To analyze the renal transplant patients survival and associated factors to their mortality. Data on 863 kidney transplant patients (data file: kidney1a.txt or kidney1.xlsx).

  1. Please use the log-rank test to compare the overall survival curves between the white and black groups and plot Kaplan-Meier survival curves.

  2. Please use the log-rank test to compare the overall survival curves between the age≥40 and age<40 groups and plot Kaplan-Meier survival curves.

  3. Please use the multiple Cox regression to estimate the hazard ratio of death between group A (age≥40) and group B (age<40).

(Predictors: age(≥40 or < 40), sex, race)

資料匯入、檢視資料

dta <- read.table("/Users/User/Desktop/LearnR/CA/CAdata/kidney1a.txt", header=T , stringsAsFactor=F, fill=T )
dim(dta)
## [1] 863   6
str(dta)
## 'data.frame':    863 obs. of  6 variables:
##  $ id  : int  1 2 3 4 5 6 7 8 9 10 ...
##  $ time: int  1 5 7 9 13 13 17 20 26 26 ...
##  $ dead: int  0 0 1 0 0 0 1 0 1 1 ...
##  $ sex : int  1 1 1 1 1 1 1 1 1 1 ...
##  $ race: int  1 1 1 1 1 1 1 1 1 1 ...
##  $ age : int  46 51 55 57 45 43 47 65 55 44 ...

查看data

class(dta)
## [1] "data.frame"
names(dta)
## [1] "id"   "time" "dead" "sex"  "race" "age"
head(dta)
##   id time dead sex race age
## 1  1    1    0   1    1  46
## 2  2    5    0   1    1  51
## 3  3    7    1   1    1  55
## 4  4    9    0   1    1  57
## 5  5   13    0   1    1  45
## 6  6   13    0   1    1  43
View(dta)

(a)

