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Hazards Models (hazard + models)
Kinds of Hazards Models Selected AbstractsConstructivist Implications of Material Power: Military Engagement and the Socialization of States, 1972,2000INTERNATIONAL STUDIES QUARTERLY, Issue 3 2006CAROL ATKINSON The research presented in this article examines one aspect of state socialization, the extent to which transnational military-to-military interactions have served as an effective mechanism of the democratic political socialization of states. Military organizations are very interesting when we consider avenues by which state socialization might occur because military organizations are an influential part of governments, and members share common beliefs and values as soldiers and officers that transcend borders. Thus, it would seem that a state's military structure is one likely channel whereby politically relevant individuals might learn new ideas and have the capability to reform existing institutional structures. The socialization process described in this study is three level: (1) individuals acquire new ideas; (2) coercion, incentives, and persuasion aid in institutionalizing these ideas in the underlying political structure of the state; and (3) once institutionalized, these new ideas/identity of the state influence the material and ideational structure of international society. Using Cox Proportional Hazard models and an original data set encompassing over 160 states during the years 1972,2000, the analyses find U.S. military-to-military contacts to be positively and systematically associated with liberalizing trends. This finding provides evidence that constructivist mechanisms do have observable effects, and that ideationally based processes play an important role in U.S. national security. [source] Genetic polymorphisms in the metabolic pathway and non-Hodgkin lymphoma survival,AMERICAN JOURNAL OF HEMATOLOGY, Issue 1 2010Xuesong Han Metabolic pathway enzymes, such as Cytochrome P450 (CYP), glutathione S-transferase (GST), and N -acetyltransferases (NAT) are involved in activation and detoxification of environmental carcinogens as well as drug metabolism. We hypothesized that the genetic variations in such metabolic pathways may affect NHL prognosis and survival. Follow-up information of 496 female NHL incident cases diagnosed during 1996,2000 in Connecticut were abstracted from the Connecticut Tumor Registry in 2008; survival analyses were conducted by comparing the Kaplan-Meier curves, and hazard ratios (HR) were computed from the Cox Proportional Hazard models adjusting for demographic and tumor characteristics which were suggested by previous studies to be determinants of NHL survival. We identified six SNPs from four metabolism genes (CYP2E1, GSTP1, GSTT1, and NAT1) that were associated with NHL survival. Specifically, polymorphisms in GSTT1 were associated with follicular lymphoma survival; and polymorphisms in CYP2E1, GSTP1, and NAT1 were associated with survival of chronic lymphocytic leukemia/small lymphocytic lymphoma. Our study suggests that genetic polymorphisms in metabolic pathways may help improve the prediction of NHL survival and prognosis. Am. J. Hematol., 2010. © 2009 Wiley-Liss, Inc. [source] Fitting Semiparametric Additive Hazards Models using Standard Statistical SoftwareBIOMETRICAL JOURNAL, Issue 5 2007Douglas E. Schaubel Abstract The Cox proportional hazards model has become the standard in biomedical studies, particularly for settings in which the estimation covariate effects (as opposed to prediction) is the primary objective. In spite of the obvious flexibility of this approach and its wide applicability, the model is not usually chosen for its fit to the data, but by convention and for reasons of convenience. It is quite possible that the covariates add to, rather than multiply the baseline hazard, making an additive hazards model a more suitable choice. Typically, proportionality is assumed, with the potential for additive covariate effects not evaluated or even seriously considered. Contributing to this phenomenon is the fact that many popular software packages (e.g., SAS, S-PLUS/R) have standard procedures to fit the Cox model (e.g., proc phreg, coxph), but as of yet no analogous procedures to fit its additive analog, the Lin and Ying (1994) semiparametric additive hazards model. In this article, we establish the connections between the Lin and Ying (1994) model and both Cox and least squares regression. We demonstrate how SAS's phreg and reg procedures may be used to fit the additive hazards model, after some straightforward data manipulations. We then apply the additive hazards model to examine the relationship between Model for End-stage Liver Disease (MELD) score and mortality among patients wait-listed for liver transplantation. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Smoothing Spline-Based Score Tests for Proportional Hazards ModelsBIOMETRICS, Issue 3 2006Jiang Lin Summary We propose "score-type" tests for the proportional hazards assumption and for covariate effects in the Cox model using the natural smoothing spline representation of the corresponding nonparametric functions of time or covariate. The tests are based on the penalized partial likelihood and are derived by viewing the inverse of the smoothing parameter as a variance component and testing an equivalent null hypothesis that the variance component is zero. We show that the tests have a size close to the nominal level and good power against general alternatives, and we apply them to data from a cancer clinical trial. [source] Flexible Maximum Likelihood Methods for Bivariate Proportional Hazards ModelsBIOMETRICS, Issue 4 2003Wenqing He Summary. This article presents methodology for multivariate proportional hazards (PH) regression models. The methods employ flexible piecewise constant or spline specifications for baseline hazard functions in either marginal or conditional PH models, along with assumptions about the association among lifetimes. Because the models are parametric, ordinary maximum likelihood can be applied; it is able to deal easily with such data features as interval censoring