Abstract

Survival analysis is described as collection of statistical methods for which the response variable of interest is time until an event occurs. In this context, the time can be days, week, months and years from the beginning of follow-up of an individual until an event occurs, or the age of an individual when the event occurs. Moreover, the event can be death, disease, remission, recovery or any experience of interest that may occur to an individual. A more detailed information can be found in Kleinbaum and Marubini and Valsecchi.

Here we developed an easy-to-use, up-to-date, comprehensive and interactive web-based tool for survival analysis. This tool includes analysis procedures for life table, Kaplan-Meier and Cox regression. Each procedure includes following features:

Life table: descriptive statistics, life table, median life time, hazard ratios and comparison tests including Log-rank, Gehan-Breslow, Tarone-Ware, Peto-Peto, Modified Peto-Peto, Flemington-Harrington.

Kaplan-Meier: descriptive statistics, survival table, mean and median life time, hazard ratios, comparison tests including Log-rank, Gehan-Breslow, Tarone-Ware, Peto-Peto, Modified Peto-Peto, Flemington-Harrington, and interactive plots such as Kaplan-Meier curves and hazard plots.

Cox regression: coefficient estimates, hazard ratios, goodness of fit test, analysis of deviance, save predictions, save residuals, save Martingale residuals, save Schoenfeld residuals, save dfBetas, proportional hazard assumption test, and interactive plots including Schoenfeld residual plot and Log-Minus-Log plot.

Regularized Cox regression: variable selection and coefficient estimations using ridge, elastic net and lasso penalties.

Random survival forests: individual survival and cumulative hazard predictions using random survival forests, and interactive plots including, survival (with OOB), hazard (with OOB), error rate vs number of tree and cox regression vs random survival forest model.

1.Data upload

This tool requires a dataset in *.txt format, which is seperated by comma, semicolon, space or tab delimiter. First row of dataset must include header. When the appropriate file is uploaded, the dataset will be appear immediately on the main page of the tool. Alternatively users can upload one of the example datasets provided within the tool for testing and understanding the operating logic of the tool.

Data upload

Data upload help

2. Analysis Methods

2.1. Life Table

A life table can be constructed for a cohort group using the following steps:

  1. Select the analysis method as Life Table from Analysis tab.
  2. Select suitable variables for the analysis, such as survival time, status variable, category value for status variable and factor variable, if exists.
  3. Define an appropriate time interval from beginning to end of study by a specific step.
  4. In advanced options, one can change confidence interval type as log, log-log or plain, variance estimation method as Greenwood or Tsiatis and reference category as first or last.
  5. Click Run button to run the analysis.

Data upload help

Desired outputs can be selected by clicking Outputs checkbox. Available outputs are;

a. Case summary

b. Life table

c. Median life time

c. Hazard ratio

c. Comparison tests

2.2. Kaplan-Meier

A life table can be constructed for a cohort group using the following steps:

  1. Select the analysis method as Kaplan Meier from Analysis tab.
  2. Select suitable variables for the analysis, such as survival time, status variable, category value for status variable and factor variable, if exists.
  3. In advanced options, one can change confidence interval type, as log, log-log or plain, variance estimation method, as Greenwood or Tsiatis, comparison test type, as Log-rank, Gehan-Breslow, Tarone-Ware, Peto-Peto, Modifi Peto-Peto or Flemington-Harrington, confidence level and reference category, as first or last.
  4. Click Run button to run the analysis.

Data upload help

Desired outputs can be selected by clicking Outputs checkbox. Available outputs are;

a. Case summary

b. Survival table

c. Survival plot

d. Mean and Median life time

e. Hazard ratio

e. Hazard plot

g. Comparison tests