- Department of Epidemiology & Biostatistics, McGill University, Montréal, Québec, Canada
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7
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Wang C, Wei K, Huang C, Yu Y, Qin G. Multiply robust estimator for the difference in survival functions using pseudo-observations. BMC Med Res Methodol 2023; 23:247. [PMID: 37872495 PMCID: PMC10591363 DOI: 10.1186/s12874-023-02065-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 10/11/2023] [Indexed: 10/25/2023] Open
Abstract
BACKGROUND When estimating the causal effect on survival outcomes in observational studies, it is necessary to adjust confounding factors due to unbalanced covariates between treatment and control groups. There is no study on multiple robust method for estimating the difference in survival functions. In this study, we propose a multiply robust (MR) estimator, allowing multiple propensity score models and outcome regression models, to provide multiple protection. METHOD Based on the previous MR estimator (Han 2014) and pseudo-observation approach, we proposed a new MR estimator for estimating the difference in survival functions. The proposed MR estimator based on the pseudo-observation approach has several advantages. First, the proposed estimator has a small bias when any PS and OR models were correctly specified. Second, the proposed estimator considers the advantage pf the pseudo-observation approach, which avoids proportional hazards assumption. A Monte Carlo simulation study was performed to evaluate the performance of the proposed estimator. And the proposed estimator was used to estimate the effect of chemotherapy on triple-negative breast cancer (TNBC) in real data. RESULTS The simulation studies showed that the bias of the proposed estimator was small, and the coverage rate was close to 95% when any model for propensity score or outcome regression is correctly specified regardless of whether the proportional hazard assumption holds, finite sample size and censoring rate. And the simulation results also showed that even though the propensity score models are misspecified, the bias of the proposed estimator was still small when there is a correct model in candidate outcome regression models. And we applied the proposed estimator in real data, finding that chemotherapy could improve the prognosis of TNBC. CONCLUSIONS The proposed estimator, allowing multiple propensity score and outcome regression models, provides multiple protection for estimating the difference in survival functions. The proposed estimator provided a new choice when researchers have a "difficult time" choosing only one model for their studies.
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Affiliation(s)
- Ce Wang
- Department of Biostatistics, Key Laboratory for Health Technology Assessment, National Commission of Health, Key Laboratory of Public Health Safety of Ministry of Education, School of Public Health, Fudan University, Shanghai, China
| | - Kecheng Wei
- Department of Biostatistics, Key Laboratory for Health Technology Assessment, National Commission of Health, Key Laboratory of Public Health Safety of Ministry of Education, School of Public Health, Fudan University, Shanghai, China
| | - Chen Huang
- Department of Biostatistics, Key Laboratory for Health Technology Assessment, National Commission of Health, Key Laboratory of Public Health Safety of Ministry of Education, School of Public Health, Fudan University, Shanghai, China
| | - Yongfu Yu
- Department of Biostatistics, Key Laboratory for Health Technology Assessment, National Commission of Health, Key Laboratory of Public Health Safety of Ministry of Education, School of Public Health, Fudan University, Shanghai, China.
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai, China.
| | - Guoyou Qin
- Department of Biostatistics, Key Laboratory for Health Technology Assessment, National Commission of Health, Key Laboratory of Public Health Safety of Ministry of Education, School of Public Health, Fudan University, Shanghai, China.
- Shanghai Institute of Infectious Disease and Biosecurity, Shanghai, China.
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8
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Yang S, Zhou R, Li F, Thomas LE. Propensity score weighting methods for causal subgroup analysis with time-to-event outcomes. Stat Methods Med Res 2023; 32:1919-1935. [PMID: 37559475 DOI: 10.1177/09622802231188517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/11/2023]
Abstract
Evaluating causal effects of an intervention in pre-specified subgroups is a standard goal in comparative effectiveness research. Despite recent advancements in causal subgroup analysis, research on time-to-event outcomes has been lacking. This article investigates the propensity score weighting method for causal subgroup survival analysis. We introduce two causal estimands, the subgroup marginal hazard ratio and subgroup restricted average causal effect, and provide corresponding propensity score weighting estimators. We analytically established that the bias of subgroup-restricted average causal effect is determined by subgroup covariate balance. Using extensive simulations, we compare the performance of various combinations of propensity score models (logistic regression, random forests, least absolute shrinkage and selection operator, and generalized boosted models) and weighting schemes (inverse probability weighting, and overlap weighting) for estimating the causal estimands. We find that the logistic model with subgroup-covariate interactions selected by least absolute shrinkage and selection operator consistently outperforms other propensity score models. Also, overlap weighting generally outperforms inverse probability weighting in terms of balance, bias and variance, and the advantage is particularly pronounced in small subgroups and/or in the presence of poor overlap. We applied the methods to the observational Comparing Options for Management: PAtient-centered REsults for Uterine Fibroids study to evaluate the causal effects of myomectomy versus hysterectomy on the time to disease recurrence in a number of pre-specified subgroups of patients with uterine fibroids.
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Affiliation(s)
- Siyun Yang
- Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC, USA
| | - Ruiwen Zhou
- Division of Biostatistics, Washington University in St. Louis, Missouri, USA
| | - Fan Li
- Department of Statistical Science, Duke University, Durham, NC, USA
| | - Laine E Thomas
- Department of Biostatistics and Bioinformatics, Duke University School of Medicine, Durham, NC, USA
- Duke Clinical Research Institute, Durham, NC, USA
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Yu Y, Zhang M, Mukherjee B. An inverse probability weighted regression method that accounts for right-censoring for causal inference with multiple treatments and a binary outcome. Stat Med 2023; 42:3699-3715. [PMID: 37392070 DOI: 10.1002/sim.9826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 05/29/2023] [Accepted: 06/01/2023] [Indexed: 07/02/2023]
Abstract
Comparative effectiveness research often involves evaluating the differences in the risks of an event of interest between two or more treatments using observational data. Often, the post-treatment outcome of interest is whether the event happens within a pre-specified time window, which leads to a binary outcome. One source of bias for estimating the causal treatment effect is the presence of confounders, which are usually controlled using propensity score-based methods. An additional source of bias is right-censoring, which occurs when the information on the outcome of interest is not completely available due to dropout, study termination, or treatment switch before the event of interest. We propose an inverse probability weighted regression-based estimator that can simultaneously handle both confounding and right-censoring, calling the method CIPWR, with the letter C highlighting the censoring component. CIPWR estimates the average treatment effects by averaging the predicted outcomes obtained from a logistic regression model that is fitted using a weighted score function. The CIPWR estimator has a double robustness property such that estimation consistency can be achieved when either the model for the outcome or the models for both treatment and censoring are correctly specified. We establish the asymptotic properties of the CIPWR estimator for conducting inference, and compare its finite sample performance with that of several alternatives through simulation studies. The methods under comparison are applied to a cohort of prostate cancer patients from an insurance claims database for comparing the adverse effects of four candidate drugs for advanced stage prostate cancer.
