Survival of Red Maasai, Dorper and crossbred lambs in the sub-humid tropics

2003 ◽  
Vol 76 (1) ◽  
pp. 3-17 ◽  
Author(s):  
R. Nguti ◽  
P. Janssen ◽  
G.J. Rowlands ◽  
J.O. Audho ◽  
R.L. Baker
Keyword(s):  
Body Weight ◽  
Standard Error ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Survival Rates ◽  
Risk Of Death ◽  
Intestinal Nematode ◽  
Hazards Model ◽  
Faecal Egg Count ◽  
Time Varying Covariates

AbstractThe survival rates of Dorper, Red Maasai and crossbred lambs born over a period of 6 years at Diani Estate, Coast Province, Kenya were compared using the Cox mixed proportional hazards model with a random (frailty) term for sire. Of the 1785 lambs born, proportionately 0·44 died before they were 1 year old. Almost half of these deaths occurred before weaning; a third were associated with mis-mothering and a fifth with gastro-intestinal nematode parasite (endoparasite) infections. Half of the deaths post weaning were associated with endoparasite infections, predominantly Haemonchus contortus. The Red Maasai lambs had a lower risk of death than the Dorper lambs with a relative hazard of 0·27 pre-weaning and 0·25 post weaning. Other crosses and back crosses had relative hazards in between these values and 1; there was no evidence of heterosis. Survival rates were different among years and appeared to be associated to some degree with variations in rainfall. There were highly significant effects of both birth weight and weaning weight on survival. Body weight, together with packed red cell volume and faecal egg count, were also introduced into the proportional hazard model as time-varying covariates. All three variables had major influences on survival. The risk of death over the following month in animals individually treated with an anthelmintic drug pre weaning was reduced by 0·61 compared with those not treated. The sire frailty variance estimate was similar to its standard error pre-weaning but larger post weaning. When adjusted for lamb body weight the sire variance post weaning increased to three times its standard error.

scholarly journals Dementia Adjudication Triggers Associated With Increased Mortality for Older Australians: Evidence From ASPREE

2020 ◽  
Vol 4 (Supplement_1) ◽  
pp. 161-161
Author(s):  
Jane Banaszak-Holl ◽  
Xiaoping Lin ◽  
Jing Xie ◽  
Stephanie Ward ◽  
Henry Brodaty ◽  
...  
Keyword(s):  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
The Elderly ◽  
Cox Proportional Hazards ◽  
Service Planning ◽  
Cox Proportional Hazards Model ◽  
Cognitive Test ◽  
Risk Of Death ◽  
Hazards Model ◽  
Using Data

Abstract Research Aims: This study seeks to understand whether those with dementia experience higher risk of death, using data from the ASPREE (ASPirin in Reducing Events in the Elderly) clinical trial study. Methods: ASPREE was a primary intervention trial of low-dose aspirin among healthy older people. The Australian cohort included 16,703 dementia-free participants aged 70 years and over at enrolment. Participants were triggered for dementia adjudication if cognitive test results were poorer than expected, self-reporting dementia diagnosis or memory problems, or dementia medications were detected. Incidental dementia was adjudicated by an international adjudication committee using the Diagnostic and Statistical Manual for Mental Disorders (DSM-IV) criteria and results of a neuropsychological battery and functional measures with medical record substantiation. Statistical analyses used a cox proportional hazards model. Results: As previously reported, 1052 participants (5.5%) died during a median of 4.7 years of follow-up and 964 participants had a dementia trigger, of whom, 575 (60%) were adjucated as having dementia. Preliminary analyses has shown that the mortality rate was higher among participants with a dementia trigger, regardless of dementia adjudication outcome, than those without (15% vs 5%, Χ2 = 205, p <.001). Conclusion: This study will provide important analyses of differences in the hazard ratio for mortality and causes of death among people with and without cognitive impairment and has important implications on service planning.

scholarly journals Comorbidities and Outcome of Alcoholic and Non-Alcoholic Liver Cirrhosis in Taiwan: A Population-Based Study

2020 ◽  
Vol 17 (8) ◽  
pp. 2825
Author(s):  
Tzu-Wei Yang ◽  
Chi-Chih Wang ◽  
Ming-Chang Tsai ◽  
Yao-Tung Wang ◽  
Ming-Hseng Tseng ◽  
...  
Keyword(s):  
Liver Cirrhosis ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Survival Rates ◽  
Study Groups ◽  
Population Based ◽  
Cox Proportional Hazards ◽  
Cox Proportional Hazards Model ◽  
Study Cohort ◽  
Hazards Model

