Zhengxing Huang

Discovery of clinical pathway patterns from event logs using probabilistic topic models

Discovery of clinical pathway (CP) patterns has experienced increased attention over the years due to its importance for revealing the structure, semantics and dynamics of CPs, and to its usefulness for providing clinicians with explicit knowledge which can be directly used to guide treatment activities of individual patients. Generally, discovery of CP patterns is a challenging task as treatment behaviors in CPs often have a large variability depending on factors such as time, location and patient individual. Based on the assumption that CP patterns can be derived from clinical event logs which usually record various treatment activities in CP executions, this study proposes a novel approach to CP pattern discovery by modeling CPs using mixtures of an extension to the Latent Dirichlet Allocation family that jointly models various treatment activities and their occurring time stamps in CPs. Clinical case studies are performed to evaluate the proposed approach via real-world data sets recording typical treatment behaviors in patient careflow. The obtained results demonstrate the suitability of the proposed approach for CP pattern discovery, and indicate the promise in research efforts related to CP analysis and optimization.

On mining latent treatment patterns from electronic medical records

Clinical pathway (CP) analysis plays an important role in health-care management in ensuring specialized, standardized, normalized and sophisticated therapy procedures for individual patients. Recently, with the rapid development of hospital information systems, a large volume of electronic medical records (EMRs) has been produced, which provides a comprehensive source for CP analysis. In this paper, we are concerned with the problem of utilizing the heterogeneous EMRs to assist CP analysis and improvement. More specifically, we develop a probabilistic topic model to link patient features and treatment behaviors together to mine treatment patterns hidden in EMRs. Discovered treatment patterns, as actionable knowledge representing the best practice for most patients in most time of their treatment processes, form the backbone of CPs, and can be exploited to help physicians better understand their specialty and learn from previous experiences for CP analysis and improvement. Experimental results on a real collection of 985 EMRs collected from a Chinese hospital show that the proposed approach can effectively identify meaningful treatment patterns from EMRs.

Similarity Measure Between Patient Traces for Clinical Pathway Analysis: Problem, Method, and Applications

Clinical pathways leave traces, described as event sequences with regard to a mixture of various latent treatment behaviors. Measuring similarities between patient traces can profitably be exploited further as a basis for providing insights into the pathways, and complementing existing techniques of clinical pathway analysis (CPA), which mainly focus on looking at aggregated data seen from an external perspective. Most existing methods measure similarities between patient traces via computing the relative distance between their event sequences. However, clinical pathways, as typical human-centered processes, always take place in an unstructured fashion, i.e., clinical events occur arbitrarily without a particular order. Bringing order in the chaos of clinical pathways may decline the accuracy of similarity measure between patient traces, and may distort the efficiency of further analysis tasks. In this paper, we present a behavioral topic analysis approach to measure similarities between patient traces. More specifically, a probabilistic graphical model, i.e., latent Dirichlet allocation (LDA), is employed to discover latent treatment behaviors of patient traces for clinical pathways such that similarities of pairwise patient traces can be measured based on their underlying behavioral topical features. The presented method provides a basis for further applications in CPA. In particular, three possible applications are introduced in this paper, i.e., patient trace retrieval, clustering, and anomaly detection. The proposed approach and the presented applications are evaluated via a real-world dataset of several specific clinical pathways collected from a Chinese hospital.

