8 results on '"Leon LF"'
Search Results
2. The Bidirectional Relationship between Posttraumatic Stress Symptoms and Social Support in a 9/11-Exposed Cohort: A Longitudinal Cross-Lagged Analysis.
- Author
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Liu SY, Li J, Leon LF, Schwarzer R, and Cone JE
- Subjects
- Health Surveys, Humans, Longitudinal Studies, Social Support, Surveys and Questionnaires, September 11 Terrorist Attacks psychology, Stress Disorders, Post-Traumatic epidemiology, Stress Disorders, Post-Traumatic psychology
- Abstract
Research on the longitudinal relationship between posttraumatic stress disorder (PTSD) and social support among survivors of large-scale trauma is limited. This study assessed bidirectional relationships between PTSD and perceived social support in a large sample of the 9/11-exposed cohort over a 14-year follow-up. We used data from 23,165 World Trade Center Health Registry (WTCHR) enrollees who were exposed to the 9/11 attacks and participated in the first four WTCHR surveys (Wave 1 (2003−2004) to Wave 4 (2015−2016)). PTSD symptoms were measured using the 17-item PTSD Checklist. Perceived social support was measured using the five-item version of the Modified Social Support Survey. We used a cross-lagged panel analysis and found an inverse relationship between PTSD symptoms and social support. PTSD at Wave 2 (W2) predicted less social support at Wave 3 (W3) (β = −0.10, p < 0.01), and PTSD at W3 predicted less social support at W4 (β = −0.05, p < 0.01). Conversely, social support at W3 buffered PTSD symptoms at W4 (β = −0.03, p < 0.05). Sub-analyses by types of perceived social support suggest greater effects of PTSD on emotional support than tangible support and in community members than rescue/recovery workers. Our findings suggest a bidirectional effect between PTSD symptoms and social support in a longitudinal study of 9/11-exposed populations.
- Published
- 2022
- Full Text
- View/download PDF
3. Rejoinder to Letter to the Editor "The Hazards of Period Specific and Weighted Hazard Ratios".
- Author
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Lin RS, Lin J, Roychoudhury S, Anderson KM, Hu T, Huang B, Leon LF, Liao JJZ, Liu R, Luo X, Mukhopadhyay P, Qin R, Tatsuoka K, Wang X, Wang Y, Zhu J, Chen TT, and Iacona R
- Published
- 2020
- Full Text
- View/download PDF
4. Post-Traumatic Stress Disorder among Survivors of the September 11, 2001 World Trade Center Attacks: A Review of the Literature.
- Author
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Hamwey MK, Gargano LM, Friedman LG, Leon LF, Petrsoric LJ, and Brackbill RM
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- Chronic Disease psychology, Comorbidity, Humans, New York City epidemiology, Prevalence, Quality of Life, Retrospective Studies, Risk Factors, Chronic Disease epidemiology, September 11 Terrorist Attacks psychology, September 11 Terrorist Attacks statistics & numerical data, Stress Disorders, Post-Traumatic epidemiology, Stress Disorders, Post-Traumatic psychology, Survivors psychology, Survivors statistics & numerical data
- Abstract
Prior reviews of 9/11-related post-traumatic stress disorder (PTSD) have not focused on the civilian survivors most directly exposed to the attacks. Survivors include those individuals who were occupants of buildings in or near the World Trade Center (WTC) towers, those whose primary residence or workplace was in the vicinity, and persons who were on the street passing through the area. This review reports published information on the prevalence of and risk factors for PTSD, as well as comorbidities associated with PTSD among 9/11 survivors. Articles selected for inclusion met the following criteria: (1) full-length, original peer-reviewed empirical articles; (2) published in English from 2002-2019; (3) collected data from persons directly exposed; (4) adult populations; and (5) focused on non-rescue or recovery workers (i.e., survivors). Data were extracted with focus on study design, sample size, time frame of data collection post-9/11, PTSD assessment instrument, and PTSD prevalence, risk factors, and comorbidities. Our review identified the use of cross-sectional and longitudinal designs, finding multiple direct comorbidities with PTSD, as well as the prevalence and persistence of PTSD. Future research would benefit from incorporating more mixed methods designs, and exploring the mediating mechanisms and protective factors of the known associations of PTSD among the 9/11 survivor population.
