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Chu P, Huang J, Prasath A, Hwang W. 124: Mesenchymal Stem Cells Support ex vivo Umbilical Cord Blood Expansion by a Contact-Dependent Anti-Apoptotic Effect. Biol Blood Marrow Transplant 2008. [DOI: 10.1016/j.bbmt.2007.12.133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Teoh G, Tan D, Chuah C, Hwang W, Yiu R, Kuperan P, Tien S, Lee L, Ang A, Kam G. Low-dose dexamethasone and thalidomide with higher frequency zoledronic acid (dtZ) for newly diagnosed multiple myeloma. J Clin Oncol 2007. [DOI: 10.1200/jco.2007.25.18_suppl.18506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
18506 Background: Although dexamethasone (Dex), thalidomide (Thal) and zoledronic acid (Zol) have frequently been combined for the treatment of multiple myeloma (MM), the ideal dosing schedule is unknown. We previously reported that lower doses of Dex and Thal can be effectively combined with high-frequency dosing of Zol (Haematologica 2005). Methods: This “dtZ” regimen - which comprises weekly Dex 20 mg OM for 4 days, Thal 50 mg ON, and 3-weekly Zol 4 mg - resulted in an impressive response rate (RR) of 61.6% and near complete remission (nCR)/complete remission (CR) rate of 7.7% in 26 patients with relapsed/refractory MM. Results: In this present study, we treated 22 newly diagnosed MM patients with “dtZ” and report an even more impressive RR of 100.0% and nCR/CR rate of 20–35%. The median time to response was 1.8 months and median time to maximum response was 2.2 months. The median time to progression (TTP) has not been achieved yet. As expected, low-dose Dex/Thal resulted in lower (18.1%) grade 3 or 4 toxicities. These were all infections; which lead to further dose-reduction of Dex. There were no thromboembolic events, despite the fact that aspirin was not routinely given. Of particular interest, 3- weekly Zol was not associated with any significant decrease in renal function, and none of our patients developed osteonecrosis of the jaw (ONJ). In fact, at the time of writing of this abstract, more than 1,000 doses of Zol had been administered in a 3-weekly fashion to these as well as other patients, and only 1 patient developed ONJ. This patient who had already received greater than 20 doses of Zol healed uneventfully after receiving appropriate outpatient dental treatment, and subsequently received another 8 doses of Zol with no recurrence of ONJ. Conclusion: In conclusion, the Zol-based “dtZ” regimen is potentially a highly-effective and safe frontline regimen for MM. Using Zol every 3 weeks with lower doses of Dex and Thal does not appear to increase the rate or severity of nephrotoxicity or ONJ. Although we do not know exactly why every patient responded to “dtZ”, we speculate that this could be due to a critical balance that has been achieved between the anti-MM, anti-osteoclastic and immunostimulatory effects of the individual drugs of the combination. No significant financial relationships to disclose.
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Harris EE, Urtishak SL, Hwang W, Kinosian B, Solin LJ. Comorbidity and outcomes in elderly women treated with breast-conserving therapy. J Clin Oncol 2006. [DOI: 10.1200/jco.2006.24.18_suppl.599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
599 Background: Breast cancer incidence increases with age and is a major cause of morbidity and mortality among elderly women. Co-morbidities are often considered in treatment management of elderly women. Methods: Between 1979 and 2002, 238 women age 70 or older with unilateral stage I or II invasive breast cancer underwent conventional breast conservation treatment with radiation. The age distribution was 122 women (51%) age 70–74 years, 71 women (30%) age 75–79 years, and 45 women (19%) age ≥80 years. Surgical axillary staging was performed in 73% (n= 173) of patients, of which 73% (n=126) were N0, and 27% (n=47) were N1. Co-morbidities were scored using the Charlson Comorbidity Index and Cumulative Illness Rating Scale (CIRS). Median follow-up was 6.2 years. Results: On analysis by age groups, the 10-year cancer specific outcomes were not significantly different (see Table ). However, distant metastases were the most common site of first failure in all age groups: 9% for age 70–74; 12% for age 75–79 and 11% for age >/= 80. Second malignancies were the second most common cause of first failure in all age groups. Death from intercurrent disease was significantly more likely in the older age groups. In this cohort, moderate and severe co-morbidities were not significantly more common in the older age groups, and CIRS score did not correlate with overall survival. Conclusions: Breast conserving surgery and definitive breast irradiation provide excellent outcomes in appropriately selected elderly women. Older age itself is not a contraindication to breast conserving therapy. Women of any age with lower co-morbidity indices should be offered standard treatment. [Table: see text] No significant financial relationships to disclose.
