Application of the Weibull Accelerated Failure Time Model in the Determination of Disease-Free Survival Rate of Patients with Breast Cancer

Ghorbani, Narges; Yazdani-Charati, Jamshid; Anvari, Kazem; Nasrin, Ghorbani

doi:10.18869/acadpub.jhs.4.2.11

Cited by 13 publications

(12 citation statements)

References 8 publications

(13 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With many available statistical software packages, such as ‘survival’ and ‘flexsurv’ in R, STATA, SAS, Python, etc., AFT models have become popular in survival data analysis with a wide range of clinical and epidemiological applications. Among others, AFT models have been utilized in acute liver, cancer, and HIV AIDS studies [ 3 , 22 – 25 ]. However, the validity of an inference depends on the realization of model assumptions.…”

Section: Discussionmentioning

confidence: 99%

Accelerated failure-time model with weighted least-squares estimation: application on survival of HIV positives

Mustefa

Chen

2021

Arch Public Health

View full text Add to dashboard Cite

Background Survival analysis is the most appropriate method of analysis for time-to-event data. The classical accelerated failure-time model is a more powerful and interpretable model than the Cox proportional hazards model, provided that model imposed distribution and homoscedasticity assumptions satisfied. However, most of the real data are heteroscedastic which violates the fundamental assumption and consequently, the statistical inference could be erroneous in accelerated failure-time modeling. The weighted least-squares estimation for the accelerated failure-time model is an efficient semi-parametric approach for time-to-event data without the homoscedasticity assumption, which is developed recently and not often utilized for real data analysis. Thus, this study was conducted to ascertain the better performance of the weighted least-squares estimation method over the classical methods. Methods We analyzed a REAL dataset on Antiretroviral Therapy patients we recently collected. We compared the results from classical methods of estimation for the accelerated failure-time model with the results revealed from the weighted least-squares estimation. Results We found that the data are heteroscedastic and indicated that the weighted least-square method should be used to analyze this data. The weighted least-squares estimation revealed more accurate, and efficient estimates of covariates effect since its confidence intervals were shorter and it identified more significant covariates. Accordingly, the survival of HIV positives was found to be significantly linked with age, weight, functional status, CD4 (Cluster of Differentiation agent 4 glycoproteins), and clinical stages. Conclusions The weighted least-squares estimation performed the best in providing more significant effects and precise estimates than the classical accelerated failure-time methods of estimation if data are heteroscedastic. Thus, we recommend future researchers should utilize weighted least-squares estimation rather than the classical methods when the homoscedasticity assumption is violated.

show abstract

Section: Discussionmentioning

confidence: 99%

Accelerated failure-time model with weighted least-squares estimation: application on survival of HIV positives

Mustefa

Chen

2021

Arch Public Health

View full text Add to dashboard Cite

show abstract

“…Therefore, the effect of the predictor variable x is multiplicative (logarithmic) on the time scale, so it is said that this model accelerates (increases or decreases) the estimated average survival time of the specimens studied up to time T, which depends on the effectiveness or ineffectiveness of the treatments evaluated. Said time T is always longer than the duration of the evaluation (Carroll, 2003;Ghorbani et al, 2016;Zhang, 2016). On the other hand, it is also necessary to apply the exponent "time" T(e (T) ) to obtain a linear result of the estimated survival time after the graft evaluation period.…”

Section: Adjustment Of the Weibull Accelerated Failure Time Model Andmentioning

confidence: 99%

“…If λ > 1 the value of HR increases, while HR decreases if λ < 1 (Carroll, 2003;Zhang, 2016). If the value of the hazard ratio is 1.0, means that the risk of death is equal between treatments; if the value of the hazard ratio is less than one, it means a reduction in the risk of death in one of the treatments, while if the hazard ratio is greater than one, the risk of death increases in one of the treatments (Carroll, 2003;Ghorbani et al, 2016) The HR is determined by the following equation (Igl, 2018):…”

Section: Adjustment Of the Weibull Accelerated Failure Time Model Andmentioning

confidence: 99%

Survival of side grafts with scions from pure species Pinus engelmannii Carr. and the P. engelmannii × P. arizonica Engelm. var. arizonica hybrid