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- 2020
- Full Text
- View/download PDF
5. Land use change impacts on water quality in three lake winnipeg watersheds.
- Author
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Yang Q, Leon LF, Booty WG, Wong IW, McCrimmon C, Fong P, Michiels P, Vanrobaeys J, and Benoy G
- Abstract
Lake Winnipeg eutrophication results from excess nutrient loading due to agricultural activities across the watershed. Estimating nonpoint-source pollution and the mitigation effects of beneficial management practices (BMPs) is an important step in protecting the water quality of streams and receiving waters. The use of computer models to systematically compare different landscapes and agricultural systems across the Red-Assiniboine basin has not been attempted at watersheds of this size in Manitoba. In this study, the Soil and Water Assessment Tool was applied and calibrated for three pilot watersheds of the Lake Winnipeg basin. Monthly flow calibration yielded overall satisfactory Nash-Sutcliffe efficiency (NSE), with values above 0.7 for all simulations. Total phosphorus (TP) calibration NSE ranged from 0.64 to 0.76, total N (TN) ranged from 0.22 to 0.75, and total suspended solids (TSS) ranged from 0.29 to 0.68. Based on the assessment of the TP exceedance levels from 1993 to 2007, annual loads were above proposed objectives for the three watersheds more than half of the time. Four BMP scenarios based on land use changes were studied in the watersheds: annual cropland to hay land (ACHL), wetland restoration (WR), marginal annual cropland conversion to hay land (MACHL), and wetland restoration on marginal cropland (WRMAC). Of these land use change scenarios, ACHL had the greatest impact: TSS loads were reduced by 33 to 65%, TN by 58 to 82%, and TP by 38 to 72% over the simulation period. By analyzing unit area and percentage of load reduction, the results indicate that the WR and WRMAC scenarios had a significant impact on water quality in high loading zones in the three watersheds. Such reductions of sediment, N, and P are possible through land use change scenarios, suggesting that land conservation should be a key component of any Lake Winnipeg restoration strategy., (Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.)
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- 2014
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6. If the ratio of hazards r(t)=λe(t)/λc(t) does not depend on time t then the proportional hazards assumption holds.
- Author
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Leon LF, Day BM, and Hu XS
- Subjects
- Humans, Biostatistics, Clinical Competence, Proportional Hazards Models
- Published
- 2013
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- View/download PDF
7. Identification of prognostic factors in advanced epithelial ovarian carcinoma.
- Author
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Chi DS, Liao JB, Leon LF, Venkatraman ES, Hensley ML, Bhaskaran D, and Hoskins WJ
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- Adult, Age Factors, Aged, Aged, 80 and over, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Carboplatin administration & dosage, Cisplatin administration & dosage, Cyclophosphamide administration & dosage, Epithelial Cells pathology, Female, Humans, Middle Aged, Neoplasm Staging, Ovarian Neoplasms mortality, Ovarian Neoplasms therapy, Paclitaxel administration & dosage, Prognosis, Retrospective Studies, Survival Rate, Treatment Outcome, Ovarian Neoplasms pathology
- Abstract
Objective: The Gynecologic Oncology Group (GOG) has demonstrated that age, tumor grade, and size and number of residual lesions after primary cytoreductive surgery are significant prognostic factors in advanced ovarian carcinoma. Recent studies have reported numerous other clinical features as having prognostic value. We sought to identify the independent prognostic factors for survival in a cohort of patients with advanced ovarian cancer., Methods: We performed a retrospective chart review of all patients with stage III and IV ovarian carcinoma who received their primary treatment at our institution between 1987 and 1994., Results: A total of 295 patients were identified, 282 of whom were evaluable. Of these 282 patients, 214 (76%) have died of disease or other causes. The median follow-up is 32 months (range: 1-139). Eighteen factors were evaluated for prognostic significance. Significant factors in univariate analysis included patient age, gravidity (0 vs > 0), parity (0 vs > 0), preoperative albumin level, preoperative total protein level, ascites (presence vs absence), disease stage (IIIA/IIIB vs IIIC vs IV), number of residual lesions (< or =20 vs >20), and diameter of largest residual tumor nodule (< or = 1 cm vs 1-2 cm vs > 2 cm). However, on multivariate analysis, only patient age (P < 0.001), ascites (P = 0.001), and size of residual disease (P = 0.005) retained prognostic significance. Substage of disease was of borderline significance (P = 0.086)., Conclusion: Although numerous clinical variables have recently been reported to have prognostic value in advanced ovarian carcinoma, only patient age, presence or absence of ascites, and diameter of the largest residual tumor nodule proved to be of statistical significance in our analysis., (Copyright 2001 Academic Press.)
