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Hazards Regression Models (hazard + regression_models)
Kinds of Hazards Regression Models Selected AbstractsPolynomial Spline Estimation and Inference of Proportional Hazards Regression Models with Flexible Relative Risk FormBIOMETRICS, Issue 3 2006Jianhua Z. Huang Summary The Cox proportional hazards model usually assumes an exponential form for the dependence of the hazard function on covariate variables. However, in practice this assumption may be violated and other relative risk forms may be more appropriate. In this article, we consider the proportional hazards model with an unknown relative risk form. Issues in model interpretation are addressed. We propose a method to estimate the relative risk form and the regression parameters simultaneously by first approximating the logarithm of the relative risk form by a spline, and then employing the maximum partial likelihood estimation. An iterative alternating optimization procedure is developed for efficient implementation. Statistical inference of the regression coefficients and of the relative risk form based on parametric asymptotic theory is discussed. The proposed methods are illustrated using simulation and an application to the Veteran's Administration lung cancer data. [source] Stage 2 Pressure Ulcer Healing in Nursing HomesJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 7 2008Nancy Bergstrom PhD OBJECTIVES: To identify resident and wound characteristics associated with Stage 2 pressure ulcer (PrU) healing time in nursing home residents. DESIGN: Retrospective cohort study with convenience sampling. SETTING: One hundred two nursing homes participating in the National Pressure Ulcer Long-Term Care Study (NPULS) in the United States. PARTICIPANTS: Seven hundred seventy-four residents aged 21 and older with length of stay of 14 days or longer who had at least one initial Stage 2 (hereafter Stage 2) PrU. MEASUREMENTS: Data collected for each resident over a 12-week period included resident characteristics and PrU characteristics, including area when first reached Stage 2. Data were obtained from medical records and logbooks. RESULTS: There were 1,241 initial Stage 2 PrUs on 774 residents; 563 (45.4%) healed. Median time to heal was 46 days. Initial area was significantly associated with days to heal. Using Kaplan-Meier survival analyses, median days to heal was 33 for small (,1 cm2), 53 days for medium (>1 to ,4 cm2), and 73 days for large (>4 cm2) ulcers. Using Cox proportional hazard regression models to examine effects of multiple variables simultaneously, small and medium ulcers and ulcers on residents with agitation and those who had oral eating problem healed more quickly, whereas ulcers on residents who required extensive assistance with seven to eight activities of daily living (ADLs), who temporarily left the facility for the emergency department (ED) or hospital, or whose PrU was on an extremity healed more slowly. CONCLUSION: PrUs on residents with agitation or with oral eating problems were associated with faster healing time. PrUs located on extremities, on residents who went temporarily to the ED or hospital, and on residents with high ADL disabilities were associated with slower healing time. Interaction between PrU size and place of onset was also associated with healing time. For PrU onset before or after admission to the facility, smaller size was associated with faster healing time. [source] Divalproex sodium vs. valproic acid: drug utilization patterns, persistence rates and predictors of hospitalization among VA patients diagnosed with bipolar disorderJOURNAL OF CLINICAL PHARMACY & THERAPEUTICS, Issue 6 2007S. U. Iqbal MBA MPH MD Summary Objectives:, To compare divalproex sodium and valproic acid for therapeutic patterns, persistence rates and predictors of hospitalization among bipolar patients on monotherapy in the Veterans Affairs (VA) healthcare system. Methods:, Using VA administrative data bases, we conducted a retrospective inception cohort study of VA patients', 18 years of age who had at least one outpatient diagnoses of bipolar disorder and two continuous prescription records for the study drugs in the VA PBM pharmacy database during the study period of 1st April 2001 to 30th September 2003. Persistence for the comparative drugs was reported as continuous variable and compared using t -tests. Logistic regression models were used to examine the risk of hospitalization whereas Cox proportional hazard regression models were used to evaluate the time to hospitalization and time to interruption of therapy for the two drug groups. Results:, We identified 4624 bipolar patients on monotherapy with valproic acid (n = 4036) and divalproex sodium (n = 588) during the study period. The descriptive statistics included sociodemographics, disability and comorbidity status and were similar for the two groups. For the crude persistence rates there were no statistically significant differences between divalproex sodium (120 days) and valproic acid (110 