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Teoh G, Tan D, Hwang W, Koh LP, Chuah C, Ng HJ. Addition of bortezomib to thalidomide, dexamethasone and zoledronic acid (VTD-Z regimen) significantly improves complete remission rates in patients with relapsed/refractory multiple myeloma. J Clin Oncol 2006. [DOI: 10.1200/jco.2006.24.18_suppl.17537] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
17537 Background: We previously treated 26 patients with relapsed/refractory multiple myeloma (MM) with thalidomide (Thal), dexamethasone (Dex) and zoledronic acid (Zol); dtZ regimen; and demonstrated an overall response rate of 75.0%. However, the rate immunofixation (IF)-negative complete remissions (CR) was only 7.7%. Recently, the bortezomib (Velcade) has been shown to be effective against MM. In this study, we added bortezomib (Vel) to dtZ (VTD-Z regimen) in a subgroup of patients to determine whether the CR rate can be improved. Methods: A non-randomized, single-arm study was conducted. Consecutive patients (n = 14) who either failed to achieve a partial response (PR) after 3 cycles; or CR after 9 cycles of dtZ were treated with 2 to 11 three-weekly cycles of VTD-Z; comprising: Vel 1.3 mg/m2 on days 1, 4, 8 and 11; Thal 50 mg ON; Dex 20 mg OM on days 1 to 4, 8 to 11, 15 to 18; and Zol 4 mg on day 1. The primary study objective was to determine the maximal response rates (RR). The end-point of the study was maximum response, graded by Bladè’s criteria. Results: Fourteen patients (3 males, 11 females; median age 63.3 years) were studied. Complex karyotypes, including 5 patients with deletion of chromosome 13 (del(13)), were present in 11 patients at diagnosis. The overall RR was 92.9% (13 out of 14), of which 42.9% (6) achieved CR (p < 0.001, chi-squared test). In addition, 21.4% (3) achieved near-CR (nCR), and 28.6% (4) achieved PR. There were no minimal responders (MR) and 1 (7.1%) non-responder (NR). Two patients who achieved CR had del(13). Painful grade 3 peripheral neuropathy was observed in 2 (14.3%) patients. Grade 1 and 2 peripheral neuropathy was observed in another 4 (25.0%) of patients; transient grade 3 thrombocytopenia was observed in 5 (35.7%) patients; and papular rashes were observed in 3 (21.4%) patients. The single NR was the only death that occurred during the period of study. Conclusions: Our study demonstrates that the VTD-Z regimen is exceptionally effective and safe in patients with relapsed/refractory MM. Addition of Vel to dtZ significantly increases the CR rate from 7.7% to 42.9%. These data suggest that combination of these 4 drugs may be at least additive, if not, even synergistic. No significant financial relationships to disclose.
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Tan D, Wong GC, Koh LP, Hwang W, Loh Y, Linn YC, Goh YT. Successful treatment of primary granulocytic sarcoma by non-myeloablative stem cell transplant. Leuk Lymphoma 2006; 47:159-62. [PMID: 16321843 DOI: 10.1080/10428190500301140] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Pre-leukemic granulocytic sarcoma (GS) may pose an initial diagnostic problem and its therapeutic approach has never been formally established. To our knowledge, non-myeloablative stem cell transplantation has been reported in cases of leukemic GS, but not in primary GS. We report a case of primary GS with extensive and aggressive presenting features and successfully treated with intensive chemotherapy followed by non-myeloablative allogeneic stem cell transplant. This resulted in complete remission with minimal complications. Our case demonstrates the potential of graft-vs.-tumour effect in the treatment of GS and suggests that non-myeloablative allogeneic stem cell transplant may be a feasible therapeutic approach for primary GS.