  • race
library(survival)
# Create the survival data object
surv.fit<-with(dta, Surv(time, dead == 1))
surv.fit
##   [1]    1+    5+    7     9+   13+   13+   17    20+   26    26    28    32+
##  [13]   32+   43+   43    44    51+   51+   51+   56    57    59    62    66+
##  [25]   66+   67+   68    69    79+   79    79+   87+   88    91    93+   98 
##  [37]   98   104+  105+  106   112+  116+  116+  118+  119   121+  121+  135 
##  [49]  144+  150   150+  162   162+  167+  183+  186+  190   198+  198+  200+
##  [61]  211+  215+  223+  224+  228   236+  238+  242   243+  248   249   251+
##  [73]  252   253+  256+  257+  259+  261+  271+  271+  277+  283+  284+  289+
##  [85]  291   311   312+  316+  316+  331+  334   338+  340+  340   341+  346 
##  [97]  347+  354   361+  367+  370+  370+  386+  391   392+  403+  406+  410+
## [109]  421   428+  432+  432+  439   452+  478   481   485+  486+  490+  494+
## [121]  495   512+  512+  535+  543+  545+  545+  545+  563+  570+  570   572+
## [133]  579+  582+  583   590+  596+  615   621   630+  631+  633+  652   654+
## [145]  655+  659+  670+  670+  692+  697   701+  719+  723+  725+  730   734+
## [157]  753+  757+  773   776   790   806   834+  835+  864+  864+  875   888+
## [169]  890+  903+  909+  915+  932+  939   945   945   946   951+  961+  965+
## [181]  968+ 1016+ 1028+ 1050+ 1058+ 1058+ 1092+ 1092+ 1105  1110+ 1110+ 1114+
## [193] 1115+ 1118+ 1124+ 1124+ 1125+ 1128+ 1128+ 1145+ 1149+ 1154+ 1154+ 1165+
## [205] 1186  1191  1196+ 1208+ 1208+ 1210  1224+ 1224+ 1229+ 1230+ 1252+ 1256+
## [217] 1274+ 1291+ 1297+ 1297+ 1302+ 1313+ 1316+ 1350+ 1357  1383+ 1383+ 1383+
## [229] 1383+ 1386+ 1388  1395+ 1418  1428+ 1429+ 1435+ 1449+ 1449+ 1450+ 1457+
## [241] 1463+ 1470+ 1497+ 1497+ 1500+ 1509  1522+ 1527+ 1527+ 1541+ 1567+ 1571+
## [253] 1578+ 1586+ 1594+ 1610+ 1610+ 1611+ 1617+ 1624+ 1638+ 1641+ 1655+ 1668+
## [265] 1674+ 1699+ 1700+ 1700+ 1707+ 1717+ 1717+ 1718+ 1718+ 1734  1736+ 1736+
## [277] 1739+ 1739+ 1739+ 1745+ 1745+ 1746+ 1749+ 1770+ 1770+ 1795+ 1802+ 1802+
## [289] 1803+ 1808+ 1808+ 1815+ 1820  1839+ 1861+ 1861+ 1893+ 1900+ 1920+ 1937+
## [301] 1947+ 1947+ 1959+ 1959+ 1975+ 1988+ 1988+ 1995+ 1995+ 2001+ 2016+ 2025+
## [313] 2032+ 2035+ 2038+ 2041+ 2043+ 2048+ 2049+ 2056  2060+ 2090+ 2090+ 2095+
## [325] 2096+ 2096+ 2098+ 2102+ 2109+ 2135+ 2135+ 2147+ 2190+ 2211+ 2221+ 2223+
## [337] 2253+ 2253+ 2264+ 2267+ 2270+ 2291  2291+ 2313  2313+ 2313+ 2330+ 2332+
## [349] 2335+ 2356+ 2367+ 2384+ 2418+ 2421+ 2421  2430+ 2433+ 2434+ 2462+ 2462+
## [361] 2488+ 2489  2497+ 2516+ 2531+ 2533+ 2575+ 2585+ 2589+ 2601+ 2607+ 2625+
## [373] 2630+ 2646+ 2654+ 2690+ 2696+ 2700+ 2712+ 2714+ 2716+ 2716+ 2740+ 2761+
## [385] 2762+ 2765+ 2789+ 2789+ 2812+ 2815+ 2827+ 2831+ 2846+ 2867+ 2871+ 2889+
## [397] 2909+ 2922+ 2936+ 2948+ 2955+ 2957+ 2994+ 2994+ 2999+ 3007+ 3045+ 3060+
## [409] 3078+ 3078+ 3084+ 3084+ 3110+ 3130+ 3131+ 3146  3147+ 3172+ 3179+ 3187+
## [421] 3187+ 3255+ 