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- 2001
- Full Text
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8. Identification of risk factors for requiring transfusion during front-line chemotherapy for ovarian cancer.
- Author
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Hensley ML, Lebeau D, Leon LF, Venkatraman E, Waltzman R, Sabbatini P, Almadrones L, Chi D, and Spriggs D
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- Adult, Aged, Aged, 80 and over, Anemia chemically induced, Antineoplastic Combined Chemotherapy Protocols therapeutic use, Carboplatin administration & dosage, Carboplatin adverse effects, Cisplatin administration & dosage, Cisplatin adverse effects, Cohort Studies, Combined Modality Therapy, Female, Hemoglobins metabolism, Humans, Logistic Models, Middle Aged, Ovarian Neoplasms surgery, Paclitaxel administration & dosage, Paclitaxel adverse effects, Predictive Value of Tests, Retrospective Studies, Risk Factors, Anemia etiology, Anemia therapy, Antineoplastic Combined Chemotherapy Protocols adverse effects, Erythrocyte Transfusion, Ovarian Neoplasms blood, Ovarian Neoplasms drug therapy
- Abstract
Objective: Anemia requiring red blood cell (RBC) transfusion is common in ovarian cancer (OC) patients receiving post-debulking surgery chemotherapy. Erythropoietin use has been shown to decrease transfusion requirements in patients receiving chemotherapy. We sought to identify pretreatment risk factors that could identify patients at increased risk for requiring RBC transfusion during first-line treatment for ovarian cancer., Methods: One hundred seventy-five consecutive patients who received chemotherapy with either carboplatin-paclitaxel or cisplatin-paclitaxel following debulking surgery for epithelial OC from 1993 to 1996 were identified. No patient received erythropoietin. Patient characteristics recorded included: age, stage, prechemotherapy hemoglobin, nadir hemoglobin, number of cycles and doses of chemotherapy received. The outcome was requiring RBC transfusion. Independent predictors of requiring RBC transfusion were identified using multivariate analyses., Results: Median age of the cohort was 62 years (range, 28-86). Seventy-one and four-tenths percent had FIGO stage III/IV disease. Median prechemotherapy hemoglobin was 11 g/dL (range, 7.1-15.4); median nadir hemoglobin was 9.3 g/dL (range, 6.6-11.1). One hundred nineteen (66%) patients received cisplatin-paclitaxel, and 61 (34%) received carboplatin-paclitaxel. Of 175 patients, 31 (18%, 95% CI = 12-23%) required RBC transfusion. Independent risk factors for RBC transfusion were prechemotherapy hemoglobin <10 g/dL (P < 0.01, odds ratio = 3.78, 95% CI = 1.52-9.44) and carboplatin-paclitaxel versus cisplatin-paclitaxel treatment (P = 0.01, odds ratio = 3.14, 95% CI = 1.27-7.76). Of 175 patients, 40 (22.8%) had a prechemotherapy hemoglobin <10 g/dL. Fifty percent of patients with prechemotherapy hemoglobin <10 g/dL who received carboplatin-paclitaxel required RBC transfusion, compared with 7.7% of patients with hemoglobin >10 g/dL who received cisplatin-paclitaxel., Conclusion: Ovarian cancer patients frequently require RBC transfusion during postdebulking platinum-paclitaxel chemotherapy. Patients with prechemotherapy hemoglobin <10 g/dL and those receiving carboplatin-paclitaxel are at increased risk of requiring RBC transfusion. Early initiation of erythropoietin use in such patients may reduce transfusion needs., (Copyright 2001 Academic Press.)
- Published
- 2001
- Full Text
- View/download PDF
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