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Affiliation(s)
- Youfei Yu
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Min Zhang
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
| | - Bhramar Mukherjee
- Department of Biostatistics, School of Public Health, University of Michigan, Ann Arbor, Michigan, USA
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10
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Ciocănea-Teodorescu I, Goetghebeur E, Waernbaum I, Schön S, Gabriel EE. Causal inference in survival analysis under deterministic missingness of confounders in register data. Stat Med 2023; 42:1946-1964. [PMID: 36890728 DOI: 10.1002/sim.9706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Revised: 01/17/2023] [Accepted: 02/27/2023] [Indexed: 03/10/2023]
Abstract
Long-term register data offer unique opportunities to explore causal effects of treatments on time-to-event outcomes, in well-characterized populations with minimum loss of follow-up. However, the structure of the data may pose methodological challenges. Motivated by the Swedish Renal Registry and estimation of survival differences for renal replacement therapies, we focus on the particular case when an important confounder is not recorded in the early period of the register, so that the entry date to the register deterministically predicts confounder missingness. In addition, an evolving composition of the treatment arms populations, and suspected improved survival outcomes in later periods lead to informative administrative censoring, unless the entry date is appropriately accounted for. We investigate different consequences of these issues on causal effect estimation following multiple imputation of the missing covariate data. We analyse the performance of different combinations of imputation models and estimation methods for the population average survival. We further evaluate the sensitivity of our results to the nature of censoring and misspecification of fitted models. We find that an imputation model including the cumulative baseline hazard, event indicator, covariates and interactions between the cumulative baseline hazard and covariates, followed by regression standardization, leads to the best estimation results overall, in simulations. Standardization has two advantages over inverse probability of treatment weighting here: it can directly account for the informative censoring by including the entry date as a covariate in the outcome model, and allows for straightforward variance computation using readily available software.
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Affiliation(s)
- Iuliana Ciocănea-Teodorescu
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden.,Victor Babeş National Institute of Pathology, Bucharest, Romania
| | - Els Goetghebeur
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden.,Department of Applied Mathematics, Computer Science and Statistics, Ghent University, Ghent, Belgium
| | | | - Staffan Schön
- Swedish Renal Registry, Jönköping County Hospital, Jönköping, Sweden
| | - Erin E Gabriel
- Department of Medical Epidemiology and Biostatistics, Karolinska Institute, Stockholm, Sweden.,Section of Biostatistics, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
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11
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Denz R, Klaaßen-Mielke R, Timmesfeld N. A comparison of different methods to adjust survival curves for confounders. Stat Med 2023; 42:1461-1479. [PMID: 36748630 DOI: 10.1002/sim.9681] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Revised: 11/17/2022] [Accepted: 01/30/2023] [Indexed: 02/08/2023]
Abstract
Treatment specific survival curves are an important tool to illustrate the treatment effect in studies with time-to-event outcomes. In non-randomized studies, unadjusted estimates can lead to biased depictions due to confounding. Multiple methods to adjust survival curves for confounders exist. However, it is currently unclear which method is the most appropriate in which situation. Our goal is to compare forms of inverse probability of treatment weighting, the G-Formula, propensity score matching, empirical likelihood estimation and augmented estimators as well as their pseudo-values based counterparts in different scenarios with a focus on their bias and goodness-of-fit. We provide a short review of all methods and illustrate their usage by contrasting the survival of smokers and non-smokers, using data from the German Epidemiological Trial on Ankle-Brachial-Index. Subsequently, we compare the methods using a Monte-Carlo simulation. We consider scenarios in which correctly or incorrectly specified models for describing the treatment assignment and the time-to-event outcome are used with varying sample sizes. The bias and goodness-of-fit is determined by taking the entire survival curve into account. When used properly, all methods showed no systematic bias in medium to large samples. Cox regression based methods, however, showed systematic bias in small samples. The goodness-of-fit varied greatly between different methods and scenarios. Methods utilizing an outcome model were more efficient than other techniques, while augmented estimators using an additional treatment assignment model were unbiased when either model was correct with a goodness-of-fit comparable to other methods. These "doubly-robust" methods have important advantages in every considered scenario.
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Affiliation(s)
- Robin Denz
- Department of Medical Informatics, Biometry and Epidemiology, Ruhr-University of Bochum, Bochum, North-Rhine Westphalia, Germany
| | - Renate Klaaßen-Mielke
- Department of Medical Informatics, Biometry and Epidemiology, Ruhr-University of Bochum, Bochum, North-Rhine Westphalia, Germany
| | - Nina Timmesfeld
- Department of Medical Informatics, Biometry and Epidemiology, Ruhr-University of Bochum, Bochum, North-Rhine Westphalia, Germany
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12
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Su CL, Chiou SH, Lin FC, Platt RW. Analysis of survival data with cure fraction and variable selection: A pseudo-observations approach. Stat Methods Med Res 2022; 31:2037-2053. [PMID: 35754373 PMCID: PMC9660265 DOI: 10.1177/09622802221108579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
In biomedical studies, survival data with a cure fraction (the proportion of subjects cured of disease) are commonly encountered. The mixture cure and bounded cumulative hazard models are two main types of cure fraction models when analyzing survival data with long-term survivors. In this article, in the framework of the Cox proportional hazards mixture cure model and bounded cumulative hazard model, we propose several estimators utilizing pseudo-observations to assess the effects of covariates on the cure rate and the risk of having the event of interest for survival data with a cure fraction. A variable selection procedure is also presented based on the pseudo-observations using penalized generalized estimating equations for proportional hazards mixture cure and bounded cumulative hazard models. Extensive simulation studies are conducted to examine the proposed methods. The proposed technique is demonstrated through applications to a melanoma study and a dental data set with high-dimensional covariates.
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Affiliation(s)
- Chien-Lin Su
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Québec, Canada
- Centre for Clinical Epidemiology, Lady Davis Institute, Jewish
General Hospital, Montréal, Québec, Canada
- Peri and Post Approval Studies, Strategic and Scientific Affairs,
PPD, part of Thermo Fisher Scientific, Montréal, Québec, Canada
| | - Sy Han Chiou
- Department of Mathematical Sciences, University of Texas at Dallas,
Richardson, TX, USA
| | - Feng-Chang Lin
- Department of Biostatistics, University of North Carolina, Chapel
Hill, NC, USA
| | - Robert W Platt
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Québec, Canada
- Centre for Clinical Epidemiology, Lady Davis Institute, Jewish
General Hospital, Montréal, Québec, Canada
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13
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Abstract
Randomized controlled trials (RCTs) are the gold standard design to establish the efficacy of new drugs and to support regulatory decision making. However, a marked increase in the submission of single-arm trials (SATs) has been observed in recent years, especially in the field of oncology due to the trend towards precision medicine contributing to the rise of new therapeutic interventions for rare diseases. SATs lack results for control patients, and information from external sources can be compiled to provide context for better interpretability of study results. External comparator arm (ECA) studies are defined as a clinical trial (most commonly a SAT) and an ECA of a comparable cohort of patients-commonly derived from real-world settings including registries, natural history studies, or medical records of routine care. This publication aims to provide a methodological overview, to sketch emergent best practice recommendations and to identify future methodological research topics. Specifically, existing scientific and regulatory guidance for ECA studies is reviewed and appropriate causal inference methods are discussed. Further topics include sample size considerations, use of estimands, handling of different data sources regarding differential baseline covariate definitions, differential endpoint measurements and timings. In addition, unique features of ECA studies are highlighted, specifically the opportunity to address bias caused by unmeasured ECA covariates, which are available in the SAT.
