DOI: 10.3886/icpsr39528
title: Handling of Missing Data Induced by Time-Varying Covariates in Comparative Effectiveness Research HIV Patients [Methods Study], 2013-2018
title: Archival Version

description: Researchers can use data from health registries or electronic health records to compare two or more treatments. Registries store data about patients with a specific health problem. These data include how well those patients respond to treatments and information about patient traits, such as age, weight, or blood pressure. But sometimes data about patient traits are missing.
Missing data about patient traits can lead to incorrect study results, especially when traits change over time. For example, weight can change over time, and the patient may not report their weight at some points along the way. Researchers use statistical methods to fill in these missing data.
In this study, the research team compared a new statistical method to fill in missing data with traditional methods. Traditional methods remove patients with missing data or fill in each missing number with a single estimate. The new method creates multiple possible estimates to fill in each missing number.
 To access the methods, software, and R package, please visit the SimulateCER GitHub and
SimTimeVar CRAN website.
description: To evaluate statistical approaches for handling missing data in longitudinal studies of comparative effectiveness research through the following goals:
(1) the creation of a tool to simulate studies observed in CER for method
evaluation, (2) how to perform MI of derived predictors such as interactions, (3) how to perform MI of outcomes derived from repeated measures, and (4) performances of MI and commonly applied approaches when describing relationships between time-varying covariates with and without missing values and a right-censored outcome.
description: The research team conducted 3 simulation studies to address key questions in which they assessed performance using metrics including mean squared error, bias, and standard errors. To
investigate imputation of interactions, the team evaluated active and passive MI strategies, in which active involves imputing the interaction term as if it were any other variable and passive
involves deriving--and not imputing--the term only after imputing the main effects (ie, by
simply taking the product of the main effects). They evaluated these approaches under the joint
modeling (JM) approach, in which a joint parametric distribution is assumed for the imputation
model, and the fully conditional specification (FCS) approach, in which specification of a joint
model is bypassed, and, instead, conditional models for each variable are assumed. The team
assessed similar approaches when addressing the imputation of an outcome, rate of change,
when a 2-stage linear model was employed. Finally, the team investigated commonly applied
methods including complete case (CC) and single imputation (SI) for handling missing time_x0002_varying covariates and MI that ignores the clustered data structure (MI Naïve). For the latter, they established a comprehensive R package to simulate data including time-varying covariates with a complex correlation structure to represent realistic CER studies.
description: Datasets: 
DS1: Handling of Missing Data Induced by Time-Varying Covariates in Comparative Effectiveness Research HIV Patients [Methods Study], 2013-2018