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Diaz FJ, Zhang X, Pantazis N, De Leon J. Measuring Individual Benefits of Medical Treatments Using Longitudinal Hospital Data with Non-Ignorable Missing Responses Caused by Patient Discharge: Application to the Study of Benefits of Pain Management Post Spinal Fusion. REVISTA COLOMBIANA DE ESTADÍSTICA 2022. [DOI: 10.15446/rce.v45n2.101597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Electronic health records (EHR) provide valuable resources for longitudinal studies and understanding risk factors associated with poor clinical outcomes. However, they may not contain complete follow-ups, and the missing data may not be at random since hospital discharge may depend in part on expected but unrecorded clinical outcomes that occur after patient discharge. These non-ignorable missing data requires appropriate analysis methods. Here, we are interested in measuring and analyzing individual treatment benefits of medical treatments in patients recorded in EHR databases. We present a method for predicting individual benefits that handles non-ignorable missingness due to hospital discharge. The longitudinal clinical outcome of interest is modeled simultaneously with the hospital length of stay using a joint mixed-effects model, and individual benefits are predicted through a frequentist approach: the empirical Bayesian approach. We illustrate our approach by assessing individual pain management benefits to patients who underwent spinal fusion surgery. By calculating sample percentiles of empirical Bayes predictors of individual benefits, we examine the evolution of individual benefits over time. We additionally compare these percentiles with percentiles calculated with a Monte Carlo approach. We showed that empirical Bayes predictors of individual benefits do not only allow examining benefits in specific patients but also reflect overall population trends reliably.
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Diaz FJ. Using population crossover trials to improve the decision process regarding treatment individualization in N-of-1 trials. Stat Med 2021; 40:4345-4361. [PMID: 34213011 PMCID: PMC10773237 DOI: 10.1002/sim.9030] [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: 11/06/2020] [Revised: 03/26/2021] [Accepted: 04/25/2021] [Indexed: 11/08/2022]
Abstract
Healthcare researchers are showing renewed interest in the utilization of N-of-1 clinical trials for the individualization of pharmacological treatments. Here, we propose a frequentist approach to conducting treatment individualization in N-of-1 trials that we call "partial empirical Bayes." We infer the most beneficial treatment for the patient from combining the information provided by a previously conducted population crossover trial with individual patient data. We propose a method for estimating an optimal number of treatment cycles and investigate the statistical conditions under which N-of-1 trials are more beneficial than traditional clinical approaches. We represent the patient population with a random-coefficients linear model and calculate estimators of posttreatment individual disease severities. We show the estimators' consistency under the most common N-of-1 designs and examine their prediction errors and performance with small numbers of patient's responses. We demonstrate by simulating new patients that our approach is equivalent or superior to both the common clinical practice of recommending the on-average best treatment for all patients and the common individualization method that simply compares average responses to the tested treatments. We conclude that some situations exist in which individualization with N-of-1 trials is highly beneficial while other situations exist in which individualization may be unfruitful.
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Affiliation(s)
- Francisco J Diaz
- Department of Biostatistics & Data Science, The University of Kansas Medical Center, Kansas City, Kansas, USA
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Zhou W, Zhu R, Zeng D. A parsimonious personalized dose-finding model via dimension reduction. Biometrika 2021; 108:643-659. [PMID: 34658383 PMCID: PMC8514170 DOI: 10.1093/biomet/asaa087] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Learning an individualized dose rule in personalized medicine is a challenging statistical problem. Existing methods often suffer from the curse of dimensionality, especially when the decision function is estimated nonparametrically. To tackle this problem, we propose a dimension reduction framework that effectively reduces the estimation to a lower-dimensional subspace of the covariates. We exploit that the individualized dose rule can be defined in a subspace spanned by a few linear combinations of the covariates, leading to a more parsimonious model. Also, our framework does not require the inverse probability of the propensity score under observational studies due to a direct maximization of the value function. This distinguishes us from the outcome weighted learning framework, which also solves decision rules directly. Under the same framework, we further propose a pseudo-direct learning approach focuses more on estimating the dimensionality-reduced subspace of the treatment outcome. Parameters in both approaches can be estimated efficiently using an orthogonality constrained optimization algorithm on the Stiefel manifold. Under mild regularity assumptions, the asymptotic normality results of the proposed estimators can are established, respectively. We also derive the consistency and convergence rate for the value function under the estimated optimal dose rule. We evaluate the performance of the proposed approaches through extensive simulation studies and a warfarin pharmacogenetic dataset.
