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Jorge AES, Dantas LO, Aburquerque-Sendín F, Ferrari AV, Cunha JE, Dantas GADF, Barbosa GM, Serrão PRMDS, Salvini TDF. Photobiomodulation does not provide incremental benefits to patients with knee osteoarthritis who receive a strengthening exercises program: a randomized controlled trial. Braz J Phys Ther 2023; 27:100519. [PMID: 37572382 PMCID: PMC10440468 DOI: 10.1016/j.bjpt.2023.100519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 04/05/2023] [Accepted: 06/15/2023] [Indexed: 08/14/2023] Open
Abstract
BACKGROUND There is lack of agreement in the literature about the effectiveness of photobiomodulation (PBM) for reducing pain-related symptoms in patients with knee osteoarthritis (OA). OBJECTIVE To evaluate whether PBM, when combined to exercises, provides incremental therapeutic benefits for pain, physical function, and quality of life (QoL) in patients with knee OA. METHODS A six-month double-blind placebo-controlled randomized trial was conducted. Patients with knee OA were randomly assigned to one of three treatment groups: Exercise, Exercise plus Active PBM, or Exercise plus Placebo PBM. Treatment was provided over an eight-week period, three times per week. The primary outcomes were pain at rest and upon movement, assessed by a visual analogue scale (VAS). WOMAC global score, QoL, and a core-set of performance-based tests were measured as secondary outcomes. All outcomes were collected at baseline, immediately after treatment, and after three- and six-month post-treatment. RESULTS 127 participants were allocated as follows: Exercise, N = 41; Exercise plus Active PBM, N = 44; and Exercise plus Placebo PBM, N = 42. There was no between-groups difference in improvement in pain, physical function, and QoL for all follow-up times. However, all groups presented significant, clinically relevant improvements in pain, physical function, and QoL immediately and three months after treatment compared with baseline measures. CONCLUSION Patients with knee OA who received a strengthening exercises program did not experience incremental benefits regarding pain, physical function, or QoL when adding PBM to their therapeutic exercises.
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Affiliation(s)
| | - Lucas Ogura Dantas
- Physical Therapy Department, Universidade Federal de São Carlos, São Carlos, SP, Brazil
| | - Francisco Aburquerque-Sendín
- Department of Nursing, Pharmacology and Physical Therapy, Sociosanitary Sciences, Radiology and Physical Medicine, University of Córdoba, and Maimonides Biomedical Research Institute of Cordoba, Córdoba, Spain
| | | | | | | | - Germanna Medeiros Barbosa
- Physical Therapy Department, Universidade Federal de São Carlos, São Carlos, SP, Brazil; Faculty of Health Sciences of Trairi, Universidade Federal do Rio Grande do Norte, Santa Cruz, RN, Brazil
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Lu H, Cole SR, Howe CJ, Westreich D. Toward a Clearer Definition of Selection Bias When Estimating Causal Effects. Epidemiology 2022; 33:699-706. [PMID: 35700187 PMCID: PMC9378569 DOI: 10.1097/ede.0000000000001516] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Selection bias remains a subject of controversy. Existing definitions of selection bias are ambiguous. To improve communication and the conduct of epidemiologic research focused on estimating causal effects, we propose to unify the various existing definitions of selection bias in the literature by considering any bias away from the true causal effect in the referent population (the population before the selection process), due to selecting the sample from the referent population, as selection bias. Given this unified definition, selection bias can be further categorized into two broad types: type 1 selection bias owing to restricting to one or more level(s) of a collider (or a descendant of a collider) and type 2 selection bias owing to restricting to one or more level(s) of an effect measure modifier. To aid in explaining these two types-which can co-occur-we start by reviewing the concepts of the target population, the study sample, and the analytic sample. Then, we illustrate both types of selection bias using causal diagrams. In addition, we explore the differences between these two types of selection bias, and describe methods to minimize selection bias. Finally, we use an example of "M-bias" to demonstrate the advantage of classifying selection bias into these two types.
