Study design · Planning

Prevalent New-User Design Diagram

The prevalent new-user (time-conditional matching) design drawn in the Schneeweiss/Gatto convention — assessment, exposure, and follow-up windows anchored on a timeline so the design's temporal logic is explicit.

Download SVG Open code and full worked example

When to use it

When a strict new-user design discards too many patients (e.g., switchers/augmenters): match initiators of the comparator to prevalent users of the referent drug on time since referent initiation, recovering a valid contrast without losing prevalent users.

How to read it

Comparator (B) initiators are matched to prevalent referent (A) users at the same time since A initiation (the exposure set), so the two are aligned on disease duration — the look-back is conditioned on that matching time.

Worked example

An established Drug A user is matched, at a given time since starting A, to a Drug B initiator at the same time-since-A; both are followed forward for the outcome.

Windows: A prior use [−12, 0]; A continues / B initiates [0, 18]; follow-up [0, 18] months, aligned at the time-conditional matching point.

Result: Matching on time since referent initiation aligns the arms on disease duration and prior exposure, so the diagram shows how the design avoids both prevalent-user bias and the heavy attrition of a strict new-user restriction.

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Prevalent new-user design

Reference: Schneeweiss S, Rassen JA, Brown JS, et al. Graphical Depiction of Longitudinal Study Designs in Health Care Databases. Ann Intern Med. 2019;170(6):398-406.