Skip to main content

Table 1 Combinations of intercurrent event strategies that were illustrated in this case study and their corresponding analysis methods

From: The role of the estimand framework in the analysis of patient-reported outcomes in single-arm trials: a case study in oncology

Figure

Intercurrent event strategies

Analysis

Strategy

While no IE

Composite

Hypothetical

Treatment policy

QoL data included in the analysisa

Estimation of mean QoL at each cycle

Figure 3

 1a,b

Death

  

PD, TD

All outcomes until each patient’s respective death in the first 40 cyclesb, including outcomes after TD or PD

1a. GEE with independence correlation structure, where cycle number was included as a categorical variable [26]

1b. An LMM with random intercept and slope was estimated, where the cycle number was included as a categorical variable. Individual outcome predictions from this LMM were computed at each cycle and averaged only over those patients alive at that cycle.

 2

 

Death

 

PD, TD

All outcomes until each patient’s respective death in the first 40 cycles, including outcomes after TD or PD. After death, the outcome was set to 0 until cycle 40

Estimated means using a GEE with independence correlation structure, where cycle number was included as a categorical variable

(Applying an LMM would also be possible here)

 3a,b

  

Death

PD, TD

All outcomes until each patient’s respective death in the first 40 cycles, including outcomes after TD or PD

3a. Marginal means from an estimated LMM with random intercept, where the cycle number was included as a categorical variable

3b. same as 3a, but with additional random slope

Figure 4

 1

Death, TD

  

PD

All outcomes before each patient’s respective TD or death in the first 40 cycles, including outcomes after PD

GEE with independence correlation structure, where cycle number was included as a categorical variable. (Averaging individual LMM predictions over those still on treatment at each cycle would also be possible)

 2a

  

Death, TD

PD

All outcomes before each patient’s respective TD or death in the first 40 cycles, including outcomes after PD

Marginal means from an estimated LMM with random intercept, where the cycle number was included as a categorical variable

 2b

Death

 

TD

PD

All outcomes before each patient’s respective TD or death in the first 40 cycles, including outcomes after PD

Estimating an LMM and averaging individual predictions at each cycle over those still alive at that cycle

 3

Death

  

PD, TD

Same as estimates 1a,b in Fig. 3

 

 Figure 5

    

The analyses for Fig. 5 below are analogous to those for Fig. 4 but with “TD” replaced by “PD” and vice versa

 1

Death, PD

  

TD

All outcomes before each patient’s respective PD or death in the first 40 cycles, including outcomes after TD

GEE with independence correlation structure, where cycle number was included as a categorical variable. (Averaging individual LMM predictions over those still without PD and alive at each cycle would also be possible)

 2a

  

Death, PD

TD

All outcomes before each patient’s respective PD or death in the first 40 cycles, including outcomes after TD

Marginal means from an estimated LMM with random intercept, where the cycle number was included as a categorical variable

 2b

Death

 

PD

TD

All outcomes before each patient’s respective PD or death in the first 40 cycles, including outcomes after TD

Estimating an LMM and averaging individual predictions at each cycle over those still alive at that cycle

 3

Death

  

TD, PD

Same as estimates 1a,b in Fig. 3

 
  1. aAssuming complete QoL data for each patient from study registration until cycle 40 or death; to obtain such complete data(sets) for analysis in practice likely requires imputation to be performed before the analyses listed here
  2. bSome patients in the study were censored for overall survival before cycle 40. As censoring was mostly administrative at the end of the study, we assumed uninformative censoring in our analyses. If an informative censoring mechanism is plausible, weighted GEE approaches or joint models may be used to account for such censoring [26, 27]. PD disease progression, TD treatment discontinuation, GEE generalized estimating equations, LMM linear mixed model