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Affiliation(s)
- Haidong Lu
- Public Health Modeling Unit and Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA
| | - Stephen R. Cole
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, NC, USA
| | - Chanelle J. Howe
- Department of Epidemiology, School of Public Health, Brown University, RI, USA
| | - Daniel Westreich
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, NC, USA
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Li F, Buchanan AL, Cole SR. Generalizing trial evidence to target populations in non-nested designs: Applications to AIDS clinical trials. J R Stat Soc Ser C Appl Stat 2022; 71:669-697. [PMID: 35968541 PMCID: PMC9367209 DOI: 10.1111/rssc.12550] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Comparative effectiveness evidence from randomized trials may not be directly generalizable to a target population of substantive interest when, as in most cases, trial participants are not randomly sampled from the target population. Motivated by the need to generalize evidence from two trials conducted in the AIDS Clinical Trials Group (ACTG), we consider weighting, regression and doubly robust estimators to estimate the causal effects of HIV interventions in a specified population of people living with HIV in the USA. We focus on a non-nested trial design and discuss strategies for both point and variance estimation of the target population average treatment effect. Specifically in the generalizability context, we demonstrate both analytically and empirically that estimating the known propensity score in trials does not increase the variance for each of the weighting, regression and doubly robust estimators. We apply these methods to generalize the average treatment effects from two ACTG trials to specified target populations and operationalize key practical considerations. Finally, we report on a simulation study that investigates the finite-sample operating characteristics of the generalizability estimators and their sandwich variance estimators.
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Affiliation(s)
- Fan Li
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
- Center for Methods in Implementation and Prevention Science, Yale University, New Haven, Connecticut, USA
| | - Ashley L. Buchanan
- Department of Pharmacy Practice, College of Pharmacy, University of Rhode Island, Kingston, Rhode Island, USA
| | - Stephen R. Cole
- Department of Epidemiology, Gillings School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Lu H, Cole SR, Westreich D, Hudgens MG, Adimora AA, Althoff KN, Silverberg MJ, Buchacz K, Li J, Edwards JK, Rebeiro PF, Lima VD, Marconi VC, Sterling TR, Horberg MA, Gill MJ, Kitahata MM, Eron JJ, Moore RD. Virologic outcomes among adults with HIV using integrase inhibitor-based antiretroviral therapy. AIDS 2022; 36:277-286. [PMID: 34934020 PMCID: PMC9048218 DOI: 10.1097/qad.0000000000003069] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Integrase strand transfer inhibitor (InSTI)-based regimens have been recommended as first-line antiretroviral therapy (ART) for adults with HIV. But data on long-term effects of InSTI-based regimens on virologic outcomes remain limited. Here we examined whether InSTI improved long-term virologic outcomes compared with efavirenz (EFV). METHODS We included adults from the North American AIDS Cohort Collaboration on Research and Design who initiated their first ART regimen containing either InSTI or EFV between 2009 and 2016. We estimated differences in the proportion virologically suppressed up to 7 years of follow-up in observational intention-to-treat and per-protocol analyses. RESULTS Of 15 318 participants, 5519 (36%) initiated an InSTI-based regimen and 9799 (64%) initiated the EFV-based regimen. In observational intention-to-treat analysis, 81.3% of patients in the InSTI group and 67.3% in the EFV group experienced virologic suppression at 3 months after ART initiation, corresponding to a difference of 14.0% (95% CI 12.4-15.6). At 1 year after ART initiation, the proportion virologically suppressed was 89.5% in the InSTI group and 90.2% in the EFV group, corresponding to a difference of -0.7% (95% CI -2.1 to 0.8). At 7 years, the proportion virologically suppressed was 94.5% in the InSTI group and 92.5% in the EFV group, corresponding to a difference of 2.0% (95% CI -7.3 to 11.3). The observational per-protocol results were similar to intention-to-treat analyses. CONCLUSIONS Although InSTI-based initial ART regimens had more rapid virologic response than EFV-based regimens, the long-term virologic effect was similar. Our findings may inform guidelines regarding preferred initial regimens for HIV treatment.
