| Class | Analysis and data manipulation command |
| Name | lifetable |
| Arguments | (<start> | 0) <end> <censor> [<cohort stratum width> [<period stratum width>]] [cov <covariate>] [time]. |
Prints the life table for the quantitative trait end, where censor is the binary outcome trait, which is affected when end represents the date at which the individual first expressed the trait. The quantitative trait start represents the date of entry into the study of the individual. If start is the digit "0", then the start of the observation period is taken to be zero for all individuals (this option would usually be used with the time option, see below). The cohort stratum width is the bin width used to divide up the entry dates into the study. The period stratum width is the bin width used to divide up person years of followup.
A test for the presence of age-period-cohort interactions is calculated. One categorical covariate can be used to stratify the data and test for association.
The time modifier causes the start and end values to be treated as a continuous measure (eg age), rather than a Julian date.
Example:
>> #
>> # Analyse the nickel data from Breslow and Day
>> # Statistical Methods in Cancer Research
>> # Volume II - The design and analysis of cohort studies
>> # IARC Scientific Publications No. 82
>> # 1987.
>> # Appendix VIII
>> #
>> set loc icd7 qua
>> set loc exposure qua
>> set loc dob qua
>> set loc jobstart qua
>> set loc start qua
>> set loc stop qua
>> read cases nickel.dat
>> run
>> set loc lungca aff . Lung cancer deaths (ICD7=162 or 163)
>> lungca=(icd7==162 or icd7==163)
>> set loc EXP1 aff . exposure 0-
>> set loc EXP2 aff . exposure 0.5-4.0
>> set loc EXP3 aff . exposure 4.5-8.0
>> set loc EXP4 aff . exposure 8.5-12.0
>> set loc EXP5 aff . exposure 12.5-
>> EXP1 = (exposure == 0.0)
>> EXP2 = (exposure >= 0.5 and exposure <= 4.0)
>> EXP3 = (exposure >= 4.5 and exposure <= 8.0)
>> EXP4 = (exposure >= 8.5 and exposure <= 12.0)
>> EXP5 = (exposure >= 12.5)
>> set loc EXP qua
>> EXP = EXP1 + 2*EXP2 + 3*EXP3 + 4*EXP4 + 5*EXP5
>> lifetable start stop lungca 100 10 time cov EXP
------------------------------------------------
Life table analysis for "lungca"
------------------------------------------------
"start" is start of observation period.
"stop" is end of observation period.
"EXP" is covariate.
Variable Range Strata Stratum width
-------- --------------------- -------- -------------
Start 23.7 -- 70.7 1 100.0
Stop 33.7 -- 97.8 5 10.0
Followed 0.4 -- 48.7 5 10.0
Covariate levels ( 5)
1.00000 290
2.00000 225
3.00000 103
4.00000 41
5.00000 20
Covariate = 1.00000
Entered Time Stratum Riskset Events Person-time Incidence
------------- ------------- --------- ------ ------------ ----------
23.7 - 0.0 - 290 5 2720. 0.00183807
10.0 - 251 14 2277. 0.00614800
20.0 - 197 14 1619. 0.00864656
30.0 - 125 5 878. 0.00569790
40.0 - 58 4 308. 0.01300049
--------- ------- ------------ ----------
290 42 7802. 0.00538342
Covariate = 2.00000
Entered Time Stratum Riskset Events Person-time Incidence
------------- ------------- --------- ------ ------------ ----------
23.7 - 0.0 - 225 10 2080. 0.00480870
10.0 - 182 23 1504. 0.01529531
20.0 - 115 16 855. 0.01870698
30.0 - 58 1 373. 0.00268244
40.0 - 21 0 113. 0.00000000
--------- ------- ------------ ----------
225 50 4924. 0.01015333
Covariate = 3.00000
Entered Time Stratum Riskset Events Person-time Incidence
------------- ------------- --------- ------ ------------ ----------
23.7 - 0.0 - 103 9 909. 0.00989936
10.0 - 75 14 518. 0.02701423
20.0 - 32 2 202. 0.00988718
30.0 - 12 0 87. 0.00000000
40.0 - 6 2 27. 0.07356187
--------- ------- ------------ ----------
103 27 1744. 0.01548113
Covariate = 4.00000
Entered Time Stratum Riskset Events Person-time Incidence
------------- ------------- --------- ------ ------------ ----------
23.7 - 0.0 - 41 5 314. 0.01593775
10.0 - 24 5 194. 0.02577686
20.0 - 16 1 85. 0.01171428
30.0 - 3 1 15. 0.06793155
40.0 - 1 0 0. 0.00000000
--------- ------- ------------ ----------
41 12 608. 0.01973394
Covariate = 5.00000
Entered Time Stratum Riskset Events Person-time Incidence
------------- ------------- --------- ------ ------------ ----------
23.7 - 0.0 - 20 2 160. 0.01248709
10.0 - 12 4 73. 0.05491850
20.0 - 5 0 34. 0.00000000
30.0 - 1 0 3. 0.00000000
40.0 - 0 0 0. 0.00000000
--------- ------- ------------ ----------
20 6 270. 0.02224876
No interaction model LRTS = 22.0
Degrees of freedom = 16
Nominal P-value = 0.1429
No effect of covariate = 33.3
Degrees of freedom = 4
Nominal P-value = 0.0000
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