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Hill C, Harris E, Hwang W, Solin L. Twenty-Year Incidence and Patterns of Contralateral Breast Cancer After Breast Conservation Treatment. Int J Radiat Oncol Biol Phys 2005. [DOI: 10.1016/j.ijrobp.2005.07.407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Tan D, Hwang W, Goh YT. Therapeutic leukapheresis in hyperleukocytic leukaemias--the experience of a tertiary institution in Singapore. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2005; 34:229-34. [PMID: 15902342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
INTRODUCTION Hyperleukocytic leukaemias are associated with early mortality due to respiratory or neurological complications. They result from endothelial damage secondary to leukostasis. Leukapheresis, which aims to lower the white blood cell (WBC) count, has been used in certain patients to reduce the threat from leukostasis. However, there are very few published clinical investigations on the most appropriate use of leukapheresis in hyperleukocytosis. MATERIALS AND METHODS We performed a retrospective analysis of 14 patients with hyperleukocytic leukaemia who presented to our institution and underwent therapeutic leukapheresis. We compare their clinical and biological characteristics and investigate the impact of leukapheresis on early mortality and long-term prognosis. RESULTS The median presenting WBC count was 439 x 10(3)/mm(3). Although patients with acute myeloid leukaemia (AML) had the lowest median presenting WBC counts, they constituted the largest group of patients with symptomatic hyperleukocytosis. Leukapheresis was highly effective, with the mean absolute and percentage reduction in WBC after each cycle being 126 x 10(3)/mm(3) and 31.9% respectively. Four patients with AML died within 2 weeks of presentation despite prompt and effective leukapheresis. CONCLUSION The interaction between the leukaemic cells and the vascular environment, a mechanism that none of the current therapies directly address, is probably more important in causing leukostasis than the absolute cell count itself.
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Lopez MA, Mayer U, Hwang W, Taylor T, Hashmi MA, Jannapureddy SR, Boriek AM. Force transmission, compliance, and viscoelasticity are altered in the alpha7-integrin-null mouse diaphragm. Am J Physiol Cell Physiol 2005; 288:C282-9. [PMID: 15643051 DOI: 10.1152/ajpcell.00362.2003] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Alpha7beta1 integrin is a transmembrane structural and receptor protein of skeletal muscles, and the absence of alpha7-integrin causes muscular dystrophy. We hypothesized that the absence of alpha7-integrin alters compliance and viscoelasticity and disrupts the mechanical coupling between passive transverse and axial contractile elements in the diaphragm. In vivo the diaphragm is loaded with pressure, and therefore axial and transverse length-tension relationships are important in assessing its function. We determined diaphragm passive length-tension relationships and the viscoelastic properties of its muscle in 1-month-old alpha7-integrin-null mice and age-matched controls. Furthermore, we measured the isometric contractile properties of the diaphragm from mutant and normal mice in the absence and presence of passive force applied in the transverse direction to fibers in 1-month-old and 5-month-old mutant mice. We found that compared with controls, the diaphragm direction of alpha7-integrin-null mutants showed 1) a significant decrease in muscle extensibility in 1-year-old mice, whereas muscle extensibility increased in the 1-month-old mice; 2) altered muscle viscoelasticity in the transverse direction of the muscle fibers of 1-month-old mice; 3) a significant increase in force-generating capacity in the diaphragms of 1-month-old mice, whereas in 5-month-old mice muscle contractility was depressed; and 4) significant reductions in mechanical coupling between longitudinal and transverse properties of the muscle fibers of 1-month-old mice. These findings suggest that alpha7-integrin serves an important mechanical function in the diaphragm by contributing to passive compliance, viscoelasticity, and modulation of its muscle contractile properties.
