Weighted composite time to event endpoints with recurrent events: comparison of three analytical approaches

Background

In clinical trials the study interest often lies in the comparison of a treatment to a control regarding a time to event endpoint. A composite endpoint allows to consider several time to event endpoints at once. Usually, only the time to the first occurring event for a patient is thereby analyzed. However, an individual may experience more than one non-fatal event. Including all observed events in the analysis can increase the power and provides a more complete picture of the disease. Thus, analytical methods for recurrent events are required. A challenge is that the different event types belonging to the composite often are of different clinical relevance. In this case, weighting the event types according to their clinical relevance is an option. Different weight-based methods for composite time to event endpoints were proposed. So far, there exists no systematic comparison of these methods.

Methods

Within this work we provide a systematic comparison of three methods proposed for weighted composite endpoints in a recurrent event setting combining non-fatal and fatal events of different clinical relevance. We consider an extension of an approach proposed by Wei and Lachin, an approach by Rauch et al., and an approach by Bakal et al.. Comparison is done based on a simulation study and based on a clinical study example.

Results

For all three approaches closed formula test statistics are available. The Wei-Lachin approach and the approach by Rauch et al. show similar results in mean squared error. For the approach by Wei and Lachin confidence intervals are provided. The approach by Bakal et al. is not related to a quantifiable estimand. The relevance weights of the different approaches work on different level, i.e. either on cause-specific hazard ratios or on event count.

Conclusion

The provided comparison and simulations can help to guide applied researchers to choose an adequate method for the analysis of composite endpoints combining (recurrent) events of different clinical relevance. The approach by Wei and Lachin and Rauch et al. can be recommended in scenarios where the composite effect is time-independent. The approach by Bakal et al. should be applied carefully.

Supplementary Information

The online version contains supplementary material available at (10.1186/s12874-022-01511-1).

Comparative Methodological Assessment of the Randomized GLOBAL LEADERS Trial Using Total Ischemic and Bleeding Events

BACKGROUND

Time-to-first-event analysis considers only the first event irrespective of its severity. There are several methods to assess trial outcomes beyond time-to-first-event analysis, such as analyzing total events and ranking outcomes. In the GLOBAL LEADERS study, time-to-first-event analysis did not show superiority of ticagrelor monotherapy following one-month dual antiplatelet therapy (DAPT) after percutaneous coronary intervention to conventional 12-month DAPT followed by aspirin monotherapy in the reduction of the primary composite end point of all-cause mortality or new Q-wave myocardial infarction. This study sought to explore various analytical approaches in assessing total ischemic and bleeding events after percutaneous coronary intervention in the GLOBAL LEADERS study.

METHODS AND RESULTS

Total ischemic and bleeding events were defined as all-cause mortality, any stroke, any myocardial infarction, any revascularization, or Bleeding Academic Research Consortium grade 2 or 3 bleeding. We used various analytical approaches to analyze the benefit of ticagrelor monotherapy over conventional DAPT. For ischemic and bleeding events at 2 years after percutaneous coronary intervention, ticagrelor monotherapy demonstrated a 6% risk reduction, compared with conventional 12-month DAPT in time-to-first-event analysis (hazard ratio, 0.94 [95% CI, 0.88-1.01]; log-rank P=0.10). In win ratio analysis, win ratio was 1.05 (95% CI, 0.97-1.13; P=0.20). Negative binomial regression and Andersen-Gill analyses which include repeated events showed statistically significant advantage for ticagrelor monotherapy (rate ratio, 0.92 [95% CI, 0.85-0.99; P=0.020] and hazard ratio, 0.92 [95% CI, 0.85-0.99; P=0.028], respectively), although in weighted composite end point analysis, the hazard ratio was 0.93 (95% CI, 0.84-1.04; log-rank P=0.22).

CONCLUSIONS

Statistical analyses considering repeated events or event severity showed that ticagrelor monotherapy consistently reduced ischemic and bleeding events by 5% to 8%, compared with conventional 1-year DAPT. Applying multiple statistical methods could emphasize the multiple facets of a trial and result in accurate and more appropriate analyses. Considering the recurrence of ischemic and bleeding events, ticagrelor monotherapy appeared to be beneficial after percutaneous coronary intervention. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01813435.