Stanford Advisors

Research Projects

  • Factors Associated with Patient Satisfaction Scores for Cataract and Glaucoma Patients (MedScholars Project)
  • Tissue-Engineered Composite Tendon-Bone Interface (TBI) Grafts for Extremity Reconstruction (MedScholars Project)

All Publications

  • Cranioplasty Complications and Costs: A National Population-Level Analysis Using the MarketScan Longitudinal Database. World neurosurgery Li, A., Azad, T. D., Veeravagu, A., Bhatti, I., Long, C., Ratliff, J. K., Li, G. 2017; 102: 209-220


    To characterize cranioplasty complications and costs at a population level using a longitudinal national claims database.We identified cranioplasty patients between 2007-2014 in the MarketScan national database. We evaluated age, autograft usage, cranioplasty size, and cranioplasty timing on postoperative outcomes. We further analyzed associated costs. A subset analysis of adult cranioplasty patients with emergent indications, including stroke and trauma, was also performed.We identified 8,275 patients (mean 44.0±20.0 years, 45.2% male) consisting of 13.8% pediatric (<18 years), 76.0% adults (18-64 years), and 10.2% elderly adults (>65 years). Overall complication rate was 36.6%, mortality rate 0.5%, and 30-day readmission rate 12.0%. Elderly patients had the highest complication rate (p<0.0001). Overall, large cranioplasties (>5 cm) saw higher complication rates than small cranioplasties (≤5 cm, p=0.047). In those with emergent indications only(N=1,282), size did not influence complications-though large cranioplasties showed higher infection risk (p=0.02). Overall, autograft use did not affect outcomes, but was associated with higher complication risk-including infections-in the subset with only emergent indications (p<0.001, p=0.001). Late (>90 days) cranioplasty timing had higher complication rates in both the overall cohort and subset with emergent indications (p<0.001, p<0.001). Index costs of care were mainly driven by hospital payments in both the overall cohort and those with emergent indications.We found a high complication rate associated with cranioplasty in the U.S.A. Older age, large cranioplasties, and delayed cranioplasties increased complication risk overall. Among those with only emergent indications, complications were associated with a delayed time to cranioplasty and autograft usage.

    View details for DOI 10.1016/j.wneu.2017.03.022

    View details for PubMedID 28315803

  • Intratendinous Injection of Hydrogel for Reseeding Decellularized Human Flexor Tendons. Plastic and reconstructive surgery Long, C., Galvez, M. G., Legrand, A., Joubert, L., Wang, Z., Chattopadhyay, A., Chang, J., Fox, P. M. 2017; 139 (6): 1305e-1314e


    Decellularized cadaveric tendons are a potential source for reconstruction. Reseeding to enhance healing is ideal; however, cells placed on the tendon surface result in inadequate delivery. The authors used an injection technique to evaluate intratendinous cell delivery.Decellularized tendons were reseeded with adipose-derived stem cells in culture, and injected with fetal bovine serum or hydrogel. PKH26-stained cells in cross-section were quantified. To evaluate cell viability, the authors delivered luciferase-labeled cells and performed bioluminescent imaging. To evaluate synthetic ability, the authors performed immunohistochemistry of procollagen. Adipose-derived stem cells' ability to attract tenocytes was assessed using transwell inserts. Cell-to-cell interaction was assessed by co-culturing, measuring proliferation and collagen production, and quantifying synergy. Finally, tensile strength was tested.Both fetal bovine serum (p < 0.001) and hydrogel (p < 0.001) injection led to more cells inside the tendon compared with culturing. Hydrogel injection initially demonstrated greater bioluminescence than culturing (p < 0.005) and fetal bovine serum injection (p < 0.05). Injection groups demonstrated intratendinous procollagen staining correlating with the cells' location. Co-culture led to greater tenocyte migration (p < 0.05). Interaction index of proliferation and collagen production assays were greater than 1 for all co-culture ratios, demonstrating synergistic proliferation and collagen production compared with controls (p < 0.05). There were no differences in tensile strength.Hydrogel injection demonstrated the greatest intratendinous seeding efficiency and consistency, without compromising tensile strength. Intratendinous cells demonstrated synthetic capabilities and can potentially attract tenocytes inside the tendon, where synergy would promote intrinsic tendon healing.Therapeutic, V.