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14
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Rong R, Ning J, Zhu H. Regression modeling of restricted mean survival time for left-truncated right-censored data. Stat Med 2022; 41:3003-3021. [PMID: 35708238 PMCID: PMC10014036 DOI: 10.1002/sim.9399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 01/27/2022] [Accepted: 03/05/2022] [Indexed: 11/10/2022]
Abstract
The restricted mean survival time (RMST) is a clinically meaningful summary measure in studies with survival outcomes. Statistical methods have been developed for regression analysis of RMST to investigate impacts of covariates on RMST, which is a useful alternative to the Cox regression analysis. However, existing methods for regression modeling of RMST are not applicable to left-truncated right-censored data that arise frequently in prevalent cohort studies, for which the sampling bias due to left truncation and informative censoring induced by the prevalent sampling scheme must be properly addressed. The pseudo-observation (PO) approach has been used in regression modeling of RMST for right-censored data and competing-risks data. For left-truncated right-censored data, we propose to directly model RMST as a function of baseline covariates based on POs under general censoring mechanisms. We adjust for the potential covariate-dependent censoring or dependent censoring by the inverse probability of censoring weighting method. We establish large sample properties of the proposed estimators and assess their finite sample performances by simulation studies under various scenarios. We apply the proposed methods to a prevalent cohort of women diagnosed with stage IV breast cancer identified from surveillance, epidemiology, and end results-medicare linked database.
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Affiliation(s)
- Rong Rong
- Department of Statistical Science, Southern Methodist University, Dallas, Texas, USA.,Division of BiostatisticsDepartment of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Jing Ning
- Department of Biostatistics, University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Hong Zhu
- Division of BiostatisticsDepartment of Population and Data Sciences, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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15
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Lu Y, Gehr AW, Meadows RJ, Ghabach B, Neerukonda L, Narra K, Ojha RP. Timing of adjuvant chemotherapy initiation and mortality among colon cancer patients at a safety-net health system. BMC Cancer 2022; 22:593. [PMID: 35641921 PMCID: PMC9158363 DOI: 10.1186/s12885-022-09688-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Accepted: 05/24/2022] [Indexed: 11/21/2022] Open
Abstract
Background Prior studies reported survival benefits from early initiation of adjuvant chemotherapy for stage III colon cancer, but this evidence was derived from studies that may be sensitive to time-related biases. Therefore, we aimed to estimate the effect of initiating adjuvant chemotherapy ≤8 or ≤ 12 weeks on overall and disease-free survival among stage III colon cancer patients using a study design that helps address time-related biases. Methods We used institutional registry data from JPS Oncology and Infusion Center, a Comprehensive Community Cancer Program. Eligible patients were adults aged < 80 years, diagnosed with first primary stage III colon cancer between 2011 and 2017, and received surgical resection with curative intent. We emulated a target trial with sequential eligibility. We subsequently pooled the trials and estimated risk ratios (RRs) along with 95% confidence limits (CL) for all-cause mortality and recurrence or death at 5-years between initiators and non-initiators of adjuvant chemotherapy ≤8 or ≤ 12 weeks using pseudo-observations and a marginal structural model with stabilized inverse probability of treatment weights. Results Our study population comprised 222 (for assessing initiation ≤8 weeks) and 310 (for assessing initiation ≤12 weeks) observations, of whom the majority were racial/ethnic minorities (64–65%), or uninsured with or without enrollment in our hospital-based medical assistance program (68–71%). Initiation of adjuvant chemotherapy ≤8 weeks of surgical resection did not improve overall survival (RR for all-cause mortality = 1.04, 95% CL: 0.57, 1.92) or disease-free survival (RR for recurrence or death = 1.07, 95% CL: 0.61, 1.88). The results were similar for initiation of adjuvant chemotherapy ≤12 weeks of surgical resection. Conclusions Our results suggest that the overall and disease-free survival benefits of initiating adjuvant chemotherapy ≤8 or ≤ 12 weeks of surgical resection may be overestimated in prior studies, which may be attributable to time-related biases. Nevertheless, our estimates were imprecise and differences in population characteristics are an alternate explanation. Additional studies that address time-related biases are needed to clarify our findings. Supplementary Information The online version contains supplementary material available at 10.1186/s12885-022-09688-w.
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Affiliation(s)
- Yan Lu
- Center for Epidemiology & Healthcare Delivery Research, JPS Health Network, 1500 S. Main Street, Fort Worth, TX, 76104, USA
| | - Aaron W Gehr
- Center for Epidemiology & Healthcare Delivery Research, JPS Health Network, 1500 S. Main Street, Fort Worth, TX, 76104, USA
| | - Rachel J Meadows
- Center for Epidemiology & Healthcare Delivery Research, JPS Health Network, 1500 S. Main Street, Fort Worth, TX, 76104, USA.,Department of Medical Education, TCU School of Medicine, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA
| | - Bassam Ghabach
- Oncology and Infusion Center, JPS Health Network, 1450 8th Ave, Fort Worth, TX, 76104, USA
| | - Latha Neerukonda
- Oncology and Infusion Center, JPS Health Network, 1450 8th Ave, Fort Worth, TX, 76104, USA
| | - Kalyani Narra
- Oncology and Infusion Center, JPS Health Network, 1450 8th Ave, Fort Worth, TX, 76104, USA
| | - Rohit P Ojha
- Center for Epidemiology & Healthcare Delivery Research, JPS Health Network, 1500 S. Main Street, Fort Worth, TX, 76104, USA. .,Department of Medical Education, TCU School of Medicine, 3430 Camp Bowie Blvd, Fort Worth, TX, 76107, USA.
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16
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Lin J, Trinquart L. Doubly-robust estimator of the difference in restricted mean times lost with competing risks data. Stat Methods Med Res 2022; 31:1881-1903. [PMID: 35607287 DOI: 10.1177/09622802221102625] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the context of competing risks data, the subdistribution hazard ratio has limited clinical interpretability to measure treatment effects. An alternative is the difference in restricted mean times lost (RMTL), which gives the mean time lost to a specific cause of failure between treatment groups. In non-randomized studies, the average causal effect is conventionally used for decision-making about treatment and public health policies. We show how the difference in RMTL can be estimated by contrasting the integrated cumulative incidence functions from a Fine-Gray model. We also show how the difference in RMTL can be estimated by using inverse probability of treatment weighting and contrasts between weighted non-parametric estimators of the area below the cumulative incidence. We use pseudo-observation approaches to estimate both component models and we integrate them into a doubly-robust estimator. We demonstrate that this estimator is consistent when either component is correctly specified. We conduct simulation studies to assess its finite-sample performance and demonstrate its inherited consistency property from its component models. We also examine the performance of this estimator under varying degrees of covariate overlap and under a model misspecification of nonlinearity. We apply the proposed method to assess biomarker-treatment interaction in subpopulations of the POPLAR and OAK randomized controlled trials of second-line therapy for advanced non-small-cell lung cancer.
