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Cortés J, González JA, Medina MN, Vogler M, Vilaró M, Elmore M, Senn SJ, Campbell M, Cobo E. Does evidence support the high expectations placed in precision medicine? A bibliographic review. F1000Res 2018; 7:30. [PMID: 31143439 DOI: 10.12688/f1000research.13490.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/08/2018] [Indexed: 12/11/2022] Open
Abstract
Background: Precision medicine is the Holy Grail of interventions that are tailored to a patient's individual characteristics. However, conventional clinical trials are designed to find differences in averages, and interpreting these differences depends on untestable assumptions. Although only an ideal, a constant effect of treatment would facilitate individual management. A direct consequence of a constant effect is that the variance of the outcome measure would be the same in the treated and control arms. We reviewed the literature to explore the similarity of these variances as a foundation for examining whether and how often precision medicine is definitively required. Methods: We reviewed parallel clinical trials with numerical primary endpoints published in 2004, 2007, 2010 and 2013. We collected the baseline and final standard deviations of the main outcome measure. We assessed homoscedasticity by comparing the variance of the primary endpoint between arms through the outcome variance ratio (treated to control group). Results: The review provided 208 articles with enough information to conduct the analysis. One out of five studies (n = 40, 19.2%) had statistically different variances between groups, implying a non-constant-effect. The adjusted point estimate of the mean outcome variance ratio (treated to control group) is 0.89 (95% CI 0.81 to 0.97). Conclusions: The mean variance ratio is significantly lower than 1 and the lower variance was found more often in the intervention group than in the control group, suggesting it is more usual for treated patients to be stable. This observed reduction in variance might also imply that there could be a subgroup of less ill patients who derive no benefit from treatment. This would require further study as to whether the treatment effect outweighs the side effects as well as the economic costs. We have shown that there are ways to analyze the apparently unobservable constant effect.
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Affiliation(s)
- Jordi Cortés
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | - José Antonio González
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | | | - Markus Vogler
- Department of Statistics, Ludwig-Maximilians-Universität München, München, 80539, Germany
| | - Marta Vilaró
- Fundació lliga per a la investigació i prevenció del càncer, Reus, 43201, Spain
| | - Matt Elmore
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | - Stephen John Senn
- Competence Center for Methodology and Statistics, Luxembourg Institute of Health, Strassen, 1445, Luxembourg
| | - Michael Campbell
- School of Health and Related Research, University of Sheffield, Sheffield, S1 4DA, UK
| | - Erik Cobo
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
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Cortés J, González JA, Medina MN, Vogler M, Vilaró M, Elmore M, Senn SJ, Campbell M, Cobo E. Does evidence support the high expectations placed in precision medicine? A bibliographic review. F1000Res 2018; 7:30. [PMID: 31143439 PMCID: PMC6524747 DOI: 10.12688/f1000research.13490.5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/03/2019] [Indexed: 12/14/2022] Open
Abstract
Background: Precision medicine is the Holy Grail of interventions that are tailored to a patient’s individual characteristics. However, conventional clinical trials are designed to find differences in averages, and interpreting these differences depends on untestable assumptions. Although only an ideal, a constant effect of treatment would facilitate individual management. A direct consequence of a constant effect is that the variance of the outcome measure would be the same in the treated and control arms. We reviewed the literature to explore the similarity of these variances as a foundation for examining whether and how often precision medicine is definitively required. Methods: We reviewed parallel clinical trials with numerical primary endpoints published in 2004, 2007, 2010 and 2013. We collected the baseline and final standard deviations of the main outcome measure. We assessed homoscedasticity by comparing the variance of the primary endpoint between arms through the outcome variance ratio (treated to control group). Results: The review provided 208 articles with enough information to conduct the analysis. One out of five studies (n = 40, 19.2%) had statistically different variances between groups, implying a non-constant-effect. The adjusted point estimate of the mean outcome variance ratio (treated to control group) is 0.89 (95% CI 0.81 to 0.97). Conclusions: The mean variance ratio is significantly lower than 1 and the lower variance was found more often in the intervention group than in the control group, suggesting it is more usual for treated patients to be stable. This observed reduction in variance might also imply that there could be a subgroup of less ill patients who derive no benefit from treatment. This would require further study as to whether the treatment effect outweighs the side effects as well as the economic costs. We have shown that there are ways to analyze the apparently unobservable constant effect.