    View details for DOI 10.1097/PRS.0000000000003359

    View details for PubMedID 28538572

  • Epitendinous-First Repair of Zone II Flexor Digitorum Profundus Results in Decreased Gliding Resistance. journal of hand surgery Galvez, M. G., Comer, G. C., Chattopadhyay, A., Long, C., Behn, A. W., Chang, J. 2017


    The importance of flexor tendon repair with both core and epitendinous suture placement has been well established. The objective of this study was to determine whether suture placement order affects gliding resistance and bunching in flexor digitorum profundus tendons in a human ex vivo model.The flexor digitorum profundus tendons of the index, middle, ring, and little fingers of paired cadaver forearms were tested intact for excursion and mean gliding resistance in flexion and extension across the A2 pulley. Tendons were subsequently transected and repaired with either an epitendinous-first (n = 12) or a control (n = 12) repair. Gliding resistance of pair-matched tendons were analyzed at cycle 1 and during the steady state of tendon motion. The tendon repair breaking strength was also measured.The mean steady state gliding resistance was less for the epitendinous-first repair than for the control repair in flexion (0.61 N vs 0.72 N) and significantly less in extension (0.68 N vs 0.85 N). Similar results were seen for cycle 1. None of the repairs demonstrated gap formation; however, control repairs exhibited increased bunching. Load to failure was similar for both groups.The order of suture placement for flexor tendon repair is important. Epitendinous-first repair significantly decreased mean gliding resistance, allowed for easier placement of core sutures, and resulted in decreased bunching.Epitendinous-first flexor tendon repairs may contribute to improved clinical outcomes compared with control repairs by decreasing gliding resistance and bunching.

    View details for DOI 10.1016/j.jhsa.2017.04.013

    View details for PubMedID 28501340

  • Management of Mastectomy Skin Necrosis in Implant Based Breast Reconstruction. Annals of plastic surgery Sue, G. R., Long, C., Lee, G. K. 2017; 78 (5): S208-S211


    Mastectomy skin necrosis is a significant problem after breast reconstruction. This complication may lead to poor wound healing and need for implant removal, which may delay subsequent oncologic treatment. We sought to characterize factors associated with mastectomy skin necrosis and propose a management algorithm.A retrospective review was performed on consecutive patients undergoing implant-based breast reconstruction by the senior author from 2006 through 2015. Patient-level factors including age, race, body mass index, history of hypertension, history of diabetes, history of smoking, and history of radiation were collected. Surgical factors including type of mastectomy, location of implant placement, and immediate versus delayed reconstruction were collected. The incidence and treatment of mastectomy skin necrosis were analyzed.A total of 293 patients underwent either unilateral or bilateral implant-based breast reconstructions after mastectomy with a total of 471 reconstructed breasts. Mastectomy skin necrosis was observed in 8.1% of reconstructed breasts. Skin necrosis was not associated with age, hypertension, diabetes, prior radiation, or type of mastectomy. The incidence of skin necrosis was higher among smokers (17.9% vs 5.0%, P < 0.001), among patients with higher body mass index (11.4% vs 6.1%, P = 0.05), patients who underwent immediate reconstruction compared to delayed (9.6% vs 0%, P = 0.004), placement of expander under acellular dermal matrix compared with submuscular placement (12.0% vs 5.2%, P = 0.02), and use of higher initial expander fill volume compared with lower fill volume (11.4% vs 5.4%, P = 0.02).The median necrosis size was 8 cm. The median time to treatment was 15 days postoperatively. In 55% of patients minor necrosis was treated with clinic debridement, whereas 43% had larger areas of necrosis requiring operative debridement. The median size treated with clinic debridement was 5.5 cm, compared to 15 cm for operative debridement. All necrosis was treated in a timely fashion and did not delay adjuvant therapy.Mastectomy skin necrosis occurred in 8.1% of breasts after implant-based reconstruction. Necrosis less than 10 cm can be treated successfully with local debridement in the clinic setting. Timely and appropriate treatment of skin necrosis with debridement and primary closure expedites wound healing and facilitates tissue expander breast reconstruction.