A probabilistic topic model for clinical risk stratification from electronic health records

BACKGROUND AND OBJECTIVE Risk stratification aims to provide physicians with the accurate assessment of a patients clinical risk such that an individualized prevention or management strategy can be developed and delivered. Existing risk stratification techniques mainly focus on predicting the overall risk of an individual patient in a supervised manner, and, at the cohort level, often offer little insight beyond a flat score-based segmentation from the labeled clinical dataset. To this end, in this paper, we propose a new approach for risk stratification by exploring a large volume of electronic health records (EHRs) in an unsupervised fashion. METHODS Along this line, this paper proposes a novel probabilistic topic modeling framework called probabilistic risk stratification model (PRSM) based on Latent Dirichlet Allocation (LDA). The proposed PRSM recognizes a patient clinical state as a probabilistic combination of latent sub-profiles, and generates sub-profile-specific risk tiers of patients from their EHRs in a fully unsupervised fashion. The achieved stratification results can be easily recognized as high-, medium- and low-risk, respectively. In addition, we present an extension of PRSM, called weakly supervised PRSM (WS-PRSM) by incorporating minimum prior information into the model, in order to improve the risk stratification accuracy, and to make our models highly portable to risk stratification tasks of various diseases. RESULTS We verify the effectiveness of the proposed approach on a clinical dataset containing 3463 coronary heart disease (CHD) patient instances. Both PRSM and WS-PRSM were compared with two established supervised risk stratification algorithms, i.e., logistic regression and support vector machine, and showed the effectiveness of our models in risk stratification of CHD in terms of the Area Under the receiver operating characteristic Curve (AUC) analysis. As well, in comparison with PRSM, WS-PRSM has over 2% performance gain, on the experimental dataset, demonstrating that incorporating risk scoring knowledge as prior information can improve the performance in risk stratification. CONCLUSIONS Experimental results reveal that our models achieve competitive performance in risk stratification in comparison with existing supervised approaches. In addition, the unsupervised nature of our models makes them highly portable to the risk stratification tasks of various diseases. Moreover, patient sub-profiles and sub-profile-specific risk tiers generated by our models are coherent and informative, and provide significant potential to be explored for the further tasks, such as patient cohort analysis. We hypothesize that the proposed framework can readily meet the demand for risk stratification from a large volume of EHRs in an open-ended fashion.

A genetic fuzzy system for unstable angina risk assessment

BackgroundUnstable Angina (UA) is widely accepted as a critical phase of coronary heart disease with patients exhibiting widely varying risks. Early risk assessment of UA is at the center of the management program, which allows physicians to categorize patients according to the clinical characteristics and stratification of risk and different prognosis. Although many prognostic models have been widely used for UA risk assessment in clinical practice, a number of studies have highlighted possible shortcomings. One serious drawback is that existing models lack the ability to deal with the intrinsic uncertainty about the variables utilized.MethodsIn order to help physicians refine knowledge for the stratification of UA risk with respect to vagueness in information, this paper develops an intelligent system combining genetic algorithm and fuzzy association rule mining. In detail, it models the input information’s vagueness through fuzzy sets, and then applies a genetic fuzzy system on the acquired fuzzy sets to extract the fuzzy rule set for the problem of UA risk assessment.ResultsThe proposed system is evaluated using a real data-set collected from the cardiology department of a Chinese hospital, which consists of 54 patient cases. 9 numerical patient features and 17 categorical patient features that appear in the data-set are selected in the experiments. The proposed system made the same decisions as the physician in 46 (out of a total of 54) tested cases (85.2%).ConclusionsBy comparing the results that are obtained through the proposed system with those resulting from the physician’s decision, it has been found that the developed model is highly reflective of reality. The proposed system could be used for educational purposes, and with further improvements, could assist and guide young physicians in their daily work.

