Figure S2.3. DAG illustrating causal relationships among formulary policy (C1) and treatment with a CCB (A) and treatment for erectile dysfunction (C4).

Figure S2.3DAG illustrating causal relationships among formulary policy (C1) and treatment with a CCB (A) and treatment for erectile dysfunction (C4)

Alcohol abuse (C2) influences impotence (C3), which influences treatment of erectile dysfunction (C4) and is a cause of acute liver disease (Y). In this example C4 is a confounder and collider. Adjustment of C4 is additional to adjustment for at least one other variable on the open C1-3 pathways.

From: Supplement 2, Use of Directed Acyclic Graphs

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Developing a Protocol for Observational Comparative Effectiveness Research: A User's Guide.
Velentgas P, Dreyer NA, Nourjah P, et al., editors.
Copyright © 2013, Agency for Healthcare Research and Quality.

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