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Wai E, Solin L, Fourquet A, Vincini F, Taylor M, Haffty B, Olivotto I, Strom E, Pierce L, Marks L, Bartelink H, Hwang W. Salvage treatment for local recurrence after breast-conserving surgery followed by radiation as initial treatment for mammographically-detected ductal carcinoma in situ of the breast. Int J Radiat Oncol Biol Phys 2004. [DOI: 10.1016/j.ijrobp.2004.06.033] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Sun L, Tan P, Yap C, Hwang W, Koh LP, Lim CK, Aw SE. In vitro biological characteristics of human cord blood-derived megakaryocytes. ANNALS OF THE ACADEMY OF MEDICINE, SINGAPORE 2004; 33:570-5. [PMID: 15531951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Abstract
INTRODUCTION Umbilical cord blood (CB) has been used as an alternative source for haematopoietic stem cell transplantation (HSCT) in recent years. However, delayed platelet recovery is frequently associated with CB HSCT. Megakaryocytes (Mk) are the specialised precursors of platelets and they are among the rarest haemopoietic cell types. Despite the rapid expansion of our knowledge of megakaryopoiesis in recent years, many questions, such as the molecular regulatory mechanisms in Mk differentiation and maturation, platelet formation and release, remain unanswered in CB-derived megakaryopoiesis. Variations can be seen from the literature by individual investigators using different approaches for Mk-specific differentiation and maturation induction. The development of in vitro culture methods to obtain sufficient numbers of Mks from readily available haematopoietic stem cells is of value for both basic research and clinical applications. MATERIALS AND METHODS The CD34+ cells from cord blood samples were cultured in serum-free medium with haematopoietic growth factors (GFs), such as IL-3, stem cell factor (SCF), and thrombopoietin (Tpo). The differentiation of Mk was monitored using Mk- and platelet-specific monoclonal antibodies and flow cytometric analysis. The morphology of the cultured cells was studied by both light and electronic microscopy (LM and EM). The involvement of the human Notch gene family members was studied by real time-polymerase chain reaction (RT-PCR). Maturation of the cultured Mks was studied using flow cytometric analysis for both platelet-specific surface markers and enodomitosis. Platelet activation was assessed in the cytoplasmic fragments harvested from the cultures. RESULTS Specific Mk differentiation of >70% resulted from a 2-step culture approach using IL-3, SCF and Tpo for 7 days followed by Tpo only for another 14 days. RT-PCR showed high-level expression of both Notch-1 and its ligand, Jagged-1, in the cultured Mks. Limited levels of polyploidy (>4N, endomitosis, EnM) were observed in the cultured Mks. The results also showed that the cytoplasmic fragments from the cultures responded to platelet activation reagents, including ADP and collagen, marked by upregulation of platelet-specific activation markers, such as CD62P (P-selectin) and PAC-1 (gpalphaIIbbeta3). CONCLUSION The methods used in this study are specific for differentiation of Mk from CB CD34+ cell, which can partially mature and produce functional platelets in vitro. This approach for human Mk differentiation could be further optimised and may be adapted on larger scales for clinical purposes.
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Tan D, Hwang W, Ng HJ, Goh YT, Tan P. Successful treatment of idiopathic hypereosinophilic syndrome with imatinib mesylate: a case report. Int J Hematol 2004; 80:75-7. [PMID: 15293573 DOI: 10.1532/ijh97.a20309] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Patients with idiopathic hypereosinophilic syndrome (HES) show persistent hypereosinophilia of unknown etiology that is associated with end-organ damage. Different treatments, including the use of corticosteroids and cytotoxics, have been investigated for HES with modest success. We describe a patient with HES who had significant end-organ damage from hypereosinophilia and remained refractory to conventional therapy. Therapy with imatinib mesylate, a selective tyrosine kinase inhibitor that is highly effective in treating patients with BCR-ABL-positive chronic myeloid leukemia, was tried with the patient. The result was impressive, with hematologic remission achieved after 12 days of administration. Our finding concurs with recent reports that imatinib mesylate may be a promising agent in the treatment of some cases of HES.