The prognosis of different etiologies of liver cirrhosis (LC) is not well understood. Previous studies performed on alcoholic LC-dominated cohorts have demonstrated a few conflicting results. We aimed to compare the outcome and the effect of comorbidities on survival between alcoholic and non-alcoholic LC in a viral hepatitis-dominated LC cohort. We identified newly diagnosed alcoholic and non-alcoholic LC patients, aged ≥40 years old, between 2006 and 2011, by using the Longitudinal Health Insurance Database. The hazard ratios (HRs) were calculated using the Cox proportional hazards model and the Kaplan–Meier method. A total of 472 alcoholic LC and 4313 non-alcoholic LC patients were identified in our study cohort. We found that alcoholic LC patients were predominantly male (94.7% of alcoholic LC and 62.6% of non-alcoholic LC patients were male) and younger (78.8% of alcoholic LC and 37.4% of non-alcoholic LC patients were less than 60 years old) compared with non-alcoholic LC patients. Non-alcoholic LC patients had a higher rate of concomitant comorbidities than alcoholic LC patients (79.6% vs. 68.6%, p < 0.001). LC patients with chronic kidney disease demonstrated the highest adjusted HRs of 2.762 in alcoholic LC and 1.751 in non-alcoholic LC (all p < 0.001). In contrast, LC patients with hypertension and hyperlipidemia had a decreased risk of mortality. The six-year survival rates showed no difference between both study groups (p = 0.312). In conclusion, alcoholic LC patients were younger and had lower rates of concomitant comorbidities compared with non-alcoholic LC patients. However, all-cause mortality was not different between alcoholic and non-alcoholic LC patients.

Modelling heterogeneity in survival data

1991 ◽  
Vol 28 (03) ◽  
pp. 695-701 ◽  
Author(s):  
Philip Hougaard
Keyword(s):  
Survival Data ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Mixture Distribution ◽  
Survival Models ◽  
Risk Of Death ◽  
Hazards Model ◽  
Occupational Mortality ◽  
Heterogeneity Distribution ◽  
Biased Estimates

Ordinary survival models implicitly assume that all individuals in a group have the same risk of death. It may, however, be relevant to consider the group as heterogeneous, i.e. a mixture of individuals with different risks. For example, after an operation each individual may have constant hazard of death. If risk factors are not included, the group shows decreasing hazard. This offers two fundamentally different interpretations of the same data. For instance, Weibull distributions with shape parameter less than 1 can be generated as mixtures of constant individual hazards. In a proportional hazards model, neglect of a subset of the important covariates leads to biased estimates of the other regression coefficients. Different choices of distributions for the unobserved covariates are discussed, including binary, gamma, inverse Gaussian and positive stable distributions, which show both qualitative and quantitative differences. For instance, the heterogeneity distribution can be either identifiable or unidentifiable. Both mathematical and interpretational consequences of the choice of distribution are considered. Heterogeneity can be evaluated by the variance of the logarithm of the mixture distribution. Examples include occupational mortality, myocardial infarction and diabetes.

G CSF association with prolonged survival in HIV infected patients with disseminated Mycobacterium avium complex infection

1998 ◽  
Vol 9 (7) ◽  
pp. 394-399 ◽  
Author(s):  
Philip Keiser ◽  
Steven Rademacher ◽  
James Smith ◽  
Daniel Skiest
Keyword(s):  
Mycobacterium Avium ◽  
Mycobacterium Avium Complex ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Cox Proportional Hazards ◽  
Cox Proportional Hazards Model ◽  
Cd4 Count ◽  
Risk Of Death ◽  
Hazards Model

