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Introduction to Artificial Intelligence and Deep Learning with a Case Study in Analyzing Electronic Health Records for Drug Development
Published in Harry Yang, Binbing Yu, Real-World Evidence in Drug Development and Evaluation, 2021
Note that the individual treatment effect should not be interpreted as a reliable indication of what would have happened assuming the patient took another type of medication. Although the bias is controlled, there is still a chance that our estimate has a high variance due to the noisy nature of the EHR data set. Nonetheless, the estimated individual treatment effects can be used collectively, for example, one can estimate the average treatment effect (ATE) by averaging over individual treatment effects (ITEs) of all individuals, or one can estimate the ATE for a subpopulation. The tree-based methods can serve for the latter by automatically identifying the subpopulations in which the ATE is significantly higher or lower than the overall ATE for the population.
Causal Inference and Estimands
Published in Craig Mallinckrodt, Geert Molenberghs, Ilya Lipkovich, Bohdana Ratitch, Estimands, Estimators and Sensitivity Analysis in Clinical Trials, 2019
Craig Mallinckrodt, Geert Molenberghs, Ilya Lipkovich, Bohdana Ratitch
Causal estimands can be defined in terms of expectations of POs. In the context of a clinical trial, the PO Y(z) and the observed Y can, for example, be defined for a specific time or time interval (e.g., at week 24). The average treatment effect can be defined in terms of expectation of the individual treatment effect, that is, expected difference between POs (say for a continuous or binary Y) as
Methods of nutritional assessment and surveillance
Published in Geoffrey P. Webb, Nutrition, 2019
Twenty-four-hour recall has frequently been used to retrospectively assess the food and nutrient intakes of subjects. Traditionally an interviewer asks subjects to recount the types and amounts of all food and drink consumed during the previous day. Questionnaires that in some cases can be accessed and completed online are sometimes used as an alternative to face-to-face interviews. This recalled list is then translated into estimates of energy and nutrient intakes by the use of food tables. The method has been used in large-scale epidemiological surveys where large numbers of subjects need to be dealt with quickly and cheaply and where precision in assessing the intake of any individual is deemed not to be essential. The method requires relatively little commitment from the subject and thus cooperation rates tend to be good. As the assessment is retrospective, subjects do not alter their intakes in response to monitoring although there is no guarantee that what is recorded is a true record of what the subject really ate.
Daytime variation in non-cardiac surgery impacts the recovery after general anesthesia
Published in Annals of Medicine, 2023
Feng Xu, Qingtong Zhang, Dongsheng Xuan, Shuai Zhao, Yafeng Wang, Linlin Han, Shiqian Huang, Hongyu Zhu, Tingting Wang, Xiangdong Chen
The present study has several significant strengths. At first, to the best of our knowledge, this retrospective cohort study was the first large sample of patients and incorporated a wide variety of surgeries, focusing on exploring circadian variations in the recovery after general anesthesia. From a statistical perspective, both propensity score matching and univariable/multivariable linear regression were utilized to control the covariates, which helped capture more accuracy and efficacy in data analyses. Furthermore, to avoid imbalance and non-randomization of observation data in the study, ATE was harnessed as a treatment-effects estimator to examine the main outcome. Finally, we eliminated a small number of patients with missing information, which prevented their influence on results. All cases used in the study were stored in AIMS and strictly reviewed by clinicians, which guaranteed the correctness of the data.
Blinding and expectancy confounds in psychedelic randomized controlled trials
Published in Expert Review of Clinical Pharmacology, 2021
Suresh D. Muthukumaraswamy, Anna Forsyth, Thomas Lumley
For a potential therapeutic RCT using pre-treatment, a design similar to the dose-response design could be used, with dose modification of the pre-treatment rather than the active drug. In that way all participants would receive the full dose but not all would receive its full effect. We note that while participants may need to be informed that a pre-treatment is being used, it may be ethically permittable to not disclose its experimental purpose. For example, ketanserin could be accurately described as ‘controlling blood pressure’ during the intervention while concealing its real purpose of limiting the psychedelic experience. One advantage of the pre-treatment design is that it may allow for the examination of the impact of specific receptors on ATE generation. For example, in the case of LSD and psilocybin, ketanserin allows specific neurobiological inferences around activity at the 5HT2A receptor.
Performance evaluation of propensity score methods for estimating average treatment effects with multi-level treatments*
Published in Journal of Applied Statistics, 2019
Hui Nian, Chang Yu, Juan Ding, Huiyun Wu, William D. Dupont, Steve Brunwasser, Tebeb Gebretsadik, Tina V. Hartert, Pingsheng Wu
One limitation of PS methodology that it only controls for observed covariates also applies to GPS. This is always a limitation of non-randomized studies, which makes assessment of unconfoundedness assumption difficult if not completely impossible[12,37]. So in practice, one should make every effort to collect data on the variables that might even potentially affect the outcome and the treatment assignment. In addition, in this study we estimated ATE instead of ATT, ATE among treated. ATE is clinically meaningful and relevant when the population at risk ought to be treated, and comparative TE size needs to be estimated. This is particularly important when treatment tend to be underutilized. In our application study, it is clinically relevant and important to know the potential impact of anti-depressant treatment on pregnancy outcomes among pregnant women with depression for whom treatment is indicated. It would be of interest to estimate ATT using the four GPS methods if all pregnant women regardless of depression are included in the study sample[24].