days). The logistic regression model for risk of hospitalization showed no statistically significant difference between the two comparators [odds ratio = 1·06, 95% confidence interval (CI) = 0·787,1·444]. The Cox model for time to interruption of therapy showed an insignificant hazard ratio (HR) for divalproex sodium vs. valproic acid (HR = 0·928, 95% CI = 0·844,1·020) and for time to hospitalization also no statistically significant difference in the HR for the two drugs (HR = 0·984, 95% CI = 0·784,1·295). Conclusion:, The study showed a comparable profile of generic valproic acid with divalproex sodium for persistence and predictors of hospitalization for bipolar patients on monotherapy in the VA. Results have important healthcare implications for treatment and costs. [source] Breast Cancer in the Elderly: Treatment of 1500 PatientsTHE BREAST JOURNAL, Issue 4 2006Lorenzo Livi MD Abstract: There is a significant difference in the extent of treatment offered to the elderly with breast cancer; in the United States, while 98% of patients less than 65 years of age receive standard treatment, 81% of those older than 65 years were treated according to protocol. This study's goal was to evaluate disease-specific survival and local-regional recurrence in breast cancer patients more than 65 years of age at diagnosis. A total of 1500 patients with invasive breast carcinoma were treated consecutively from May 1971 to July 2002 at the University of Florence, Florence, Italy. All patients were more than 65 years of age. The median age was 70.6 years (range 65.1,87.3 years). The median follow-up was 8.7 years (range 1,30 years). The crude probability of survival (or relapse occurrence) was estimated using the Kaplan,Meier method and survival (or relapse occurrence) comparisons were carried out using Cox proportional hazard regression models. The Cox regression model by stepwise selection showed as independent prognostic factors for disease-specific survival (DSS), the occurrence of a local relapse (p < 0.0001), pN status (p < 0.0001), the type of surgery (p < 0.0001), and the use of radiotherapy (p < 0.0006) and chemotherapy (p = 0.01). For local disease-free survival (LDFS), the Cox regression model by stepwise selection showed that mastectomy (p < 0.0001), histotype (p < 0.0001), pN status (p < 0.0001), and pT status (p = 0.001) were the only independent prognostic factors. Age was not a prognostic factor for DSS nor LDFS. We suggest treating patients with appropriate treatment for their prognostic factors., [source] Perioperative detection of disseminated tumour cells is an independent prognostic factor in patients with colorectal cancer ,BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 7 2003B. Bosch Background: The objective of the present investigation was to assess the prognostic significance of disseminated tumour cells in peritoneal lavage, and peripheral and mesenteric venous blood in patients undergoing curative resection of colorectal cancer. Methods: The prognostic impact of perioperative cytological and immunocytochemical detection of disseminated colorectal cancer cells was evaluated prospectively. Peritoneal lavage fluid, and peripheral and mesenteric venous blood from 53 consecutive patients undergoing curative surgery for colorectal cancer were analysed. The dichotomous results (positive versus negative) from the cytological and immunocytochemical analysis were used as a predictor along with other co-variates in proportional hazard regression models of disease-free and overall survival. Results: Disseminated colorectal cancer cells were found in 13 of 53 patients (25 per cent) using cytology (CYT) and/or immunocytochemistry (ICC). The median follow-up at the time of the analysis was 37 months. In multivariate proportional hazard regression models CYT/ICC status was a significant predictor for disease-free (P = 0·002) and overall (P = 0·006) survival. Conclusion: Disseminated tumour cells detected by CYT and ICC represent an independent prognostic factor in patients undergoing surgery for colorectal cancer and may identify patients at high risk of recurrence. Copyright © 2003 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] A prospective study of cardiovascular risk factors and incident hearing loss in men,,THE LARYNGOSCOPE, Issue 9 2010Josef Shargorodsky MD Abstract Objectives/Hypothesis: Hearing loss is the most common sensory disorder in the United States, affecting more than 36 million people. Cardiovascular risk factors have been associated with the risk of hearing loss in cross-sectional studies, but prospective data are currently lacking. Study Design: Prospective cohort study. Methods: We prospectively evaluated the association between diagnosis of hypertension, diabetes mellitus, hypercholesterolemia, smoking, or body mass index (BMI) and incident hearing loss. Participants were 26,917 men in the Health Professionals Follow-up Study, aged 40 to 74 years at baseline in 1986. Study participants completed questionnaires about lifestyle and medical history every 