@article{kang_lu_zhang_2018, title={ON ESTIMATION OF THE OPTIMAL TREATMENT REGIME WITH THE ADDITIVE HAZARDS MODEL}, volume={28}, ISSN={["1996-8507"]}, DOI={10.5705/ss.202016.0543}, abstractNote={We propose a doubly robust estimation method for the optimal treatment regime based on an additive hazards model with censored survival data. Specifically, we introduce a new semiparametric additive hazard model which allows flexible baseline covariate effects in the control group and incorporates marginal treatment effect and its linear interaction with covariates. In addition, we propose a time-dependent propensity score to construct an A-learning type of estimating equations. The resulting estimator is shown to be consistent and asymptotically normal when either the baseline effect model for covariates or the propensity score is correctly specified. The asymptotic variance of the estimator is consistently estimated using a simple resampling method. Simulation studies are conducted to evaluate the finite-sample performance of the estimators and an application to AIDS clinical trial data is also given to illustrate the methodology.}, number={3}, journal={STATISTICA SINICA}, author={Kang, Suhyun and Lu, Wenbin and Zhang, Jiajia}, year={2018}, month={Jul}, pages={1539–1560} }
 @article{kang_lu_liu_2017, title={Efficient Estimation for Accelerated Failure Time Model under Case-Cohort and Nested Case-Control Sampling}, volume={73}, ISSN={["1541-0420"]}, DOI={10.1111/biom.12573}, abstractNote={Summary}, number={1}, journal={BIOMETRICS}, author={Kang, Suhyun and Lu, Wenbin and Liu, Mengling}, year={2017}, month={Mar}, pages={114–123} }
 @article{kang_lu_song_2017, title={Subgroup detection and sample size calculation with proportional hazards regression for survival data}, volume={36}, ISSN={0277-6715}, url={http://dx.doi.org/10.1002/sim.7441}, DOI={10.1002/sim.7441}, abstractNote={In this paper, we propose a testing procedure for detecting and estimating the subgroup with an enhanced treatment effect in survival data analysis. Here, we consider a new proportional hazard model that includes a nonparametric component for the covariate effect in the control group and a subgroup‐treatment–interaction effect defined by a change plane. We develop a score‐type test for detecting the existence of the subgroup, which is doubly robust against misspecification of the baseline effect model or the propensity score but not both under mild assumptions for censoring. When the null hypothesis of no subgroup is rejected, the change‐plane parameters that define the subgroup can be estimated on the basis of supremum of the normalized score statistic. The asymptotic distributions of the proposed test statistic under the null and local alternative hypotheses are established. On the basis of established asymptotic distributions, we further propose a sample size calculation formula for detecting a given subgroup effect and derive a numerical algorithm for implementing the sample size calculation in clinical trial designs. The performance of the proposed approach is evaluated by simulation studies. An application to an AIDS clinical trial data is also given for illustration.}, number={29}, journal={Statistics in Medicine}, publisher={Wiley}, author={Kang, Suhyun and Lu, Wenbin and Song, Rui}, year={2017}, month={Aug}, pages={4646–4659} }
 @article{leary_kang_kolb_maron_ralph_rao_tedford_zamanian_2017, title={What's in a side effect? The association between pulmonary vasodilator adverse drug events and clinical outcomes in patients with pulmonary arterial hypertension}, volume={240}, ISSN={["1874-1754"]}, DOI={10.1016/j.ijcard.2017.04.016}, abstractNote={Background Adverse drug events (ADEs) with pulmonary vasodilator use in pulmonary arterial hypertension (PAH) are common. ADEs may contribute to worse quality of life; however, their relationship to prognosis is unknown. The objective of this study was to determine whether common ADEs after initiating subcutaneous treprostinil were associated with prognosis in PAH. Methods We assembled a retrospective cohort of participants from four clinical trials of treprostinil for PAH, including 908 participants who received subcutaneous treprostinil and 243 who received placebo at the time ADEs were ascertained. The occurrences of four common early ADEs (infusion reactions, headaches, jaw pain, or gastrointestinal side effects) were assessed during the eight weeks after starting the infusion. We used Cox proportional hazards to estimate associations between ADEs and mortality. Results No ADEs related to placebo were associated with mortality. In participants who received treprostinil, infusion reactions, headaches, and jaw pain were not associated with mortality. Gastrointestinal side effects occurring during the first eight weeks following treprostinil infusion were associated with a 57% increase in the hazard of mortality (95% CI: 14–118%). This relationship was unchanged after adjusting for demographic differences and differences in baseline PAH severity. Conclusions Gastrointestinal ADEs after starting subcutaneous treprostinil were associated with an increased risk for mortality. Increased mortality was not observed with other early ADEs or with gastrointestinal symptoms in participants who were not receiving treprostinil at the time. This hypothesis-generating association suggests ADEs may identify different phenotypes in PAH.}, journal={INTERNATIONAL JOURNAL OF CARDIOLOGY}, author={Leary, Peter J. and Kang, Suhyun and Kolb, Todd M. and Maron, Bradley A. and Ralph, David D. and Rao, Youlan and Tedford, Ryan J. and Zamanian, Roham T.}, year={2017}, month={Aug}, pages={386–391} }