3260+ 3287+ 3289+ 3300+ 3301+ 3319+ 3361+ 3402+ 3425+ 3434+
## [433]   37    43    57    80+   82+   93+  114+  116+  116+  119+  152+  158 
## [445]  172+  200+  206   211+  231+  280+  311   312+  402   414+  443+  450 
## [457]  452+  479+  499+  535+  642+  646+  661+  663+  663+  671+  750+  777+
## [469]  863+  863+  864+  868+  934+  951+  992+ 1001  1002+ 1109+ 1122+ 1124+
## [481] 1149+ 1178+ 1230+ 1232+ 1242+ 1275  1352+ 1384  1450+ 1586+ 1624+ 1668+
## [493] 1681+ 1778+ 1795+ 1795+ 1877+ 1989+ 2049+ 2094+ 2095+ 2264+ 2291+ 2369+
## [505] 2369  2414  2425+ 2451+ 2455+ 2557  2598+ 2625+ 2659+ 2688+ 2726+ 2741+
## [517] 2750+ 2909+ 2961+ 2994+ 3019+ 3255+ 3281+ 3430+    1+    2     3     5+
## [529]    7     9+   10    10    17+   20+   21    26+   33+   43+   43+   48+
## [541]   50    51+   52    62    62+   68    78    79+   82+   97   104   105+
## [553]  112+  115+  124+  141+  142+  143   150+  154   162+  162+  167+  173+
## [565]  193+  205+  209   231+  238+  239+  246+  246+  250+  253+  260+  269+
## [577]  271+  273   280+  297   306+  331+  337+  341+  341+  347+  366   377+
## [589]  387+  388+  399+  417+  424+  428+  448+  448+  448+  459+  470   490 
## [601]  507+  512+  549+  593+  604+  614   642+  652+  654+  660+  670+  675+
## [613]  678+  693+  715+  731+  750+  753+  757+  759+  762+  772+  772+  777+
## [625]  777+  793   840   852   900+  907+  907+  909+  915+  963+  995+  995+
## [637] 1012+ 1013  1051+ 1072+ 1086+ 1114+ 1125+ 1164  1196+ 1229+ 1242+ 1252+
## [649] 1254+ 1254+ 1269+ 1291+ 1291+ 1299+ 1304+ 1309+ 1315+ 1326  1331  1350+
## [661] 1365+ 1368+ 1368+ 1427+ 1435+ 1449+ 1473  1497+ 1594+ 1605+ 1606+ 1611+
## [673] 1623+ 1638+ 1673+ 1681+ 1698+ 1699+ 1702+ 1702+ 1707+ 1732+ 1736+ 1746+
## [685] 1777  1778+ 1785+ 1786+ 1786+ 1791+ 1795+ 1815+ 1835  1875+ 1877  1893+
## [697] 1914+ 1939+ 1940  1942+ 1962+ 1966+ 1973+ 1980+ 2001+ 2014+ 2014+ 2025+
## [709] 2034+ 2034  2034+ 2038+ 2048+ 2060+ 2083+ 2094+ 2102+ 2108  2129+ 2193+
## [721] 2211+ 2221+ 2223+ 2233+ 2236+ 2252+ 2252+ 2271+ 2301  2312+ 2332+ 2335+
## [733] 2356+ 2392+ 2405+ 2405+ 2421+ 2433+ 2462+ 2486+ 2488+ 2504+ 2529+ 2529+
## [745] 2531+ 2556+ 2567  2632+ 2638+ 2638+ 2654+ 2659+ 2663+ 2670+ 2680+ 2700+
## [757] 2701+ 2705+ 2726+ 2750+ 2759+ 2768+ 2783+ 2795  2870+ 2871+ 2876+ 2900+
## [769] 2906+ 2918+ 2948+ 2993+ 3028+ 3042+ 3063+ 3063+ 3072+ 3077+ 3084+ 3086+
## [781] 3096+ 3102+ 3106+ 3116+ 3124+ 3142+ 3145+ 3145+ 3172+ 3173+ 3175+ 3186+
## [793] 3202+ 3215+ 3224+ 3229+ 3265+ 3300+ 3325+ 3360+ 3372+ 3379+ 3412+ 3420+
## [805]   14+   40    45    93+  106   116+  116+  121   229   250+  259+  261+
## [817]  306+  312+  344   392+  442+  512+  625+  673+  731+  777+  864   879+
## [829]  887+  899+  899+  903+  920+  929   943   953+  953+ 1016  1151+ 1196 
## [841] 1291+ 1291+ 1457+ 1508+ 1567+ 1674+ 1736+ 1739+ 1942+ 2026+ 2171  2268+
## [853] 2276  2413+ 2434+ 2463+ 2650  2680+ 2935+ 3072+ 3161+ 3211+ 3304+

