Jichun Xie

Positions:

Associate Professor of Biostatistics & Bioinformatics

Integrative Genomics
School of Medicine

Member of the Duke Cancer Institute

Duke Cancer Institute
School of Medicine

Education:

Ph.D. 2011

University of Pennsylvania

Grants:

Duke CTSA (UL1)

Administered By
Institutes and Centers
Awarded By
National Institutes of Health
Role
Biostatistician Investigator
Start Date
End Date

Bioinformatics and Computational Biology Training Program

Administered By
Basic Science Departments
Awarded By
National Institutes of Health
Role
Mentor
Start Date
End Date

A hands-on, integrative next-generation sequencing course: design, experiment, and analysis

Administered By
Integrative Genomics
Awarded By
National Institutes of Health
Role
Training Faculty
Start Date
End Date

Race-Related Alternative Splicing: Novel Targets in Prostate Cancer

Administered By
Medicine, Medical Oncology
Awarded By
National Institutes of Health
Role
Biostatistician
Start Date
End Date

Statistical/Computational Methods for Pharmacogenomics and Individualized Therapy

Administered By
Integrative Genomics
Awarded By
University of North Carolina - Chapel Hill
Role
Co Investigator
Start Date
End Date

Publications:

Prevalence and Cost Analysis of Chronic Pain After Hernia Repair: A Potential Alternative Approach With Neurostimulation.

OBJECTIVES: Chronic pain (CP) affects a significant number of patients following hernia repair, ranging from 11 to 54% in the literature. The aim of this study was to assess the prevalence, overall costs, and health care utilization associated with CP after hernia repair. MATERIALS AND METHODS: A retrospective longitudinal study was performed using the Truven MarketScan® data base to identify patients who develop chronic neuropathic posthernia repair pain from 2001 to 2012. Patients were grouped into CP and No Chronic Pain (No CP) cohorts. Patients were excluded if they 1) were under 18 years of age; 2) had a previous pain diagnosis; 3) had CP diagnosed <90 days after the index hernia repair; 4) had less than one year of follow-up; or 5) had less than one-year baseline record before hernia repair. Patients were grouped into the CP cohort if their CP diagnosis was made within the two years following index hernia repair. Total, outpatient, and pain prescription costs were collected in the period of five years prehernia to nine years posthernia repair. A longitudinal multivariate analysis was used to model the effects of chronic neuropathic posthernia repair pain on total inpatient/outpatient and pain prescription costs. RESULTS: We identified 76,173 patients who underwent hernia repair and met inclusion criteria (CP: n = 14,919, No CP: n = 61,254). There was a trend for increased total inpatient/outpatient and pain prescription costs one-year posthernia repair, when compared to baseline costs for both cohorts. In both cohorts, total inpatient/outpatient costs remained elevated from baseline through nine years posthernia repair, with the CP cohort experiencing significantly higher cumulative median costs (CP: $51,334, No CP: $37,388). The CP diagnosis year was associated with a 1.75-fold increase (p < 0.001) in total inpatient/outpatient costs and a 2.26-fold increase (p < 0.001) in pain prescription costs versus all other years. In the longitudinal analysis, the CP cohort had a 1.14-fold increase (p < 0.001) in total inpatient/outpatient costs and 2.00-fold increase (p < 0.001) in pain prescription costs. CONCLUSIONS: Our study demonstrates the prevalence of CP after hernia surgery to be nearly 20%, with significantly increased costs and healthcare resource utilization. While current treatment paradigms are effective for many, there remains a large number of patients that could benefit from an overall approach that includes nonopioid treatments, such as potentially incorporating neurostimulation, for CP that presents posthernia repair.
Authors
Elsamadicy, AA; Ashraf, B; Ren, X; Sergesketter, AR; Charalambous, L; Kemeny, H; Ejikeme, T; Yang, S; Pagadala, P; Parente, B; Xie, J; Pappas, TN; Lad, SP
MLA Citation
Elsamadicy, Aladine A., et al. “Prevalence and Cost Analysis of Chronic Pain After Hernia Repair: A Potential Alternative Approach With Neurostimulation..” Neuromodulation, vol. 22, no. 8, Dec. 2019, pp. 960–69. Pubmed, doi:10.1111/ner.12871.
URI
https://scholars.duke.edu/individual/pub1355141
PMID
30320933
Source
pubmed
Published In
Neuromodulation
Volume
22
Published Date
Start Page
960
End Page
969
DOI
10.1111/ner.12871

Long-term Cost Utility of Spinal Cord Stimulation in Patients with Failed Back Surgery Syndrome.