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Affiliation(s)
- Jingyi Lin
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Ludovic Trinquart
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA.,550030Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, MA, USA.,551843Tufts Clinical and Translational Science Institute, Tufts University, Boston, MA, USA
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17
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Maeng CV, Christiansen CF, Liu KD, Kamper P, Christensen S, Medeiros BC, Østgård LSG. Factors associated with risk and prognosis of intensive care unit admission in patients with acute leukemia: a Danish nationwide cohort study. Leuk Lymphoma 2022; 63:2290-2300. [DOI: 10.1080/10428194.2022.2074984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
| | | | - Kathleen Dori Liu
- Division of Nephrology, Department of Medicine and Anesthesia, University of California, San Francisco, San Francisco, CA, USA
| | - Peter Kamper
- Department of Hematology, Aarhus University Hospital, Aarhus, Denmark
| | | | - Bruno C. Medeiros
- Department of Hematology, Stanford Cancer Center, Stanford University, Palo Alto, CA, USA
| | - Lene Sofie Granfeldt Østgård
- Department of Hematology, Aarhus University Hospital, Aarhus, Denmark
- Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
- Department of Hematology, Odense University Hospital, Odense, Denmark
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18
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Choi S, Choi T, Lee HY, Han SW, Bandyopadhyay D. Doubly-robust methods for differences in restricted mean lifetimes using pseudo-observations. Pharm Stat 2022; 21:1185-1198. [PMID: 35524651 DOI: 10.1002/pst.2223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 04/13/2022] [Accepted: 04/20/2022] [Indexed: 11/07/2022]
Abstract
In clinical studies or trials comparing survival times between two treatment groups, the restricted mean lifetime (RML), defined as the expectation of the survival from time 0 to a prespecified time-point, is often the quantity of interest that is readily interpretable to clinicians without any modeling restrictions. It is well known that if the treatments are not randomized (as in observational studies), covariate adjustment is necessary to account for treatment imbalances due to confounding factors. In this article, we propose a simple doubly-robust pseudo-value approach to effectively estimate the difference in the RML between two groups (akin to a metric for estimating average causal effects), while accounting for confounders. The proposed method combines two general approaches: (a) group-specific regression models for the time-to-event and covariate information, and (b) inverse probability of treatment assignment weights, where the RMLs are replaced by the corresponding pseudo-observations for survival outcomes, thereby mitigating the estimation complexities in presence of censoring. The proposed estimator is double-robust, in the sense that it is consistent if at least one of the two working models remains correct. In addition, we explore the potential of available machine learning algorithms in causal inference to reduce possible bias of the causal estimates in presence of a complex association between the survival outcome and covariates. We conduct extensive simulation studies to assess the finite-sample performance of the pseudo-value causal effect estimators. Furthermore, we illustrate our methodology via application to a dataset from a breast cancer cohort study. The proposed method is implementable using the R package drRML, available in GitHub.
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Affiliation(s)
- Sangbum Choi
- Department of Statistics, Korea University, Seoul, South Korea
| | - Taehwa Choi
- Department of Statistics, Korea University, Seoul, South Korea
| | - Hye-Young Lee
- Department of Statistics, Korea University, Seoul, South Korea
| | - Sung Won Han
- School of Industrial Management Engineering, Korea University, Seoul, South Korea
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19
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Lu Y, Gehr AW, Narra K, Lingam A, Ghabach B, Meadows RJ, Ojha RP. Impact of prognostic factor distributions on mortality disparities for socioeconomically disadvantaged cancer patients. Ann Epidemiol 2021; 65:31-37. [PMID: 34601096 DOI: 10.1016/j.annepidem.2021.09.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 09/16/2021] [Accepted: 09/22/2021] [Indexed: 12/23/2022]
Abstract
PURPOSE We aimed to assess whether differences in the distributions of prognostic factors explain reported mortality disparities between urban safety-net and Surveillance, Epidemiology, and End Results (SEER) cancer populations. METHODS We used data from SEER and a safety-net cancer center in Texas. Eligible patients were adults aged ≤64 years and diagnosed with first primary female breast, colorectal, or lung cancer between 2008 and 2016. We estimated crude and adjusted risk differences (RD) in 3- and 5-year all-cause mortality (1- and 3-year for lung cancer), where adjustment was based on entropy balancing weights that standardized the distribution of sociodemographic and tumor characteristics between the two populations. RESULTS Our study populations comprised 1914 safety-net patients and 389,709 SEER patients. For breast cancer, the crude 3- and 5-year mortality RDs between safety-net and SEER populations were 7.7% (95% confidence limits [CL]: 4.3%, 11%) and 11% (95% CL: 6.7%, 16%). Adjustment for measured prognostic factors reduced the mortality RDs (3-year adjusted RD = 0.049%, 95% CL: -2.6%, 2.6%; 5-year adjusted RD = 5.6%, 95% CL: -0.83%, 12%). We observed similar patterns for colorectal and lung cancer albeit less magnitude. CONCLUSIONS Sociodemographic and tumor characteristics may largely explain early mortality disparities between safety-net and SEER populations but not late mortality disparities.
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Affiliation(s)
- Yan Lu
- Center for Epidemiology and Healthcare Delivery Research, JPS Health Network, Fort Worth, TX
| | - Aaron W Gehr
- Center for Epidemiology and Healthcare Delivery Research, JPS Health Network, Fort Worth, TX
| | - Kalyani Narra
- Oncology and Infusion Center, JPS Health Network, Fort Worth, Texas; Department of Internal Medicine, TCU & UNTHSC School of Medicine, Fort Worth, Texas
| | - Anuradha Lingam
- Oncology and Infusion Center, JPS Health Network, Fort Worth, Texas
| | - Bassam Ghabach
- Oncology and Infusion Center, JPS Health Network, Fort Worth, Texas
| | - Rachel J Meadows
- Center for Epidemiology and Healthcare Delivery Research, JPS Health Network, Fort Worth, TX
| | - Rohit P Ojha
- Center for Epidemiology and Healthcare Delivery Research, JPS Health Network, Fort Worth, TX; Department of Medical Education, TCU & UNTHSC School of Medicine, Fort Worth, Texas.
