Triangulation in aetiological epidemiology

TLDR

Triangulation combines multiple approaches with unrelated biases to strengthen causal inference, especially when consistent results arise despite biases that would predict opposite directions, and inconsistencies highlight needed further research. The aim is to illustrate how triangulation can improve causal inference in aetiological epidemiology. The authors propose a minimal set of criteria for triangulation, summarizing key bias sources across approaches, emphasizing explicit bias direction, selecting methods that bias in opposite directions, and accounting for exposure timing differences. They illustrate these principles with three examples.

Abstract

Triangulation is the practice of obtaining more reliable answers to research questions through integrating results from several different approaches, where each approach has different key sources of potential bias that are unrelated to each other. With respect to causal questions in aetiological epidemiology, if the results of different approaches all point to the same conclusion, this strengthens confidence in the finding. This is particularly the case when the key sources of bias of some of the approaches would predict that findings would point in opposite directions if they were due to such biases. Where there are inconsistencies, understanding the key sources of bias of each approach can help to identify what further research is required to address the causal question. The aim of this paper is to illustrate how triangulation might be used to improve causal inference in aetiological epidemiology. We propose a minimum set of criteria for use in triangulation in aetiological epidemiology, summarize the key sources of bias of several approaches and describe how these might be integrated within a triangulation framework. We emphasize the importance of being explicit about the expected direction of bias within each approach, whenever this is possible, and seeking to identify approaches that would be expected to bias the true causal effect in different directions. We also note the importance, when comparing results, of taking account of differences in the duration and timing of exposures. We provide three examples to illustrate these points.