KM estimates

# Create KM estimates broken out by race
surv.byrace= survfit(Surv(time,dead == 1) ~ race, data = dta)
summary(surv.byrace)
## Call: survfit(formula = Surv(time, dead == 1) ~ race, data = dta)
## 
##                 race=1 
##  time n.risk n.event survival std.err lower 95% CI upper 95% CI
##     2    710       1    0.999 0.00141        0.996        1.000
##     3    709       1    0.997 0.00199        0.993        1.000
##     7    706       2    0.994 0.00281        0.989        1.000
##    10    702       2    0.992 0.00345        0.985        0.998
##    17    698       1    0.990 0.00372        0.983        0.997
##    21    694       1    0.989 0.00398        0.981        0.997
##    26    693       2    0.986 0.00445        0.977        0.995
##    28    690       1    0.984 0.00467        0.975        0.994
##    43    686       1    0.983 0.00488        0.973        0.993
##    44    682       1    0.982 0.00508        0.972        0.992
##    50    680       1    0.980 0.00527        0.970        0.990
##    52    675       1    0.979 0.00546        0.968        0.989
##    56    674       1    0.977 0.00564        0.966        0.988
##    57    673       1    0.976 0.00582        0.964        0.987
##    59    672       1    0.974 0.00599        0.963        0.986
##    62    671       2    0.971 0.00631        0.959        0.984
##    68    665       2    0.968 0.00662        0.956        0.982
##    69    663       1    0.967 0.00677        0.954        0.980
##    78    662       1    0.966 0.00692        0.952        0.979
##    79    661       1    0.964 0.00706        0.950        0.978
##    88    655       1    0.963 0.00720        0.949        0.977
##    91    654       1    0.961 0.00734        0.947        0.976
##    97    652       1    0.960 0.00747        0.945        0.974
##    98    651       2    0.957 0.00774        0.942        0.972
##   104    649       1    0.955 0.00786        0.940        0.971
##   106    645       1    0.954 0.00799        0.938        0.970
##   119    638       1    0.952 0.00812        0.936        0.968
##   135    634       1    0.951 0.00824        0.935        0.967
##   143    631       1    0.949 0.00836        0.933        0.966
##   150    629       1    0.948 0.00849        0.931        0.965
##   154    626       1    0.946 0.00861        0.929        0.963
##   162    625       1    0.945 0.00872        0.928        0.962
##   190    616       1    0.943 0.00884        0.926        0.961
##   209    610       1    0.942 0.00896        0.924        0.959
##   228    605       1    0.940 0.00908        0.922        0.958
##   242    599       1    0.938 0.00920        0.921        0.957
##   248    595       1    0.937 0.00932        0.919        0.955
##   249    594       1    0.935 0.00944        0.917        0.954
##   252    591       1    0.934 0.00955        0.915        0.953
##   273    579       1    0.932 0.00967        0.913        0.951
##   291    573       1    0.931 0.00979        0.912        0.950
##   297    572       1    0.929 0.00991        0.910        0.949
##   311    570       1    0.927 0.01002        0.908        0.947
##   334    564       1    0.926 0.01014        0.906        0.946
##   340    561       1    0.924 0.01026        0.904        0.944
##   346    556       1    0.922 0.01037        0.902        0.943
##   354    553       1    0.921 0.01049        0.900        0.941
##   366    551       1    0.919 0.01060        0.898        0.940
##   391    543       1    0.917 0.01071        0.897        0.939
##   421    536       1    0.916 0.01083        0.895        0.937
##   439    530       1    0.914 0.01095        0.893        0.936
##   470    524       1    0.912 0.01106        0.891        0.934
##   478    523       1    0.910 0.01118        0.889        0.933
##   481    522       1    0.909 0.01129        0.887        0.931
##   490    519       1    0.907 0.01141        0.885        0.929
##   495    516       1    0.905 0.01152        0.883        0.928
##   570    504       1    0.903 0.01163        0.881        0.926
##   583    499       1    0.901 0.01175        0.879        0.925
##   614    494       1    0.900 0.01187        0.877        0.923
##   615    493       1    0.898 0.01198        0.875        0.922
##   621    492       1    0.896 0.01210        0.873        0.920
##   652    487       1    0.894 0.01221        0.871        0.918
##   697    473       1    0.892 0.01233        0.868        0.917
##   730    467       1    0.890 0.01245        0.866        0.915
##   773    455       1    0.888 0.01258        0.864        0.913
##   776    454       1    0.886 0.01270        0.862        0.912
##   790    451       1    0.884 0.01282        0.860        0.910
##   793    450       1    0.883 0.01294        0.858        0.908
##   806    449       1    0.881 0.01306        0.855        0.907
##   840    446       1    0.879 0.01318        0.853        0.905
##   852    445       1    0.877 0.01330        0.851        0.903
##   875    442       1    0.875 0.01342        0.849        0.901
##   939    430       1    0.873 0.01354        0.846        0.900
##   945    429       2    0.869 0.01378        0.842        0.896
##   946    427       1    0.866 0.01390        0.840        0.894
##  1013    418       1    0.864 0.01402        0.837        0.892
##  1105    407       1    0.862 0.01414        0.835        0.890
##  1164    390       1    0.860 0.01428        0.833        0.889
##  1186    388       1    0.858 0.01441        0.830        0.887
##  1191    387       1    0.856 0.01454        0.828        0.885
##  1210    382       1    0.853 0.01468        0.825        0.883
##  1326    356       1    0.851 0.01483        0.822        0.881
##  1331    355       1    0.849 0.01498        0.820        0.878
##  1357    352       1    0.846 0.01513        0.817        0.876
##  1388    343       1    0.844 0.01529        0.814        0.874
##  1418    341       1    0.841 0.01544        0.812        0.872
##  1473    328       1    0.839 0.01561        0.809        0.870
##  1509    323       1    0.836 0.01577        0.806        0.868
##  1734    281       1    0.833 0.01599        0.802        0.865
##  1777    267       1    0.830 0.01624        0.799        0.862
##  1820    252       1    0.827 0.01650        0.795        0.860
##  1835    251       1    0.823 0.01676        0.791        0.857
##  1877    246       1    0.820 0.01702        0.787        0.854
##  1940    238       1    0.817 0.01730        0.783        0.851
##  2034    215       1    0.813 0.01763        0.779        0.848
##  2056    204       1    0.809 0.01799        0.774        0.845
##  2108    191       1    0.805 0.01839        0.769        0.841
##  2291    167       1    0.800 0.01890        0.764        0.838
##  2301    165       1    0.795 0.01939        0.758        0.834
##  2313    163       1    0.790 0.01988        0.752        0.830
##  2421    147       1    0.785 0.02046        0.746        0.826
##  2489    134       1    0.779 0.02113        0.739        0.821
##  2567    124       1    0.773 0.02187        0.731        0.817
##  2795     85       1    0.763 0.02342        0.719        0.811
##  3146     33       1    0.740 0.03217        0.680        0.806
## 
##                 race=2 
##  time n.risk n.event survival std.err lower 95% CI upper 95% CI
##    37    150       1    0.993 0.00664        0.980        1.000
##    40    149       1    0.987 0.00937        0.968        1.000
##    43    148       1    0.980 0.01143        0.958        1.000
##    45    147       1    0.973 0.01315        0.948        0.999
##    57    146       1    0.967 0.01466        0.938        0.996
##   106    141       1    0.960 0.01608        0.929        0.992
##   121    134       1    0.953 0.01748        0.919        0.988
##   158    132       1    0.945 0.01878        0.909        0.983
##   206    129       1    0.938 0.02001        0.900        0.978
##   229    127       1    0.931 0.02117        0.890        0.973
##   311    120       1    0.923 0.02237        0.880        0.968
##   344    117       1    0.915 0.02353        0.870        0.962
##   402    115       1    0.907 0.02463        0.860        0.957
##   450    111       1    0.899 0.02573        0.850        0.951
##   864     91       1    0.889 0.02728        0.837        0.944
##   929     82       1    0.878 0.02902        0.823        0.937
##   943     80       1    0.867 0.03067        0.809        0.929
##  1001     75       1    0.856 0.03236        0.795        0.922
##  1016     73       1    0.844 0.03398        0.780        0.913
##  1196     66       1    0.831 0.03579        0.764        0.904
##  1275     62       1    0.818 0.03764        0.747        0.895
##  1384     58       1    0.804 0.03954        0.730        0.885
##  2171     36       1    0.781 0.04430        0.699        0.873
##  2276     33       1    0.758 0.04888        0.668        0.860
##  2369     31       1    0.733 0.05306        0.636        0.845
##  2414     28       1    0.707 0.05726        0.603        0.829
##  2557     22       1    0.675 0.06304        0.562        0.810
##  2650     19       1    0.639 0.06901        0.517        0.790
plot(surv.byrace)