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Affiliation(s)
- Wenzhuo Zhou
- Department of Statistics, University of Illinois at Urbana-Champaign, Champaign, Illinois 61820, U.S.A
| | - Ruoqing Zhu
- Department of Statistics, University of Illinois at Urbana-Champaign, Champaign, Illinois 61820, U.S.A
| | - Donglin Zeng
- Department of Biostatistics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, U.S.A
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Guo B, Holscher HD, Auvil LS, Welge ME, Bushell CB, Novotny JA, Baer DJ, Burd NA, Khan NA, Zhu R. Estimating Heterogeneous Treatment Effect on Multivariate Responses Using Random Forests. STATISTICS IN BIOSCIENCES 2021. [DOI: 10.1007/s12561-021-09310-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Yue M, Huang L. A new approach of subgroup identification for high-dimensional longitudinal data. J STAT COMPUT SIM 2020. [DOI: 10.1080/00949655.2020.1764555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Mu Yue
- Engineering Systems and Design (ESD), Singapore University of Technology and Design, Singapore, Singapore
| | - Lei Huang
- School of Mathematical Sciences, University of Electronic Science and Technology of China, Chengdu, People's Republic of China
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Zhang X, de Leon J, Crespo-Facorro B, Diaz FJ. Measuring individual benefits of psychiatric treatment using longitudinal binary outcomes: Application to antipsychotic benefits in non-cannabis and cannabis users. J Biopharm Stat 2020; 30:916-940. [DOI: 10.1080/10543406.2020.1765371] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Xuan Zhang
- Department of Biostatistics, The University of Kansas Medical Center, Kansas City, KS, United States
- Boston Strategic Partners, Inc, Boston, MA, United States
| | - Jose de Leon
- Mental Health Research Center at Eastern State Hospital, Lexington, KY, United States
| | - Benedicto Crespo-Facorro
- University Hospital Virgen Del Rocío, Seville, Spain
- CIBERSAM G26-IBiS, University of Seville, Seville, Spain
- Department of Psychiatry, Marqués De Valdecilla University Hospital, IDIVAL, Santander, Spain
- School of Medicine, University of Cantabria, Santander, Spain
| | - Francisco J. Diaz
- Department of Biostatistics, The University of Kansas Medical Center, Kansas City, KS, United States
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Affiliation(s)
- Xiwei Tang
- Department of Statistics, University of Virginia , Charlottesville , VA
| | - Fei Xue
- Department of Biostatistics and Epidemiology, University of Pennsylvania , Philadelphia , PA
| | - Annie Qu
- Department of Statistics, University of Illinois at Irvine , Irvine , CA
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Li J, Yue M, Zhang W. Subgroup identification via homogeneity pursuit for dense longitudinal/spatial data. Stat Med 2019; 38:3256-3271. [PMID: 31066095 DOI: 10.1002/sim.8192] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 04/08/2019] [Accepted: 04/12/2019] [Indexed: 12/23/2022]
Abstract
In the clinical trial community, it is usually not easy to find a treatment that benefits all patients since the reaction to treatment may differ substantially across different patient subgroups. The heterogeneity of treatment effect plays an essential role in personalized medicine. To facilitate the development of tailored therapies and improve the treatment efficacy, it is important to identify subgroups that exhibit different treatment effects. We consider a very general framework for subgroup identification via the homogeneity pursuit methods usually employed in econometric time series analysis. The change point detection algorithm in our procedure is most suitable for analyzing dense longitudinal or spatial data which are quite common for biomedical studies these days. We demonstrate that our proposed method is fast and accurate through extensive numerical studies. In particular, our method is illustrated by analyzing a diffusion tensor imaging data set.