Online Treatment Compliance Checking for Clinical Pathways

Compliance checking for clinical pathways (CPs) is getting increasing attention in health-care organizations due to stricter requirements for cost control and treatment excellence. Many compliance measures have been proposed for treatment behavior inspection in CPs. However, most of them look at aggregated data seen from an external perspective, e.g. length of stay, cost, infection rate, etc., which may provide only a posterior impression of the overall conformance with the established CPs such that in-depth and in near real time checking on the compliance of the essential/critical treatment behaviors of CPs is limited. To provide clinicians real time insights into violations of the established CP specification and support online compliance checking, this article presents a semantic rule-based CP compliance checking system. In detail, we construct a CP ontology (CPO) model to provide a formal grounding of CP compliance checking. Using the proposed CPO, domain treatment constraints are modeled into Semantic Web Rule Language (SWRL) rules to specify the underlying treatment behaviors and their quantified temporal structure in a CP. The established SWRL rules are integrated with the CP workflow such that a series of applicable compliance checking and evaluation can be reminded and recommended during the pathway execution. The proposed approach can, therefore, provides a comprehensive compliance checking service as a paralleling activity to the patient treatment journey of a CP rather than an afterthought. The proposed approach is illustrated with a case study on the unstable angina clinical pathway implemented in the Cardiology Department of a Chinese hospital. The results demonstrate that the approach, as a feasible solution to provide near real time conformance checking of CPs, not only enables clinicians to uncover non-compliant treatment behaviors, but also empowers clinicians with the capability to make informed decisions when dealing with treatment compliance violations in the pathway execution.

On mining latent topics from healthcare chat logs

BACKGROUND Public and internet-based social media such as online healthcare-oriented chat groups provide a convenient channel for patients and people concerned about health to communicate and share information with each other. The chat logs of an online healthcare-oriented chat group can potentially be used to extract latent topics, to encourage participation, and to recommend relevant healthcare information to users. OBJECTIVE This paper addresses the use of online healthcare chat logs to automatically discover both underlying topics and user interests. METHOD We present a new probabilistic model that exploits healthcare chat logs to find hidden topics and changes in these topics over time. The proposed model uses separate but associated hidden variables to explore both topics and individual interests such that it can provide useful insights to the participants of online healthcare chat groups about their interests in terms of weighted topics or vice versa. RESULTS We evaluate the proposed model on a real-world chat log by comparing its performance to benchmark topic models, i.e., latent Dirichlet allocation (LDA) and Author Topic Model (ATM), on the topic extraction task. The chat log is obtained from an online chat group of pregnant women, which consists of 233,452 chat word tokens contributed by 118 users. Both detected individual interests and underlying topics with their progressive information over time are demonstrated. The results show that the performance of the proposed model exceeds that of the benchmark models. CONCLUSION The experimental results illustrate that the proposed model is a promising method for extracting healthcare knowledge from social media data.

Predictive monitoring of clinical pathways

We propose a learning framework for predictive monitoring of clinical pathways.Both offline analysis and online monitoring services are provided.A probabilistic topic model is developed to describe essential behaviors of CPs.Two predictive monitoring services are presented to illustrate the potential of our framework.Evaluation is done using a real clinical datasetfrom a Chinese hospital. ObjectiveAccurate and timely monitoring, as a key aspect of clinical pathway management, provides crucial information to medical staff and hospital managers for determining the efficient medical service delivered to individual patients, and for promptly handling unusual treatment behaviors in clinical pathways (CPs). In many applications, CP monitoring is performed in a reactive manner, e.g., variant treatment events are detected only after they have occurred in CPs. Alternatively, this article presents an intelligent learning system for predictive monitoring of CPs and from a large volume of electronic medical records (EMRs). MethodsThe proposed system is composed of both offline analysis and online monitoring phases. In the offline phase, a particular probabilistic topic model, i.e., treatment pattern model (TPM), is generated from electronic medical records to describe essential/critical medical behaviors of CPs. Using TPM-based measures as a descriptive vocabulary, online monitoring of CPs can be provided for ongoing patient-care journeys. Specifically, this article presents two typical predictive monitoring services, i.e., unusual treatment event prediction and clinical outcome prediction, to illustrate how the potential of the proposed system can be exploited to provide online monitoring services from both internal and external perspectives of CPs. ResultsThe proposed monitoring services have been evaluated using a real clinical dataset pertaining to the unstable angina CP and collected from a large hospital in China. In terms of unusual treatment event prediction, the overall precision and recall of our system are 0.834, and 0.96, respectively, which is comparable to identify unusual treatment events in CPs in comparison with human evaluation. In terms of clinical outcome prediction, the stable model was characterized by 0.849 accuracy, 0.064 hamming-loss and 0.053 one-loss, which outperforms the benchmark multi-label classification algorithms on clinical outcome prediction. ConclusionExtensive evaluations on a real clinical data-set, typically missing from other work, demonstrate that the proposed system, as a crucial advantage over traditional expert systems for CP management, not only provides an efficient and general surveillance of CPs, but also empowers clinicians with the capability to look insights into CPs to gain a deeper understanding of the situations in which the proposed prediction technique performs well.