plot(surv.byrace, ylab="survival rate", xlab="time", col=c("red", "black"), lty= 1:2 , mark.time=T) 
#lty=c(1,2) -> 2為虛線(Dashed line)
legend(800, 0.3, c("white", "black"),
lty=c(1, 2), lwd=2, col=c("red", "black"))

Logranktest for difference in survival by race

surv.diff.race= survdiff(Surv(time,dead == 1) ~ race, data = dta)
surv.diff.race
## Call:
## survdiff(formula = Surv(time, dead == 1) ~ race, data = dta)
## 
##          N Observed Expected (O-E)^2/E (O-E)^2/V
## race=1 712      112    116.6     0.185      1.11
## race=2 151       28     23.4     0.925      1.11
## 
##  Chisq= 1.1  on 1 degrees of freedom, p= 0.3
  • p=0.3

(b)

  • age變項分組
dta$age_gp<-ifelse(dta$age>= 40, 2, 1) #年齡分為大於等於40(=2),小於40(=1)
View(dta)

Logranktest for difference in survival by age_gp

surv.diff.age_gp= survdiff(Surv(time , dead == 1) ~ age_gp, data = dta)
surv.diff.age_gp
## Call:
## survdiff(formula = Surv(time, dead == 1) ~ age_gp, data = dta)
## 
##            N Observed Expected (O-E)^2/E (O-E)^2/V
## age_gp=1 333       22     62.4      26.2      47.7
## age_gp=2 530      118     77.6      21.0      47.7
## 
##  Chisq= 47.7  on 1 degrees of freedom, p= 5e-12
  • p=<.0001