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Harris E, Hwang W, Santiago R, Solin L. Long-term outcomes for breast conservation therapy in invasive lobular carcinoma of the breast. Int J Radiat Oncol Biol Phys 2003. [DOI: 10.1016/s0360-3016(03)01262-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Hwang W, Krapivsky PL, Redner S. Fitness versus longevity in age-structured population dynamics. J Math Biol 2002; 44:375-93. [PMID: 11984646 DOI: 10.1007/s002850100128] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We examine the dynamics of an age-structured population model in which the life expectancy of an offspring may be mutated with respect to that of the parent. While the total population of the system always reaches a steady state, the fitness and age characteristics exhibit counter-intuitive behavior as a function of the mutational bias. By analytical and numerical study of the underlying rate equations, we show that if deleterious mutations are favored, the average fitness of the population reaches a steady state, while the average population age is a decreasing function of the average fitness. When advantageous mutations are favored, the average population fitness grows linearly with time t, while the average age is independent of the average fitness. For no mutational bias, the average fitness grows as t2/3.
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Hwang W, Weller W, Ireys H, Anderson G. Out-of-pocket medical spending for care of chronic conditions. Health Aff (Millwood) 2001; 20:267-78. [PMID: 11816667 DOI: 10.1377/hlthaff.20.6.267] [Citation(s) in RCA: 303] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We examined out-of-pocket medical spending by persons with and without chronic conditions using data from the 1996 Medical Expenditure Panel Survey (MEPS). Our results show that mean out-of-pocket spending increased with the number of chronic conditions. The level of this spending also varied by age and insurance coverage, among other characteristics. Out-of-pocket spending for prescription drugs was substantial for both elderly and nonelderly persons with chronic conditions. As policymakers continue to use cost sharing and design of benefit packages to contain health spending, it is important to consider the impact of these policies on persons with chronic conditions and their families.
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Hwang W, Redner S. Dissolution in a field. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2001; 64:041606. [PMID: 11690039 DOI: 10.1103/physreve.64.041606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2001] [Indexed: 05/23/2023]
Abstract
We study the dissolution of a solid by continuous injection of reactive "acid" particles at a single point, with the reactive particles undergoing biased diffusion in the dissolved region. When acid encounters the substrate material, both an acid particle and a unit of the material disappear. We find that the lengths of the dissolved cavity parallel and perpendicular to the bias grow as t(2/(d+1)) and t(1/(d+1)), respectively, in d dimensions, while the number of reactive particles within the cavity grows as t(2/(d+1)). We also obtain the exact density profile of the reactive particles and the relation between this profile and the motion of the dissolution boundary. The extension to variable acid strength is also discussed.
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Furth SL, Alexander DC, Neu AM, Hwang W, Powe NR, Fivush BA. Does growth retardation indicate suboptimal clinical care in children with chronic renal disease and those undergoing dialysis? Semin Nephrol 2001; 21:463-9. [PMID: 11559887 DOI: 10.1053/snep.2001.24941] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Growth failure is an important problem for children with end-stage renal disease (ESRD). Patients receiving replacement therapy for longstanding renal failure since childhood are likely to report dissatisfaction with certain aspects of their lives, especially with final adult height. Additionally, recent data suggest that growth failure in children with ESRD is associated with adverse clinical outcomes, including more frequent hospitalizations, and increased mortality. Although poor growth is unlikely to be the cause of this increased morbidity, growth failure may be a marker for a group of patients at high risk of adverse events. In this review, the authors describe the prevalence of growth retardation in children in the US with chronic renal disease, and present recent data on morbidity associated with growth failure. After reviewing published reports documenting available strategies to optimize growth, the authors conclude that despite vigilance and aggressive clinical management, a subset of children with long-term renal insufficiency and ESRD may still have poor linear growth. A discussion of "optimal care" leads one to consider evidence of current variability in the management of growth retardation in ESRD, and the strengths and limitations of developing practice guidelines to optimize growth in this population.
