Wednesday, April 21, 2021

In Studies of Patients at High Risk of Death, More Explicit Reporting of Functional Outcomes is Needed

Randomized controlled trials examining the effects of an intervention in patients with a high risk of death will often also include functional outcomes - such as quality of life, cognition, or physical disability. However, the death of patients before these outcomes can be assessed (also known as "truncation due to death") can confound the results of a "survivors-only" analysis, especially if mortality rates are higher in certain groups than others. 

A new methodology review of studies published within 5 high-impact general medical journals from 2014 to 2019 provides insight into this phenomenon and suggestions for improving how functional outcomes are handled. To be eligible for the review, a study needed to be a randomized controlled trial (RCT) with a mortality rate of at least 10% in one arm and to report at least one functional outcome in addition to mortality. The authors recorded the outcomes analyzed, the type of statistical analyses used, and the sample population of each of the 434 included studies. For most (351, or 79%) of these, function was a secondary outcome, while it was a primary outcome for 91 (21%) of them.

Only one-quarter (25%) of the functional outcomes within the studies that examined them as secondary outcomes used an approach that included all randomized patients (intention-to-treat); for the studies for which functional outcomes were the primary outcomes analyzed, this proportion was 60%.

The authors provide suggestions for best ways to handle and report data in these studies:
  • In the methods rather than only in tables or supplementary material, explicitly state the sample population from which the functional outcomes were drawn, whether it's survivors-only or another type of analysis.
  • If a survivors-only analysis is used, the authors should report the baseline characteristics between the groups analyzed and transparently discuss this as a limitation within the discussion section.
  • If all randomized participants are analyzed regardless of mortality, authors should report the assumptions upon which these analyses are based; for instance, if death is one outcome ranked among others in a worst-rank analysis, the justification for the ranking of outcomes should be discussed in the methods, and the implications of these decisions included in the discussion section. 
Colantuoni E, Li X, Hashem MD et al. (2021). A structured methodology review showed analyses of functional outcomes are frequently limited to "survivors only" in trials enrolling patients at high risk of death. J Clin Epidemiol (e-pub ahead of print).

Manuscript available here.