KM estimates

surv.byagegp= survfit(Surv(time , dead ==1 ) ~ age_gp, data = dta)
summary(surv.byagegp)
## Call: survfit(formula = Surv(time, dead == 1) ~ age_gp, data = dta)
## 
##                 age_gp=1 
##  time n.risk n.event survival std.err lower 95% CI upper 95% CI
##     3    333       1    0.997 0.00300        0.991        1.000
##     7    332       1    0.994 0.00423        0.986        1.000
##    62    323       1    0.991 0.00522        0.981        1.000
##   135    311       1    0.988 0.00610        0.976        1.000
##   143    310       1    0.985 0.00686        0.971        0.998
##   209    302       1    0.981 0.00757        0.967        0.996
##   229    300       1    0.978 0.00822        0.962        0.994
##   242    297       1    0.975 0.00883        0.958        0.992
##   311    288       1    0.971 0.00943        0.953        0.990
##   366    283       1    0.968 0.01000        0.949        0.988
##   450    278       1    0.964 0.01055        0.944        0.985
##   570    271       1    0.961 0.01110        0.939        0.983
##   621    269       1    0.957 0.01162        0.935        0.980
##   773    256       1    0.954 0.01216        0.930        0.978
##   793    253       1    0.950 0.01268        0.925        0.975
##   852    251       1    0.946 0.01318        0.921        0.972
##  1001    237       1    0.942 0.01372        0.916        0.969
##  1186    222       1    0.938 0.01430        0.910        0.966
##  1196    221       1    0.934 0.01485        0.905        0.963
##  1877    148       1    0.927 0.01603        0.896        0.959
##  2108    119       1    0.919 0.01769        0.885        0.955
##  3146     21       1    0.876 0.04593        0.790        0.970
## 
##                 age_gp=2 
##  time n.risk n.event survival std.err lower 95% CI upper 95% CI
##     2    528       1    0.998 0.00189        0.994        1.000
##     7    525       1    0.996 0.00268        0.991        1.000
##    10    522       2    0.992 0.00379        0.985        1.000
##    17    518       1    0.990 0.00424        0.982        0.999
##    21    515       1    0.989 0.00465        0.979        0.998
##    26    514       2    0.985 0.00537        0.974        0.995
##    28    512       1    0.983 0.00569        0.972        0.994
##    37    509       1    0.981 0.00600        0.969        0.993
##    40    508       1    0.979 0.00629        0.967        0.991
##    43    507       2    0.975 0.00683        0.962        0.989
##    44    503       1    0.973 0.00709        0.959        0.987
##    45    502       1    0.971 0.00733        0.957        0.986
##    50    501       1    0.969 0.00757        0.955        0.984
##    52    498       1    0.967 0.00780        0.952        0.983
##    56    497       1    0.965 0.00803        0.950        0.981
##    57    496       2    0.961 0.00845        0.945        0.978
##    59    494       1    0.960 0.00866        0.943        0.977
##    62    493       1    0.958 0.00885        0.940        0.975
##    68    488       2    0.954 0.00924        0.936        0.972
##    69    486       1    0.952 0.00943        0.933        0.970
##    78    485       1    0.950 0.00961        0.931        0.969
##    79    484       1    0.948 0.00979        0.929        0.967
##    88    479       1    0.946 0.00997        0.926        0.966
##    91    478       1    0.944 0.01014        0.924        0.964
##    97    475       1    0.942 0.01031        0.922        0.962
##    98    474       2    0.938 0.01065        0.917        0.959
##   104    472       1    0.936 0.01081        0.915        0.957
##   106    469       2    0.932 0.01112        0.910        0.954
##   119    460       1    0.930 0.01128        0.908        0.952
##   121    459       1    0.928 0.01144        0.906        0.950
##   150    453       1    0.926 0.01159        0.903        0.949
##   154    450       1    0.924 0.01175        0.901        0.947
##   158    449       1    0.922 0.01190        0.899        0.945
##   162    448       1    0.920 0.01205        0.896        0.944
##   190    441       1    0.917 0.01220        0.894        0.942
##   206    437       1    0.915 0.01236        0.892        0.940
##   228    432       1    0.913 0.01251        0.889        0.938
##   248    426       1    0.911 0.01266        0.887        0.936
##   249    425       1    0.909 0.01281        0.884        0.934
##   252    422       1    0.907 0.01296        0.882        0.933
##   273    411       1    0.905 0.01312        0.879        0.931
##   291    406       1    0.902 0.01327        0.877        0.929
##   297    405       1    0.900 0.01342        0.874        