Novel trial sequential analysis (TSA) method for time-to-event outcomes

Article type
Authors
Miladinovic B1, Hozo I2, Kumar A1, Mhaskar R1, Georgiev H1, Djulbegovic B1
1Center for Evidence Based Medicine, University of South Florida, USA
2Department of Mathematics, Indiana University Northwest, USA
Abstract
Background: TSA has been proposed as a method to assess whether the results of meta-analyses (MAs) are conclusive. However, the current TSA method can only be applied on count data and cannot incorporate time-to-event outcomes, which are prevalent in cancer studies.

Objectives: Present a novel method for the application of TSA for time-to-event outcomes. We use data from systematicreviews in multiple myeloma as an example to demonstrate the usefulness of the method. Pooled outcomes of overall survival (OS) and progression-free survival (PFS) were assessed for conclusiveness.

Methods: Extensive literature search identified 11 systematic reviews (23 MAs) of treatments for multiple myeloma. Based on the relative risk reduction (RRR) of 15% obtained from literature, we calculated the a priori anticipated information size (APIS) and the low-bias heterogeneity-adjusted information size (LBHIS) under the type I error of 5% and power of 80%. Both APIS and LBHIS incorporate the average rate of survival between the intervention and control groups, and potential patient loss to follow-up.

Results: Twenty three separate MAs (13 included OS and 10 PFS as outcome) were extracted (Table 1). The heterogeneity index I-sq varied between 0% and 85%and observed power from 9% to 100%. For OS, at a baseline RRR of 15% and using APIS, 54% of results (7/13) were false negative and 8% (1/13) were false positive. For the same RRR, LBHIS identified 77% (10/13) of results as false negative and 15% (2/13) as false positive results. For PFS, APIS identified 10% (1/10) as false negative and false positive results (1/10), and LBHIS also identified 10% (1/10) as false negative and zero false positive results.

Conclusions: For TSA, the new methods demonstrate the possibility of incorporating time-to-event data, which are important patient oriented outcomes. Time-to-event TSA can be extended to other fields where time-to-event outcomes are crucial.
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