2 years. Information on self-reported professionally diagnosed hearing loss and year of diagnosis was obtained from the 2004 questionnaire, and cases were defined as hearing loss diagnosed between 1986 and 2004. Multivariable-adjusted hazard ratios (HRs) were calculated using Cox proportional hazards regression models. Results: A total of 3,488 cases of hearing loss were identified. History of hypertension (HR 0.96; 95% confidence interval [CI], 0.88-1.03), diabetes mellitus (HR 0.92; 95% CI, 0.78,1.08), or obesity (HR 1.02; 95% CI, 0.90,1.15 for BMI ,30 compared to normal range of 19,24.9) was not significantly associated with hearing-loss risk. Hypercholesterolemia (HR 1.10; 95% CI, 1.02,1.18) and past smoking history (HR 1.09; 95% CI, 1.01,1.17) were associated with a significantly increased risk of hearing loss after multivariate adjustment. Conclusions: A history of hypertension, diabetes mellitus, or obesity is not associated with increased risk of hearing loss; a history of past smoking or hypercholesterolemia has a small but statistically significant association with increased risk of hearing loss in adult males. Laryngoscope, 2010 [source] Real-life impact of early interferon, therapy in relapsing multiple sclerosis,ANNALS OF NEUROLOGY, Issue 4 2009M. Trojano MD Objective Recent findings support greater efficacy of early vs. delayed interferon beta (IFN,) treatment in patients with a first clinical event suggestive of multiple sclerosis (MS). We aimed to evaluate the effectiveness of early IFN, treatment in definite relapsing-remitting MS (RRMS) and to assess the optimal time to initiate IFN, treatment with regard to the greatest benefits on disability progression. Methods A cohort of 2,570 IFN,-treated RRMS patients was prospectively followed for up to 7 years in 15 Italian MS Centers. A Cox proportional hazards regression model adjusted for propensity score (PS) quintiles was used to assess differences between groups of patients with early vs. delayed IFN, treatment on risk of reaching a 1-point progression in the Expanded Disability Status Scale (EDSS) score, and the EDSS 4.0 and 6.0 milestones. A set of PS-adjusted Cox hazards regression models were calculated according to different times of treatment initiation (within 1 year up to within 5 years from disease onset). A sensitivity analysis was performed to assess the robustness of findings. Results The lowest hazard ratios (HRs) for the three PS quintiles,adjusted models were obtained by a cutoff of treatment initiation within 1 year from disease onset. Early treatment significantly reduced the risk of reaching a 1-point progression in EDSS score (HR = 0.63; 95% CI = 0.48,0.85; p < 0.002), and the EDSS 4.0 milestone (HR = 0.56; 95% CI = 0.36,0.90; p = 0.015). Sensitivity analysis showed the bound of significance for unmeasured confounders. Interpretation Greater benefits on disability progression may be obtained by an early IFN, treatment in RRMS. Ann Neurol 2009;66:513,520 [source] Caesarean section and subsequent fertility in sub-Saharan AfricaBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 3 2006SM Collin Objective, To determine the impact of caesarean section on fertility among women in sub-Saharan Africa. Design, Analysis of standardised cross-sectional surveys (Demographic and Health Surveys). Setting, Twenty-two countries in sub-Saharan Africa, 1993,2003. Sample, A total of 35 398 women of childbearing age (15,49 years). Methods, Time to subsequent pregnancy was compared by mode of delivery using Cox proportional hazards regression models. Main outcome measures, Natural fertility rates subsequent to delivery by caesarean section compared with natural fertility rates subsequent to vaginal delivery. Results, The natural fertility rate subsequent to delivery by caesarean section was 17% lower than the natural fertility rate subsequent to vaginal delivery (hazard ratio = 0.83, 95% CI 0.73,0.96, P < 0.01; controlling for age, parity, level of education, urban/rural residence and young age at first intercourse). Caesarean section was also associated with prior fertility and desire for further children: among multiparous women, an interval ,3 versus <3 years between the index birth and the previous birth was associated with higher odds of caesarean section at the index birth (OR = 1.4, 95% CI 1.1,1.7, P= 0.005); among all women, the odds of desiring further children were lower among women who had previously delivered by caesarean section (OR = 0.67, 95% CI 0.54,0.84, P < 0.001). Caesarean section did not appear to increase the risk of a subsequent pregnancy ending in miscarriage, abortion or stillbirth. Conclusions, Among women in sub-Saharan Africa, caesarean section is associated with lower subsequent natural fertility. Although this reflects findings from developed countries, the roles of pathological and psychological factors may be quite different because a much higher proportion of caesarean sections in sub-Saharan Africa are emergency procedures for maternal indication. [source] Invasion of renal sinus