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Hwang W, Ireys HT, Anderson GF. Comparison of risk adjusters for medicaid-enrolled children with and without chronic health conditions. AMBULATORY PEDIATRICS : THE OFFICIAL JOURNAL OF THE AMBULATORY PEDIATRIC ASSOCIATION 2001; 1:217-24. [PMID: 11888404 DOI: 10.1367/1539-4409(2001)001<0217:corafm>2.0.co;2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE Several capitation payment systems have been developed and implemented recently by public and private insurers as well as by individual managed care organizations. Many pediatricians have expressed concern that methods for establishing capitation rates may not adequately account for the higher expected expenditures for children with chronic health conditions. In this study, we evaluate a demographic- and 4 diagnosis-based models, paying particular attention to their performance for children with chronic health conditions. METHODS We selected children 18 years of age and under who were enrolled in the Maryland Medicaid Program in 1995 and 1996. We defined the population of children with chronic health conditions using ICD-9 codes. Individual and group-level analyses were utilized to measure the ability of the different risk adjustment models to predict expenditures in 1996 based upon information available in 1995. RESULTS All 4 diagnosis-based models significantly outperformed the demographic model for children overall and for children with chronic health conditions. Differences between diagnosis-based models were small, especially as the size of test populations increased. CONCLUSIONS Risk adjustment methods that account directly for health status promise to reduce incentives to exclude children with chronic illnesses from managed care plans and to provide a foundation for more appropriate payments to pediatricians who care for these children.
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Furth SL, Hwang W, Yang C, Neu AM, Fivush BA, Powe NR. Relation between pediatric experience and treatment recommendations for children and adolescents with kidney failure. JAMA 2001; 285:1027-33. [PMID: 11209173 DOI: 10.1001/jama.285.8.1027] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
CONTEXT Children and adolescent patients with renal failure are frequently cared for by adult subspecialists. While peritoneal dialysis is used in less than 17% of adults with kidney failure, it is the preferred dialysis treatment for children. National data show that 45% of children receiving dialysis are treated with peritoneal dialysis and pediatric nephrologists report its use in 65% of patients receiving dialysis. Whether differences in peritoneal dialysis use among children are due to the pediatric experience of the clinician has not been examined. OBJECTIVE To assess whether the pediatric experience of nephrologists directly affects treatment recommendations for children with kidney failure. DESIGN Cross-sectional survey using 10 case vignettes per survey based on random combinations of 8 patient characteristics (age, sex, race, distance from facility, cause of renal failure, family structure, education, and compliance). SETTING AND PARTICIPANTS National random sample of office-, hospital-, and academic medical center-based adult and pediatric nephrologists, stratified by geographic region and conducted June to November 1999. Of 519 eligible physicians, 316 (61%) responded, including 191 adult and 125 pediatric nephrologists. MAIN OUTCOME MEASURE Treatment recommendations for peritoneal dialysis vs hemodialysis, compared based on nephrologists' pediatric experience. RESULTS After controlling for patient characteristics, pediatric nephrologists were 60% more likely than adult nephrologists to recommend peritoneal dialysis for identical patients (odds ratio, 1.61; 95% confidence interval, 1.35-1.92). This was true regardless of dialysis training, years in practice, practice setting, geography, or patient characteristics. CONCLUSIONS Our data indicate that pediatric specialization of clinicians influences treatment recommendations for children and adolescents with end-stage renal disease. Referring children to adult subspecialists may lead to differences in treatment choices and processes of care.