    View details for DOI 10.1097/SAP.0000000000001045

    View details for PubMedID 28301366

  • Reverse Radial Forearm Flap. Plastic and reconstructive surgery. Global open Maan, Z. N., Legrand, A., Long, C., Chang, J. C. 2017; 5 (4)


    Supplemental Digital Content is available in the text.

    View details for DOI 10.1097/GOX.0000000000001287

    View details for PubMedID 28507856

    View details for PubMedCentralID PMC5426875

  • Global scientific collaboration in COPD research. International journal of chronic obstructive pulmonary disease Su, Y., Long, C., Yu, Q., Zhang, J., Wu, D., Duan, Z. 2017; 12: 215–25


    This study aimed to investigate the multiple collaboration types, quantitatively evaluate the publication trends and review the performance of institutions or countries (regions) across the world in COPD research.Scientometric methods and social network analysis were used to survey the development of publication trends and understand current collaboration in the field of COPD research based on the Web of Science publications during the past 18 years.The number of publications developed through different collaboration types has increased. Growth trends indicate that the percentage of papers authored through multinational and domestic multi-institutional collaboration (DMIC) have also increased. However, the percentage of intra-institutional collaboration and single-authored (SA) studies has reduced. The papers that produced the highest academic impact result from international collaboration. The second highest academic impact papers are produced by DMIC. Out of the three, the papers that are produced by SA studies have the least amount of impact upon the scientific community. A handful of internationally renowned institutions not only take the leading role in the development of the research within their country (region) but also play a crucial role in international research collaboration in COPD. Both the amount of papers produced and the amount of cooperation that occurs in each study are disproportionally distributed between high-income countries (regions) and low-income countries (regions). Growing attention has been generated toward research on COPD from more and more different academic domains.Despite the rapid development in COPD research, collaboration in the field of COPD research still has room to grow, especially between different institutions or countries (regions), which would promote the progress of global COPD research.

    View details for DOI 10.2147/COPD.S124051

    View details for PubMedID 28123294

    View details for PubMedCentralID PMC5230730

  • Tendon Tissue Engineering: Mechanism and Effects of Human Tenocyte Coculture With Adipose-Derived Stem Cells. The Journal of hand surgery Long, C., Wang, Z., Legrand, A., Chattopadhyay, A., Chang, J., Fox, P. M. 2017


    Adipose-derived stem cells (ASCs) are a potential candidate for cell-based therapy targeting tendon injury; however, their therapeutic benefit relies on their ability to interact with native tenocytes. This study examines the mechanism and effects of coculturing human tenocytes and ASCs.Tenocytes (T) were directly cocultured with either ASCs (A) or fibroblasts (F) (negative control) in the following ratios: 50% T/50% A or F; 25% T/75% A or F; and 75% T/25% A or F. Cells were indirectly cocultured using a transwell insert that allowed for exchange of soluble factors only. Proliferation and collagen I production were measured and compared with monoculture controls. Synergy was quantified using the interaction index (II), which normalizes measured values by the expected values assuming no interaction (no synergy when II = 1). The ability of ASCs to elicit tenocyte migration was examined in vitro using a transwell migration assay and ex vivo using decellularized human flexor tendon explants.Compared with monoculture controls, II of proliferation was greater than 1 for all tenocyte and ASC direct coculture ratios, but not for tenocyte and fibroblast direct coculture ratios or for tenocyte and ASC indirect coculture. The ASCs elicited greater tenocyte migration in vitro and ex vivo. The II of collagen I production was greater than 1 for direct coculture groups with 25% T/75% A and 75% T/25% A.Direct coculture of ASCs and tenocytes demonstrated synergistic proliferation and collagen I production, and ASCs elicited tenocyte migration in vitro and ex vivo. These interactions play a key role in tendon healing and were absent when ASCs were replaced with fibroblasts, supporting the use of ASCs for cell-based therapy targeting tendon injuries.When ASCs are delivered for cell-based therapy, they directly interact with native tenocytes to increase cell proliferation, collagen I production, and tenocyte migration, which may enhance tendon healing.