0.927
##   311    402       1    0.898 0.01358        0.872        0.925
##   334    395       1    0.896 0.01373        0.869        0.923
##   340    394       1    0.893 0.01388        0.867        0.921
##   344    390       1    0.891 0.01403        0.864        0.919
##   346    389       1    0.889 0.01418        0.861        0.917
##   354    386       1    0.887 0.01433        0.859        0.915
##   391    378       1    0.884 0.01449        0.856        0.913
##   402    375       1    0.882 0.01464        0.854        0.911
##   421    370       1    0.879 0.01479        0.851        0.909
##   439    365       1    0.877 0.01495        0.848        0.907
##   470    357       1    0.875 0.01510        0.845        0.905
##   478    356       1    0.872 0.01526        0.843        0.903
##   481    354       1    0.870 0.01541        0.840        0.900
##   490    352       1    0.867 0.01557        0.837        0.898
##   495    350       1    0.865 0.01572        0.834        0.896
##   583    335       1    0.862 0.01588        0.832        0.894
##   614    330       1    0.859 0.01605        0.829        0.892
##   615    329       1    0.857 0.01621        0.826        0.889
##   652    323       1    0.854 0.01638        0.823        0.887
##   697    308       1    0.851 0.01656        0.820        0.885
##   730    304       1    0.849 0.01674        0.816        0.882
##   776    294       1    0.846 0.01693        0.813        0.880
##   790    291       1    0.843 0.01712        0.810        0.877
##   806    290       1    0.840 0.01730        0.807        0.875
##   840    288       1    0.837 0.01749        0.803        0.872
##   864    285       1    0.834 0.01767        0.800        0.869
##   875    281       1    0.831 0.01785        0.797        0.867
##   929    269       1    0.828 0.01805        0.793        0.864
##   939    268       1    0.825 0.01825        0.790        0.862
##   943    267       1    0.822 0.01844        0.787        0.859
##   945    266       2    0.816 0.01881        0.780        0.853
##   946    264       1    0.813 0.01899        0.776        0.851
##  1013    257       1    0.809 0.01918        0.773        0.848
##  1016    256       1    0.806 0.01936        0.769        0.845
##  1105    247       1    0.803 0.01956        0.766        0.842
##  1164    235       1    0.800 0.01977        0.762        0.839
##  1191    232       1    0.796 0.01998        0.758        0.836
##  1210    230       1    0.793 0.02020        0.754        0.833
##  1275    217       1    0.789 0.02043        0.750        0.830
##  1326    211       1    0.785 0.02067        0.746        0.827
##  1331    210       1    0.782 0.02091        0.742        0.824
##  1357    206       1    0.778 0.02115        0.737        0.820
##  1384    201       1    0.774 0.02140        0.733        0.817
##  1388    199       1    0.770 0.02164        0.729        0.814
##  1418    198       1    0.766 0.02188        0.724        0.810
##  1473    190       1    0.762 0.02213        0.720        0.807
##  1509    188       1    0.758 0.02238        0.715        0.803
##  1734    166       1    0.753 0.02271        0.710        0.799
##  1777    156       1    0.749 0.02307        0.705        0.795
##  1820    144       1    0.743 0.02349        0.699        0.791
##  1835    143       1    0.738 0.02389        0.693        0.787
##  1940    137       1    0.733 0.02432        0.687        0.782
##  2034    122       1    0.727 0.02485        0.680        0.777
##  2056    116       1    0.721 0.02541        0.672        0.772
##  2171    106       1    0.714 0.02607        0.664        0.767
##  2276     95       1    0.706 0.02685        0.656        0.761
##  2291     94       1    0.699 0.02760        0.647        0.755
##  2301     92       1    0.691 0.02832        0.638        0.749
##  2313     90       1    0.683 0.02903        0.629        0.743
##  2369     86       1    0.676 0.02976        0.620        0.736
##  2414     83       1    0.667 0.03050        0.610        0.730
##  2421     82       1    0.659 0.03119        0.601        0.723
##  2489     74       1    0.650 0.03202        0.591        0.716
##  2557     69       1    0.641 0.03291        0.580        0.709
##  2567     68       1    0.631 0.03375        0.569        0.701
##  2650     61       1    0.621 0.03475        0.557        0.693
##  2795     45       1    0.607 0.03661        0.540        0.684
plot(surv.byagegp, ylab="survival rate", xlab="time", col=c("gray", "blue"), lty= 1:2 ,mark.time=T) 
#lty=c(1,2) -> 2為虛線(Dashed line)
legend(800, 0.3, c("age>= 40", "age<40"),
lty=c(1, 2), lwd=2, col=c("gray", "blue"))

