Title: Re-calibrated Wasserstein GAN for large-scale imputation with informative missing. Abstract: Missing data are pervasive in electronic health records (EHR) and oftentimes the missingness is informative (i.e. Missing Not At Random). Presently available imputation methods typically do not account for this informative missingness or are computationally infeasible to handle the scale of EHR data. We develop a deep learning imputation method based on \textit{recalibrating} a Wasserstein Generative Adversarial Network (WGAN) to account for informative missingness in high-dimensional quantitative medical data. We propose a new quantile re-weighting technique to ensure distributional equivariance under informative missingness and integrate it with WGAN to enable efficient imputations in large-scale observational data in presence of informative missingness and covariate imbalance. Results from our proposed algorithm show better recovery compared to present methods in both synthetic and real-world data from the Reactions to Acute Hospitalization (REACH)  and laboratory test results of COVID-19 patients in the New York Metropolitan area from the INSIGHT dataset.