fat is not an independent predictor of survival in pT3a renal cell carcinomaBJU INTERNATIONAL, Issue 12 2009Stephen A. Poon OBJECTIVE To clarify the significance of the location of extrarenal tumour extension of renal cell carcinoma (RCC) as in the 2002 Tumour-Nodes-Metastasis classification. Renal cortical tumours with perirenal fat invasion (PFI) or sinus fat invasion (SFI) are consolidated within the pT3a grouping; tumours with SFI are close to the renal veins, lymphatics and the collecting system. This might carry a worse prognosis for disease-specific survival (DSS), but reports are limited and contradictory. PATIENTS AND METHODS We retrospectively reviewed 1244 patients treated with nephrectomy from 1988 to 2007, to identify patients with pT3a renal tumours. They were classified as having PFI or SFI. Kaplan-Meier analysis and Cox proportional hazards regression models were used to assess predictors of survival. RESULTS The 230 patients who met the inclusion criteria had a median follow-up of 24 months. SFI was found in 63 (27.4%) patients and was associated with a worse 5-year DSS than the 167 (72.6%) with PFI (62.5% vs 75.0%; log rank P = 0.022). On univariate analysis, diameter (hazard ratio, HR 1.1), nuclear grade (HR 4.5), margin status (HR 5.8), lymph node metastases (HR 6.4), and systemic metastases (HR 15.4) were significant for DSS. In a multivariate model, only nuclear grade (HR 3.1), margin status (HR 8.9) and systemic metastases (HR 9.8) were independent predictors. CONCLUSION Patients with renal tumours with SFI are more likely to die from RCC than those with PFI. However, in the present patients the presence of SFI was not an independent predictor of DSS. [source] The prognostic value of hemoglobin change after initiating androgen-deprivation therapy for newly diagnosed metastatic prostate cancerCANCER, Issue 3 2006A Multivariate Analysis of Southwest Oncology Group Study 889 Abstract BACKGROUND. The objective of this study was to characterize changes in hemoglobin (HGB) levels after the initiation of androgen-deprivation therapy (ADT) in patients with previously untreated, metastatic prostate cancer who were enrolled in a large clinical trial. METHODS. The multivariate associations between 3-month change in HGB and baseline characteristics were evaluated with a linear regression model. The associations between 3-month change in HGB level and time-to-event outcomes, including overall survival and progression-free survival, were evaluated by using proportional hazards regression models. RESULTS. Quartiles of baseline HGB levels were ,12.0 g/dL, from 12.1 to 13.7 g/dL, from 13.8 to 14.7 g/dL, and >14.7 g/dL. Overall, 3 months after initiating ADT, the mean HGB level declined 0.54 g/dL (standard deviation [SD], 1.68 g/dL); however, the mean HGB level increased by 0.99 g/dL (SD, 1.83 g/dL) in patients who had baseline HGB levels <12 g/dL and decreased 1.04 g/dL (SD, 1.28 g/dL) in patients who had baseline HGB levels ,12 g/dL. After adjusting for potential confounders, including baseline HGB level, a decline in HGB after 3 months of ADT was associated independently with shorter survival (hazards ratio [HR], 1.10 per 1 g/dL decline; P = .0035) and shorter progression-free survival (HR, 1.08 per 1 g/dL decline; P = .013). An unexpected finding was that the effect of baseline HGB on overall and progression-free survival varied significantly by race. CONCLUSIONS. In a sample of men with newly diagnosed, metastatic prostate cancer, a decline in HGB level after 3 months of ADT was associated with shorter survival and progression-free survival after adjusting for disease status and other baseline covariates. Although race alone was not a strong predictor of death or disease progression, the effect of the baseline HGB level on overall and progression-free survival varied significantly by race. Cancer 2006. © 2006 American Cancer Society. [source] Mononuclear cell infiltration in clear-cell renal cell carcinoma independently predicts patient survivalCANCER, Issue 1 2006W. Scott Webster MD Abstract BACKGROUND The impact of mononuclear cell infiltration on renal cell carcinoma (RCC) biology has been controversial, previously reported to be associated with either a favorable or unfavorable prognosis. The objective of the current study was to evaluate associations between mononuclear cell infiltration in routinely prepared paraffin-embedded specimens with survival in patients with clear-cell RCC. METHODS A total of 306 patients were identified treated with nephrectomy for clear-cell RCC between 1990 and 1994. A single urologic pathologist, blinded to patient outcome, reviewed the specimens and quantified the extent of mononuclear cell infiltration as absent, focal, moderate, or marked. Cancer-specific survival was estimated using the Kaplan,Meier method. Associations of mononuclear cell infiltration with death from RCC were assessed using Cox proportional hazards regression models. RESULTS At last follow-up, 173 of the 306 patients studied had died, including 96 patients who died