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20
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Ibsen DB, Jakobsen MU, Halkjær J, Tjønneland A, Kilpeläinen TO, Parner ET, Overvad K. Replacing Red Meat with Other Nonmeat Food Sources of Protein is Associated with a Reduced Risk of Type 2 Diabetes in a Danish Cohort of Middle-Aged Adults. J Nutr 2021; 151:1241-1248. [PMID: 33693801 DOI: 10.1093/jn/nxaa448] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 09/10/2020] [Accepted: 12/22/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Few cohort studies have modelled replacements of red meat with other sources of protein on subsequent risk of type 2 diabetes using dietary changes. OBJECTIVES To determine whether replacing red meat with other food sources of protein is associated with a lower risk of type 2 diabetes. METHODS We used data from the Danish Diet, Cancer, and Health cohort (n = 39,437) of middle-aged (55-72 years old) men and women who underwent 2 dietary assessments roughly 5 years apart to investigate dietary changes. The pseudo-observation method was used to model the average exposure effect of decreasing the intake of red meat while increasing the intake of either poultry, fish, eggs, milk, yogurt, cheese, whole grains, or refined grains on the subsequent 10-year risk of developing type 2 diabetes, compared with no changes in the intakes of these foods. RESULTS Replacing 1 serving/day (100 g/day) of red meat with 1 serving/day of eggs [risk difference (RD), -2.7%; 95% CI: -4.0 to -1.1%; serving size: 50 g/day], milk (RD, -1.2%; 95% CI: -2.1 to -0.4%; 200 g/day), yogurt (RD, -1.5%; 95% CI: -2.4 to -0.7%; 70 g/day), whole grains (RD, -1.7%; 95% CI: -2.5 to -0.9%; 30 g/day), or refined grains (RD, -1.2%; 95% CI: -2.0 to -0.3%; 30 g/day) was associated with a reduced risk of type 2 diabetes. Analyses of replacements with poultry or cheese, but not fish, also suggested a lower risk, but with wide CIs. After further adjustment for potential mediators (BMI, waist circumference, and history of hypertension or hypercholesterolemia), only the replacement with eggs was associated with a reduced risk (RD, -1.7%; 95% CI: -3.0 to -0.5%; 50 g/day). CONCLUSIONS Replacing red meat with eggs in middle-aged adults may reduce the risk of type 2 diabetes. In models not adjusted for potential mediators, replacing red meat with milk, yogurt, whole grains, or refined grains was also associated with a reduced risk of type 2 diabetes.
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Affiliation(s)
- Daniel B Ibsen
- Department of Public Health, Aarhus University, Aarhus, Denmark
| | - Marianne U Jakobsen
- National Food Institute, Division for Diet, Disease Prevention and Toxicology, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Jytte Halkjær
- Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Anne Tjønneland
- Danish Cancer Society Research Center, Copenhagen, Denmark.,Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Tuomas O Kilpeläinen
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Erik T Parner
- Department of Public Health, Aarhus University, Aarhus, Denmark
| | - Kim Overvad
- Department of Public Health, Aarhus University, Aarhus, Denmark.,Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark
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21
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Ward MA, Kuttab HI, Lykins V JD, Wroblewski K, Hughes MD, Keast EP, Kopec JA, Rourke EM, Purakal J. The Effect of Body Mass Index and Weight-Adjusted Fluid Dosing on Mortality in Sepsis. J Intensive Care Med 2020; 37:83-91. [PMID: 33213268 DOI: 10.1177/0885066620973917] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
PURPOSE The Surviving Sepsis Campaign guidelines recommend 30 mL/kg of fluids within 3 hours (30by3) of sepsis-induced hypoperfusion, but a national mandate released an allowance for dosing based on ideal instead of actual body weight (IBW/ABW) for obese patients. This study aims to determine the dose-effect of 30by3 for patients with severe sepsis or septic shock (SS/SS) with respect to body mass index (BMI) categories and secondarily, examine the clinical impact of IBW vs. ABW-based dosing. METHODS Retrospective cohort study of adults (≥18 years; n = 1,032) with SS/SS presenting to an urban, tertiary-care emergency department. Models include MEDS score, antibiotic timing, lactate, renal and heart failure, among others. RESULTS The cohort was 10.2% underweight and 28.7% obese. Overall mortality was 17.1% with 20.4% shock mortality. An exponential increase in mortality was observed for each 5 mL/kg under 30by3 for underweight (p = 0.02), but not obese patients. ABW vs IBW-30by3 dosing was reached in 80.0 vs 52.4% (underweight), 56.4 vs 56.9% (normal/overweight), and 23.3 vs 46.0% (obese). Across all BMI categories, there was increased mortality for not reaching ABW-based 30by3 dosing (OR 1.78, 95% CI 1.18-2.69) with no significant impact for IBW (OR 1.28, 95% CI 0.87 -1.91). The increased mortality for failing to reach ABW-dosed 30by3 remained for underweight patients ABW (OR 5.82, 95% CI 1.32-25.57) but not obese patients. Longer ICU stays were observed for not reaching 30by3 based on ABW (β = 2.40, 95% CI 0.84-3.95) and IBW dosing (β = 1.58, 95% CI 0.07-3.08) overall. This effect remained for obese and underweight (except IBW dosing) patients. CONCLUSIONS An exponential, dose-effect increase in mortality was observed for underweight patients not receiving 30by3. Therefore, the mortality impact of under-dosing may be amplified using ABW for underweight patients. Fluid dosing did not impact mortality for obese patients, but we caution against deviation from guidelines without further studies.
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Affiliation(s)
- Michael A Ward
- BerbeeWalsh Department of Emergency Medicine, 5232University of Wisconsin-Madison, Madison, WI, USA
| | - Hani I Kuttab
- BerbeeWalsh Department of Emergency Medicine, 5232University of Wisconsin-Madison, Madison, WI, USA
| | - Joseph D Lykins V
- Department of Emergency Medicine and Internal Medicine, 6887Virginia Commonwealth University Health System, Richmond, VA, USA
| | - Kristen Wroblewski
- Department of Public Health Sciences, 21727University of Chicago, Chicago, IL, USA
| | - Michelle D Hughes
- BerbeeWalsh Department of Emergency Medicine, 5232University of Wisconsin-Madison, Madison, WI, USA
| | - Eric P Keast
- Division of Emergency Medicine, 3271NorthShore University HealthSystem, Evanston, IL, USA
| | - Jason A Kopec
- Division of Emergency Medicine, 8100Carle Foundation Hospital, Urbana, IL, USA
| | - Erron M Rourke
- Section of Emergency Medicine, 21727University of Chicago, Chicago, IL, USA
| | - John Purakal
- Division of Emergency Medicine, Duke University Medical Center, Durham, NC, USA
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22
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Tanaka S, Brookhart MA, Fine JP. G-estimation of structural nested mean models for competing risks data using pseudo-observations. Biostatistics 2020; 21:860-875. [PMID: 31056651 DOI: 10.1093/biostatistics/kxz015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Revised: 03/19/2019] [Accepted: 03/19/2019] [Indexed: 11/13/2022] Open
Abstract
This article provides methods of causal inference for competing risks data. The methods are formulated as structural nested mean models of causal effects directly related to the cumulative incidence function or subdistribution hazard, which reflect the survival experience of a subject in the presence of competing risks. The effect measures include causal risk differences, causal risk ratios, causal subdistribution hazard ratios, and causal effects of time-varying exposures. Inference is implemented by g-estimation using pseudo-observations, a technique to handle censoring. The finite-sample performance of the proposed estimators in simulated datasets and application to time-varying exposures in a cohort study of type 2 diabetes are also presented.
