SEMI-NONPARAMETRIC INTERVAL-CENSORED MIXED PROPORTIONAL HAZARD MODELS: IDENTIFICATION AND CONSISTENCY RESULTS

2008 ◽  
Vol 24 (3) ◽  
pp. 749-794 ◽  
Author(s):  
Herman J. Bierens
Keyword(s):  
Legendre Polynomials ◽  
Unobserved Heterogeneity ◽  
Unit Interval ◽  
Hazard Models ◽  
Nonparametric Identification ◽  
Proportional Hazard ◽  
Proportional Hazard Models ◽  
Consistency Results ◽  
Interval Censored ◽  
Mixed Proportional Hazard Models

In this paper I propose estimating distributions on the unit interval semi-nonparametrically using orthonormal Legendre polynomials. This approach will be applied to the interval-censored mixed proportional hazard (ICMPH) model, where the distribution of the unobserved heterogeneity is modeled semi-nonparametrically. Various conditions for the nonparametric identification of the ICMPH model are derived. I will prove general consistency results for M-estimators of (partly) non-euclidean parameters under weak and easy-to-verify conditions and specialize these results to sieve estimators. Special attention is paid to the case where the support of the covariates is finite.

Urn sampling, interval censoring and proportional hazard models

2009 ◽  
Vol 9 (4) ◽  
pp. 361-379
Author(s):  
Lu Zheng ◽  
Marvin Zelen
Keyword(s):  
Survival Data ◽  
Interval Censoring ◽  
Interval Length ◽  
Hazard Models ◽  
Proportional Hazard ◽  
Survival Times ◽  
Proportional Hazard Models ◽  
Interval Censored ◽  
The Mean ◽  
Censored Observations

This paper proposes a new distribution-free statistical method for testing hypotheses about covariates for survival data having simultaneously right-, left- and interval-censored survival times. The new test is motivated by the analogue between urn sampling and the Cox’s proportional hazard models. Investigations of the significance levels and power as a function of the proportion of interval-censored observations and interval length show that the test performs well for most censoring situations encountered in practice. Simulation results also suggest that there is negligible loss of power in the practical situation in which the mean interval length for interval-censored observations is less than the mean survival time. This holds even with heavy interval censoring. Comparison with the widely used Mantel’s method for comparing two groups shows that the power of the new method appears to be superior. Furthermore, the test is relatively simple to carry out and generalizes to comparing k populations as well as the testing of general linear hypothesis for arbitrary covariates.

scholarly journals LAMB1 Is Related to the T Stage and Indicates Poor Prognosis in Gastric Cancer

2021 ◽  
Vol 20 ◽  
pp. 153303382110049
Author(s):  
Tao Ran ◽  
ZhiJi Chen ◽  
LiWen Zhao ◽  
Wei Ran ◽  
JinYu Fan ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Poor Prognosis ◽  
Hazard Models ◽  
Proportional Hazard ◽  
Kegg Analysis ◽  
Proportional Hazard Models ◽  
Cox Proportional Hazard ◽  
Kaplan Meier ◽  
Cox Proportional Hazard Models ◽  
Gastric Cancer Patients

Background and Objective: Gastric cancer (GC) is a common tumor malignancy with high incidence and poor prognosis. Laminin is an indispensable component of basement membrane and extracellular matrix, which is responsible for bridging the internal and external environment of cells and transmitting signals. This study mainly explored the association of the LAMB1 expression with clinicopathological characteristics and prognosis in gastric cancer. Methods: The expression data and clinical information of gastric cancer patients were downloaded from The Cancer Genome Atlas (TCGA) and Asian Cancer Research Group (ACRG). And we analyzed the relationship between LAMB1 expression and clinical characteristics through R. CIBERSORTx was used to calculate the absolute score of immune cells in gastric tumor tissues. Then COX proportional hazard models and Kaplan-Meier curves were performed to evaluate the role of LAMB1 and its influence on prognosis in gastric cancer patients. Finally, GO and KEGG analysis were applied for LAMB1-related genes in gastric cancer, and PPI network was constructed in Cytoscape software. Results: In the TCGA cohort, patients with gastric cancer frequently generated LAMB1 gene copy number variation, but had little effect on mRNA expression. Both in the TCGA and ACRG cohorts, the mRNA expression of LAMB1 in gastric cancer tissues was higher than it in normal tissues. All patients were divided into high expression group and low expression group according to the median expression level of LAMB1. The elevated expression group obviously had more advanced cases and higher infiltration levels of M2 macrophages. COX proportional hazard models and Kaplan-Meier curves revealed that patients with enhanced expression of LAMB1 have a worse prognosis. GO/KEGG analysis showed that LAMB1-related genes were enriched in PI3K-Akt signaling pathway, focal adhesion, ECM-receptor interaction, etc. Conclusions: The high expression of LAMB1 in gastric cancer is related to the poor prognosis of patients, and it may be related to microenvironmental changes in tumors.

scholarly journals Low rather than high mean corpuscular volume is associated with mortality in Japanese patients under hemodialysis

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Hirokazu Honda ◽  
Miho Kimachi ◽  
Noriaki Kurita ◽  
Nobuhiko Joki ◽  
Masaomi Nangaku
Keyword(s):  
Mean Corpuscular Volume ◽  
Japanese Patients ◽  
Cubic Spline ◽  
Hazard Models ◽  
Proportional Hazard ◽  
Corpuscular Volume ◽  
Proportional Hazard Models ◽  
Cox Proportional Hazard ◽  
All Cause Mortality ◽  
Cox Proportional Hazard Models

Abstract Recent studies have reported that high mean corpuscular volume (MCV) might be associated with mortality in patients with advanced chronic kidney disease (CKD). However, the question of whether a high MCV confers a risk for mortality in Japanese patients remains unclear. We conducted a longitudinal analysis of a cohort of 8571 patients using data derived from the Japan Dialysis Outcomes and Practice Patterns Study (J-DOPPS) phases 1 to 5. Associations of all-cause mortality, vascular events, and hospitalization due to infection with baseline MCV were examined via Cox proportional hazard models. Non-linear relationships between MCV and these outcomes were examined using restricted cubic spline analyses. Associations between time-varying MCV and these outcomes were also examined as sensitivity analyses. Cox proportional hazard models showed a significant association of low MCV (< 90 fL), but not for high MCV (102 < fL), with a higher incidence of all-cause mortality and hospitalization due to infection compared with 94 ≤ MCV < 98 fL (reference). Cubic spline analysis indicated a graphically U-shaped association between baseline MCV and all-cause mortality (p for non-linearity p < 0.001). In conclusion, a low rather than high MCV might be associated with increased risk for all-cause mortality and hospitalization due to infection among Japanese patients on hemodialysis.

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