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Affiliation(s)
- Haidong Lu
- Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Connecticut
| | | | | | | | - Adaora A. Adimora
- Department of Epidemiology
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, North Carolina
| | - Keri N. Althoff
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
| | | | - Kate Buchacz
- Division of HIV/AIDS Prevention Centers for Disease Control and Prevention, Atlanta, Georgia
| | - Jun Li
- Division of HIV/AIDS Prevention Centers for Disease Control and Prevention, Atlanta, Georgia
| | | | | | - Viviane D. Lima
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vincent C. Marconi
- Division of Infectious Diseases, Emory University School of Medicine, Atlanta
- Department of Global Health, Emory University Rollins School of Public Health, Atlanta, Georgia, USA
| | | | - Michael A. Horberg
- Mid-Atlantic Permanente Research Institute, Kaiser Permanente Mid-Atlantic States, Rockville, Maryland, USA
| | - M. John Gill
- Department of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Mari M. Kitahata
- Department of Medicine, University of Washington, Seattle, Washington
| | - Joseph J. Eron
- Department of Epidemiology
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, North Carolina
| | - Richard D. Moore
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Butala NM, Secemsky E, Kazi DS, Song Y, Strom JB, Faridi KF, Brennan JM, Elmariah S, Shen C, Yeh RW. Applicability of Transcatheter Aortic Valve Replacement Trials to Real-World Clinical Practice: Findings From EXTEND-CoreValve. JACC Cardiovasc Interv 2021; 14:2112-2123. [PMID: 34620389 DOI: 10.1016/j.jcin.2021.08.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 07/28/2021] [Accepted: 08/03/2021] [Indexed: 01/15/2023]
Abstract
OBJECTIVES The aim of this study was to examine the applicability of pivotal transcatheter aortic valve replacement (TAVR) trials to the real-world population of Medicare patients undergoing TAVR. BACKGROUND It is unclear whether randomized controlled trial results of novel cardiovascular devices apply to patients encountered in clinical practice. METHODS Characteristics of patients enrolled in the U.S. CoreValve pivotal trials were compared with those of the population of Medicare beneficiaries who underwent TAVR in U.S. clinical practice between November 2, 2011, and December 31, 2017. Inverse probability weighting was used to reweight the trial cohort on the basis of Medicare patient characteristics, and a "real-world" treatment effect was estimated. RESULTS A total of 2,026 patients underwent TAVR in the U.S. CoreValve pivotal trials, and 135,112 patients underwent TAVR in the Medicare cohort. Trial patients were mostly similar to real-world patients at baseline, though trial patients were more likely to have hypertension (50% vs 39%) and coagulopathy (25% vs 17%), whereas real-world patients were more likely to have congestive heart failure (75% vs 68%) and frailty. The estimated real-world treatment effect of TAVR was an 11.4% absolute reduction in death or stroke (95% CI: 7.50%-14.92%) and an 8.7% absolute reduction in death (95% CI: 5.20%-12.32%) at 1 year with TAVR compared with conventional therapy (surgical aortic valve replacement for intermediate- and high-risk patients and medical therapy for extreme-risk patients). CONCLUSIONS The trial and real-world populations were mostly similar, with some notable differences. Nevertheless, the extrapolated real-world treatment effect was at least as high as the observed trial treatment effect, suggesting that the absolute benefit of TAVR in clinical trials is similar to the benefit of TAVR in the U.S. real-world setting.
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Affiliation(s)
- Neel M Butala
- Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA; Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Eric Secemsky
- Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Dhruv S Kazi
- Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Yang Song
- Baim Institute for Clinical Research, Boston, Massachusetts, USA
| | - Jordan B Strom
- Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Kamil F Faridi
- Section of Cardiology, Department of Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - J Matthew Brennan
- Duke Clinical Research Institute, Duke University School of Medicine, Durham, North Carolina, USA
| | - Sammy Elmariah
- Cardiology Division, Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, USA
| | - Changyu Shen
- Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA
| | - Robert W Yeh
- Richard A. and Susan F. Smith Center for Outcomes Research in Cardiology, Division of Cardiovascular Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA.