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Affiliation(s)
- Jordi Cortés
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | - José Antonio González
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | | | - Markus Vogler
- Department of Statistics, Ludwig-Maximilians-Universität München, München, 80539, Germany
| | - Marta Vilaró
- Fundació lliga per a la investigació i prevenció del càncer, Reus, 43201, Spain
| | - Matt Elmore
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | - Stephen John Senn
- Competence Center for Methodology and Statistics, Luxembourg Institute of Health, Strassen, 1445, Luxembourg
| | - Michael Campbell
- School of Health and Related Research, University of Sheffield, Sheffield, S1 4DA, UK
| | - Erik Cobo
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
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103
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Cortés J, González JA, Medina MN, Vogler M, Vilaró M, Elmore M, Senn SJ, Campbell M, Cobo E. Does evidence support the high expectations placed in precision medicine? A bibliographic review. F1000Res 2018; 7:30. [PMID: 31143439 DOI: 10.12688/f1000research.13490.1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/03/2018] [Indexed: 12/20/2022] Open
Abstract
Background: Precision medicine is the Holy Grail of interventions that are tailored to a patient's individual characteristics. However, conventional clinical trials are designed to find differences in averages, and interpreting these differences depends on untestable assumptions. Although only an ideal, a constant effect of treatment would facilitate individual management. A direct consequence of a constant effect is that the variance of the outcome measure would be the same in the treated and control arms. We reviewed the literature to explore the similarity of these variances as a foundation for examining whether and how often precision medicine is definitively required. Methods: We reviewed parallel clinical trials with numerical primary endpoints published in 2004, 2007, 2010 and 2013. We collected the baseline and final standard deviations of the main outcome measure. We assessed homoscedasticity by comparing the variance of the primary endpoint between arms through the outcome variance ratio (treated to control group). Results: The review provided 208 articles with enough information to conduct the analysis. One out of five studies (n = 40, 19.2%) had statistically different variances between groups, implying a non-constant-effect. The adjusted point estimate of the mean outcome variance ratio (treated to control group) is 0.89 (95% CI 0.81 to 0.97). Conclusions: The mean variance ratio is significantly lower than 1 and the lower variance was found more often in the intervention group than in the control group, suggesting it is more usual for treated patients to be stable. This observed reduction in variance might also imply that there could be a subgroup of less ill patients who derive no benefit from treatment. This would require further study as to whether the treatment effect outweighs the side effects as well as the economic costs. We have shown that there are ways to analyze the apparently unobservable constant effect.