from RCC. Mononuclear cell infiltration was absent in 165 (54%), focal in 70 (23%), moderate in 53 (17%), and marked in 18 (6%). Univariately, patients with specimens that had mononuclear cell infiltration were over 2 times more likely to die from RCC compared with patients whose specimens exhibited no mononuclear cell infiltration (risk ratio, 2.63; P<.001). After adjusting for the Mayo Clinic SSIGN (stage, size, grade, and necrosis) score, patients with specimens that had mononuclear cell infiltration exhibited a significantly increased likelihood of dying from RCC compared with patients whose specimens had no mononuclear cell infiltration (risk ratio, 1.61; P = .028). CONCLUSIONS Mononuclear cell infiltration is associated with death from RCC even after multivariate adjustment. Routine documentation of mononuclear cell infiltration is recommended during the pathologic assessment of RCC. Cancer 2006. © 2006 American Cancer Society. [source] Cancer incidence in parents who lost a childCANCER, Issue 10 2002A nationwide study in Denmark Abstract BACKGROUND It has been debated whether psychological stress causes cancer, but the scientific evidence remains contradictory. The objective of this study was to investigate whether the death of a child is related to cancer risk in bereaved parents. METHODS The authors undertook a follow-up study based on national registers. All 21,062 parents who lost a child from 1980 to 1996 were recruited for the exposed cohort together with 293,745 randomly selected, unexposed parents. Cox proportional hazards regression models were used to evaluate the relative risk of cancer incidence up to 18 years after the bereavement. The main outcomes of interest were all incident cancers, breast carcinoma, smoking-related malignancies (International Classification of Diseases [ICD] 7 codes 140, 141, 143,149, 150, 157, 160,162, 180, and 181), alcohol-related malignancies (ICD7 codes 141, 143,146, 148,150, 155, and 161), virus/immune-related malignancies (ICD7 codes 155, 171, 191, 200,202, and 204), lymphatic/hematopoietic malignancies (ICD7 codes 200,205), and hormone related malignancies (ICD7 codes 170, 172, 175, and 177). RESULTS The authors observed a slightly increased overall cancer risk in bereaved mothers (relative risk [RR], 1.18; 95% confidence interval [95%CI], 1.01,1.37; P = 0.028) at 7,18 years of follow-up. There was an increased risk for smoking-related malignancies (RR, 1.65; 95%CI, 1.05,2.59; P = 0.010) among bereaved mothers during the 7,18 years of follow-up. The authors observed no significantly increased relative risk of breast carcinoma, alcohol-related malignancies, virus/immune-related malignancies, or hormone-related malignancies. CONCLUSIONS The current data suggest that the death of a child was associated with a slightly increased overall cancer risk in mothers and that the increase may be related to stress-induced adverse life styles. Cancer 2002;95:2237,42. © 2002 American Cancer Society. DOI 10.1002/cncr.10943 [source] Potential biomarkers involving IKK/RelA signal in early stage non-small cell lung cancerCANCER SCIENCE, Issue 3 2008Xianqing Jin The clinical relevance of nuclear factor ,B (NF-,B) and its regulatory molecules on prognosis of patient with early stages of non-small cell lung cancer (NSCLC), remains unclear. Therefore, we conducted biomarker analyses with survival in patients with stages I and II NSCLC. Tumor samples were collected from 88 patients with early-stage NSCLC (stages I, II). A minimum follow-up period of 5 years was required. RelA, phosphorylated I,B (pI,B,), pIKK,/, were detected by immunostaining. NF-,B DNA binding activity was assessed by electrophoretic mobility shift assay. Association of clinical and pathologic variables (e.g. sex, age, pathologic stage) with relevant molecules was determined by Pearson's ,2 test or Fisher's exact test. Survival analysis based on single expression of RelA, pI,B,, pIKK,/, as well as composite expressions were evaluated using Cox proportional hazards regression models, and log rank test followed Kaplan-Meier estimates. RelA, pI,B,, pIKK,/, were observed as increased expression in NSCLC tissues compared with adjacent normal tissues and normal lung tissues. These molecules were associated with tumor-node-metastasis stages, T stages and histological status, respectively. Among the molecules analyzed, RelA and pI,B,-positive were statistically significant predictors of patient death in the entire patient population adjusted by age, gender and smoking status; furthermore both RelA and pI,B,-positive was the strongest prognostic indicators of poor prognosis by univariate and multivariate analyses. Borderline positive correlations were observed between RelA and pI,B, or pIKK,/, expression. In this cohort of early-stage NSCLC patients, molecular markers, especially composite application of multiple biomarkers (both nuclear RelA and cytoplasmic pI,B-, expression) that independently predict overall survival have been identified. (Cancer Sci 2008; 99: 582,589) [source] | ||||||||||