    View details for DOI 10.1016/j.jhsa.2017.07.031

    View details for PubMedID 28888566

  • Molecular Biology of Flexor Tendon Healing in Relation to Reduction of Tendon Adhesions. The Journal of hand surgery Legrand, A., Kaufman, Y., Long, C., Fox, P. M. 2017


    Tendon injuries are encountered after major and minor hand trauma. Despite meticulous repair technique, adhesion formation can occur, limiting recovery. Although a great deal of progress has been made toward understanding the mechanism of tendon healing and adhesions, clinically applicable solutions to prevent adhesions remain elusive. The goal of this paper is to review the most recent literature relating to the tendon healing and adhesion prevention.

    View details for DOI 10.1016/j.jhsa.2017.06.013

    View details for PubMedID 28709791

  • Critical Evaluation of Risk Factors of Infection Following 2-Stage Implant-Based Breast Reconstruction. Plastic and reconstructive surgery. Global open Long, C., Sue, G. R., Chattopadhyay, A., Huis In't Veld, E., Lee, G. K. 2017; 5 (7): e1386


    Infection is a dreaded complication following 2-stage implant-based breast reconstruction that can prolong the reconstructive process and lead to loss of implant. This study aimed to characterize outcomes of reconstructions complicated by infection, identify patient and surgical factors associated with infection, and use these to develop an infection management algorithm.We performed a retrospective review of all consecutive implant-based breast reconstructions performed by the senior author (2006-2015) and collected data regarding patient demographics, medical history, operative variables, presence of other complications (necrosis, seroma, hematoma), and infection characteristics. Univariate and multivariate binomial logistic regression analyses were performed to identify independent predictors of infection.We captured 292 patients who underwent 469 breast reconstructions. In total, 14.1% (n = 66) of breasts were complicated by infection, 87.9% (n = 58) of those were admitted and given intravenous antibiotics, 80.3% (n = 53) of all infections were cleared after the first attempt, whereas the remaining recurred at least once. The most common outcome was explantation (40.9%; n = 27), followed by secondary implant insertion (21.2%; n = 14) and operative salvage (18.2%; n = 12). Logistic regression analysis demonstrated that body mass index (P = 0.01), preoperative radiation (P = 0.02), necrosis (P < 0.001), seroma (P < 0.001), and hematoma (P = 0.03) were independent predictors of infection.We observed an overall infectious complication rate of 14.1%. Heavier patients and patients who received preoperative radiation were more likely to develop infectious complications, suggesting that closer monitoring of high risk patients can potentially minimize infectious complications. Further, more aggressive management may be warranted for patients whose operations are complicated by necrosis, seroma, or hematoma.

    View details for DOI 10.1097/GOX.0000000000001386

    View details for PubMedID 28831338

    View details for PubMedCentralID PMC5548561

  • An Inexpensive Bismuth-Petrolatum Dressing for Treatment of Burns. Plastic and reconstructive surgery. Global open Chattopadhyay, A., Chang, K., Nguyen, K., Galvez, M. G., Legrand, A., Davis, C., McGoldrick, R., Long, C., Pham, H., Chang, J. 2016; 4 (6)


    Xeroform remains the current standard for treating superficial partial-thickness burns but can be prohibitively expensive in developing countries with prevalent burn injuries. This study (1) describes the production of an alternative low-cost dressing and (2) compares the alternative dressing and Xeroform using the metrics of cost-effectiveness, antimicrobial activity, and biocompatibility in vitro, and wound healing in vivo.To produce the alternative dressing, 3% bismuth tribromophenate powder was combined with petroleum jelly by hand and applied to Kerlix gauze. To assess cost-effectiveness, the unit costs of Xeroform and components of the alternative dressing were compared. To assess antimicrobial properties, the dressings were placed on agar plated with Escherichia coli and the Kirby-Bauer assay performed. To assess biocompatibility, the dressings were incubated with human dermal fibroblasts and cells stained with methylene blue. To assess in vivo wound healing, dressings were applied to excisional wounds on rats and the rate of re-epithelialization calculated.The alternative dressing costs 34% of the least expensive brand of Xeroform. Antimicrobial assays showed that both dressings had similar bacteriostatic effects. Biocompatibility assays showed that there was no statistical difference (P < 0.05) in the cytotoxicity of Xeroform, alternative dressing, and Kerlix gauze. Finally, the in vivo healing model showed no statistical difference (P < 0.05) in mean re-epithelialization time between Xeroform (13.0 ± 1.6 days) and alternative dressing (13.5 ± 1.0 days).Xeroform is biocompatible, reduces infection, and enhances healing of burn wounds by preventing desiccation and mechanical trauma. Handmade petrolatum gauze may be a low-cost replacement for Xeroform. Future studies will focus on clinical trials in burn units.