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Hwang W, Redner S. Infiltration through porous media. PHYSICAL REVIEW E 2001; 63:021508. [PMID: 11308499 DOI: 10.1103/physreve.63.021508] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2000] [Indexed: 11/07/2022]
Abstract
We study the kinetics of infiltration in which contaminant particles, which are suspended in a flowing carrier fluid, penetrate a porous medium. The progress of the "invader" particles is impeded by their trapping on active "defender" sites which are on the surfaces of the medium. As the defenders are used up, the invader penetrates further and ultimately breaks through. We study this process in the regime where the particles are much smaller than the pores so that the permeability change due to trapping is negligible. We develop a family of microscopic models of increasing realism to determine the propagation velocity of the invasion front, as well as the shapes of the invader and defender profiles. The predictions of our model agree qualitatively with experimental results on breakthrough times and the time dependence of the invader concentration at the output. Our results also provide practical guidelines for improving the design of deep bed filters in which infiltration is the primary separation mechanism.
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Thamer M, Hwang W, Fink NE, Sadler JH, Bass EB, Levey AS, Brookmeyer R, Powe NR. U.S. nephrologists' attitudes towards renal transplantation: results from a national survey. Transplantation 2001; 71:281-8. [PMID: 11213074 DOI: 10.1097/00007890-200101270-00020] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Renal transplantation is the optimal treatment for persons with end-stage renal disease (ESRD). A shortage of kidneys in the U.S. has focused increasing attention on the process by which kidneys are allocated. A national survey was undertaken to determine the relative importance of both clinical and nonclinical factors in the recommendation for renal transplantation by U.S. nephrologists. METHODS We conducted a national random survey of 271 U.S. nephrologists using hypothetical patient scenarios to determine their recommendation for renal transplantation based on demographic, clinical, and social factors. Specifically, eight unique patient scenarios were randomly distributed to each survey respondent. RESULTS According to responding nephrologists (response rate 53%), females were less likely than males to be recommended for renal transplantation [adjusted odds ratio (OR)=0.41; confidence interval (CI) 0.21, 0.79; for whites]. Asian males were less likely than white males to be recommended for transplantation (OR=0.46, CI 0.24, 0.91). Black-white differences in rates of recommendation were not found. Other factors associated with low rates of recommendation for renal transplantation included history of noncompliance (OR=0.17, CI 0.13, 0.23), <25% cardiac ejection fraction (OR=0.15, CI 0.10, 0.21), HIV infection (OR=0.01, CI 0.00, 0.01), and being >200 lbs (OR=0.73, CI 0.56, 0.95). CONCLUSIONS Female gender, and Asian but not black race, were associated with a decreased likelihood that nephrologists would recommend renal transplantation for patients with end stage renal disease. The well-documented black-white disparities in use of renal transplantation may be due to unaccounted for factors or may arise at a subsequent step in the transplantation process.
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Boriek AM, Capetanaki Y, Hwang W, Officer T, Badshah M, Rodarte J, Tidball JG. Desmin integrates the three-dimensional mechanical properties of muscles. Am J Physiol Cell Physiol 2001; 280:C46-52. [PMID: 11121375 DOI: 10.1152/ajpcell.2001.280.1.c46] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Striated muscle is a linear motor whose properties have been defined in terms of uniaxial structures. The question addressed here is what contribution is made to the properties of this motor by extramyofilament cytoskeletal structures that are not aligned in parallel with the myofilaments. This question arose from observations that transverse loads increase muscle force production in diaphragm but not in the hindlimb muscle, thereby indicating the presence of structures that couple longitudinal and transverse properties of diaphragmatic muscle. Furthermore, we find that the diaphragms of null mutants for the cytoskeletal protein desmin show 1) significant reductions in coupling between the longitudinal and transverse properties, indicating for the first time a role for a specific protein in integrating the three-dimensional mechanical properties of muscle, 2) significant reductions in the stiffness and viscoelasticity of muscle, and 3) significant increases in tetanic force production. Thus desmin serves a complex mechanical function in diaphragm muscle by contributing both to passive stiffness and viscoelasticity and to modulation of active force production in a three-dimensional structural network. Our finding changes the paradigm of force transmission among cells by placing our understanding of the function of the cytoskeleton in the context of the structural and mechanical complexity of muscles.