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Affiliation(s)
- Shiro Tanaka
- Department of Clinical Biostatistics, Graduate School of Medicine, Kyoto University, Yoshida Konoe-cho Sakyo-ku, Kyoto 606-8501, Japan
| | - M Alan Brookhart
- Department of Epidemiology, University of North Carolina, 2105F McGavran-Greenberg Hall, Chapel Hill, North Carolina 27599, USA
| | - Jason P Fine
- Department of Biostatistics, University of North Carolina, 3103B McGavran-Greenberg Hall, Chapel Hill, North Carolina 27599, USA
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23
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Tabib S, Larocque D. Non-parametric individual treatment effect estimation for survival data with random forests. Bioinformatics 2020; 36:629-636. [PMID: 31373350 DOI: 10.1093/bioinformatics/btz602] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 07/06/2019] [Accepted: 07/30/2019] [Indexed: 01/19/2023] Open
Abstract
MOTIVATION Personalized medicine often relies on accurate estimation of a treatment effect for specific subjects. This estimation can be based on the subject's baseline covariates but additional complications arise for a time-to-event response subject to censoring. In this paper, the treatment effect is measured as the difference between the mean survival time of a treated subject and the mean survival time of a control subject. We propose a new random forest method for estimating the individual treatment effect with survival data. The random forest is formed by individual trees built with a splitting rule specifically designed to partition the data according to the individual treatment effect. For a new subject, the forest provides a set of similar subjects from the training dataset that can be used to compute an estimation of the individual treatment effect with any adequate method. RESULTS The merits of the proposed method are investigated with a simulation study where it is compared to numerous competitors, including recent state-of-the-art methods. The results indicate that the proposed method has a very good and stable performance to estimate the individual treatment effects. Two examples of application with a colon cancer data and breast cancer data show that the proposed method can detect a treatment effect in a sub-population even when the overall effect is small or nonexistent. AVAILABILITY AND IMPLEMENTATION The authors are working on an R package implementing the proposed method and it will be available soon. In the meantime, the code can be obtained from the first author at sami.tabib@hec.ca. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Sami Tabib
- Department of Decision Sciences, HEC Montréal, Montréal, QC H3T 2A7, Canada
| | - Denis Larocque
- Department of Decision Sciences, HEC Montréal, Montréal, QC H3T 2A7, Canada
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24
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Barnett TE, Lu Y, Gehr AW, Ghabach B, Ojha RP. Smoking cessation and survival among people diagnosed with non-metastatic cancer. BMC Cancer 2020; 20:726. [PMID: 32758159 PMCID: PMC7405359 DOI: 10.1186/s12885-020-07213-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 07/24/2020] [Indexed: 11/27/2022] Open
Abstract
Background We aimed to estimate the effects of smoking cessation on survival among people diagnosed with cancer. Methods We used data from a Comprehensive Community Cancer Program that is part of a large urban safety-net hospital system. Eligible patients were diagnosed with primary invasive solid tumors between 2013 and 2015, and were current smokers at time of diagnosis. Our exposure of interest was initiation of smoking cessation within 6 months of cancer diagnosis. We estimated inverse probability weighted restricted mean survival time (RMST) differences and risk ratio (RR) for all cause 3-year mortality. Results Our study population comprised 369 patients, of whom 42% were aged < 55 years, 59% were male, 44% were racial/ethnic minorities, and 59% were uninsured. The 3-year RMST was 1.8 (95% CL: − 1.5, 5.1) months longer for individuals who initiated smoking cessation within 6 months of cancer diagnosis. The point estimate for risk of 3-year mortality was lower for initiation of smoking cessation within 6 months of diagnosis compared with no initiation within 6 months (RR = 0.72, 95% CL: 0.37, 1.4). Conclusions Our point estimates suggest longer 3-year survival, but the results are compatible with 1.5 month shorter or 5.1 longer 3-year overall survival after smoking cessation within 6 months of cancer diagnosis. Future studies with larger sample sizes that test the comparative effectiveness of different smoking cessation strategies are needed for more detailed evidence to inform decision-making about the effect of smoking cessation on survival among cancer patients. Implications for Cancer survivors The benefits of smoking cessation after cancer diagnosis may include longer survival, but the magnitude of benefit is unclear.
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Affiliation(s)
- Tracey E Barnett
- School of Public Health, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX, 76107, USA.
| | - Yan Lu
- Center for Outcomes Research, JPS Health Network, 1500 S. Main Street, Fort Worth, TX, 76104, USA
| | - Aaron W Gehr
- Center for Outcomes Research, JPS Health Network, 1500 S. Main Street, Fort Worth, TX, 76104, USA
| | - Bassam Ghabach
- JPS Oncology and Infusion Center, JPS Health Network, 610 W. Terrell Ave., Fort Worth, TX, 76104, USA
| | - Rohit P Ojha
- School of Public Health, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX, 76107, USA.,Department of Biostatistics and Epidemiology, University of North Texas Health Science Center, 3500 Camp Bowie Blvd., Fort Worth, TX, 76107, USA
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25
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Nygård Johansen M, Lundbye-Christensen S, Thorlund Parner E. Regression models using parametric pseudo-observations. Stat Med 2020; 39:2949-2961. [PMID: 32519771 DOI: 10.1002/sim.8586] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 03/01/2020] [Accepted: 05/05/2020] [Indexed: 11/07/2022]
Abstract
Pseudo-observations based on the nonparametric Kaplan-Meier estimator of the survival function have been proposed as an alternative to the widely used Cox model for analyzing censored time-to-event data. Using a spline-based estimator of the survival has some potential benefits over the nonparametric approach in terms of less variability. We propose to define pseudo-observations based on a flexible parametric estimator and use these for analysis in regression models to estimate parameters related to the cumulative risk. We report the results of a simulation study that compares the empirical standard errors of estimates based on parametric and nonparametric pseudo-observations in various settings. Our simulations show that in some situations there is a substantial gain in terms of reduced variability using the proposed parametric pseudo-observations compared with the nonparametric pseudo-observations. The gain can be measured as a reduction of the empirical standard error by up to about one third; corresponding to an additional 125% larger sample size. We illustrate the use of the proposed method in a brief data example.
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Affiliation(s)
| | | | - Erik Thorlund Parner
- Section for Biostatistics, Department of Public Health, Aarhus University, Aarhus, Denmark
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Evaluation and Predictors of Fluid Resuscitation in Patients With Severe Sepsis and Septic Shock. Crit Care Med 2020; 47:1582-1590. [PMID: 31393324 DOI: 10.1097/ccm.0000000000003960] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVES Rapid fluid resuscitation has become standard in sepsis care, despite "low-quality" evidence and absence of guidelines for populations "at risk" for volume overload. Our objectives include as follows: 1) identify predictors of reaching a 30 mL/kg crystalloid bolus within 3 hours of sepsis onset (30by3); 2) assess the impact of 30by3 and fluid dosing on clinical outcomes; 3) examine differences in perceived "at-risk" volume-sensitive populations, including end-stage renal disease, heart failure, obesity, advanced age, or with documentation of volume "overload" by bedside examination. DESIGN Retrospective cohort study. All outcome analyses controlled for sex, end-stage renal disease, heart failure, sepsis severity (severe sepsis vs septic shock), obesity, Mortality in Emergency Department Sepsis score, and time to antibiotics. SETTING Urban, tertiary care center between January 1, 2014, and May 31, 2017. PATIENTS Emergency Department treated adults (age ≥18 yr; n = 1,032) with severe sepsis or septic shock. INTERVENTIONS Administration of IV fluids by bolus. MEASUREMENTS AND MAIN RESULTS In total, 509 patients received 30by3 (49.3%). Overall mortality was 17.1% (n = 176), with 20.4% mortality in the shock group. Patients who were elderly (odds ratio, 0.62; 95% CI, 0.46-0.83), male (odds ratio, 0.66; CI, 0.49-0.87), obese (odds ratio, 0.18; CI, 0.13-0.25), or with end-stage renal disease (odds ratio, 0.23; CI, 0.13-0.40), heart failure (odds ratio, 0.42; CI, 0.29-0.60), or documented volume "overload" (odds ratio, 0.30; CI, 0.20-0.45) were less likely to achieve 30by3. Failure to meet 30by3 had increased odds of mortality (odds ratio, 1.52; CI, 1.03-2.24), delayed hypotension (odds ratio, 1.42; CI, 1.02-1.99), and increased ICU stay (~2 d) (β = 2.0; CI, 0.5-3.6), without differential effects for "at-risk" groups. Higher fluid volumes administered by 3 hours correlated with decreased mortality, with a plateau effect between 35 and 45 mL/kg (p < 0.05). CONCLUSIONS Failure to reach 30by3 was associated with increased odds of in-hospital mortality, irrespective of comorbidities. Predictors of inadequate resuscitation can be identified, potentially leading to interventions to improve survival. These findings are retrospective and require future validation.