or sequentially observed lifetimes, unlike existing semiparametric methods. A bivariate Clayton model (1978, Biometrika65, 141,151) is used to illustrate the approach taken. Because a parametric assumption about association is made, efficiency and robustness comparisons are made between estimation based on the bivariate Clayton model and "working independence" methods that specify only marginal distributions for each lifetime variable. [source] Racial Differences in the Receipt of Bowel Surveillance Following Potentially Curative Colorectal Cancer SurgeryHEALTH SERVICES RESEARCH, Issue 6p2 2003Gary L. Ellison Objective. To investigate racial differences in posttreatment bowel surveillance after colorectal cancer surgery in a large population of Medicare patients. Data Sources. We used a large population-based dataset: Surveillance, Epidemiology, and End Results (SEER) linked to Medicare data. Study Design. This is a retrospective cohort study. We analyzed data from 44,768 non-Hispanic white, 2,921 black, and 4,416 patients from other racial/ethnic groups, aged 65 and older at diagnosis, who had a diagnosis of local or regional colorectal cancer between 1986 and 1996, and were followed through December 31, 1998. Cox Proportional Hazards models were used to investigate the relation of race and receipt of posttreatment bowel surveillance. Data Collection. Sociodemographic, hospital, and clinical characteristics were collected at the time of diagnosis for all members of the cohort. Surgery and bowel surveillance with colonoscopy, sigmoidoscopy, and barium enema were obtained from Medicare claims using ICD-9-CM and CPT-4 codes. Principal Findings. The chance of surveillance within 18 months of surgery was 57 percent, 48 percent, and 45 percent for non-Hispanic whites, blacks, and others, respectively. After adjusting for sociodemographic, hospital, and clinical characteristics, blacks were 25 percent less likely than whites to receive surveillance if diagnosed between 1991 and 1996 (RR=0.75, 95 percent CI=0.70,0.81). Conclusions. Elderly blacks were less likely than non-Hispanic whites to receive posttreatment bowel surveillance and this result was not explained by measured racial differences in sociodemographic, hospital, and clinical characteristics. More research is needed to explore the influences of patient- and provider-level factors on racial differences in posttreatment bowel surveillance. [source] Prognostic factors of radiotherapy in patients with node-positive thoracic esophageal squamous cell carcinoma after radical surgeryDISEASES OF THE ESOPHAGUS, Issue 6 2009Jin-Cheng Lu SUMMARY The aim of this study was to retrospectively analyze and assess the outcomes and prognostic factors of radiotherapy in patients with node-positive thoracic esophageal squamous cell carcinoma after radical surgery. One hundred twenty-six patients with node-positive thoracic esophageal squamous cell carcinoma who had undergone adjuvant therapy (postoperative radiotherapy alone or postoperative sequential chemoradiotherapy without receiving postoperative concurrent chemoradiotherapy) after radical surgery, were retrospectively reviewed from January 1996 to December 2003. Univariate and multivariate analyses were performed using log-rank and Cox proportional hazard models, and survival curves were estimated using the Kaplan-Meier method. The 1-, 3- and 5-year overall survival rates of all 126 patients were 71.4, 39.1, and 22.0%, and disease-free survival rates were 64.3, 36.4, and 21.5%, respectively. Lymph node ratio (the ratio of the number of metastatic lymph nodes to the number of lymph nodes removed, LNR) ,0.2 (P= 0.006), pT3 + pT4 (P= 0.06) and sequential chemoradiotherapy (P= 0.08) were associated with a poorer survival by univariate analysis. In multivariate analysis, LNR (P= 0.01, hazard ratio = 0.57, 95% confidence interval, 0.37,0.87) and tumor depth of invasion (P= 0.03, hazard ratio = 0.62, 95% confidence interval, 0.41,0.96) were the independent predictors of survival. Sequential chemoradiotherapy receded survival tendency without significant difference (P= 0.09, hazard ratio = 0.64, 95% confidence interval, 0.37,1.08). Therefore, LNR and tumor depth of invasion were the independent prognostic factors of radiotherapy in patients with node-positive thoracic esophageal squamous cell carcinoma after radical surgery. The addition of chemotherapy does not seem to confer a survival benefit. [source] Two new potent and convenient predictors of mortality in older nursing home residents in JapanGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 2 2004Orie Tajima Background: Malnourishment is closely connected with poor health outcomes in frail elderly. However, the relative importance of specific nutritional predictors of mortality remains unclear in the Japanese population. We investigated the potent nutritional factors associated with mortality from nutritional assessments of three parameters in Japanese frail elderly. Methods: Ninety residents in a nursing home in Japan, aged 65 and over (18 men, 72 women; mean age 82.2 ± 8.0 years) were enrolled in a 38-month follow-up study. The eligibility condition for analysis was having lived at the nursing home for more than 30 days, so three participants were excluded. Three nutritional parameters, which included: anthropometric measurements (body mass index, mid-arm circumference, triceps skinfold thickness and calf circumference); serum markers (albumin, total protein, prealbumin, retinol binding protein and total cholesterol); and food intake, were assessed. After categorizing each putative factor according to tertile distribution, risk of mortality was analyzed using Cox proportional hazard models. Results: At the end of the 38-month follow-up period, 29 participants had died. After adjustment for gender, age, clinical status, and functional status, three indicators (i.e. mid-arm circumference, triceps skinfold thickness and lipid intake) showed a significant relationship with mortality. When all of the putative factors were included in a stepwise procedure, mid-arm circumference and lipid intake were significantly associated with adjusted mortality. Conclusion: