Heterogeneous Causal Effect of Polysubstance Usage on Drug Overdose

In this paper, we propose a system to estimate heterogeneous concurrent drug usage effects on overdose estimation, that consists of efficient co-variate selection, sub-group selection, generation of and heterogeneous causal effect estimation. Although, there has been several association studies have been proposed in the state-of-art methods, heterogeneous causal effects have never been studied in concurrent drug usage and drug overdose problem. We apply our framework to answer a critical question, "can concurrent usage of benzodiazepines and opioids has heterogeneous causal effects on opioid overdose epidemic?" Using Truven MarketScan claim data collected from 2001 to 2013 have shown significant promise of our proposed framework's efficacy. Our efficient causal inference model estimated that the causal effect is higher (19%) than the regression studies (15%) to estimate the risks associated with the concurrent usage of opioid and benzodiazepines on opioid overdose.