Analysis of Grouped Survival Data: A Synthesis of Various Traditions and Application to Modeling Childhood Mortality in Eritrea

2013 ◽  
pp. 107-122
Author(s):  
Gebrenegus Ghilagaber
Keyword(s):  
Survival Data ◽  
Childhood Mortality

scholarly journals Approximation of the Cox survival regression model by MCMC Bayesian Hierarchical Poisson modelling of factors associated with childhood mortality in Nigeria

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
A. F. Fagbamigbe ◽  
M. M. Salawu ◽  
S. M. Abatan ◽  
O. Ajumobi
Keyword(s):  
Regression Model ◽  
Survival Data ◽  
Poisson Regression ◽  
Maternal Education ◽  
Contextual Factors ◽  
Childhood Mortality ◽  
Bayesian Hierarchical ◽  
Under Five ◽  
Factors Associated ◽  
Survival Regression

AbstractThe need for more pragmatic approaches to achieve sustainable development goal on childhood mortality reduction necessitated this study. Simultaneous study of the influence of where the children live and the censoring nature of children survival data is scarce. We identified the compositional and contextual factors associated with under-five (U5M) and infant (INM) mortality in Nigeria from 5 MCMC Bayesian hierarchical Poisson regression models as approximations of the Cox survival regression model. The 2018 DHS data of 33,924 under-five children were used. Life table techniques and the Mlwin 3.05 module for the analysis of hierarchical data were implemented in Stata Version 16. The overall INM rate (INMR) was 70 per 1000 livebirths compared with U5M rate (U5MR) of 131 per 1000 livebirth. The INMR was lowest in Ogun (17 per 1000 live births) and highest in Kaduna (106), Gombe (112) and Kebbi (116) while the lowest U5MR was found in Ogun (29) and highest in Jigawa (212) and Kebbi (248). The risks of INM and U5M were highest among children with none/low maternal education, multiple births, low birthweight, short birth interval, poorer households, when spouses decide on healthcare access, having a big problem getting to a healthcare facility, high community illiteracy level, and from states with a high proportion of the rural population in the fully adjusted model. Compared with the null model, 81% vs 13% and 59% vs 35% of the total variation in INM and U5M were explained by the state- and neighbourhood-level factors respectively. Infant- and under-five mortality in Nigeria is influenced by compositional and contextual factors. The Bayesian hierarchical Poisson regression model used in estimating the factors associated with childhood deaths in Nigeria fitted the survival data.

scholarly journals Survival of children with sickle cell disease

Blood ◽  
2004 ◽  
Vol 103 (11) ◽  
pp. 4023-4027 ◽  
Author(s):  
Charles T. Quinn ◽  
Zora R. Rogers ◽  
George R. Buchanan
Keyword(s):  
Sickle Cell Disease ◽  
Sickle Cell ◽  
Survival Data ◽  
Childhood Mortality ◽  
Age At Death ◽  
Cell Disease ◽  
Inception Cohort ◽  
Free Survival ◽  
Hemoglobin C ◽  
The Mean

Abstract Contemporary survival data are not available for children with sickle cell disease (SCD). The few previous childhood SCD cohort studies do not reflect the benefits of modern therapy. We defined an inception cohort of newborns with sickle cell anemia (SS), sickle-β°-thalassemia (S β°), sickle-hemoglobin C disease (SC), or sickle-β+-thalassemia (Sβ+) who were identified by newborn screening and followed for up to 18 years. The incidence of death and stroke were calculated. Overall survival, SCD-related survival (considering only SCD-related deaths), and strokefree survival were determined. The 711 subjects provided 5648 patient-years of observation. Twenty-five subjects died; mean age at death was 5.6 years. Five patients died from infection. Thirty had at least one stroke. Among SS and Sβ° subjects (n = 448), the overall rates of death and stroke were 0.59 and 0.85/100 patient-years. Survival analysis of SS and Sβ° subjects predicted the cumulative overall, SCD-related, and stroke-free survival to be 85.6%, 93.6%, and 88.5% by 18 years of age. No SCD-related deaths or strokes occurred in SC or Sβ+ subjects (n = 263). Childhood mortality from SCD is decreasing, the mean age at death is increasing, and a smaller proportion of deaths are from infection.

The Effect of Partly Missing Covariates on Statistical Power in Randomized Controlled Trials With Discrete-Time Survival Endpoints

Methodology ◽  
2017 ◽  
Vol 13 (2) ◽  
pp. 41-60
Author(s):  
Shahab Jolani ◽  
Maryam Safarkhani
Keyword(s):  
Randomized Controlled Trials ◽  
Discrete Time ◽  
Treatment Effect ◽  
Survival Data ◽  
Controlled Trials ◽  
Missing Covariates ◽  
Indicator Method ◽  
Imputation Methods ◽  
Randomized Controlled ◽  
Baseline Covariates

Abstract. In randomized controlled trials (RCTs), a common strategy to increase power to detect a treatment effect is adjustment for baseline covariates. However, adjustment with partly missing covariates, where complete cases are only used, is inefficient. We consider different alternatives in trials with discrete-time survival data, where subjects are measured in discrete-time intervals while they may experience an event at any point in time. The results of a Monte Carlo simulation study, as well as a case study of randomized trials in smokers with attention deficit hyperactivity disorder (ADHD), indicated that single and multiple imputation methods outperform the other methods and increase precision in estimating the treatment effect. Missing indicator method, which uses a dummy variable in the statistical model to indicate whether the value for that variable is missing and sets the same value to all missing values, is comparable to imputation methods. Nevertheless, the power level to detect the treatment effect based on missing indicator method is marginally lower than the imputation methods, particularly when the missingness depends on the outcome. In conclusion, it appears that imputation of partly missing (baseline) covariates should be preferred in the analysis of discrete-time survival data.

