The sequential comparison of survival curves

Biometrika ◽  
1980 ◽  
Vol 67 (1) ◽  
pp. 247-249 ◽  
Author(s):  
N. J. D. NAGELKERKE ◽  
A. A. M. HART
Keyword(s):  
Survival Curves ◽  
Sequential Comparison

On large sample sequential analysis with applications to survivorship data

1969 ◽  
Vol 6 (2) ◽  
pp. 261-274 ◽  
Author(s):  
Norman Breslow
Keyword(s):  
Random Walk ◽  
Sequential Analysis ◽  
Research Problem ◽  
Maximum Likelihood Estimates ◽  
Sequential Testing ◽  
Survival Curves ◽  
Large Sample ◽  
Large Sample Theory ◽  
Composite Hypotheses ◽  
Sequential Comparison

Although his work on the application of invariance concepts to the sequential testing of composite hypotheses is better known, Cox (1963) has also outlined a large sample approach to the same problem. His method is based on Bartlett's (1946) recognition that the sequence of maximum likelihood estimates (MLE) of the parameter of interest, calculated from an increasing number of observations, resembles asymptotically a random walk of normally distributed variables. However, the large sample theory needed to justify this approach rigorously is left largely implicit. At the end of his paper, Cox suggests that these methods may be extended to yield a sequential comparison of survival curves (Armitage (1959)), a suggestion which has been reiterated as a research problem in the monograph of Wetherill (1966).

On large sample sequential analysis with applications to survivorship data

1969 ◽  
Vol 6 (02) ◽  
pp. 261-274 ◽  
Author(s):  
Norman Breslow
Keyword(s):  
Random Walk ◽  
Sequential Analysis ◽  
Research Problem ◽  
Maximum Likelihood Estimates ◽  
Sequential Testing ◽  
Survival Curves ◽  
Large Sample ◽  
Large Sample Theory ◽  
Composite Hypotheses ◽  
Sequential Comparison

Although his work on the application of invariance concepts to the sequential testing of composite hypotheses is better known, Cox (1963) has also outlined a large sample approach to the same problem. His method is based on Bartlett's (1946) recognition that the sequence of maximum likelihood estimates (MLE) of the parameter of interest, calculated from an increasing number of observations, resembles asymptotically a random walk of normally distributed variables. However, the large sample theory needed to justify this approach rigorously is left largely implicit. At the end of his paper, Cox suggests that these methods may be extended to yield a sequential comparison of survival curves (Armitage (1959)), a suggestion which has been reiterated as a research problem in the monograph of Wetherill (1966).

scholarly journals Thermal Inactivation of Susceptible and Multiantimicrobial-Resistant Salmonella Strains Grown in the Absence or Presence of Glucose

2003 ◽  
Vol 69 (7) ◽  
pp. 4123-4128 ◽  
Author(s):  
R. T. Bacon ◽  
J. R. Ransom ◽  
J. N. Sofos ◽  
P. A. Kendall ◽  
K. E. Belk ◽  
...  
Keyword(s):  
Heat Stress ◽  
Protective Effect ◽  
Thermal Tolerance ◽  
Thermal Inactivation ◽  
Survival Curves ◽  
Acid Adaptation ◽  
Circulating Water ◽  
Glucose Levels ◽  
Study Results ◽  
Peptone Water