Among institutionalized Japanese frail elderly, lower levels of mid-arm circumference and lipid intake could potently predict an increased risk of mortality. These two indicators may be useful for many kinds of assessments and intervention for the improvement of health conditions in Japanese frail elderly. [source] Healthy, wealthy and insured?HEALTH ECONOMICS, Issue 3 2008The role of self-assessed health in the demand for private health insurance Abstract Both adverse selection and moral hazard models predict a positive relationship between risk and insurance; yet the most common finding in empirical studies of insurance is that of a negative correlation. In this paper, we investigate the relationship between ex ante risk and private health insurance using Australian data. The institutional features of the Australian system make the effects of asymmetric information more readily identifiable than in most other countries. We find a strong positive association between self-assessed health and private health cover. By applying the Lokshin and Ravallion (J. Econ. Behav. Organ 2005; 56:141,172) technique we identify the factors responsible for this result and recover the conventional negative relationship predicted by adverse selection when using more objective indicators of health. Our results also provide support for the hypothesis that self-assessed health captures individual traits not necessarily related to risk of health expenditures, in particular, attitudes towards risk. Specifically, we find that those persons who engage in risk-taking behaviours are simultaneously less likely to be in good health and less likely to buy insurance. Copyright © 2007 John Wiley & Sons, Ltd. [source] Consolidations and closures: an empirical analysis of exits from the hospital industryHEALTH ECONOMICS, Issue 5 2007Teresa D. Harrison Abstract This paper investigates the pre-exit characteristics of hospital mergers, acquisitions, and closures. We estimate competing risk hazard models using an 18-year national data set that spans the wave of closures in the 1980s and of mergers in the 1990s. Evidence shows that weak productivity of the hospital is a strong determinant for closures while competitive pressures are more influential in the decision to consolidate. Thus, increased market power, relative to cost reductions, appears to play a larger role in the merger decision. Our results also provide insight into possible correlations between mergers and closures. Copyright © 2006 John Wiley & Sons, Ltd. [source] Expression of microRNA-221 is progressively reduced in aggressive prostate cancer and metastasis and predicts clinical recurrenceINTERNATIONAL JOURNAL OF CANCER, Issue 2 2010Martin Spahn Abstract Emerging evidence shows that microRNAs (miR) are involved in the pathogenesis of a variety of cancers, including prostate carcinoma (PCa). Little information is available regarding miR expression levels in lymph node metastasis of prostate cancer or the potential of miRs as prognostic markers in this disease. Therefore, we analyzed the global expression of miRs in benign, hyperplastic prostate tissue (BPH), primary PCa of a high risk group of PCa patients, and corresponding metastatic tissues by microarray analysis. Consistent with the proposal that some miRs are oncomirs, we found aberrant expression of several miRs, including the downregulation of miR-221, in PCa metastasis. Downregulation of miR-221 was negatively correlated with the expression of the proto-oncogen c-kit in primary carcinoma. In a large study cohort, the prostate-specific oncomir miR-221 was progressively downregulated in aggressive forms of PCa. Downregulation of miR-221 was associated with clinicopathological parameters, including the Gleason score and the clinical recurrence during follow up. Kaplan,Meier estimates and Cox proportional hazard models showed that miR-221 downregulation was linked to tumor progression and recurrence in a high risk prostate cancer cohort. Our results showed that progressive miR-221 downregulation hallmarks metastasis and presents a novel prognostic marker in high risk PCa. This suggests that miR-221 has potential as a diagnostic marker and therapeutic target in PCa. [source] p73 G4C14-to-A4T14 polymorphism and risk of second primary malignancy after index squamous cell carcinoma of head and neckINTERNATIONAL JOURNAL OF CANCER, Issue 11 2009Fanglin Li Abstract P73 plays an important role in modulating cell-cycle control, inducing apoptosis, and inhibiting cell growth. A novel noncoding p73 G4C14-to-A4T14 exon 2 polymorphism was associated with risk of squamous cell carcinoma of the head and neck (SCCHN). We hypothesized that p73 G4C14-to-A4T14 polymorphism modulates risk of second primary malignancies (SPM) in patients after index SCCHN. We followed a cohort of 1,384 patients diagnosed with incident SCCHN between May 1995 and January 2007 for SPM development. Log-rank test and Cox proportional hazard models were used to compare SPM-free survival and SPM risk between the different genotype groups. Our results showed that patients carrying the p73 variant AT allele were less likely to develop SPM compared with the patients with p73 GC/GC genotype (Log-rank test, p = 0.013). Compared with the p73 GC/GC genotype, there was a significantly reduced risk of SPM associated with the p73 GC/AT genotype (HR, 0.61, 95% CI, 0.40,0.93) and the combined p73 GC/AT+AT/AT genotypes (HR, 0.59, 95% CI, 0.39,0.89), but a nonsignificantly reduced risk for p73 AT/AT genotype (HR, 0.44, 95% CI, 0.14,1.41). The p73 AT allele was significantly associated with risk of SPM in an allele dose-response manner (p = 0.011 for trend). The risk of SPM associated with p73 variant genotypes (GC/AT+AT/AT) was more pronounced in several subgroups (e.g., older patients, men, minorities, ever smokers, and ever drinkers). Our results support that this p73 polymorphism may be a marker for risk of SPM among patients with an incident SCCHN. © 2009 UICC [source] Putative functional polymorphisms of MMP9 predict survival of NSCLC in a Chinese populationINTERNATIONAL JOURNAL OF CANCER, Issue 9 2009Guangfu Jin Abstract Matrix metalloproteinases (MMPs) play