Gamma Knife surgery combined with resection for treatment of a single brain metastasis: preliminary results

2010 ◽  
Vol 113 (Special_Supplement) ◽  
pp. 90-96 ◽  
Author(s):  
M. Yashar S. Kalani ◽  
Aristotelis S. Filippidis ◽  
Maziyar A. Kalani ◽  
Nader Sanai ◽  
David Brachman ◽  
...  
Keyword(s):  
Survival Data ◽  
Initial Treatment ◽  
Median Survival Time ◽  
Local Tumor Control ◽  
Survival Duration ◽  
Tumor Control ◽  
Local Tumor ◽  
Systemic Control ◽  
Cranial Metastasis

Object Resection and whole-brain radiation therapy (WBRT) have classically been the standard treatment for a single metastasis to the brain. The objective of this study was to evaluate the use of Gamma Knife surgery (GKS) as an alternative to WBRT in patients who had undergone resection and to evaluate patient survival and local tumor control. Methods The authors retrospectively reviewed the charts of 150 patients treated with a combination of stereotactic radiosurgery and resection of a cranial metastasis at their institution between April 1997 and September 2009. Patients who had multiple lesions or underwent both WBRT and GKS were excluded, as were patients for whom survival data beyond the initial treatment were not available. Clinical and imaging follow-up was assessed using notes from clinic visits and MR imaging studies when available. Follow-up data beyond the initial treatment and survival data were available for 68 patients. Results The study included 37 women (54.4%) and 31 men (45.6%) (mean age 60 years, range 28–89 years). In 45 patients (66.2%) there was systemic control of the primary tumor when the cranial metastasis was identified. The median duration between resection and radiosurgery was 15.5 days. The median volume of the treated cavity was 10.35 cm3 (range 0.9–45.4 cm3), and the median dose to the cavity margin was 15 Gy (range 14–30 Gy), delivered to the 50% isodose line (range 50%–76% isodose line). The patients' median preradiosurgery Karnofsky Performance Scale (KPS) score was 90 (range 40–100). During the follow-up period we identified 27 patients (39.7%) with recurrent tumor located either local or distant to the site of treatment. The median time from primary treatment of metastasis to recurrence was 10.6 months. The patients' median length of survival (interval between first treatment of cerebral metastasis and last follow-up) was 13.2 months. For the patient who died during follow-up, the median time from diagnosis of cerebral metastasis to death was 11.5 months. The median duration of survival from diagnosis of the primary cancer to last follow-up was 30.2 months. Patients with a pretreatment KPS score ≥ 90 had a median survival time of 23.2 months, and patients with a pretreatment KPS score < 90 had a median survival time of 10 months (p < 0.008). Systemic control of disease at the time of metastasis was not predictive of increased survival duration, although it did tend to improve survival. Conclusions Although the debate about the ideal form of radiation treatment after resection continues, these findings indicate that GKS combined with surgery offers comparable survival duration and local tumor control to WBRT for patients with a diagnosis of a single metastasis.

Gamma Knife surgery for the treatment of melanoma metastases: the effect of intratumoral hemorrhage on survival

2008 ◽  
Vol 109 (Supplement) ◽  
pp. 99-105 ◽  
Author(s):  
Andy J. Redmond ◽  
Michael L. DiLuna ◽  
Ryan Hebert ◽  
Jennifer A. Moliterno ◽  
Rani Desai ◽  
...  
Keyword(s):  
Gamma Knife ◽  
Survival Data ◽  
Tumor Burden ◽  
Gamma Knife Surgery ◽  
Survival Sex ◽  
Whole Brain Radiation ◽  
Melanoma Metastases ◽  
History Of ◽  
Independent Association ◽  
Intratumoral Bleeding

Object Gamma Knife surgery (GKS) improves overall survival in patients with malignant melanoma metastatic to the brain. In this study the authors investigated which patient- or treatment-specific factors influence survival of patients with melanoma brain metastases; they pay particular interest to pre- and post-GKS hemorrhage. Methods Demographic, treatment, and survival data on 59 patients with a total of 208 intracranial metastases who underwent GKS between 1998 and 2007 were abstracted from treatment records and from the Connecticut Tumor Registry. Multivariate analysis was used to identify factors that independently affected survival. Results Survival was significantly better in patients with solitary metastasis (p = 0.04), lesions without evidence of pre-GKS hemorrhage (p = 0.004), and in patients with total tumor volume treated < 4 cm3 (p = 0.02). Intratumoral bleeding occurred in 23.7% of patients pre-GKS. Intratumoral bleeding occurred at a mean of 1.8 months post-GKS at a rate of 15.2%. Unlike the marked effect of pretreatment bleeding, posttreatment bleeding did not independently affect survival. Sex, systemic control, race, metastases location, whole-brain radiation therapy, chemotherapy, history of antithrombotic medications, and cranial surgery had no independent association with survival. Conclusions These data corroborate previous findings that tumor burden (either as increased number or total volume of lesions) at the time of GKS is associated with diminished patient survival in those with intracerebral melanoma metastases. Patients who were noted to have hemorrhagic melanoma metastases prior to GKS appear to have a worse prognosis following GKS compared with patients with nonhemorrhagic metastases, despite similar rates of bleeding pre- and post-GKS treatment. Gamma Knife surgery itself does not appear to increase the rate of hemorrhage.

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