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Lu H, Cole SR, Westreich D, Hudgens MG, Adimora AA, Althoff KN, Silverberg MJ, Buchacz K, Li J, Edwards JK, Rebeiro PF, Lima VD, Marconi VC, Sterling TR, Horberg MA, Gill MJ, Kitahata MM, Eron JJ, Moore RD. Clinical Effectiveness of Integrase Strand Transfer Inhibitor-Based Antiretroviral Regimens Among Adults With Human Immunodeficiency Virus: A Collaboration of Cohort Studies in the United States and Canada. Clin Infect Dis 2021; 73:e1408-e1414. [PMID: 32780095 PMCID: PMC8492356 DOI: 10.1093/cid/ciaa1037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 07/17/2020] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Integrase strand transfer inhibitor (InSTI)-based regimens are now recommended as first-line antiretroviral therapy (ART) for adults with human immunodeficiency virus, but evidence on long-term clinical effectiveness of InSTI-based regimens remains limited. We examined whether InSTI-based regimens improved longer-term clinical outcomes. METHODS We included participants from clinical cohorts in the North American AIDS Cohort Collaboration on Research and Design who initiated their first ART regimen, containing either InSTI (ie, raltegravir, dolutegravir, and elvitegravir-cobicistat) or efavirenz (EFV) as an active comparator, between 2009 and 2016. We estimated observational analogs of 6-year intention-to-treat and per-protocol risks, risk differences (RDs), and hazard ratios (HRs) for the composite outcome of AIDS, acute myocardial infarction, stroke, end-stage renal disease, end-stage liver disease, or death. RESULTS Of 15 993 participants, 5824 (36%) initiated an InSTI-based and 10 169 (64%) initiated an EFV-based regimen. During the 6-year follow-up, 440 in the InSTI group and 1097 in the EFV group incurred the composite outcome. The estimated 6-year intention-to-treat risks were 14.6% and 14.3% for the InSTI and EFV groups, respectively, corresponding to a RD of 0.3% (95% confidence interval, -2.7% to 3.3%) and a HR of 1.08 (.97-1.19); the estimated 6-year per-protocol risks were 12.2% for the InSTI group and 11.9% for the EFV group, corresponding to a RD of 0.3% (-3.0% to 3.7%) and a HR of 1.09 (.96-1.25). CONCLUSIONS InSTI- and EFV-based initial ART regimens had similar 6-year composite clinical outcomes. The risk of adverse clinical outcomes remains substantial even when initiating modern ART.
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Affiliation(s)
- Haidong Lu
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Stephen R Cole
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Daniel Westreich
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Michael G Hudgens
- Department of Biostatistics, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Adaora A Adimora
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Keri N Althoff
- Department of Epidemiology, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland, USA
| | - Michael J Silverberg
- Division of Research, Kaiser Permanente Northern California, Oakland, California, USA
| | - Kate Buchacz
- Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Jun Li
- Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia, 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
| | - Peter F Rebeiro
- Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Viviane D Lima
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Vincent C Marconi
- Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
- Department of Global Health, Emory University Rollins School of Public Health, Atlanta, Georgia, USA
| | | | - Michael A Horberg
- Mid-Atlantic Permanente Research Institute, Kaiser Permanente Mid-Atlantic States, Rockville, Maryland, USA
| | - M John Gill
- Department of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Mari M Kitahata
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Joseph J Eron
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Division of Infectious Diseases, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Richard D Moore
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Bernasconi DP, Antolini L, Rossi E, Blanco-Lopez JG, Galimberti S, Andersen PK, Valsecchi MG. A causal inference approach to compare leukaemia treatment outcome in the absence of randomization and with dependent censoring. Int J Epidemiol 2021; 51:314-323. [PMID: 34368848 DOI: 10.1093/ije/dyab150] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Accepted: 07/06/2021] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND One cause of poor outcomes in children of low-income countries affected by acute lymphoblastic leukaemia (ALL) is loss to follow-up due to abandonment of treatment. Assuming this type of loss to follow-up as independent censoring, as in standard Kaplan-Meier estimates, ignores the likely association of abandonment with biologic and socio-economic factors related to outcome. Moreover, when comparing treatment protocols adopted in different time