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Thamer M, Hwang W, Fink NE, Sadler JH, Wills S, Levin NW, Bass EB, Levey AS, Brookmeyer R, Powe NR. US nephrologists' recommendation of dialysis modality: results of a national survey. Am J Kidney Dis 2000; 36:1155-65. [PMID: 11096040 DOI: 10.1053/ajkd.2000.19829] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Selection of a dialysis modality for persons with end-stage renal disease (ESRD) has important lifestyle and occupational implications. The factors affecting modality choice remain unclear, resulting in a low rate of peritoneal dialysis (PD) in the United States compared with other countries. A national survey of 271 US nephrologists was conducted from June 1997 to June 1998 to assess the relative importance of nonclinical and clinical factors related to dialysis modality selection for patients with ESRD. Hypothetical patient scenarios were randomly assigned to nephrologists to determine their recommendation for dialytic therapy based on patient demographic, clinical, and social factors. US nephrologists were more likely to recommend PD for men with ESRD compared with women (39% versus 33%; P: < 0.05; adjusted odds ratio, 1.44; 95% confidence interval, 1.15 to 1.80), as well as for patients with good compliance (adjusted odds ratio, 11.80; 95% confidence interval, 9.29 to 15.01), weight less than 200 lb (adjusted odds ratio, 2.3; 95% confidence interval, 1.8 to 2.9), residual renal function (adjusted odds ratio, 2.14; 95% confidence interval, 1.71 to 2.70), absence of diabetes (adjusted odds ratio, 2.0; 95% confidence interval, 1.6 to 2.5), and living with family (adjusted odds ratio, 1.7; 95% confidence interval, 1.4 to 2.1). Nephrologists in practice for 11 or more years were less likely to recommend PD. The association of male sex with PD therapy suggests a potential bias or sensitivity to women's perception of body image. Race was not associated with PD recommendations after controlling for other demographic and clinical characteristics. Because the incident US ESRD population is increasingly characterized by factors associated with not selecting PD (diabetes, obesity, malnourishment, living alone, and substance abuse problems), our results suggest that PD use may decrease over time.
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Furth SL, Garg PP, Neu AM, Hwang W, Fivush BA, Powe NR. Racial differences in access to the kidney transplant waiting list for children and adolescents with end-stage renal disease. Pediatrics 2000; 106:756-61. [PMID: 11015519 DOI: 10.1542/peds.106.4.756] [Citation(s) in RCA: 114] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
CONTEXT Renal transplantation is the treatment of choice for pediatric patients with end-stage renal disease (ESRD). Black patients wait longer for kidney transplants than do white patients. OBJECTIVE To determine whether the increased time to transplantation for black pediatric patients is attributable not only to a shortage of suitable donor organs, but also to racial differences in the time from a child's first treatment for ESRD until activation on the cadaveric kidney transplant waitlist. DESIGN National longitudinal cohort study. SETTING US Medicare-eligible, pediatric ESRD population. PATIENTS Children and adolescents </=19 years old at the time of their first dialysis for ESRD between 1988 and 1993, followed through 1996. Patients who received living donor renal transplants were excluded from study. MAIN OUTCOME MEASURES Time from first dialysis for ESRD until activation on the kidney transplant waiting list, relative hazard of activation on the waiting list for black compared with white pediatric patients. RESULTS Comparisons of the time from first dialysis for ESRD to waitlisting among the 2162 white (60.7%) and 1122 black (31.5%) patients studied using survival analysis revealed that blacks were less likely to be waitlisted at any given time in follow-up. In multivariate analysis, even after controlling for patient age, gender, socioeconomic status, geographic region, incident year of renal failure, and cause of ESRD, blacks were 12% less likely to be waitlisted than were whites at any point in time (relative hazard:. 88: 95% confidence interval:.79-.97). CONCLUSIONS Racial disparities in access to the renal transplant waiting list exist in pediatrics. Whether these disparities are attributable to differences in time of presentation to a nephrologist, physician bias in identification of transplant candidates, or patient preferences warrants further study.
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