On the use and utility of the Weibull model in the analysis of survival data

Carroll, Kevin

doi:10.1016/s0197-2456(03)00072-2

Cited by 210 publications

(169 citation statements)

References 16 publications

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“…Additionally, the determination of age of breast development used a somewhat novel application of a well-established approach, an accelerated failure time model (specifically the Weibull model), which both allows determination of event rates as well as extension in survival time. 8 The direct comparison of our participants, from a longitudinal study, with participants from 2 cross-sectional studies that used different BMI standards from this study, might appear to be of limited relevance; when we excluded our participants with elevated BMI, the BMI distribution is similar to the results reported by Kaplowitz et al 3 and by Rosenfield et al, 4 and the remaining participants had similar age of breast maturation. Unlike the NHANES III and most (61%) of PROS participants, we used breast palpation for all of our participants, but this should have increased the age of breast development, rather than decreased it.…”

Section: Figuresupporting

confidence: 65%

Onset of Breast Development in a Longitudinal Cohort

et al. 2013

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BACKGROUND AND OBJECTIVES: There is growing evidence of pubertal maturation occurring at earlier ages, with many studies based on cross-sectional observations. This study examined age at onset of breast development (thelarche), and the impact of BMI and race/ethnicity, in the 3 puberty study sites of the Breast Cancer and the Environment Research Program, a prospective cohort of >1200 girls. METHODS: Girls, 6 to 8 years at enrollment, were followed longitudinally at regular intervals from 2004 to 2011 in 3 geographic areas: the San Francisco Bay Area, Greater Cincinnati, and New York City. Sexual maturity assessment using Tanner staging was conducted by using standardized observation and palpation methods by trained and certified staff. Kaplan-Meier analyses were used to describe age at onset of breast maturation by covariates. RESULTS: The age at onset of breast stage 2 varied by race/ethnicity, BMI at baseline, and site. Median age at onset of breast stage 2 was 8.8, 9.3, 9.7, and 9.7 years for African American, Hispanic, white non-Hispanic, and Asian participants, respectively. Girls with greater BMI reached breast stage 2 at younger ages. Age-specific and standardized prevalence of breast maturation was contrasted to observations in 2 large cross-sectional studies conducted 10 to 20 years earlier (Pediatric Research in Office Settings and National Health and Nutrition Examination Survey III) and found to have occurred earlier among white, non-Hispanic, but not African American girls. CONCLUSIONS: We observed the onset of thelarche at younger ages than previously documented, with important differences associated with race/ethnicity and BMI, confirming and extending patterns seen previously. These findings are consistent with temporal changes in BMI.

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Section: Figuresupporting

confidence: 65%

Onset of Breast Development in a Longitudinal Cohort

et al. 2013

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“…This method is the most popular method for measuring statistical events involving data with timeframes [17]. Alpha is an interpretation of probability of 63.2% that the event will occur.…”

Section: Methodsmentioning

confidence: 99%

Survival Prediction for Romanian Patients with Pancreatic Cancer

Timofte¹,

Blaj²,

Petrariu³

et al. 2017

Surgery

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Journal of Surgery IntroductionPancreatic cancer is one of the most lethal malignancies worldwide, and ranks fourth in the total number of deaths related to cancer in patients of both genders. Moreover, in 2013 the United States registered about 45,000 new cases, and reported that the number of expected deaths was very similar to the number of new cases. Also, the median overall survival at 5 years is between 2 and 6% [1].Also, adenocarcinoma of the pancreas is the most common type of pancreatic neoplasm, with all of its subtypes accounting for 85% of cases [1,2].Currently, curative treatment is only possible in cases of resectable disease and during the initial stages [3]. Still, although complete surgical resection is the only potential curative approach of this disease, it can only be performed in 10 to 20% of patients, since most individuals present with advanced disease upon diagnosis [3,4]. Moreover, after surgical resection, 7 to 25% of patients have a 5-year survival rate [5], with better results in individuals which undergo curative resection (R0) [6].The prognosis for the patients with pancreatic cancer and which have indication for the resection with curative intent is determined by the lymphatic metastasis, the invasion of vascular walls and the peripancreatic nerve plexus or also by the degree of the micrometastases in nearby tissues and organs.As we mentioned before, unfortunately 95% of patients come to the doctor when the cancer is advanced and unresectable [7][8][9]. Moreover, in the recent decades the development of surgical techniques have only improved postoperative mortality, without having any significant impact on the survival, with specialized pancreatic surgery centres reporting a mortality below 5% [10,11].Approximately 60% of pancreatic cancers have cephalic location. With the reduction of operative mortality after duodenopancreatectomies, improved survival rates of 30% were reported [12], which is three times higher than previously published results [13,14]. AbstractPancreatic cancer is one of the most lethal malignancies worldwide and in some of the latest statistics ranks fourth in the total number of deaths related to cancer in patients of both genders. Currently, curative treatment is only possible in cases of resectable disease and during the initial stages. Still, although complete surgical resection is the only potential curative approach of this disease, it can only be performed in 10 to 20% of patients, since most individuals present with advanced disease upon diagnosis. Moreover, in the recent decades the development and improvement of surgical techniques have only improved postoperative mortality, without having any significant impact on the survival, with specialized pancreatic surgery centres reporting mortality below 5%. In this way, in the present study conducted on 188 patients from the "St. Spiridon" Clinical Emergency Hospital Iasi, we were interested in determining the survival rates in pancreatic cancer, as well as looking at the staging criteria for adenocarcinom...

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“…The estimated date of thelarche was calculated as the date associated with the median probability over the breast development interval. These probabilities were calculated for each girl by using an SAS macro developed by us, which incorporated s (s, the scale parameter of the Weibull distribution from LIFEREG) 8 and the x ' B matrix for the girl, and the dates at the beginning and end of her thelarche interval.…”

Section: Methodsmentioning

confidence: 99%

Onset of Breast Development in a Longitudinal Cohort

2013

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On the use and utility of the Weibull model in the analysis of survival data

Cited by 210 publications

References 16 publications

Onset of Breast Development in a Longitudinal Cohort

Onset of Breast Development in a Longitudinal Cohort

Survival Prediction for Romanian Patients with Pancreatic Cancer

Onset of Breast Development in a Longitudinal Cohort

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