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Su CL, Platt RW, Plante JF. Causal inference for recurrent event data using pseudo-observations. Biostatistics 2020; 23:189-206. [PMID: 32432686 DOI: 10.1093/biostatistics/kxaa020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 04/01/2020] [Accepted: 04/02/2020] [Indexed: 11/13/2022] Open
Abstract
Recurrent event data are commonly encountered in observational studies where each subject may experience a particular event repeatedly over time. In this article, we aim to compare cumulative rate functions (CRFs) of two groups when treatment assignment may depend on the unbalanced distribution of confounders. Several estimators based on pseudo-observations are proposed to adjust for the confounding effects, namely inverse probability of treatment weighting estimator, regression model-based estimators, and doubly robust estimators. The proposed marginal regression estimator and doubly robust estimators based on pseudo-observations are shown to be consistent and asymptotically normal. A bootstrap approach is proposed for the variance estimation of the proposed estimators. Model diagnostic plots of residuals are presented to assess the goodness-of-fit for the proposed regression models. A family of adjusted two-sample pseudo-score tests is proposed to compare two CRFs. Simulation studies are conducted to assess finite sample performance of the proposed method. The proposed technique is demonstrated through an application to a hospital readmission data set.
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Affiliation(s)
- Chien-Lin Su
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University and Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada
| | - Robert W Platt
- Department of Epidemiology, Biostatistics and Occupational Health, McGill University and Centre for Clinical Epidemiology, Lady Davis Institute, Jewish General Hospital, Montréal, Québec, Canada
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Ozenne BMH, Scheike TH, Stærk L, Gerds TA. On the estimation of average treatment effects with right‐censored time to event outcome and competing risks. Biom J 2020; 62:751-763. [DOI: 10.1002/bimj.201800298] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 10/28/2019] [Accepted: 11/04/2019] [Indexed: 12/12/2022]
Affiliation(s)
- Brice Maxime Hugues Ozenne
- Department of Biostatistics University of Copenhagen Copenhagen Denmark
- Neurobiology Research Unit University Hospital of Copenhagen Rigshospitalet Copenhagen Denmark
| | | | - Laila Stærk
- Department of Cardiology Copenhagen University Hospital Herlev and Gentofte Hellerup Denmark
| | - Thomas Alexander Gerds
- Department of Biostatistics University of Copenhagen Copenhagen Denmark
- Danish Heart Foundation Copenhagen Denmark
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Lipkovich I, Ratitch B, Mallinckrodt CH. Causal Inference and Estimands in Clinical Trials. Stat Biopharm Res 2020. [DOI: 10.1080/19466315.2019.1697739] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Unkel S, Amiri M, Benda N, Beyersmann J, Knoerzer D, Kupas K, Langer F, Leverkus F, Loos A, Ose C, Proctor T, Schmoor C, Schwenke C, Skipka G, Unnebrink K, Voss F, Friede T. On estimands and the analysis of adverse events in the presence of varying follow-up times within the benefit assessment of therapies. Pharm Stat 2019; 18:166-183. [PMID: 30458579 PMCID: PMC6587465 DOI: 10.1002/pst.1915] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 09/19/2018] [Accepted: 10/23/2018] [Indexed: 12/21/2022]
Abstract
The analysis of adverse events (AEs) is a key component in the assessment of a drug's safety profile. Inappropriate analysis methods may result in misleading conclusions about a therapy's safety and consequently its benefit-risk ratio. The statistical analysis of AEs is complicated by the fact that the follow-up times can vary between the patients included in a clinical trial. This paper takes as its focus the analysis of AE data in the presence of varying follow-up times within the benefit assessment of therapeutic interventions. Instead of approaching this issue directly and solely from an analysis point of view, we first discuss what should be estimated in the context of safety data, leading to the concept of estimands. Although the current discussion on estimands is mainly related to efficacy evaluation, the concept is applicable to safety endpoints as well. Within the framework of estimands, we present statistical methods for analysing AEs with the focus being on the time to the occurrence of the first AE of a specific type. We give recommendations which estimators should be used for the estimands described. Furthermore, we state practical implications of the analysis of AEs in clinical trials and give an overview of examples across different indications. We also provide a review of current practices of health technology assessment (HTA) agencies with respect to the evaluation of safety data. Finally, we describe problems with meta-analyses of AE data and sketch possible solutions.
