Exploratory landmark analysis of CA19-9 showed a trend towards shorter PFS for patients with higher CA19-9 levels 6 weeks after commencing treatment (HR 1.8; 95% CI 0.94 3.71; P=0.94 3.71
I also highly prioritize the use of innovative statistical methods to minimize the inherent biases of retrospective analysis, having led the development of a tool known as sequential landmark analysis to control for immortal time bias when interpreting observational analyses studying the survival impact of adjuvant radiation therapy.
The landmark analysis was performed for statistical analyses.
Given the theoretical benefit of the biodegradable polymer drug eluting stents after the polymer is absorbed (within first two to nine months), we did a landmark analysis to evaluate for late events, defined as events beyond the first year.
Therefore, 3, 6, 9, and 12 months were chosen as the time points for the landmark analysis.
A sensitivity analysis of the effect of EPP was conducted using the landmark analysis (Freedman et al, 1992) for comparison with the time-dependent model results.
Most of these patients had early progression or death and were excluded to meet the conditions required for a landmark analysis [ 14, 15], i.e., to avoid bias in favour of responders.
The interventional community should not be enticed by the irrelevant yet highly publicised result of the "landmark" analysis to forget current guideline recommendations for the treatment of patients with stable coronary disease [ 6, 7].
A landmark analysis at 6 months, to allow for sufficient duration of therapy, revealed a median OS from diagnosis of not reached, 67 months and 51 months for patients in groups 1, 2 and 3, respectively (P=0.175 between groups 2 and 3; P=0.007 between groups 1 and 2; Figure 3b).
The character states of phylogenetic analyses are discrete states, but landmark analysis used in geometric morphometric analyses allow for continuous changes of a particular landmark character.