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Affiliation(s)
- Jordi Cortés
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | - José Antonio González
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | | | - Markus Vogler
- Department of Statistics, Ludwig-Maximilians-Universität München, München, 80539, Germany
| | - Marta Vilaró
- Fundació lliga per a la investigació i prevenció del càncer, Reus, 43201, Spain
| | - Matt Elmore
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
| | - Stephen John Senn
- Competence Center for Methodology and Statistics, Luxembourg Institute of Health, Strassen, 1445, Luxembourg
| | - Michael Campbell
- School of Health and Related Research, University of Sheffield, Sheffield, S1 4DA, UK
| | - Erik Cobo
- Department of Statistics and Operations Research, Universitat Politècnica de Catalunya, Barcelona, 08034, Spain
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104
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Vincent JL. In Pursuit of Precision Medicine in the Critically Ill. ANNUAL UPDATE IN INTENSIVE CARE AND EMERGENCY MEDICINE 2018 2018. [PMCID: PMC7121780 DOI: 10.1007/978-3-319-73670-9_48] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Jean-Louis Vincent
- Dept. of Intensive Care Erasme Hospital, Université libre de Bruxelles, Brussels, Belgium
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105
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Rustamov O, Wilkinson J, La Marca A, Fitzgerald C, Roberts SA. How much variation in oocyte yield after controlled ovarian stimulation can be explained? A multilevel modelling study. Hum Reprod Open 2017; 2017:hox018. [PMID: 30895232 PMCID: PMC6276674 DOI: 10.1093/hropen/hox018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 08/21/2017] [Accepted: 10/05/2017] [Indexed: 01/07/2023] Open
Abstract
STUDY QUESTION How much variation in oocyte yield after controlled ovarian stimulation (COS) can be accounted for by known patient and treatment characteristics? SUMMARY ANSWER There is substantial variation in the COS responses of similar women and in repeated COS episodes undertaken by the same woman, which cannot be accounted for at present. WHAT IS ALREADY KNOWN The goal of individualized COS is to safely collect enough oocytes to maximize the chance of success in an ART cycle. Personalization of treatment rests on the ability to reduce variation in response through modifiable factors. STUDY DESIGN, SIZE, DURATION Multilevel modelling of a routine ART database covering the period 1 October 2008–8 August 2012 was employed to estimate the amount of variation in COS response and the extent to which this could be explained by immutable patient characteristics and by manipulable treatment variables. A total of 1851 treatment cycles undertaken by 1430 patients were included. The study was not subject to attrition, as cancelled cycles were included in the analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS Women aged 21–43 years undergoing ovarian stimulation for IVF (possibly with ICSI) using their own eggs at a tertiary care centre. MAIN RESULTS AND THE ROLE OF CHANCE Substantial unexplained variation in COS response (oocyte yield): was observed (3.4-fold (95% CI: 3.12 to 3.61)). Only a relatively small amount of this variation (around 19%) can be explained by modifiable factors. A significant, previously undescribed predictor of response was the practitioner performing oocyte retrieval, with 1.5-fold variation between surgeons with the highest and lowest yields. LIMITATIONS REASONS FOR CAUTION Although a large number of covariables were adjusted for in the analysis, including those that were used for dosing and determination of the stimulation regimen, this study is subject to confounding due to unmeasured variables and measurement error. WIDER IMPLICATIONS OF THE FINDINGS The present study suggests that there are limits to the extent that COS response can be predicted on the basis of known factors, or controlled by manipulation of treatment factors. Moreover, modifiable variation in response appears to be partially attributable to differences between surgeons performing oocyte retrieval. Consequently, consistent prevention of ineffective or unsafe responses to COS is not likely to be possible at present. Our results highlight the importance of blinding surgeons in RCTs. The data also suggest that there is likely to be limited scope for personalized treatment unless additional predictors of ovarian response can be identified. STUDY FUNDING/COMPETING INTERESTS J.W. is funded by a Doctoral Research Fellowship from the National Institute for Health Research (DRF-2014-07-050) supervised by S.A.R. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health. J.W. is a statistical editor of the Cochrane Gynaecology and Fertility Group. S.A.R. is a statistical editor for Human Reproduction. J.W. also declares that publishing peer-reviewed articles benefits his career. A.L.M. has received consultation fees from MSD, Merck Serono, Ferring, TEVA, Roche, Beckman Coulter.