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Affiliation(s)
- Jialiang Li
- Department of Statistics and Applied Probability, National University of Singapore, Singapore.,Duke-NUS Medical School, Singapore.,Singapore Eye Research Institute, Singapore
| | - Mu Yue
- School of Mathematical Sciences, University of Electronic Science and Technology of China, Chengdu, China
| | - Wenyang Zhang
- Department of Mathematics, University of York, York, UK
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Cheng Y, Ma Y, Zheng J, Deng H, Wang X, Li Y, Pang X, Chen H, He F, Wang L, Wang J, Wan X. Impact of Chemotherapy Regimens on Normal Tissue Complication Probability Models of Acute Hematologic Toxicity in Rectal Cancer Patients Receiving Intensity Modulated Radiation Therapy With Concurrent Chemotherapy From a Prospective Phase III Clinical Trial. Front Oncol 2019; 9:244. [PMID: 31024846 PMCID: PMC6465593 DOI: 10.3389/fonc.2019.00244] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 03/18/2019] [Indexed: 01/04/2023] Open
Abstract
Purpose: To determine whether there are differences in bone marrow tolerance to chemoradiotherapy (CRT) between two chemotherapy regimens according to FOWARC protocol and how chemotherapy regimens affect radiation dose parameters and normal tissue complication probability (NTCP) modelings that correlate with acute hematologic toxicity (HT) in rectal cancer patients treated with intensity modulated radiation therapy (IMRT) and concurrent chemotherapy. Materials and Methods: One hundred and twenty-eight rectal cancer patients who received IMRT from a single institution were recruited from Chinese FOWARC multicenter, open-label, randomized phase III trial. We assessed HT in these patients who were separated into two groups: Oxaliplatin (L-OHP) + 5- fluorouracil (5FU) (FOLFOX, 70 of 128) and 5FU (58 of 128). The pelvic bone marrow (PBM) was divided into three subsites: lumbosacral spine (LSS), ilium (I), and lower pelvic (LP). The endpoint for HT was grade ≥3 (HT3+) and grade ≥2 (HT2+) leukopenia, neutropenia, anemia and thrombocytopenia. Logistic regression was used to analyze the association between HT2+/HT3+ and dosimetric parameters. Lyman-Kutcher-Burman (LKB) model was used to calculate NTCP. Results: Sixty-eight patients experienced HT2+: 22 of 58 (37.9%) 5FU and 46 of 70 (65.7%) FOLFOX (p = 0.008), while twenty-six patients experienced HT3+: 4 of 58 (6.9%) 5FU and 22 of 70 (31.4%) FOLFOX (p = 0.016). PBM and LP dosimetric parameters were correlated with HT2+ in the 5FU group but not in the FOLFOX group. No PBM dosimetric parameters were correlated with HT3+ in both groups. For PBM, NTCP at HT3+ was 0.32 in FOLFOX group relative to 0.10 in 5FU subset (p < 0.05). Conclusion: Patients receiving FOLFOX have lower BM tolerance to CRT than those receiving 5FU. Low-dose radiation to the PBM is predictive for HT2+ in patients who received 5FU. NTCP modeling in FOLFOX group predicts much higher risk of HT3+ than 5FU group.
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Affiliation(s)
- Yikan Cheng
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Radiation Oncology, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Yan Ma
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Radiation Oncology, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jian Zheng
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Radiation Oncology, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Hua Deng
- Department of Radiation Oncology, Banner-University Medical Center Phoenix, Phoenix, AZ, United States
| | - Xueqin Wang
- Department of Statistical Science, Southern China Center for Statistical Science, School of Mathematics, Sun Yat-sen University, Guangzhou, China.,Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Yewei Li
- Department of Statistical Science, Southern China Center for Statistical Science, School of Mathematics, Sun Yat-sen University, Guangzhou, China.,Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, China
| | - Xiaolin Pang
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Radiation Oncology, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Haiyang Chen
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Radiation Oncology, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Fang He
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Radiation Oncology, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Lei Wang
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Colorectal Surgery, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jianping Wang
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Colorectal Surgery, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xiangbo Wan
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, Department of Radiation Oncology, Guangdong Institute of Gastroenterology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
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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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