1/27/2014
Cohort and Period Approaches
Hermann Brenner
Division of Clinical Epidemiology and Aging ResearchDivision of Clinical Epidemiology and Aging Research
German Cancer Research Center, Heidelberg
Period approaches - brief history (1)
• Introduced in 1996 (Brenner & Gefeller, Cancer 1996)
• Aim: More up-to-date survival estimates
• Ignored / boycotted for several years
• Comprehensive empirical evaluations
Hermann Brenner, German Cancer Research Center23.1.2014
• Comprehensive empirical evaluations
(e.g. Brenner & Hakulinen, IJE 2002, JCO 2002; Talbäck et al , EJC 2004)
• User friendly computer programs
(e.g. SAS, Brenner , Hakulinen & Gefeller, Epidemiology 2002
Stata
SEER Stat
R, Holleczek, Gondos & Brenner, Meth Inform Med 2009)
Period approaches - brief history (2)
• Extensions
Hybrid analysis (Brenner & Rachet, Eur J Cancer 2004)
Model based period analysis
Hermann Brenner, German Cancer Research Center23.1.2014
(Brenner & Hakulinen AJE 2006, CEBP 2007 etc)
• Increasing application
including EUROCARE, SEER etc.
Principle of period versus cohort approaches
Cohort
Hermann Brenner, German Cancer Research Center23.1.2014
Period
Complete
Example of period versus cohort approaches
ACCIS Project, Childhood Cancer Survival in Europe
period
cohort
period
cohort
Hermann Brenner, German Cancer Research Center23.1.2014
Brenner et al, Ann Oncol 2007
Emprirical evaluation of period versus cohort approaches
Observed
Cohort
Hermann Brenner, German Cancer Research Center23.1.2014
Observed
Period
Emprirical evaluation of period versus cohort analysis (Finland 1983-87)
Cohort
Period
Observed
Hermann Brenner, German Cancer Research Center23.1.2014
Brenner & Hakulinen, JCO 2002
PeriodCohort
Observed
Emprirical evaluation of period versus cohort analysis (Finland 1963-97)
Period Cohort
Hermann Brenner, German Cancer Research Center23.1.2014
Brenner & Hakulinen, AJE 2002
Period Cohort
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
1997
1998
1999
2000
Follow-up
Dx
Beyond standard period analysis
Hermann Brenner, German Cancer Research Center23.1.2014
2001
2002
2003
2004
2005
2006
,
1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
1997
1998
1999
2000
Follow-up
Dx
Model-based period analysis
=> precision, trends, tests, covariates, projections
Hermann Brenner, German Cancer Research Center23.1.2014
2001
2002
2003
2004
2005
2006
Brenner & Hakulinen, AJE 2006
Example for projections: multiple myeloma, USA
Hermann Brenner, German Cancer Research Center23.1.2014
Example for projections: multiple myeloma, USA
Hermann Brenner, German Cancer Research Center23.1.2014
Pulte et al, Haematologica 2009
Some practical issues: Cohort versus period modeling ?
DX 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
1997
1998
1999
2000
2001
Follow-up
Hermann Brenner, German Cancer Research Center23.1.2014
2001
2002
2003
2004
2005
2006
Brenner & Hakulinen IJC 2007: Period modeling mostly superior
Some practical issues: analyses of time trends
Avoid combinations of cohort and period analyses
Hermann Brenner, German Cancer Research Center23.1.2014
Some practical issues: analyses of time trends
Show period trends instead
Hermann Brenner, German Cancer Research Center23.1.2014
What to do if incidence is less up-to-date than mortality follow-up?
„Truncated period analysis“ ?
Hermann Brenner, German Cancer Research Center23.1.2014
What to do if incidence is less up-to-date than mortality follow-up?
Less up-to-date period analysis ?
Hermann Brenner, German Cancer Research Center23.1.2014
What to do if incidence is less up-to-date than mortality follow-up?
Hybrid analysis !
Hermann Brenner, German Cancer Research Center23.1.2014
Brenner & Rachet EJC 2004, Brenner & Hakulinen, EJC 2007
Full
Period
estimate
Some practical issues:
Which study population to describe for period analyses („Table 1“)?
Hermann Brenner, German Cancer Research Center23.1.2014
Full
Restricted
Length offollow-up
Length of period
2-year period 5-year period 10-year period
5-year RS Full Full Full
Some further practical issues:
Which study population to describe for period analyses („Table 1“)?
Empirical evaluation, Finnish Cancer Registry, Summary results
Hermann Brenner, German Cancer Research Center23.1.2014
5-year RS Full Full Full
10-year RS Full Full Restricted. Full Restricted
15-year RS Full
20-year RS Full
Jansen, Hakulinen & Brenner, Br J Cancer 2013
Full
Period
estimate
Some practical issues (yet to be clarified):
Which DCO proportions are relevant for period analysis?
Hermann Brenner, German Cancer Research Center23.1.2014
Full
Restricted
Hermann Brenner, German Cancer Research Center23.1.2014
Thank you for your attention!