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Affiliation(s)
- Oybek Rustamov
- Department of Reproductive Medicine, St Mary's Hospital, Central Manchester University Hospital NHS Foundation Trust, Manchester Academic Health Science Centre (MAHSC), Manchester, England M13 0JH, UK.,Primary IVF, Primary Health Care Limited, Brisbane, QLD 4075, Australia
| | - Jack Wilkinson
- Centre for Biostatistics, School of Health Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre (MAHSC), University of Manchester, Manchester M13 9PL, UK.,Research and Development, Salford Royal NHS Foundation Trust, Salford, England M6 8HD, UK
| | - Antonio La Marca
- Mother-Infant Department, University of Modena and Reggio Emilia, Modena, Italy
| | - Cheryl Fitzgerald
- Department of Reproductive Medicine, St Mary's Hospital, Central Manchester University Hospital NHS Foundation Trust, Manchester Academic Health Science Centre (MAHSC), Manchester, England M13 0JH, UK
| | - Stephen A Roberts
- Centre for Biostatistics, School of Health Sciences, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre (MAHSC), University of Manchester, Manchester M13 9PL, UK
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106
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Diaz FJ. Estimating individual benefits of medical or behavioral treatments in severely ill patients. Stat Methods Med Res 2017; 28:911-927. [DOI: 10.1177/0962280217739033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
There is a need for statistical methods appropriate for the analysis of clinical trials from a personalized-medicine viewpoint as opposed to the common statistical practice that simply examines average treatment effects. This article proposes an approach to quantifying, reporting and analyzing individual benefits of medical or behavioral treatments to severely ill patients with chronic conditions, using data from clinical trials. The approach is a new development of a published framework for measuring the severity of a chronic disease and the benefits treatments provide to individuals, which utilizes regression models with random coefficients. Here, a patient is considered to be severely ill if the patient’s basal severity is close to one. This allows the derivation of a very flexible family of probability distributions of individual benefits that depend on treatment duration and the covariates included in the regression model. Our approach may enrich the statistical analysis of clinical trials of severely ill patients because it allows investigating the probability distribution of individual benefits in the patient population and the variables that influence it, and we can also measure the benefits achieved in specific patients including new patients. We illustrate our approach using data from a clinical trial of the anti-depressant imipramine.
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Affiliation(s)
- Francisco J Diaz
- Department of Biostatistics, The University of Kansas Medical Center, Kansas City, KS, USA
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107
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Moctezuma-Velazquez C, Kalainy S, Abraldes JG. Reply. Liver Transpl 2017; 23:1353. [PMID: 28752933 DOI: 10.1002/lt.24834] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 07/21/2017] [Indexed: 02/07/2023]
Affiliation(s)
- Carlos Moctezuma-Velazquez
- Cirrhosis Care Clinic Liver Unit Division of Gastroenterology Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada
| | - Sylvia Kalainy
- Cirrhosis Care Clinic Liver Unit Division of Gastroenterology Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada
| | - Juan G Abraldes
- Cirrhosis Care Clinic Liver Unit Division of Gastroenterology Centre of Excellence for Gastrointestinal Inflammation and Immunity Research, University of Alberta, Edmonton, Canada
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108
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Andrews N, Cho H. Validating effectiveness of subgroup identification for longitudinal data. Stat Med 2017; 37:98-106. [DOI: 10.1002/sim.7500] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Revised: 07/27/2017] [Accepted: 08/26/2017] [Indexed: 01/22/2023]
Affiliation(s)
- Nichole Andrews
- Department of Statistics; Western Michigan University; Kalamazoo MI 49008 USA
| | - Hyunkeun Cho
- Department of Biostatistics; University of Iowa; Iowa City IA 52242 USA
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109
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Abstract
N-of-1 trials are trials in which patients are treated with two or more treatments on multiple occasions. They can have many different purposes and can be analysed in different frameworks. In this note, five different criteria for planning sample sizes for n-of-1 trials are identified, and formulae and advice to address the associated tasks are provided. The basic design addressed is that of randomisation to treatment and control within cycles of pairs of episodes and the model assumed is that of a Normal-Normal mixture with variance components corresponding to within-cycle within-patient variation and treatment-by-patient interaction. The code to accomplish the tasks has been written in GenStat®, SAS® and R® and the application of the approaches is illustrated.