ABSTRACT The heat resistance of susceptible and multiantimicrobial-resistant Salmonella strains grown to stationary phase in glucose-free tryptic soy broth supplemented with 0.6% yeast extract (TSBYE−G; nonadapted), in regular (0.25% glucose) TSBYE, or in TSBYE−G with 1.00% added glucose (TSBYE+G; acid adapted) was determined at 55, 57, 59, and 61°C. Cultures were heated in sterile 0.1% buffered peptone water (50 μl) in heat-sealed capillary tubes immersed in a thermostatically controlled circulating-water bath. Decimal reduction times (D values) were calculated from survival curves having r 2 values of >0.90 as a means of comparing thermal tolerance among variables. D 59°C values increased (P < 0.05) from 0.50 to 0.58 to 0.66 min for TSBYE−G, TSBYE, and TSBYE+G cultures, respectively. D 61°C values of antimicrobial-susceptible Salmonella strains increased (P < 0.05) from 0.14 to 0.19 as the glucose concentration increased from 0.00 to 1.00%, respectively, while D 61°C values of multiantimicrobial-resistant Salmonella strains did not differ (P > 0.05) between TSBYE−G and TSBYE+G cultures. When averaged across glucose levels and temperatures, there were no differences (P > 0.05) between the D values of susceptible and multiantimicrobial-resistant inocula. Collectively, D values ranged from 4.23 to 5.39, 1.47 to 1.81, 0.50 to 0.66, and 0.16 to 0.20 min for Salmonella strains inactivated at 55, 57, 59, and 61°C, respectively. zD values were 1.20, 1.48, and 1.49°C for Salmonella strains grown in TSBYE+G, TSBYE, and TSBYE−G, respectively, while the corresponding activation energies of inactivation were 497, 493, and 494 kJ/mol. Study results suggested a cross-protective effect of acid adaptation on thermal inactivation but no association between antimicrobial susceptibility and the ability of salmonellae to survive heat stress.

Outcomes of management of major aortopulmonary collaterals for pulmonary atresia and ventricular septal defect

2020 ◽  
pp. 1-9
Author(s):  
Dong Zhao ◽  
Keming Yang ◽  
Wei Feng ◽  
Shoujun Li ◽  
Jun Yan ◽  
...  
Keyword(s):  
Ventricular Septal Defect ◽  
Pulmonary Artery ◽  
Septal Defect ◽  
Pulmonary Atresia ◽  
Survival Curves ◽  
Major Aortopulmonary Collateral Arteries ◽  
Palliative Procedure ◽  
Collateral Arteries ◽  
Kaplan Meier ◽  
Aortopulmonary Collateral

Abstract Objective: This study aimed to investigate the association between long-term survival and different management of major aortopulmonary collateral arteries in patients with pulmonary atresia, ventricular septal defect, and major aortopulmonary collateral arteries. Methods: From November, 2009 to October, 2018, a total of 98 consecutive patients with pulmonary atresia, ventricular septal defect, major aortopulmonary collateral arteries, and hypoplastic pulmonary arteries treated with modified Blalock–Taussig shunt or right ventricle–pulmonary artery connection were included. Fifty-five patients who received occlusion or ligation of major aortopulmonary collateral arteries during or after palliative procedure were occlusion group, and the other 43 patients were no occlusion group. The early and late outcomes were compared. Results: The mean duration of follow-up was 30.9 months in no occlusion group and 49.8 months in the occlusion group (p < 0.001). Multivariate analysis showed that only no occlusion of major aortopulmonary collateral arteries was predictive of total mortality (Hazard Ratio: 4.42, 95% CI: 1.27 to 15.42, p = 0.02). The Kaplan–Meier survival curves confirmed that patients without occlusion of major aortopulmonary collateral arteries demonstrated worse survival as compared with the occlusion group (p = 0.013). The Kaplan–Meier survival curves of patients who underwent different palliative procedures showed no differences. Conclusions: For patients with pulmonary atresia, ventricular septal defect and major aortopulmonary collateral arteries when a primary repair is not feasible, those without occlusion of major aortopulmonary collateral arteries have a higher risk of death following an initial palliative procedure compared with patients who underwent occlusion of major aortopulmonary collateral arteries. The occlusion of major aortopulmonary collateral arteries is not associated with a higher rate of complete repair or better improvement of pulmonary artery growth.

scholarly journals The role of EORTC QLQ-C15-PAL scores and inflammatory biomarkers in predicting survival in terminally ill patients with cancer

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nanako Koyama ◽  
Chikako Matsumura ◽  
Yoshihiro Shitashimizu ◽  
Morito Sako ◽  
Hideo Kurosawa ◽  
...  
Keyword(s):  
Patient Reported Outcomes ◽  
Cox Regression ◽  
Terminally Ill ◽  
Inflammatory Biomarkers ◽  
Survival Curves ◽  
Patients With Cancer ◽  
Terminally Ill Patients ◽  
Patient Reported ◽  
Eortc Qlq