a crucial role in cancer progression and their over-expression is often associated with unfavorable survival of non-small cell lung cancer (NSCLC). Because genetic variants can alter expression level or biological activity of MMPs, we hypothesized that potentially functional single nucleotide polymorphisms (SNPs) in key MMP genes may be associated with the survival of NSCLC patients. We selected and genotyped 14 putative functional SNPs in six MMP genes (MMP1, MMP2, MMP3, MMP7, MMP9 and MMP12) using PCR-RFLP methods in 561 NSCLC patients. Kaplan-Meier method with the log-rank test and Cox proportional hazard models were used for the survival analyses. The C-1562T, Arg279Gln and Arg668Gln polymorphisms in MMP9 were significantly associated with survival of patients with NSCLC (log-rank p values = 0.032, 0.038 and 0.036, respectively). The C-1562T and Arg668Gln loci were in complete linkage disequilibrium (r2 = 1). Patients carrying the 668Gln allele had improved survival with a median survival time (MST) of 51.6 months, compared with 21.8 months for those with the 668Arg/Arg genotype (log-rank p = 0.010). In contrast, the 279Gln/Gln genotype was associated with a significantly shortened MST (17.3 months, log-rank p = 0.030) in the recessive model. In the final multivariate Cox regression model, 279Gln/Gln was identified as an independent prognostic factor with an adjusted hazard ratio of 1.60 (95% confidence interval 1.07,2.41). The MMP9 Arg279Gln and Arg668Gln SNPs are potential predictors of survival in NSCLC patients. © 2008 Wiley-Liss, Inc. [source] Fruit and vegetable consumption and pancreatic cancer risk in the European Prospective Investigation into Cancer and NutritionINTERNATIONAL JOURNAL OF CANCER, Issue 8 2009Alina Vrieling Abstract Many case-control studies have suggested that higher consumption of fruit and vegetables is associated with a lower risk of pancreatic cancer, whereas cohort studies do not support such an association. We examined the associations of the consumption of fruits and vegetables and their main subgroups with pancreatic cancer risk within the European Prospective Investigation into Cancer and Nutrition (EPIC). EPIC is comprised of over 520,000 subjects recruited from 10 European countries. The present study included 555 exocrine pancreatic cancer cases after an average follow-up of 8.9 years. Estimates of risk were obtained by Cox proportional hazard models, stratified by age at recruitment, gender, and study center, and adjusted for total energy intake, weight, height, history of diabetes mellitus, and smoking status. Total consumption of fruit and vegetables, combined or separately, as well as subgroups of vegetables and fruits were unrelated to risk of pancreatic cancer. Hazard ratios (95% CI) for the highest versus the lowest quartile were 0.92 (0.68,1.25) for total fruit and vegetables combined, 0.99 (0.73,1.33) for total vegetables, and 1.02 (0.77,1.36) for total fruits. Stratification by gender or smoking status, restriction to microscopically verified cases, and exclusion of the first 2 years of follow-up did not materially change the results. These results from a large European prospective cohort suggest that higher consumption of fruit and vegetables is not associated with decreased risk of pancreatic cancer. © 2008 Wiley-Liss, Inc. [source] Fruit and vegetable consumption and lung cancer risk: Updated information from the European Prospective Investigation into Cancer and Nutrition (EPIC)INTERNATIONAL JOURNAL OF CANCER, Issue 5 2007Jakob Linseisen Abstract The association of fruit and vegetable consumption and lung cancer incidence was evaluated using the most recent data from the European Prospective Investigation into Cancer and Nutrition (EPIC), applying a refined statistical approach (calibration) to account for measurement error potentially introduced by using food frequency questionnaire data. Between 1992 and 2000, detailed information on diet and life-style of 478,590 individuals participating in EPIC was collected. During a median follow-up of 6.4 years, 1,126 lung cancer cases were observed. Multivariate Cox proportional hazard models were applied for statistical evaluation. In the whole study population, fruit consumption was significantly inversely associated with lung cancer risk while no association was found for vegetable consumption. In current smokers, however, lung cancer risk significantly decreased with higher vegetable consumption; this association became more pronounced after calibration, the hazard ratio (HR) being 0.78 (95% CI 0.62,0.98) per 100 g increase in daily vegetable consumption. In comparison, the HR per 100 g fruit was 0.92 (0.85,0.99) in the entire cohort and 0.90 (0.81,0.99) in smokers. Exclusion of cases diagnosed during the first 2 years of follow-up strengthened these associations, the HR being 0.71 (0.55,0.94) for vegetables (smokers) and 0.86 (0.78,0.95) for fruit (entire cohort). Cancer incidence decreased with higher consumption of apples and pears (entire cohort) as well as root vegetables (smokers). In addition to an overall inverse association with fruit intake, the results of this evaluation add evidence for a significant inverse association of vegetable consumption and lung cancer incidence in smokers. © 2007 Wiley-Liss, Inc. [source] Prospective study of body mass index, height, physical activity and incidence of bladder cancer in US men and womenINTERNATIONAL JOURNAL OF CANCER, Issue 1 2007Crystal N. Holick Abstract We evaluated prospectively the association between body mass index (BMI), height, recreational physical activity and the risk of bladder cancer among US adults. Data were used from 2 ongoing cohorts, the Health Professionals Follow-up Study and the Nurses' Health Study, with 3,542,012 years of follow-up and 866 incident bladder cancer cases (men = 507; women = 359) for the anthropometric analysis and 1,890,476 years of follow-up and 706 incident bladder cancer cases (men = 502; women = 204) for the physical activity analysis. Cox proportional hazard models were used to estimate incidence rate ratios (RR) and 95% confidence intervals (CI) between BMI, height, physical activity and bladder