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Affiliation(s)
- Stephen Senn
- 1 Methodology and Statistics, Luxembourg Institute of Health, Strassen, Luxembourg.,2 School of Health and Related Research, University of Sheffield, Sheffield, UK
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110
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Weinreich SS, Vrinten C, Kuijpers MR, Lipka AF, Schimmel KJM, van Zwet EW, Gispen-de Wied C, Hekster YA, Verschuuren JJGM, Cornel MC. Aggregated N-of-1 trials for unlicensed medicines for small populations: an assessment of a trial with ephedrine for myasthenia gravis. Orphanet J Rare Dis 2017; 12:88. [PMID: 28494776 PMCID: PMC5427624 DOI: 10.1186/s13023-017-0636-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 04/17/2017] [Indexed: 11/15/2022] Open
Abstract
Background Inexpensive medicines with a long history of use may currently be prescribed off-label for rare indications. Reimbursement is at the discretion of health insurance companies, and may be unpredictable. The example addressed was ephedrine as add-on treatment for myasthenia gravis. Stakeholders from academia, a patient organization, the Dutch National Health Care Institute (NHCI) and Dutch Medicines Evaluation Board (MEB) advised on the trial design. The NHCI and MEB agreed to provide scientific advice on the suitability of the evidence generated by the trial, for regulatory decisions. This paper describes the feasibility of the trial and the utility of its aggregated results. Results The trialists experienced the trial as feasible. Retrospective interviews showed that the trial as performed was acceptable to patients. The treatment effect in the primary outcome measure, muscle strength, was statistically significant when inferred to the population level, though the effect size was modest. Secondary outcomes were statistically significant in a preplanned, fixed effects analysis within the four patients. The NHCI advised that it could potentially make reimbursement decisions based on the Fitting Evidence framework, should the trialists decide to apply for reimbursement. The MEB advised that for a licensing decision, the N-of-1 design is a last-resort option for demonstrating treatment benefit in a rare disease. N-of-1 trials alone do not provide enough evidence on potential risk. The MEB found the current trial inconclusive. It suggested doing a 2-armed trial of longer duration, possibly with a different outcome measure (postponement of corticosteroid use). It suggested engaging a consultancy or commercial sponsor, should the trialists decide to seek market authorization of the drug. Conclusions In theory, evidence from aggregated N-of-1 trials is suitable for use in licensing and reimbursement decisions. The current example illustrates differences in interpretation of N-of-1 results by health authorities. In the era of personalized medicine, consensus is required on the interpretation of data from study designs geared to small groups. Demonstrating effectiveness of inexpensive medicines in small populations may require involvement of non-commercial parties, to preserve affordability. Electronic supplementary material The online version of this article (doi:10.1186/s13023-017-0636-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Stephanie S Weinreich
- Department of Clinical Genetics, Amsterdam Public Health research institute, VU University Medical Center, Amsterdam, The Netherlands. .,Department of Care, National Health Care Institute, Diemen, The Netherlands.