Pérez-Luna

Wehenkel

Prieto-Ruíz

et al. 2020

PeerJ

View full text Add to dashboard Cite

Grafting is one of the most widely used methods for vegetative propagation, particularly for multiplying trees considered important, but there has been little research done on the effect of hybridization on grafts from the genus Pinus. Sometimes hybrids show the ability to reproduce and adapt efficiently to the environment. However, they reduce the genetic gain of seed orchards. The objective in this research was to evaluate the effect of scion grafts from pure species donor Pinus engelmannii Carr. and from putative hybrid trees P. engelmannii × P. arizonica Engelm., grafted on rootstocks of pure species P. engelmannii, along with the effect of the position of the scion in the donor tree crown (upper third and middle third). The scions were collected from three trees of the pure species and three hybrids. In each tree, 20 scions were collected from each third of the crown evaluated. 120 side-veneer grafts were made at the beginning of spring (March) 2018. Variance analyses were performed to evaluate the treatments and adjustments of the Logit and Weibull models to obtain the probability of graft survival. Significant differences were found between the origins of scions (p < 0.0083, after Bonferroni correction), showing grafts with hybrid tree scions taking hold better. In addition, the probability of survival at 5 months after grafting with hybrid tree scions was greater (p < 0.0001) than in grafts with scions from trees of the pure species (Logit model), which coincides with the results of the Weibull model, which indicated that the probability of graft death with pure species donor tree scions is greater than for grafts with hybrid scions. There were no significant differences regarding the position of the scion in the donor tree crown.

show abstract

“…Therefore, the effect of the predictor variable x is multiplicative (logarithmic) on the time scale, so it is said that this model accelerates (increases or decreases) the estimated average survival time of the specimens studied up to time T, which depends on the effectiveness or ineffectiveness of the treatments evaluated. Said time T is always longer than the duration of the evaluation (Carroll, 2003;Ghorbani et al, 2016;Zhang, 2016). On the other hand, it is also necessary to apply the exponent "time" T (e (T) ) to obtain a linear result of the estimated survival time after the graft evaluation period.…”

Section: Adjustment Of the Weibull Accelerated Failure Time Model Andmentioning

confidence: 99%

“…If λ> 1 the value of HR increases, while HR decreases if λ <1 (Carroll, 2003;Zhang, 2016). If the value of the hazard ratio is 1.0, means that the risk of death is equal between treatments; if the value of the hazard ratio is less than one, it means a reduction in the risk of death in one of the treatments, while if the hazard ratio is greater than one, the risk of death increases in one of the treatments (Carroll, 2003;Ghorbani et al, 2016) The HR is determined by the following equation (Igl, 2018): = ( -) -1 (9) The parameters β and λ of the HR equation (Eq. 9), are the same parameters calculated for the Weibull risk function (Eq.…”

Section: Adjustment Of the Weibull Accelerated Failure Time Model Andmentioning

confidence: 99%

Peer Review #2 of "Survival of side grafts with scions from pure species Pinus engelmannii Carr. and the P. engelmannii × P. arizonica Engelm. var. arizonica hybrid (v0.1)"

2020

View full text Add to dashboard Cite

Grafting is one of the most widely used methods for vegetative propagation, particularly for multiplying trees considered important, but there has been little research done on the effect of hybridization on grafts from the genus Pinus. Sometimes hybrids show the ability to reproduce and adapt efficiently to the environment. However, they reduce the genetic gain of seed orchards. The objective in this research was to evaluate the effect of scion grafts from pure species donor Pinus engelmannii Carr. and from putative hybrid trees P. engelmannii. x P. arizonica Engelm., grafted on rootstocks of pure species Pinus engelmannii, along with the effect of the position of the scion in the donor tree crown (upper third and middle third). The scions were collected from three pure species trees and three hybrids. In each tree, 20 scions were collected from each third of the crown evaluated. 120 side-veneer grafts were made at the beginning of spring (March) 2018. Variance analyses were performed to evaluate the treatments and adjustments of the Logit and Weibull models to obtain the probability of graft survival. Significant differences were found between the origins of scions (p ≤ 0.0083, after Bonferroni correction), showing grafts with hybrid tree scions taking hold better. In addition, the probability of survival at five months after grafting with hybrid tree scions was greater (p ≤ 0.0001) than in grafts with pure-species tree scions (Logit model), which coincides with the results of the Weibull model, which indicated that the probability of graft death with pure species donor tree scions is greater than for grafts with hybrid scions. There were no significant differences regarding the position of the scion in the donor tree crown.

show abstract

Application of the Weibull Accelerated Failure Time Model in the Determination of Disease-Free Survival Rate of Patients with Breast Cancer

Cited by 13 publications

References 8 publications

Accelerated failure-time model with weighted least-squares estimation: application on survival of HIV positives

Accelerated failure-time model with weighted least-squares estimation: application on survival of HIV positives

Survival of side grafts with scions from pure species Pinus engelmannii Carr. and the P. engelmannii × P. arizonica Engelm. var. arizonica hybrid

Peer Review #2 of "Survival of side grafts with scions from pure species Pinus engelmannii Carr. and the P. engelmannii × P. arizonica Engelm. var. arizonica hybrid (v0.1)"

Contact Info

Product

Resources

About