Summary: Clarithromycin can ameliorate symptoms and improve survival in disseminated Mycobacterium avium complex DMAC infection. Optimal combina tions of this drug with other agents remain unknown. Granulocyte colony stimulating factor G CSF is a cytokine that can improve phagocytosis of M. avium complex in vitro . We aim to determine if G CSF administration is associated with improved survival in patients with DMAC in a retrospective, cohort study. Case records from 1991 to 1995 of 91 patients with DMAC at Parkland Memorial Hospital were reviewed for date of initial DMAC diagnosis, baseline CD4 count, race, sex, antiretroviral use, G CSF use, therapy for DMAC clarithromycin, ethambutol, ciprofloxacin and rifabutin and date of death. Of 91 cases identified, 25 were treated with G CSF and 66 never received this drug. Baseline characteristics were similar in each group including CD4 count 40 cells mm 3 vs 33 cells mm 3, P =0.68 , clarithromycin use 18 patients vs 52 patients, P =0.90 , and antiretroviral use 20 patients vs 42 patients, P =0.21 . Subjects treated with G CSF lived longer than those who did not receive this drug 355 days vs 211 days, P 0.01 . In the subgroup treated with clarithromycin, G CSF was also associated with increased survival 377 days vs 252 days, P 0.01 . Cox proportional hazards model showed a decreased risk of death in patients treated with G CSF RH=0.22, P 0.01 , clarithromycin RH=0.13, P 0.01 and ethambutol RH=0.51, P =0.02 . Ciprofloxacin and rifabutin use did not influence survival. These data support the use of clarithromycin and ethambutol in the treatment of DMAC. Addition of G CSF to a regimen of clarithromycin and ethambutol may increase survival in DMAC and should be studied prospectively.

Early Hb Response to ESA Treatment May Be An Indicator of Better Survival Prognosis

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4587-4587
Author(s):  
Jesse A Berlin ◽  
Peter Bowers ◽  
Sudhakar Rao ◽  
Suresh Aravind ◽  
Steven Sun ◽  
...  
Keyword(s):  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Performance Status ◽  
Epoetin Alfa ◽  
Survival Prognosis ◽  
Risk Of Death ◽  
Hazards Model ◽  
Kaplan Meier ◽  
Increased Risk ◽  
Baseline Covariates

Abstract Chemotherapy induced anemia patients who respond to ESA treatment have hemoglobin increases within 4–8 weeks. Patients with inadequate Hb response after several weeks treatment often have their ESA dose escalated.. We conducted an exploratory analysis to test the hypothesis that safety outcomes in randomized studies of epoetin alfa might differ depending on the Hb response after 4–8 weeks of treatment. Methods: The analysis compared the survival across subsets of epoetin-alfa treated patients. Specifically, a landmark analysis was used, which defines a hemoglobin responder at a pre-specified point in time (in this case 4 & 8 weeks post treatment), and then examines survival subsequent to that point in time.Patients were categorized as “Hb responder” when their Hb increased by &gt;0.5 g/dL; “Hb stable” when Hb change within ≤ 0.5g/dL; “Hb non-responder” when the Hb decreased &gt;0.5 g/dL, compared to the value prior to epoetin-alfa treatment. Survival was estimated using the Kaplan-Meier method and comparisons were made between the responders and non-responders versus the stable group. Cox’s proportional hazards model was used to adjust for the following baseline covariates: hemoglobin prior to treatment, baseline performance status, and advanced disease at baseline. All analyses were stratified by study to account for any differences in the study populations and study conduct. Results: These exploratory findings suggest the possibility that patients identified as non-responders to ESAs after 4 or 8 weeks of ESA treatment may be at increased risk of death, and that this effect is most pronounced in the studies that treated patients beyond the correction of anemia. Although these analyses were adjusted for several key baseline covariates, it is unclear whether these effects result from treatment, or whether patients who fail to respond to epoetin alfa are inherently at increased risk of death (e.g., due underlying malignancy), regardless of their treatment status.

Disparities in receipt of radiotherapy and survival by age, sex, and race among patients with nonmetastatic squamous cell carcinoma of the anus.

2015 ◽  
Vol 33 (3_suppl) ◽  
pp. 721-721
Author(s):  
Doug Baughman ◽  
Krishna Bilas Ghimire ◽  
Binay Kumar Shah
Keyword(s):  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Survival Rates ◽  
Relative Survival ◽  
Population Based ◽  
Cox Proportional Hazards ◽  
Cox Proportional Hazards Model ◽  
P Value ◽  
Hazards Model ◽  
To Receive