    View details for DOI 10.1097/GOX.0000000000000741

    View details for PubMedID 27482485

    View details for PubMedCentralID PMC4956849

  • Comparing keywords plus of WOS and author keywords: A case study of patient adherence research JOURNAL OF THE ASSOCIATION FOR INFORMATION SCIENCE AND TECHNOLOGY Zhang, J., Yu, Q., Zheng, F., Long, C., Lu, Z., Duan, Z. 2016; 67 (4): 967-972

    View details for DOI 10.1002/asi.23437

    View details for Web of Science ID 000372926300016

  • Factors Associated with Patient Press Ganey Satisfaction Scores for Ophthalmology Patients. Ophthalmology Long, C., Tsay, E. L., Jacobo, S. A., Popat, R., Singh, K., Chang, R. T. 2016; 123 (2): 242-247


    To determine which metrics from the Press Ganey patient satisfaction survey best correlate with "likelihood to recommend" among patients in an academic tertiary medical center practice setting.Cross-sectional study.Over a 3-month period, patients presenting to an academic practice who agreed to participate were enrolled in the study if they met the following entry criteria: (1) age ≥18 years, (2) ability to read and speak English, and (3) followed in this practice between 4 months and 4 years. A total of 196 patients were recruited.A 26-item abridged version of the Press Ganey survey typically distributed to patients via mail or e-mail after visiting the Stanford University Hospital was administered privately to each eligible patient of 2 different attending clinics at the conclusion of his or her visit. The 26 survey items were not modified for the purposes of the study and were administered such that participants could not be individually identified. The arithmetic mean score for the item "Likelihood of your recommending our practice to others" was calculated by assigning a value (0-100) to the Likert value associated with survey responses and correlated with the 25 other items using the differences in the mean scores.Response to survey items graded on a 1 to 5 standard Likert scale.The weighted mean patient survey score for the "likelihood to recommend" item for the junior faculty member was 95.9% and for the senior faculty member was 94.5%, respectively. For the remaining 25 items, "Amount of time the care provider spent with you" (Diff[1-2]=1.03; P < 0.0001) and "Ease of scheduling your appointment" (Diff[1-2]=0.99; P < 0.0001) best correlated with likelihood to recommend. In contrast, "Friendliness/courtesy of the care provider" (Diff[1-2]=0.29; P = 0.0045) correlated least with likelihood to recommend. Stratification based on provider did not affect the study results.The perception of time spent with the practitioner and ease of appointment scheduling are the 2 variables that best correlate with patients recommending their ophthalmologists to other prospective patients.

    View details for DOI 10.1016/j.ophtha.2015.09.044

    View details for PubMedID 26545321

  • Factors Associated with Patient Press Ganey Satisfaction Scores for Ophthalmology Patients OPHTHALMOLOGY Long, C., Tsay, E. L., Jacobo, S. A., Popat, R., Singh, K., Chang, R. T. 2016; 123 (2): 242-247
  • Discussion: Unique Assessment of Hand Surgery Knowledge by Specialty. Plastic and reconstructive surgery Long, C., Chang, J. 2016; 137 (3): 925–26

    View details for DOI 10.1097/01.prs.0000479981.60298.fc

    View details for PubMedID 26910674

  • Factors associated with delays to surgical presentation in North-West Cameroon SURGERY Long, C., Tagang, E. T., Popat, R. A., Lawong, E. K., Brown, J. A., Wren, S. M. 2015; 158 (3): 756-763