| | - Charlotte Vrinten
- Department of Clinical Genetics, Amsterdam Public Health research institute, VU University Medical Center, Amsterdam, The Netherlands.,Department of Epidemiology and Public Health, University College London, London, UK
| | - Marja R Kuijpers
- Department of Care, National Health Care Institute, Diemen, The Netherlands
| | - Alexander F Lipka
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - Kirsten J M Schimmel
- Department of Clinical Pharmacy and Toxicology, Leiden University Medical Center, Leiden, The Netherlands
| | - Erik W van Zwet
- Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden, The Netherlands
| | | | | | | | - Martina C Cornel
- Department of Clinical Genetics, Amsterdam Public Health research institute, VU University Medical Center, Amsterdam, The Netherlands
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111
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Lonergan M, Senn SJ, McNamee C, Daly AK, Sutton R, Hattersley A, Pearson E, Pirmohamed M. Defining drug response for stratified medicine. Drug Discov Today 2017; 22:173-179. [DOI: 10.1016/j.drudis.2016.10.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 09/10/2016] [Accepted: 10/27/2016] [Indexed: 12/21/2022]
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112
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Araujo A, Julious S, Senn S. Understanding Variation in Sets of N-of-1 Trials. PLoS One 2016; 11:e0167167. [PMID: 27907056 PMCID: PMC5131970 DOI: 10.1371/journal.pone.0167167] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Accepted: 11/09/2016] [Indexed: 11/19/2022] Open
Abstract
A recent paper in this journal by Chen and Chen has used computer simulations to examine a number of approaches to analysing sets of n-of-1 trials. We have examined such designs using a more theoretical approach based on considering the purpose of analysis and the structure as regards randomisation that the design uses. We show that different purposes require different analyses and that these in turn may produce quite different results. Our approach to incorporating the randomisation employed when the purpose is to test a null hypothesis of strict equality of the treatment makes use of Nelder’s theory of general balance. However, where the purpose is to make inferences about the effects for individual patients, we show that a mixed model is needed. There are strong parallels to the difference between fixed and random effects meta-analyses and these are discussed.
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Affiliation(s)
- Artur Araujo
- Competence Center for Methodology and Statistics, Luxembourg Institute of Health, Strassen, Luxembourg
| | - Steven Julious
- Medical Statistics Group, School of Health and Related Research, University of Sheffield, Sheffield, United Kingdom
| | - Stephen Senn
- Competence Center for Methodology and Statistics, Luxembourg Institute of Health, Strassen, Luxembourg
- * E-mail:
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113
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Diaz FJ. Measuring the individual benefit of a medical or behavioral treatment using generalized linear mixed-effects models. Stat Med 2016; 35:4077-92. [PMID: 27323698 DOI: 10.1002/sim.7005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 05/07/2016] [Accepted: 05/11/2016] [Indexed: 11/06/2022]
Abstract
We propose statistical definitions of the individual benefit of a medical or behavioral treatment and of the severity of a chronic illness. These definitions are used to develop a graphical method that can be used by statisticians and clinicians in the data analysis of clinical trials from the perspective of personalized medicine. The method focuses on assessing and comparing individual effects of treatments rather than average effects and can be used with continuous and discrete responses, including dichotomous and count responses. The method is based on new developments in generalized linear mixed-effects models, which are introduced in this article. To illustrate, analyses of data from the Sequenced Treatment Alternatives to Relieve Depression clinical trial of sequences of treatments for depression and data from a clinical trial of respiratory treatments are presented. The estimation of individual benefits is also explained. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Francisco J Diaz
- Department of Biostatistics, The University of Kansas Medical Center, Mail Stop 1026, 3901 Rainbow Blvd., Kansas City, 66160, KS, U.S.A
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114
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Senn S. Mastering variation: variance components and personalised medicine. Stat Med 2015; 35:966-77. [PMID: 26415869 PMCID: PMC5054923 DOI: 10.1002/sim.6739] [Citation(s) in RCA: 111] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 05/05/2015] [Accepted: 08/31/2015] [Indexed: 12/16/2022]
Abstract
Various sources of variation in observed response in clinical trials and clinical practice are considered, and ways in which the corresponding components of variation might be estimated are discussed. Although the issues have been generally well‐covered in the statistical literature, they seem to be poorly understood in the medical literature and even the statistical literature occasionally shows some confusion. To increase understanding and communication, some simple graphical approaches to illustrating issues are proposed. It is also suggested that reducing variation in medical practice might make as big a contribution to improving health outcome as personalising its delivery according to the patient. It is concluded that the common belief that there is a strong personal element in response to treatment is not based on sound statistical evidence. © 2015 The Authors. Statistics in Medicine published by John Wiley & Sons Ltd.
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Affiliation(s)
- Stephen Senn
- Competence Centre for Methodology and Statistics, Luxembourg Institute of Health, L-1445, Strassen, Luxembourg
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