721 Background: Combination chemoradiotherapy is the standard of care for treatment of non-metastatic squamous cell carcinoma of the anus (SCCA). This population-based study evaluated disparities in receipt of radiotherapy (RT) and its effect on survival in patients with localized and regional SCCA in the United States. Methods: The Surveillance, Epidemiology, and End Results (SEER) 18 database was used to identify patients with localized and regional SCCA diagnosed between 1998 and 2008. We used univariate and multivariate logistic regression to model the relationships between receipt of RT and age, sex, marital status, stage, and race. Relative survival rates were calculated and compared using two sample z-tests. A Cox proportional hazards model was used to find adjusted hazard ratios (HR). Results: A total of 3,971 patients with localized or regional SCCA as the only primary malignancy were included in the study, of which 3,278 (82.6%) received RT. After adjusting for covariates, those 65 years and older (adjusted OR 0.82, p=0.029) were less likely to receive RT. Females were more likely to receive RT compared to males (adjusted OR 1.54, p<0.001). We found no difference in receipt of RT by race. Comparisons of 1- and 5-year relative survival rates showed lower survival for blacks (p-value <0.01 at 1-year and <0.0001 at 5-years), those 65 years and older, and males. A 1-year survival disparity was found for those not receiving RT (p-value <0.0001 at 1-year), but no difference was observed at 5-years. A Cox proportional hazards model adjusting for all covariates showed greater hazard for blacks (adjusted HR 1.36, p=0.001), those not receiving RT (adjusted HR 1.23, p=0.03), patients 65 years or older, and males. Conclusions: This population based study identified older patients as less likely to receive RT and females as more likely to receive RT. Survival analysis identified blacks, males, older patients, and those not receiving RT as having lower rates of survival.

scholarly journals Outcomes of Constrained Prostheses in Primary and Revision TKR

2017 ◽  
Vol 5 (5_suppl5) ◽  
pp. 2325967117S0016
Author(s):  
Ben Parkinson ◽  
Michelle Lorimer ◽  
Peter Lewis
Keyword(s):  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Survival Rates ◽  
Cox Proportional Hazards ◽  
Cox Proportional Hazards Model ◽  
Knee Prostheses ◽  
Hazards Model ◽  
Kaplan Meier ◽  
Hazard Ratios ◽  
Total Knee

Introduction: The decision to use varus/valgus constrained or hinge knee prostheses in complex Total Knee Replacement (TKR) cases is difficult. There are few publications that compare survival rates, to aid this decision-making. This study compares the survival rates of unlinked fully constrained and hinge constrained prostheses in the primary and revision settings. Methods: Data from the AOANJRR to 31st of December 2013 was analysed to determine the survival rate of unlinked and hinge constrained TKR in the primary and revision settings (excluding the diagnosis of tumour and infection). Only first-time revisions of a known primary TKR were included in the revision analysis. Kaplan-Meier estimates of survivorship were calculated for the two categories of constraint and were matched for age and diagnosis in both primary and revision TKR situations. Hazard ratios using the Cox proportional-hazards model were used. The survivorship of individual prosthesis models was determined. Results: There were 3237 prostheses implanted during the study period that met the inclusion criteria. Of these, 1896 were for primary TKR and 1341 for revision TKR. There were 1349 unlinked fully constrained and 547 hinge prostheses for primary TKR and 991 unlinked fully constrained and 350 hinge prostheses for revision TKR. In both the primary and revision settings when matched by age, there was no difference in rates of revision for either level of constraint. When matched by indication in the primary setting, there was no difference in the rates of revision for either level of constraint. The rate of revision for both categories of constrained prosthesis was significantly higher in younger patients <55 years of age (p < 0.05). There were no differences in survival rates of individual models of constrained TKR. Conclusions: The survival rates of unlinked constrained and hinge knee prostheses are similar when matched by age or diagnosis. In complex TKR instability cases, surgeons should feel confident in choosing the appropriate prosthesis to gain a stable knee and need not be concerned that a hinge prosthesis may carry a higher revision rate.

scholarly journals Clinicopathological Characteristics and Prognostic Prediction in Pseudomyxoma Peritonei Originating From Mucinous Ovarian Cancer

2021 ◽  
Vol 11 ◽  
Author(s):  
Fengxian Fu ◽  
Xulan Ma ◽  
Yiyan Lu ◽  
Hongbin Xu ◽  
Ruiqing Ma
Keyword(s):  
Ovarian Cancer ◽  
Pseudomyxoma Peritonei ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Survival Rates ◽  
Clinicopathological Characteristics ◽  
Cox Proportional Hazards ◽  
Cox Proportional Hazards Model ◽  
Rank Test ◽  
Hazards Model