    Few studies have examined critically the delays in definitive management for surgical diseases in Sub-Saharan Africa. This study investigates factors contributing to delays at Mbingo Baptist Hospital, a tertiary referral hospital in Cameroon.During a 6-week period, we randomly interviewed 220 patients (39.2%) admitted to the surgical or orthopedic service and/or their caregivers. All patients >age 15 years admitted with a diagnosis of cancer or urgent operative condition (defined as requiring a definitive operation within 48 hours of admission) including trauma were interviewed. Delay was defined as receiving treatment >7 days after symptoms appeared in the urgent cohort and >1 month for the cancer cohort.In the urgent cohort, 60.3% patients had delays >7 days to hospital presentation. Compared with nondelayed patients, delayed patients were more likely to have sought care >1 day after symptoms appeared (45.4% vs 6.3%, P < .0001) and to have received previous medical care (92.8% vs 73.4%, P = .0007). Of all patients who received previous care, those with delays, compared those with no delays, visited ≥2 other providers (50.5% vs 18.8%, P < .0001), received a surgical procedure at previous episode(s) of care (21.1% vs 6.4%, P = .026), and felt no improvement after this care (80.4% vs 61.0%, P = .003). In the cancer cohort, 100% experienced >1 month delay. 100% had received medical care prior to arriving at Mbingo Baptist Hospital, 81.4% sought care from at least 3 different facilities, and none believed this care addressed their health concerns.Significant delays most often were caused by time spent on previous failed attempts at care. This information can be used to inform policy discussions about optimal health care organization within the country.

    View details for DOI 10.1016/j.surg.2015.04.016

    View details for Web of Science ID 000359755000022

    View details for PubMedID 26067462

  • Hemophilia care in China: review of care for 417 hemophilia patients from 11 treatment centers in Shanxi Province EXPERT REVIEW OF HEMATOLOGY Zhao, H., Yang, L., Long, C., Guo, Y., Wu, R., Liu, X., Qin, X., Liang, H., Duan, Z. 2015; 8 (4): 543-550


    We analyzed the clinical features of 417 patients with hemophilia from 11 Hemophilia Treatment Centers in Shanxi Province (SP) in China.We used data collected in the national registry of hemophilia A and hemophilia B in SP from January 2010 to December 2013.Ratio of hemophilia A:hemophilia B patients was 5:1, of which 48% (200/417) were severe, 31% (129/417) moderate and 21% (88/417) mild. Episodes of joint bleeding occurred in 73% (305/417) of patients. Only 4% (15/417) of patients received tertiary prophylaxis. Three percent of patients (2/72) were hepatitis B virus-Ab positive, and 7% (5/72) of patients were hepatitis C virus-Ab positive. The incidence of inhibitors was 6% (11/182).The ability to manage hemophilia in SP remains suboptimal. However, due to limited data, the evaluation and extrapolation of large hemophilia populations in SP are restricted, therefore, further studies with a large cohort are needed.

    View details for DOI 10.1586/17474086.2015.1043263

    View details for Web of Science ID 000357617100016

    View details for PubMedID 25948487

  • Analysis on International Scientific Collaboration and Research Focus on Depression Field CHINESE MEDICAL JOURNAL Wu, Y., Long, C., Duan, Z. 2015; 128 (5): 687-693

    View details for DOI 10.4103/0366-6999.151678

    View details for Web of Science ID 000349524400022

    View details for PubMedID 25698205

    View details for PubMedCentralID PMC4834784

  • Predicting co-author relationship in medical co-authorship networks. PloS one Yu, Q., Long, C., Lv, Y., Shao, H., He, P., Duan, Z. 2014; 9 (7)


    Research collaborations are encouraged because a synergistic effect yielding good results often appears. However, creating and organizing a strong research group is a difficult task. One of the greatest concerns of an individual researcher is locating potential collaborators whose expertise complement his best. In this paper, we propose a method that makes link predictions in co-authorship networks, where topological features between authors such as Adamic/Adar, Common Neighbors, Jaccard's Coefficient, Preferential Attachment, Katzβ, and PropFlow may be good indicators of their future collaborations. Firstly, these topological features were systematically extracted from the network. Then, supervised models were used to learn the best weights associated with different topological features in deciding co-author relationships. Finally, we tested our models on the co-authorship networks in the research field of Coronary Artery Disease and obtained encouraging accuracy (the precision, recall, F1 score and AUC were, respectively, 0.696, 0.677, 0.671 and 0.742 for Logistic Regression, and respectively, 0.697, 0.678, 0.671 and 0.743 for SVM). This suggests that our models could be used to build and manage strong research groups.

    View details for DOI 10.1371/journal.pone.0101214

    View details for PubMedID 24991920

    View details for PubMedCentralID PMC4081126