cancer risk adjusting for age, pack-years of cigarette smoking and current smoking. Estimates from each cohort were pooled using a random-effects model. We observed no association between baseline BMI and bladder cancer risk, even when we compared a BMI of ,30 kg/m2 to a BMI of 18,22.9 kg/m2 [pooled multivariate (MV) RR, 1.16; 95% CI: 0.89,1.52]. A weak, but statistically significant, association was observed for the same comparison after excluding bladder cancer cases diagnosed within the first 4 years of follow-up (pooled MV RR, 1.33; 95% CI: 1.01,1.76). Height was not related to bladder cancer risk (pooled MV RR, 0.82; 95% CI: 0.65,1.03, top vs. bottom quintile). Total recreational physical activity also was not associated with the risk of bladder cancer (pooled MV RR, 0.97; 95% CI: 0.77,1.24, top vs. bottom quintile). Our findings do not support a role for BMI, height or physical activity in bladder carcinogenesis. © 2006 Wiley-Liss, Inc. [source] Holocaust Survivors in Old Age: The Jerusalem Longitudinal StudyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 3 2008Jochanan Stesssman MD OBJECTIVES: To examine the hypothesis that Holocaust exposure during young adulthood negatively affects physical aging, causing greater morbidity, faster deterioration in health parameters, and shorter survival. DESIGN: A longitudinal cohort study of the natural history of an age-homogenous representative sample born in 1920/21 and living in Jerusalem. SETTING: Community-based home assessments. PARTICIPANTS: Four hundred fifty-eight subjects of European origin aged 70 at baseline and 77 at follow-up. MEASUREMENTS: Comprehensive assessment of physical, functional, and psychosocial domains; biographical history of concentration camp internment (Camp), exposure to Nazi occupation during World War II (Exposure), or lack thereof (Controls); and 7-year mortality data from the National Death Registry. RESULTS: Holocaust survivors of the Camp (n=93) and Exposure (n=129) groups were more likely than Controls (n=236) to be male and less educated and have less social support (P=.01), less physical activity (P=.03), greater difficulty in basic activities of daily living (P=.009), poorer self-rated health (P=.04), and greater usage of psychiatric medication (P=.008). No other differences in health parameters or physical illnesses were found. Holocaust survivors had similar rates of deterioration in health and illness parameters over the follow-up period, and 7-year mortality rates were identical. Proportional hazard models showed that being an elderly Holocaust survivor was not predictive of greter 7-year mortality. CONCLUSION: Fifty years after their Holocaust trauma, survivors still displayed significant psychosocial and functional impairment, although no evidence was found to support the hypothesis that the delayed effects of the trauma of the Holocaust negatively influence physical health, health trajectories, or mortality. [source] Socioeconomic Status and Survival in Older Patients with MelanomaJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 11 2006Carlos A. Reyes-Ortiz MD OBJECTIVES: To determine the association between socioeconomic status (SES) and survival in older patients with melanoma. DESIGN: Retrospective cohort study. SETTING: Surveillance, Epidemiology and End Results (SEER): a population-based cancer registry covering 14% of the U.S. population. PARTICIPANTS: Twenty-three thousand sixty-eight patients aged 65 and older with melanoma between 1988 and 1999. MEASUREMENTS: Outcome was melanoma-specific survival. Main independent variable was SES (measured as census tract median household income) taken from the SEER-Medicare linked data. RESULTS: Subjects residing in lower-income areas (,$30,000/y) had lower 5-year survival rates (88.5% vs 91.1%, P<.001) than subjects residing in higher-income areas (>$30,000/y). In Cox proportional hazard models, higher income was associated with lower risk of death from melanoma (hazard ratio=0.88, 95% confidence interval=0.79,0.98, P=.02) after adjusting for sociodemographics, stage at diagnosis, thickness, histology, anatomic site, and comorbidity index. There was an interaction effect between SES and ethnicity and survival from melanoma. For whites and nonwhites (all other ethnic groups), 5-year survival rates increased as income increased, although the effect was greater for nonwhites (77.6% to 90.1%, 1st to 5th quintiles, P=.01) than for whites (89.0% to 91.9%, 1st to 5th quintiles, P<.001). CONCLUSION: Older subjects covered by Medicare residing in lower-SES areas had poorer melanoma survival than those residing in higher-SES areas. Further research is needed to determine whether low SES is associated with late-stage disease biology and poorer early detection of melanoma. [source] Childhood Fractures Are Associated With Decreased Bone Mass Gain During Puberty: An Early Marker of Persistent Bone Fragility?,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2006Serge L Ferrari MD Abstract Whether peak bone mass is low among children with fractures remains uncertain. In a cohort of 125 girls followed over 8.5 years, 42 subjects reported 58 fractures. Among those, BMC gain at multiple sites and vertebral bone size at pubertal maturity were significantly decreased. Hence, childhood fractures may be markers of low peak bone mass acquisition and persistent skeletal fragility. Introduction: Fractures in childhood may result from a deficit in bone mass accrual during rapid longitudinal growth. Whether low bone mass persists beyond this period however remains unknown. Materials and Methods: BMC at the spine, radius, hip, and femur diaphysis was prospectively measured over 8.5 years in 125 girls using DXA. Differences in bone mass and size between girls with and without fractures were analyzed using nonparametric tests. The contribution of genetic factors was evaluated by mother-daughter correlations and that of calcium intake by Cox proportional hazard models. Results: Fifty-eight fractures occurred in 42 among 125 girls (cumulative incidence, 46.4%), one-half of all fractures affecting the forearm and wrist. Girls with and without fractures had similar age, height, weight. and