ObjectiveTo describe the clinicopathological characteristics of mucinous ovarian cancer (MOC)-derived pseudomyxoma peritonei (PMP) and identify prognostic factors for survival.MethodsMedical records from patients with MOC-derived PMP who attended the Aerospace Center Hospital, Beijing, China between January 2009, and December 2019 were retrospectively reviewed. Survival analysis was performed with the Kaplan-Meier method, the log-rank test, and a Cox proportional hazards model.ResultsCytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for PMP originating from MOC were performed on 22 patients, who had a median age of 52 years at the time of surgery. At the last follow-up in June 2020, 9 (41%) patients were still alive. Median OS was 12 months (range, 1 to 102 months), and the 2-, 3-, and 5-year survival rates were 23, 9, and 5%, respectively.ConclusionHistopathologic subtype and PCI may be applied as predictors of prognosis in patients with MOC-derived PMP. Patients with high-grade disease could benefit from completeness of cytoreduction (CCR) 0/1.

scholarly journals Risk Indicators Affecting the Survival of the Mandibular First Molar Adjacent to an Implant at the Mandibular Second Molar Site: A Retrospective Study

2021 ◽  
Vol 10 (12) ◽  
pp. 2543
Author(s):  
Won-Bae Park ◽  
Koo-Hyun Kwon ◽  
Kyung-Gyun Hwang ◽  
Ji-Young Han
Keyword(s):  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Survival Rates ◽  
Contralateral Side ◽  
Cox Proportional Hazards ◽  
Cox Proportional Hazards Model ◽  
Risk Indicators ◽  
Second Molar ◽  
Hazards Model ◽  
Mandibular Second Molar

This study aimed to compare the survival of mandibular first molars (MnM1s) adjacent to implants placed in mandibular second molar sites (ImM2s) with MnM1s adjacent to mandibular second molars (MnM2s) and to investigate risk indicators affecting the survival of MnM1s adjacent to ImM2s. A total of 144 patients who had MnM1s adjacent to ImM2s and MnM1s adjacent to MnM2s on the contralateral side were included in this study. Clinical variables and radiographic bone levels were evaluated. The survival of MnM1s adjacent to ImM2s or MnM2s was evaluated using a Kaplan–Meier analysis and Cox proportional hazards model. The 5-year cumulative survival rates of MnM1s adjacent to ImM2s and MnM2s were 85% and 95%, respectively. MnM1s adjacent to ImM2s of the internal implant-abutment connection type had higher multivariate hazard ratios (HR) for loss. MnM1s that had antagonists with implant-supported prostheses also had higher HR for loss. The multivariate HR for the loss of MnM1s adjacent to ImM2s with peri-implant mucositis was 3.74 times higher than MnM1s adjacent to healthy ImM2s. This study demonstrated several risk indicators affecting the survival of MnM1s adjacent to ImM2s. It is suggested that supportive periodontal and peri-implant therapy combined with meticulous occlusal adjustment can prolong the survival of MnM1s and ImM2s.

Modelling heterogeneity in survival data

1991 ◽  
Vol 28 (3) ◽  
pp. 695-701 ◽  
Author(s):  
Philip Hougaard
Keyword(s):  
Survival Data ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Mixture Distribution ◽  
Survival Models ◽  
Risk Of Death ◽  
Hazards Model ◽  
Occupational Mortality ◽  
Heterogeneity Distribution ◽  
Biased Estimates

Ordinary survival models implicitly assume that all individuals in a group have the same risk of death. It may, however, be relevant to consider the group as heterogeneous, i.e. a mixture of individuals with different risks. For example, after an operation each individual may have constant hazard of death. If risk factors are not included, the group shows decreasing hazard. This offers two fundamentally different interpretations of the same data. For instance, Weibull distributions with shape parameter less than 1 can be generated as mixtures of constant individual hazards. In a proportional hazards model, neglect of a subset of the important covariates leads to biased estimates of the other regression coefficients. Different choices of distributions for the unobserved covariates are discussed, including binary, gamma, inverse Gaussian and positive stable distributions, which show both qualitative and quantitative differences. For instance, the heterogeneity distribution can be either identifiable or unidentifiable. Both mathematical and interpretational consequences of the choice of distribution are considered. Heterogeneity can be evaluated by the variance of the logarithm of the mixture distribution. Examples include occupational mortality, myocardial infarction and diabetes.

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