On local anomaly detection and analysis for clinical pathways

OBJECTIVE Anomaly detection, as an imperative task for clinical pathway (CP) analysis and improvement, can provide useful and actionable knowledge of interest to clinical experts to be potentially exploited. Existing studies mainly focused on the detection of global anomalous inpatient traces of CPs using the similarity measures in a structured manner, which brings order in the chaos of CPs, may decline the accuracy of similarity measure between inpatient traces, and may distort the efficiency of anomaly detection. In addition, local anomalies that exist in some subsegments of events or behaviors in inpatient traces are easily overlooked by existing approaches since they are designed for detecting global or large anomalies. METHOD In this study, we employ a probabilistic topic model to discover underlying treatment patterns, and assume any significant unexplainable deviations from the normal behaviors surmised by the derived patterns are strongly correlated with anomalous behaviours. In this way, we can figure out the detailed local abnormal behaviors and the associations between these anomalies such that diagnostic information on local anomalies can be provided. RESULTS The proposed approach is evaluated via a clinical data-set, including 2954 unstable angina patient traces and 483,349 clinical events, extracted from a Chinese hospital. Using the proposed method, local anomalies are detected from the log. In addition, the identified associations between the detected local anomalies are derived from the log, which lead to clinical concern on the reason resulting in these anomalies in CPs. The correctness of the proposed approach has been evaluated by three experience cardiologists of the hospital. For four types of local anomalies (i.e., unexpected events, early events, delay events, and absent events), the proposed approach achieves 94%, 71% 77%, and 93.2% in terms of recall. This is quite remarkable as we do not use a prior knowledge. CONCLUSION Substantial experimental results show that the proposed approach can effectively detect local anomalies in CPs, and also provide diagnostic information on the detected anomalies in an informative manner.

A Regularized Deep Learning Approach for Clinical Risk Prediction of Acute Coronary Syndrome Using Electronic Health Records

Objective: Acute coronary syndrome (ACS), as a common and severe cardiovascular disease, is a leading cause of death and the principal cause of serious long-term disability globally. Clinical risk prediction of ACS is important for early intervention and treatment. Existing ACS risk scoring models are based mainly on a small set of hand-picked risk factors and often dichotomize predictive variables to simplify the score calculation. Methods: This study develops a regularized stacked denoising autoencoder (SDAE) model to stratify clinical risks of ACS patients from a large volume of electronic health records (EHR). To capture characteristics of patients at similar risk levels, and preserve the discriminating information across different risk levels, two constraints are added on SDAE to make the reconstructed feature representations contain more risk information of patients, which contribute to a better clinical risk prediction result. Results: We validate our approach on a real clinical dataset consisting of 3464 ACS patient samples. The performance of our approach for predicting ACS risk remains robust and reaches 0.868 and 0.73 in terms of both AUC and accuracy, respectively. Conclusions: The obtained results show that the proposed approach achieves a competitive performance compared to state-of-the-art models in dealing with the clinical risk prediction problem. In addition, our approach can extract informative risk factors of ACS via a reconstructive learning strategy. Some of these extracted risk factors are not only consistent with existing medical domain knowledge, but also contain suggestive hypotheses that could be validated by further investigations in the medical domain.