periods, possible imbalances in patients' characteristics must be considered. We aim to compare the outcome of children enrolled in two subsequent protocols for ALL treatment (2000-2007 and 2008-2015) in Honduras, taking both dependent censoring due to abandonment of treatment and imbalances between patient characteristics into account. METHODS Marginal structural models based on inverse probability of treatment and censoring (IPTC) weighting allow the estimation of potential event-free survival (EFS) as if no abandonment of treatment occurred and the whole cohort was exposed, or not, to both protocols. An Aalen additive model and a logistic-regression model were used to build abandonment and treatment weights, respectively. RESULTS The two protocols recruited 514 and 717 patients. Measured baseline covariates in both protocols were gender, age, white blood cell count, central nervous system involvement, tumour histology and socio-economic status. The potential EFS is slightly higher under the more recent protocol in the first 3 years but no difference is estimated in the long period [survival difference at 5 years (95% confidence interval) = 0.1% (-0.97%; 1.13%)]. Both protocols would allow reducing the event rate by 12-13% if there was no abandonment of treatment. CONCLUSIONS Using IPTC weighting, we found a similar potential effect of the two treatment protocols if the imbalance due to the different distribution of potential confounders and to abandonment of therapy was removed.
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Affiliation(s)
- Davide Paolo Bernasconi
- Bicocca Bioinformatics Biostatistics and Bioimaging Centre-B4, School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Laura Antolini
- Bicocca Bioinformatics Biostatistics and Bioimaging Centre-B4, School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Emanuela Rossi
- Bicocca Bioinformatics Biostatistics and Bioimaging Centre-B4, School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | | | - Stefania Galimberti
- Bicocca Bioinformatics Biostatistics and Bioimaging Centre-B4, School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Per Kragh Andersen
- Section of Biostatistics, Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Maria Grazia Valsecchi
- Bicocca Bioinformatics Biostatistics and Bioimaging Centre-B4, School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
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Effect heterogeneity and variable selection for standardizing causal effects to a target population. Eur J Epidemiol 2019; 34:1119-1129. [PMID: 31655945 DOI: 10.1007/s10654-019-00571-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 10/11/2019] [Indexed: 12/14/2022]
Abstract
The participants in randomized trials and other studies used for causal inference are often not representative of the populations seen by clinical decision-makers. To account for differences between populations, researchers may consider standardizing results to a target population. We discuss several different types of homogeneity conditions that are relevant for standardization: Homogeneity of effect measures, homogeneity of counterfactual outcome state transition parameters, and homogeneity of counterfactual distributions. Each of these conditions can be used to show that a particular standardization procedure will result in an unbiased estimate of the effect in the target population, given assumptions about the relevant scientific context. We compare and contrast the homogeneity conditions, in particular their implications for selection of covariates for standardization and their implications for how to compute the standardized causal effect in the target population. While some of the recently developed counterfactual approaches to generalizability rely upon homogeneity conditions that avoid many of the problems associated with traditional approaches, they often require adjustment for a large (and possibly unfeasible) set of covariates.
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Dahabreh IJ, Hernán MA. Extending inferences from a randomized trial to a target population. Eur J Epidemiol 2019; 34:719-722. [PMID: 31218483 DOI: 10.1007/s10654-019-00533-2] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 06/06/2019] [Indexed: 12/17/2022]
Affiliation(s)
- Issa J Dahabreh
- Department of Health Services Policy and Practice, Center for Evidence Synthesis in Health, School of Public Health, Brown University, Box G-121-8, Providence, RI, 02912, USA.
- Department of Epidemiology, School of Public Health, Brown University, Providence, RI, USA.
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA.
| | - Miguel A Hernán
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
- Department of Biostatistics, Harvard T.H. Chan School of Public Health, Harvard University, Boston, MA, USA
- Harvard-MIT Division of Health Sciences and Technology, Boston, MA, USA
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