BACKGROUND: Failed back surgery syndrome (FBSS) is a cause of significant morbidity for up to 40% of patients following spine surgery, and is estimated to cost almost $20 billion. Treatment options for these patients currently include conventional medical management (CMM), repeat operation, or spinal cord stimulation (SCS). Much of the published data regarding cost effectiveness of SCS comprise smaller scale randomized controlled trials (RCTs) rather than large databases capturing practices throughout the US. SCS has been shown to have superior outcomes to CMM or repeat spinal operation in several landmark studies, yet there are few large studies examining its long-term economic impact. OBJECTIVES: This study compares health care utilization for SCS compared to other management in patients with FBSS. STUDY DESIGN: Retrospective. SETTING: Inpatient and outpatient sample. METHODS: Patients with a history of FBSS from 2000 to 2012 were selected. We compared those who received SCS to those who underwent conventional management. A longitudinal analysis was used to model the value of log(cost) in each one year interval using a generalized estimating equations (GEE) model to account for the correlation of the same patient's cost in multiple years. Similarly, a Poisson GEE model with the log link was applied to correlated count outcomes. RESULTS: We identified 122,827 FBSS patients. Of these, 5,328 underwent SCS implantation (4.34%) and 117,499 underwent conventional management. Total annual costs decreased over time following implantation of the SCS system, with follow-up analysis at 1, 3, 6, and 9 years. The longitudinal GEE model demonstrated that placement of an SCS system was associated with an initial increase in total costs at the time of implantation (cost ratio [CR]: 1.74; 95% confidence interval [CI]: 1.41, 2.15, P < 0.001), however there was a significant and sustained 68% decrease in cost in the year following SCS placement (CR: 0.32; 95% CI: 0.24, 0.42, P < 0.001) compared to CMM. There was also an aggregate time trend that for each additional year after SCS, cost decreased on average 40% percent annually (CR: 0.60; 95% CI: 0.55, 0.65, P < 0.001), with follow-up up to 1, 3, 6, and 9 years post-procedure. LIMITATIONS: Costs are not correlated with patient outcomes, patients are not stratified in terms of complexity of prior back surgery, as well as inherent limitations of a retrospective analysis. CONCLUSIONS: We found that from 2000 to 2012, only 4.3% of patients across the United States with FBSS were treated with SCS. Long-term total annual costs for these patients were significantly reduced compared to patients with conventional management. Although implantation of an SCS system results in a short-term increase in costs at one year, the subsequent annual cumulative costs were significantly decreased long-term in the following 9 years after implantation. This study combines the largest group of FBSS patients studied to date along with the longest follow-up interval ever analyzed. Since SCS has repeatedly been shown to have superior efficacy to CMM in randomized clinical trials, the current study demonstrating improved long-term health economics at 1, 3, 6, and 9 years supports the long-term cost utility of SCS in the treatment of FBSS patients. Key words: Failed back surgery syndrome, spinal cord stimulation, back pain, leg pain, neuromodulation, FBSS, SCS.
Authors
Farber, SH; Han, JL; Elsamadicy, AA; Hussaini, Q; Yang, S; Pagadala, P; Parente, B; Xie, J; Lad, SP
MLA Citation
Farber, S. Harrison, et al. “Long-term Cost Utility of Spinal Cord Stimulation in Patients with Failed Back Surgery Syndrome..” Pain Physician, vol. 20, no. 6, Sept. 2017, pp. E797–805.
URI
https://scholars.duke.edu/individual/pub1276266
PMID
28934786
Source
pubmed
Published In
Pain Physician
Volume
20
Published Date
Start Page
E797
End Page
E805

Sample size and power analysis for sparse signal recovery in genome-wide association studies.

Genome-wide association studies have successfully identified hundreds of novel genetic variants associated with many complex human diseases. However, there is a lack of rigorous work on evaluating the statistical power for identifying these variants. In this paper, we consider sparse signal identification in genome-wide association studies and present two analytical frameworks for detailed analysis of the statistical power for detecting and identifying the disease-associated variants. We present an explicit sample size formula for achieving a given false non-discovery rate while controlling the false discovery rate based on an optimal procedure. Sparse genetic variant recovery is also considered and a boundary condition is established in terms of sparsity and signal strength for almost exact recovery of both disease-associated variants and nondisease-associated variants. A data-adaptive procedure is proposed to achieve this bound. The analytical results are illustrated with a genome-wide association study of neuroblastoma.
Authors
Xie, J; Cai, TT; Li, H
MLA Citation
Xie, Jichun, et al. “Sample size and power analysis for sparse signal recovery in genome-wide association studies..” Biometrika, vol. 98, no. 2, June 2011, pp. 273–90. Pubmed, doi:10.1093/biomet/asr003.
URI
https://scholars.duke.edu/individual/pub1099898
PMID
23049128
Source
pubmed
Published In
Biometrika
Volume
98
Published Date
Start Page
273
End Page
290
DOI
10.1093/biomet/asr003

Explantation Rates and Healthcare Resource Utilization in Spinal Cord Stimulation.