Abstract Background The clinical use of patient-reported outcomes as compared to inflammatory biomarkers for predicting cancer survival remains a challenge in palliative care settings. We evaluated the role of the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 15 Palliative scores (EORTC QLQ-C15-PAL) and the inflammatory biomarkers C-reactive protein (CRP), albumin (Alb), and neutrophil-lymphocyte ratio (NLR) for survival prediction in patients with advanced cancer. Methods This was an observational study in terminally ill patients with cancer hospitalized in a palliative care unit between June 2018 and December 2019. Patients’ data collected at the time of hospitalization were analyzed. Cox regression was performed to examine significant factors influencing survival. A receiver operating characteristic (ROC) analysis was performed to estimate cut-off values for predicting survival within 3 weeks, and a log-rank test was performed to compare survival curves between groups divided by the cut-off values. Results Totally, 130 patients participated in the study. Cox regression suggested that the QLQ-C15-PAL dyspnea and fatigue scores and levels of CRP, Alb, and NLR were significantly associated with survival time, and cut-off values were 66.67, 66.67, 3.0 mg/dL, 2.5 g/dL, and 8.2, respectively. The areas under ROC curves of these variables were 0.6–0.7. There were statistically significant differences in the survival curves between groups categorized using each of these cut-off values (p < .05 for all cases). Conclusion Our findings suggest that the assessment of not only objective indicators for the systemic inflammatory response but also patient-reported outcomes using EORTC QLQ-C15-PAL is beneficial for the prediction of short-term survival in terminally ill patients with cancer.

Surgical Indication Optimization of Brain Metastases Based on the Evolutionary Analysis of Karnofsky Performance Status

2021 ◽  
Author(s):  
Jorge Rasmussen ◽  
Pablo Ajler ◽  
Daniela Massa ◽  
Pedro Plou ◽  
Matteo Baccanelli ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Functional Status ◽  
Surgical Resection ◽  
Pharmacological Treatment ◽  
Karnofsky Performance Status ◽  
Performance Status ◽  
Cohort Analysis ◽  
Surgical Indication ◽  
Evolutionary Analysis ◽  
Survival Curves

Abstract Background and Objective Surgical resection of brain metastases (BM) offers the highest rates of local control and survival; however, it is reserved for patients with good functional status. In particular, the presence of BM tends to oversize the detriment of the overall functional status, causing neurologic deterioration, potentially reversible following symptomatic pharmacological treatment. Thus, a timely indication of surgical resection may be dismissed. We propose to identify and quantify these variations in the functional status of patients with symptomatic BM to optimize the indication of surgical resection. Patients and Methods Historic, retrospective cohort analysis of adult patients undergoing BM microsurgical resection, consecutively from January 2012 to May 2016, was conducted. The Karnofsky performance status (KPS) variation was recorded according to the symptomatic evolution of each patient at specific moments of the diagnostic–therapeutic algorithm. Finally, survival curves were delineated for the main identified factors. Results One hundred and nineteen resection surgeries were performed. The median overall survival was 243 days, while on average it was 305.7 (95% confidence interval [CI]: 250.6–360.9) days. The indication of surgical resection of 10% of the symptomatic patients in our series (7.5% of overall) could have been initially rejected due to pharmacologically reversible neurologic impairment. Survival curves showed statistically significant differences when KPS was stratified following pharmacological symptomatic treatment (p < 0.0001), unlike when they were estimated at the time of BM diagnosis (p = 0.1128). Conclusion The preoperative determination of the functional status by KPS as an evolutive parameter after the nononcologic symptomatic pharmacological treatment allowed us to optimize the surgical indication of patients with symptomatic BM.

A SAS macro for the analysis of cell survival curves

2002 ◽  
Vol 67 (3) ◽  
pp. 201-207
Author(s):  
Mohammad A Chaudhary ◽  
Mohammad A Hannan
Keyword(s):  
Cell Survival ◽  
Survival Curves ◽  
Sas Macro
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