calcium intake at all time-points. Before and during early puberty, BMC and width of the radius diaphysis was lower in the fracture compared with no-fracture group (p < 0.05), whereas aBMD and BMAD were similar in the two groups. At pubertal maturity (Tanner's stage 5, mean age ± SD, 16.4 ± 0.5 years), BMC at the ultradistal radius (UD Rad.), femur trochanter, and lumbar spine (LS), and LS projected bone area were all significantly lower in girls with fractures. Throughout puberty, BMC gain at these sites was also decreased in the fracture group (LS, ,8.0%, p = 0.015; UD Rad., ,12.0%, p = 0.004; trochanter, ,8.4%, p = 0.05 versus no fractures). BMC was highly correlated between prepuberty and pubertal maturity (R = 0.54,0.81) and between mature daughters and their mothers (R = 0.32,0.46). Calcium intake was not related to fracture risk. Conclusions: Girls with fractures have decreased bone mass gain in the axial and appendicular skeleton and reduced vertebral bone size when reaching pubertal maturity. Taken together with the evidence of tracking and heritability for BMC, these observations indicate that childhood fractures may be markers for low peak bone mass and persistent bone fragility. [source] Premarital Living Arrangements and the Transition to First Marriage in JapanJOURNAL OF MARRIAGE AND FAMILY, Issue 2 2003James M. Raymo This article evaluates the relevance of a popular emphasis on the benefits of extended coresidence with parents as an explanation for the trend toward later marriage in Japan. Estimating hazard models for the transition to first marriage separately by gender, living arrangements, and birth cohort, I find that the trend toward later marriage is indeed more pronounced among young men and women living with parents. Conditional on coresidence, however, there is little evidence that access to parental provision of financial resources and domestic services is negatively associated with marriage. I suggest alternative scenarios in which parental resources may contribute to later marriage by facilitating children's independence rather than by keeping them at home. [source] Are Spells of Unemployment Longer in Nonmetropolitan Areas?JOURNAL OF REGIONAL SCIENCE, Issue 4 2000Nonparametric, Semiparametric Evidence I use nonparametric and semiparametric proportional hazard models to examine whether individuals resident in nonmetropolitan areas experience lower per period rates of exit from unemployment following job loss than metropolitan area residents. Results show that between 1989 and 1993 per period cumulative rates of exit from unemployment were slightly higher in nonmetropolitan areas, mainly due to nonmetropolitan–metropolitan differences in individual characteristics and local economic conditions. Employment density is found to have a positive association with rates of exit of unemployment in metropolitan areas but not in nonmetropolitan areas. [source] Direct parametric inference for the cumulative incidence functionJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 2 2006Jong-Hyeon Jeong Summary., In survival data that are collected from phase III clinical trials on breast cancer, a patient may experience more than one event, including recurrence of the original cancer, new primary cancer and death. Radiation oncologists are often interested in comparing patterns of local or regional recurrences alone as first events to identify a subgroup of patients who need to be treated by radiation therapy after surgery. The cumulative incidence function provides estimates of the cumulative probability of locoregional recurrences in the presence of other competing events. A simple version of the Gompertz distribution is proposed to parameterize the cumulative incidence function directly. The model interpretation for the cumulative incidence function is more natural than it is with the usual cause-specific hazard parameterization. Maximum likelihood analysis is used to estimate simultaneously parametric models for cumulative incidence functions of all causes. The parametric cumulative incidence approach is applied to a data set from the National Surgical Adjuvant Breast and Bowel Project and compared with analyses that are based on parametric cause-specific hazard models and nonparametric cumulative incidence estimation. [source] Smoking and venous thromboembolism: a Danish follow-up studyJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 8 2009M. T. SEVERINSEN Summary.,Background: Large-scale prospective studies are needed to assess whether smoking is associated with venous thromboembolism (VTE) (i.e. deep venous thrombosis and pulmonary embolism) independently of established risk factors. Objective: To investigate the association between smoking and the risk of VTE among middle-aged men and women. Methods: From 1993 to 1997, 27 178 men and 29 875 women, aged 50,64 years and born in Denmark, were recruited into the Danish prospective study ,Diet, Cancer and Health'. During follow-up, VTE cases were identified in the Danish National Patient Registry. Medical records were reviewed and only verified VTE cases were included in the study. Baseline data on smoking and potential confounders were included in gender stratified Cox proportional hazard models to asses the association between smoking and the risk of VTE. The analyses were adjusted for alcohol intake, body mass index, physical activity, and in women also for use of hormone replacement therapy. Results: During follow-up, 641 incident cases of VTE were verified. We found a positive association between current smoking and VTE, with a hazard ratio of 1.52 (95% CI, 1.15,2.00) for smoking women and 1.32 (95% CI, 1.00,1.74) for smoking men, and a positive dose-response relationship. Former smokers had the same hazard as never smokers. Conclusions: Smoking was an independent risk factor for VTE among middle-aged men and women. Former smokers have the same risk of VTE as never smokers, indicating acute effects of smoking, and underscoring the potential benefits of smoking cessation. [source] Human leukocyte antigen and adult living-donor liver transplantation outcomes: An analysis of the organ procurement and transplantation