OBJECTIVES: Certain patients ultimately undergo explantation of their spinal cord stimulation (SCS) devices. Understanding the predictors and rates of SCS explantation has important implications for healthcare resource utilization (HCRU) and pain management. The present study identifies explant predictors and discerns differences in HCRU for at-risk populations. METHODS: We designed a large, retrospective analysis using the Truven MarketScan Database. We included all adult patients who underwent a SCS trial from 2007 to 2012. Patients were grouped into cohorts that remained explant-free or underwent explantation over a three-year period, and multivariate models evaluated differences in healthcare resource utilization. RESULTS: A total of 8727 unique instances of trial implants between 2007 and 2012 were identified. Overall, 805 (9.2%) patients underwent device explantation. One year prior to SCS implantation, the explant cohort had significantly higher median baseline costs ($42,140.3 explant vs. $27,821.7 in non-explant groups; p < 0.0001), total number of pain encounters (180 vs. 103 p < 0.0001), and associated costs ($15,446.9 vs. $9,227.9; p < 0.0001). The explant cohort demonstrated increased use of procedures (19.0 vs. 9.0; p < 0.0001) compared to non-explanted patients. For each month after initial SCS implantation, explanted patients had a slower decrease in total costs (4% vs. 6% in non-explant; p < 0.01). At the month of explant, explant patients were expected to have incurred 2.65 times the total cost compared to the non-explant cohort (CR 2.65, 95% CI [1.83, 3.84]; p < 0.001). Medium volume providers had lower rates of explantation at one-year and three-years compared to low volume providers (p = 0.042). Increased age and Charlson index were independent predictors of explantation during the same periods. CONCLUSIONS: In this nationwide analysis, we identified that SCS device explantation is correlated with patients who have higher baseline costs, higher total cost post-SCS implantation, and increased use of procedures to control pain. The higher rates of explantation at three-years postimplant among low volume providers suggest that variations in provider experience and approach also contributes to differences in explantation rates.
Authors
Han, JL; Murphy, KR; Hussaini, SMQ; Yang, S; Parente, B; Xie, J; Pagadala, P; Lad, SP
MLA Citation
Han, Jing L., et al. “Explantation Rates and Healthcare Resource Utilization in Spinal Cord Stimulation..” Neuromodulation, vol. 20, no. 4, June 2017, pp. 331–39. Pubmed, doi:10.1111/ner.12567.
URI
https://scholars.duke.edu/individual/pub1237796
PMID
28205332
Source
pubmed
Published In
Neuromodulation
Volume
20
Published Date
Start Page
331
End Page
339
DOI
10.1111/ner.12567

A penalized likelihood approach for bivariate conditional normal models for dynamic co-expression analysis.

Gene co-expressions have been widely used in the analysis of microarray gene expression data. However, the co-expression patterns between two genes can be mediated by cellular states, as reflected by expression of other genes, single nucleotide polymorphisms, and activity of protein kinases. In this article, we introduce a bivariate conditional normal model for identifying the variables that can mediate the co-expression patterns between two genes. Based on this model, we introduce a likelihood ratio (LR) test and a penalized likelihood procedure for identifying the mediators that affect gene co-expression patterns. We propose an efficient computational algorithm based on iterative reweighted least squares and cyclic coordinate descent and have shown that when the tuning parameter in the penalized likelihood is appropriately selected, such a procedure has the oracle property in selecting the variables. We present simulation results to compare with existing methods and show that the LR-based approach can perform similarly or better than the existing method of liquid association and the penalized likelihood procedure can be quite effective in selecting the mediators. We apply the proposed method to yeast gene expression data in order to identify the kinases or single nucleotide polymorphisms that mediate the co-expression patterns between genes.
Authors
Chen, J; Xie, J; Li, H
MLA Citation
Chen, Jun, et al. “A penalized likelihood approach for bivariate conditional normal models for dynamic co-expression analysis..” Biometrics, vol. 67, no. 1, Mar. 2011, pp. 299–308. Pubmed, doi:10.1111/j.1541-0420.2010.01413.x.
URI
https://scholars.duke.edu/individual/pub1099901
PMID
20374241
Source
pubmed
Published In
Biometrics
Volume
67
Published Date
Start Page
299
End Page
308
DOI
10.1111/j.1541-0420.2010.01413.x