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Affiliation(s)
- Steffen Unkel
- Department of Medical StatisticsUniversity Medical Center GoettingenGoettingenGermany
| | - Marjan Amiri
- Center for Clinical TrialsUniversity Hospital EssenEssenGermany
| | - Norbert Benda
- Biostatistics and Special Pharmacokinetics Unit, Federal Institute for Drugs and Medical DevicesBonnGermany
| | | | | | - Katrin Kupas
- Bristol‐Myers Squibb GmbH & Co. KGaAMünchenGermany
| | | | | | | | - Claudia Ose
- Center for Clinical TrialsUniversity Hospital EssenEssenGermany
| | - Tanja Proctor
- Institute of Medical Biometry and InformaticsUniversity of HeidelbergHeidelbergGermany
| | - Claudia Schmoor
- Clinical Trials Unit, Faculty of Medicine and Medical CenterUniversity of FreiburgFreiburg im BreisgauGermany
| | - Carsten Schwenke
- Schwenke Consulting: Strategies and Solutions in Statistics (SCO:SSIS)BerlinGermany
| | - Guido Skipka
- Institute for Quality and Efficiency in Health CareCologneGermany
| | | | - Florian Voss
- Boehringer Ingelheim Pharma GmbH & Co. KGIngelheimGermany
| | - Tim Friede
- Department of Medical StatisticsUniversity Medical Center GoettingenGoettingenGermany
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Nielsen RO, Bertelsen ML, Ramskov D, Møller M, Hulme A, Theisen D, Finch CF, Fortington LV, Mansournia MA, Parner ET. Time-to-event analysis for sports injury research part 1: time-varying exposures. Br J Sports Med 2019; 53:61-68. [PMID: 30413422 PMCID: PMC6317442 DOI: 10.1136/bjsports-2018-099408] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/13/2018] [Indexed: 02/01/2023]
Abstract
BACKGROUND 'How much change in training load is too much before injury is sustained, among different athletes?' is a key question in sports medicine and sports science. To address this question the investigator/practitioner must analyse exposure variables that change over time, such as change in training load. Very few studies have included time-varying exposures (eg, training load) and time-varying effect-measure modifiers (eg, previous injury, biomechanics, sleep/stress) when studying sports injury aetiology. AIM To discuss advanced statistical methods suitable for the complex analysis of time-varying exposures such as changes in training load and injury-related outcomes. CONTENT Time-varying exposures and time-varying effect-measure modifiers can be used in time-to-event models to investigate sport injury aetiology. We address four key-questions (i) Does time-to-event modelling allow change in training load to be included as a time-varying exposure for sport injury development? (ii) Why is time-to-event analysis superior to other analytical concepts when analysing training-load related data that changes status over time? (iii) How can researchers include change in training load in a time-to-event analysis? and, (iv) Are researchers able to include other time-varying variables into time-to-event analyses? We emphasise that cleaning datasets, setting up the data, performing analyses with time-varying variables and interpreting the results is time-consuming, and requires dedication. It may need you to ask for assistance from methodological peers as the analytical approaches presented this paper require specialist knowledge and well-honed statistical skills. CONCLUSION To increase knowledge about the association between changes in training load and injury, we encourage sports injury researchers to collaborate with statisticians and/or methodological epidemiologists to carefully consider applying time-to-event models to prospective sports injury data. This will ensure appropriate interpretation of time-to-event data.
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Affiliation(s)
| | | | - Daniel Ramskov
- Section for Sports Science, Department of Public Health, Aarhus University, Aarhus, Denmark
- Department of Physiotherapy, University College Northern Denmark, Aalborg, Denmark
| | - Merete Møller
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Adam Hulme
- Centre for Human Factors and Sociotechnical Systems, Faculty of Arts, University of the Sunshine Coast, Maroochydore DC, Queensland, Australia
| | - Daniel Theisen
- Sports Medicine Research Laboratory, Luxembourg Institute of Health, Luxembourg, Luxembourg
| | - Caroline F Finch
- Australian Centre for Research into Injury in Sport and its Prevention, School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia
| | - Lauren Victoria Fortington
- Australian Centre for Research into Injury in Sport and its Prevention, School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia
- Faculty of Science and Technology, Federation University Australia, Ballarat, Victoria, Australia
| | - Mohammad Ali Mansournia
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Sports Medicine Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Erik Thorlund Parner
- Section for Biostatistics, Department of Public Health, Aarhus University, Aarhus, Denmark
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Windt J, Ardern CL, Gabbett TJ, Khan KM, Cook CE, Sporer BC, Zumbo BD. Getting the most out of intensive longitudinal data: a methodological review of workload-injury studies. BMJ Open 2018; 8:e022626. [PMID: 30282683 PMCID: PMC6169745 DOI: 10.1136/bmjopen-2018-022626] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 07/24/2018] [Accepted: 09/04/2018] [Indexed: 11/26/2022] Open
Abstract
OBJECTIVES To systematically identify and qualitatively review the statistical approaches used in prospective cohort studies of team sports that reported intensive longitudinal data (ILD) (>20 observations per athlete) and examined the relationship between athletic workloads and injuries. Since longitudinal research can be improved by aligning the (1) theoretical model, (2) temporal design and (3) statistical approach, we reviewed the statistical approaches used in these studies to evaluate how closely they aligned these three components. DESIGN Methodological review. METHODS After finding 6 systematic reviews and 1 consensus statement in our systematic search, we extracted 34 original prospective cohort studies of team sports that reported ILD (>20 observations per athlete) and examined the relationship between athletic workloads and injuries. Using Professor Linda Collins' three-part framework of aligning the theoretical model, temporal design and statistical approach, we qualitatively assessed how well the statistical approaches aligned with the intensive longitudinal nature of the data, and with the underlying theoretical model. Finally, we discussed the implications of each statistical approach and provide recommendations for future research. RESULTS Statistical methods such as correlations, t-tests and simple linear/logistic regression were commonly used. However, these methods did not adequately address the (1) themes of theoretical models underlying workloads and injury, nor the (2) temporal design challenges (ILD). Although time-to-event analyses (eg, Cox proportional hazards and frailty models) and multilevel modelling are better-suited for ILD, these were used in fewer than a 10% of the studies (n=3). CONCLUSIONS Rapidly accelerating availability of ILD is the norm in many fields of healthcare delivery and thus health research. These data present an opportunity to better address research questions, especially when appropriate statistical analyses are chosen.
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Affiliation(s)
- Johann Windt
- Experimental Medicine Program, University of British Columbia, Vancouver, British Columbia, Canada
- United States Olympic Committee, Colorado Springs, Colorado, USA
- United States Coalition for the Prevention of Illness and Injury in Sport, Colorado Springs, Colorado, USA
| | - Clare L Ardern
- Division of Physiotherapy, Linköping University, Linköping, Sweden
- School of Allied Health, La Trobe University, Melbourne, Victoria, Australia
| | - Tim J Gabbett
- Gabbett Performance Solutions, Brisbane, Queensland, Australia
- Institute for Resilient Regions, University of Southern Queensland, Ipswich, Queensland, Australia
| | - Karim M Khan
- Experimental Medicine Program, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Family Practice, University of British Columbia, Vancouver, British Columbia, Canada
| | - Chad E Cook
- Department of Orthopaedics, Duke University, Durham, North Carolina, USA
| | - Ben C Sporer
- Department of Family Practice, University of British Columbia, Vancouver, British Columbia, Canada
- Vancouver Whitecaps Football Club, Vancouver, British Columbia, Canada
| | - Bruno D Zumbo
- Measurement, Evaluation, and Research Methodology Program, University of British Columbia, Vancouver, British Columbia, Canada
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Mao H, Li L, Yang W, Shen Y. On the propensity score weighting analysis with survival outcome: Estimands, estimation, and inference. Stat Med 2018; 37:3745-3763. [DOI: 10.1002/sim.7839] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 04/26/2018] [Accepted: 05/07/2018] [Indexed: 11/05/2022]
Affiliation(s)
- Huzhang Mao
- Department of Biostatistics and Data Science, School of Public Health; The University of Texas; Houston TX USA
- Department of Biostatistics; The University of Texas MD Anderson Cancer Center; Houston TX USA
| | - Liang Li
- Department of Biostatistics; The University of Texas MD Anderson Cancer Center; Houston TX USA
| | - Wei Yang
- Department of Biostatistics, Epidemiology and Informatics; University of Pennsylvania Perelman School of Medicine; Philadelphia PA USA
| | - Yu Shen
- Department of Biostatistics; The University of Texas MD Anderson Cancer Center; Houston TX USA
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