network database,LIVER TRANSPLANTATION, Issue 10 2007S. Simona Jakab Human leukocyte antigen (HLA) compatibility has no clinically significant impact in cadaveric liver transplantation. Less is known regarding living-donor liver transplantation (LDLT). Our prior analysis of the Organ Procurement and Transplantation Network (OPTN) database suggested a higher graft failure rate in patients who underwent LDLT from donors with close HLA match. We further investigated the effect of HLA-A, -B, and -DR matching on 5-yr graft survival in adult LDLT by analyzing OPTN data regarding adult LDLT performed between 1998 and 2005. We evaluated associations between 5-yr graft survival and total, locus-specific, and haplotype match levels. Separate analyses were conducted for recipients with autoimmune (fulminant autoimmune hepatitis, cirrhosis secondary to autoimmune hepatitis, primary biliary cirrhosis, primary sclerosing cholangitis) or nonautoimmune liver disease. Multivariable Cox proportional hazard models were used to evaluate interactions and adjust for potential confounders. Among 631 patients with available donor/recipient HLA data, the degree of HLA match had no significant effect on 5-yr graft survival, even when analyzed separately in recipients with autoimmune vs. nonautoimmune liver disease. To be able to include all 1,838 adult LDLTs, we considered a first-degree related donor as substitute for a close HLA match. We found no difference in graft survival in related vs. unrelated pairs. In conclusion, our results show no detrimental impact of close HLA matching on graft survival in adult LDLT, including in recipients with underlying autoimmune liver disease. Liver Transpl 13:1405,1413, 2007. © 2007 AASLD. [source] Predictors of progression in patients with Friedreich ataxia,MOVEMENT DISORDERS, Issue 14 2008Alison La Pean MS Abstract Friedreich ataxia is an inherited, progressive, neurodegenerative disorder that is clinically heterogeneous. It is caused by a trinucleotide (GAA) repeat expansion resulting in frataxin loss and oxidative stress. We assessed clinical features including the development of cardiomyopathy and scoliosis and disease progression including loss of ambulation and interference with activities of daily living relative to the length of the GAA repeat, age of onset, and age of diagnosis in a retrospective cohort study of 61 genetically confirmed patients. The use of antioxidants such as vitamins, dietary supplements, and idebenone was also examined. Linear regression and Cox proportional hazard models assessed predictors to disease milestones. The shorter GAA allele accounted for part of the variability in the age of diagnosis (46%) and less in the age of onset (27%). Multivariate analysis demonstrated that age at diagnosis, which may incorporate other genetic and environmental factors, is more important than GAA length in predicting cardiomyopathy, scoliosis, and disease progression. © 2008 Movement Disorder Society [source] Evaluation of the prognostic value of the risk, injury, failure, loss and end-stage renal failure (RIFLE) criteria for acute kidney injuryNEPHROLOGY, Issue 5 2008JOSE R PEREZ VALDIVIESO SUMMARY: Aim: The experts have argued about the use of the risk, injury, failure, loss and end-stage renal failure (RIFLE) criteria as a prognosis scoring system. We examined the association between in-hospital mortality and the RIFLE criteria, and discussed its accuracy as a prognosis factor. Methods: In this prospective study, we analysed the data gathered from a cohort of 956 patients admitted in a Spanish tertiary hospital between January 1998 and April 2006. Hazard ratios for mortality, and survival curves within 60 days were calculated. Discrimination and calibration of the model were also assessed. Results: Excluding 53 patients, 903 patients were finally analysed. We classified them into groups according to the maximum RIFLE class reached during their admission. The RIFLE class was assessed by the glomerular filtration rate criterion. We found an increase in the in-hospital mortality risk. Cox proportional hazard models showed that RIFLE classes risk, injury, and failure were significant predictive factors (hazard ratios were 2.77, 3.23 and 3.52, respectively; P for trend was 0.005). The multivariate analyses from the cross-classification of the participants according to Liano score values (severity of illness) and RIFLE classes showed additive effects of the exposures on in-hospital mortality. Conclusion: In this population, the risk of in-hospital mortality during the acute kidney injury (AKI) episode was positively associated with RIFLE classes. We showed that the RIFLE classification system had discriminative power in predicting hospital mortality within 60 days in AKI patients, but not better than a specific AKI predictive model. However, a combined use of both may give a more robust prognosis system. [source] Early bacteremia in pediatric hematopoietic stem cell transplant patients on oral antibiotic prophylaxisPEDIATRIC BLOOD & CANCER, Issue 2 2005Leslie S. Kersun MD, MSCE Abstract Background Bacteremia occurs during hematopoietic stem cell transplant (HSCT) in 20%,25% of patients and the use of gut decontamination (GD) to decrease this risk is controversial. Our purpose was to determine the incidence of bacteremia and antimicrobial resistance post-HSCT in pediatric patients receiving GD, and to identify risk factors associated with infection. Procedures This was a retrospective cohort study of 182 pediatric patients undergoing first HSCT for malignant disease at The Children's Hospital of Philadelphia from January, 1999 to December, 2002. We examined the impact of age, sex, race, diagnosis, disease status, conditioning regimen, recent bacteremia, stem cell source, donor, graft versus host disease prophylaxis agents, and mucositis severity using Cox proportional hazard models. GD consisted of amoxicillin (azithromycin, if penicillin allergic) and oral gentamicin. Outcome was first episode of bacteremia prior to absolute neutrophil count (ANC) 500/mm3. Antibiotic susceptibilities were performed on all isolates. Results Seventy-four patients (41%) developed