Biostat Lab Section PROC LIFETESTPHREG

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Biostat Lab Section PROC LIFETEST/PHREG

• Yu-Fen Li

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Survival Analysis

• Survival data often consists of a response
  variable that measures the duration of time until
  a specified event occurs and a set of independent
  variables thought to be associated with the
  event-time variable.

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SAS procedures for analyzing survival data

• PROC LIFETEST is a nonparametric procedure for
  estimating the survivor function, comparing the
  underlying survival curves of two or more
  samples, and testing the association of survival
  time with other variables.
• PROC PHREG is a semiparametric procedure that
  fits the Cox proportional hazards model.

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SyntaxPROC LIFETEST

• PROC LIFETEST lt options gt
• TIME variable lt censor(list) gt
• BY variables
• FREQ variable
• STRATA variable lt (list) gt

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DATA EXAMPLE

• DATA myel
• INPUT dur status treat
• CARDS
• 8 1 1
• 452 1 1
• 2240 1 2
• 328 1 1
• 1296 1 2
• 1868 1 2

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DATA EXAMPLE

• PROC LIFETEST DATAmyel PLOTS(S) GRAPHICS
• TIME durstatus(0)
• STRATA treat
• RUN

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SyntaxPROC PHREG

• PROC PHREG lt options gt
• MODEL response lt censor(list) gt variables lt
  /options gt
• BY variables
• FREQ variable
• STRATA variable lt (list) gt
• RUN

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Assignment 1

• The following are the survival time (months)
  after a certain infection of 10 patients
• 0.5 1 1 1 2 5 8 9 10 12
• Censored observations are denoted with a
  sign. Please use the method of product limit to
  construct the survival curve.

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Assignment 2

• If the age of 10 patients was available as
• 60 54 50 25 30 42 28 38 20 23
• (in the same order as Assignment 1 )
• Please find the hazard ratio of getting one year
  older.