Short introduction
An example of the use of
survival analysis
SPCG-4
Expectation or radical prostatectomy on early prostate cancer.
Patients: T0-2,Nx,M0,Gr1-2, age < 75 years and expected survival 10 years
Treatment: Radical prostatectomy vs. expectants.
Inclusion period: Sep. 1989 – May 1999. Number of patients: 695 patients, 14
Centers
Principal investigator: Jan-Erik Johansson.
Sponsor: SPCG, Swedish Cancer Foundation .
Metastas
Röd= Operation
Död av annan orsak
Blå= WW
PC-död
Händelser kan:
• Ignoreras
• Censoreras
• Betraktas som ”competing risk”-händelse
Cumulative incidence of death
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
347
343
332
284
210
118
Watchful waiting
348
341
326
279
198
104
Cumulative incidence of development of distant metastasis
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
347
333
306
254
181
87
Watchful waiting
348
332
310
243
156
73
Cumulative incidence of death from prostate cancer
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
347
343
332
284
210
118
Watchful waiting
348
341
326
279
198
104
Advantages and limitations of an intention-to-treat (ITT) analysis
Advantages
•Retains balance in prognostic factors arising from the original random treatment allocation
•Gives an unbiased estimate of treatment effect
•Admits non-compliance and protocol deviations, thus reflecting a real clinical situation
Limitations
•Estimate of treatment effect is generally conservative because of dilution due to non-compliance
•In equivalence trials (attempting to prove that two treatments do not differ by more than a certain
amount), this analysis will favour equality of treatments
•Interpretation becomes difficult if a large proportion of participants cross over to opposite treatment
arms
Requirements for an ideal ITT analysis
•Full compliance with randomised treatment
•No missing responses
•Follow-up on all participants
ITT analysis is highly desirable unless:
•there is overwhelming justification for a different analysis policy (eg, an unacceptably high proportion of
ineligible participants — those without the disease under study, for whom there is no potential benefit
from the intervention. In these circumstances a “quasi” ITT approach (in which ineligible patients are
excluded) is more appropriate.
SUBGRUPPS
ANALYSER
Cumulative incidence of development of distant metastasis
Gleason < 7
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
209
205
195
159
111
53
Watchful waiting
212
206
195
160
105
49
Cumulative incidence of development of distant metastasis
Gleason >= 7
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
91
83
72
61
43
20
Watchful waiting
103
98
88
62
37
18
Cumulative incidence of development of distant metastasis
PSA <= 10
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
171
165
157
134
100
49
Watchful waiting
190
183
173
141
92
42
Cumulative incidence of development of distant metastasis
PSA > 10
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
169
162
143
114
76
34
Watchful waiting
155
146
134
100
62
30
Cumulative incidence of development of distant metastasis
Age < 65
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
157
151
142
124
92
52
Watchful waiting
166
158
145
114
74
43
Cumulative incidence of development of distant metastasis
Age >= 65
0.4
0.3
Probability
Radical prostatectomy
Watchful waiting
0.2
0.1
0
0
2
4
6
8
10
Years
No. At Risk
Radical prostatectomy
190
182
164
130
89
35
Watchful waiting
182
174
165
129
82
30