(c)

  • age->group 變項分組
dta$group<-ifelse(dta$age>= 40, "A", "B") 
View(dta)
str(dta)
## 'data.frame':    863 obs. of  8 variables:
##  $ id    : int  1 2 3 4 5 6 7 8 9 10 ...
##  $ time  : int  1 5 7 9 13 13 17 20 26 26 ...
##  $ dead  : int  0 0 1 0 0 0 1 0 1 1 ...
##  $ sex   : int  1 1 1 1 1 1 1 1 1 1 ...
##  $ race  : int  1 1 1 1 1 1 1 1 1 1 ...
##  $ age   : int  46 51 55 57 45 43 47 65 55 44 ...
##  $ age_gp: num  2 2 2 2 2 2 2 2 2 2 ...
##  $ group : chr  "A" "A" "A" "A" ...

Cox proportional hazards regression

# First, let’s look at the cox model of survival in the melanomdata set where the predictor variable is sex (male/female)
coxph.group= coxph(Surv(time , dead == 1 ) ~ group + sex + race, data = dta)
summary(coxph.group)
## Call:
## coxph(formula = Surv(time, dead == 1) ~ group + sex + race, data = dta)
## 
##   n= 863, number of events= 140 
## 
##            coef exp(coef) se(coef)      z Pr(>|z|)    
## groupB -1.46687   0.23065  0.23385 -6.273 3.55e-10 ***
## sex    -0.02812   0.97227  0.17451 -0.161    0.872    
## race    0.05238   1.05377  0.21212  0.247    0.805    
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1
## 
##        exp(coef) exp(-coef) lower .95 upper .95
## groupB    0.2306      4.336    0.1458    0.3648
## sex       0.9723      1.029    0.6906    1.3688
## race      1.0538      0.949    0.6953    1.5970
## 
## Concordance= 0.64  (se = 0.022 )
## Likelihood ratio test= 53.6  on 3 df,   p=1e-11
## Wald test            = 40.13  on 3 df,   p=1e-08
## Score (logrank) test = 47.76  on 3 df,   p=2e-10

group: HR=0.2306 (=A (age>=40) 當對照組),如果對照組顛倒 HR=4.336 sex : HR=0.9723 (=1 當對照組) ,如果對照組顛倒 HR=1.029 race : HR=1.0538 (=1 當對照組) ,如果對照組顛倒 HR=0.949