bacteremia. The majority were Gram-positive cocci, with Staphylococcal (50%) and Streptococcal species (28%) the most common. Gram-negative organisms were identified in 22% with Pseudomonas (5.7%) and Klebsiella species (3.4%) the most common. Of the Streptococcal infections, 72% were resistant to ampicillin; only 25% of the Gram-negative bacteria were resistant to gentamicin. Race was the only factor associated with early bacteremia (hazard ratio 2.3 for non-Caucasian, non-African-American patients, CI 1.3,4.3, P,=,0.007) Conclusions Early bacteremia is common after HSCT, despite the use of GD. Resistant Gram-positive organisms predominate, consistent with recent trends in immunocompromised patients. Although used in practice, there is no clear evidence for the efficacy of GD and this study provides the basis upon which to develop a randomized clinical trial evaluating the current GD regimen with placebo. © 2004 Wiley-Liss, Inc. [source] Confounder summary scores when comparing the effects of multiple drug exposures,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 1 2010Suzanne M. Cadarette PhD Abstract Purpose Little information is available comparing methods to adjust for confounding when considering multiple drug exposures. We compared three analytic strategies to control for confounding based on measured variables: conventional multivariable, exposure propensity score (EPS), and disease risk score (DRS). Methods Each method was applied to a dataset (2000,2006) recently used to examine the comparative effectiveness of four drugs. The relative effectiveness of risedronate, nasal calcitonin, and raloxifene in preventing non-vertebral fracture, were each compared to alendronate. EPSs were derived both by using multinomial logistic regression (single model EPS) and by three separate logistic regression models (separate model EPS). DRSs were derived and event rates compared using Cox proportional hazard models. DRSs derived among the entire cohort (full cohort DRS) was compared to DRSs derived only among the referent alendronate (unexposed cohort DRS). Results Less than 8% deviation from the base estimate (conventional multivariable) was observed applying single model EPS, separate model EPS or full cohort DRS. Applying the unexposed cohort DRS when background risk for fracture differed between comparison drug exposure cohorts resulted in ,7 to,+,13% deviation from our base estimate. Conclusions With sufficient numbers of exposed and outcomes, either conventional multivariable, EPS or full cohort DRS may be used to adjust for confounding to compare the effects of multiple drug exposures. However, our data also suggest that unexposed cohort DRS may be problematic when background risks differ between referent and exposed groups. Further empirical and simulation studies will help to clarify the generalizability of our findings. Copyright © 2009 John Wiley & Sons, Ltd. [source] Neurological mortality among U.S. veterans of the Persian Gulf War: 13-year follow-upAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 9 2009Shannon K. Barth MPH Abstract Background This study focuses on long-term mortality, specifically brain cancer, amyotrophic lateral sclerosis (ALS), Parkinson's disease, and multiple sclerosis (MS) of 621,902 veterans who served in the 1990,1991 Persian Gulf War (GW), and 746,248 non-GW veterans. Methods Follow-up began with the date the veteran left the GW theater or May 1, 1991 and ended with the date of death or December 31, 2004. Cox proportional hazard models were used for analyses. Results Adjusted mortality rate ratios (aRR) of GW veterans compared to non-GW veterans were not statistically significant for brain cancer (aRR,=,0.90, 95% confidence interval (CI): 0.73, 1.11), MS (aRR,=,0.61, 95% CI: 0.23, 1.63), Parkinson's disease (aRR,=,0.71, 95% CI: 0.17, 2.99), or ALS (aRR,=,0.96, 95% CI: 0.56, 1.62). GW veterans potentially exposed to nerve agents for 2 or more days and GW veterans exposed to oil well fire smoke were at increased risk for brain cancer mortality (aRR,=,2.71, 95% CI: 1.25, 5.87; aRR,=,1.81, 95% CI: 1.00, 3.27; respectively). Conclusions The risk of death due to ALS, MS, Parkinson's disease, and brain cancer was not associated with 1991 GW service in general. However, GW veterans potentially exposed to nerve agents at Khamisiyah, Iraq, and to oil well fire smoke had an increased risk of mortality due to brain cancer. Am. J. Ind. Med. 52:663,670, 2009. © 2009 Wiley-Liss, Inc. [source] Psychosocial factors and shoulder symptom development among workersAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2009Caroline K. Smith MPH Abstract Background Shoulder injuries are a common cause of pain and discomfort. Many work-related factors have been associated with the onset of shoulder symptoms. The psychosocial concepts in the demand,control model have been studied in association with musculoskeletal symptoms but with heterogeneous findings. The purpose of this study was to assess the relationship between the psychosocial concepts of the demand,control model and the incidence of shoulder symptoms in a working population. Methods After following 424 subjects for approximately 1 year, 85 incident cases were identified from self-reported data. Cox proportional hazards modeling was used to assess the associations between shoulder symptoms and demand,control model quadrants. Results Cases were more likely to be female and report other upper extremity symptoms at baseline (P,<,0.05). From the hazard models, being in either a passive or high strain job quadrant was associated with the incidence of shoulder symptoms. Hazard ratios were 2.17, 95% CI 1.02,4.66 and 2.19, 95% CI 1.08,4.42, respectively. Conclusions Using self-reporting to determine demand,control quadrants was successful in identifying subjects at risk of developing work-related shoulder symptoms. Research is needed to determine if this relationship holds with clinically diagnosed shoulder and other upper extremity musculoskeletal disorders. This may be part of a simple tool for assessing risk of developing these UEMSDs. Am. J. Ind. Med. 52:57,68, 2009. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||