Initiator Types and the Causal Question of the Prevalent New-User Design : A Simulation Study

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New-user designs restricting to treatment initiators have become the preferred design for studying drug comparative safety and effectiveness using nonexperimental data. This design reduces confounding by indication and healthy-adherer bias at the cost of smaller study sizes and reduced external validity, particularly when assessing a newly approved treatment compared with standard treatment. The prevalent new-user design includes adopters of a new treatment who switched from or previously used standard treatment (i.e., the comparator), expanding study sample size and potentially broadening the study population for inference. Previous work has suggested the use of time-conditional propensity-score matching to mitigate prevalent user bias. In this study, we describe 3 "types" of initiators of a treatment: new users, direct switchers, and delayed switchers. Using these initiator types, we articulate the causal questions answered by the prevalent new-user design and compare them with those answered by the new-user design. We then show, using simulation, how conditioning on time since initiating the comparator (rather than full treatment history) can still result in a biased estimate of the treatment effect. When implemented properly, the prevalent new-user design estimates new and important causal effects distinct from the new-user design.

Errataetall:

CommentIn: Am J Epidemiol. 2021 Jul 1;190(7):1349-1352. - PMID 33350439

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:190

Enthalten in:

American journal of epidemiology - 190(2021), 7 vom: 01. Juli, Seite 1341-1348

Sprache:

Englisch

Beteiligte Personen:

Webster-Clark, Michael [VerfasserIn]
Ross, Rachael K [VerfasserIn]
Lund, Jennifer L [VerfasserIn]

Links:

Volltext

Themen:

Causal effects
Epidemiologic methods
Journal Article
Prevalent users
Research Support, N.I.H., Extramural
Study designs

Anmerkungen:

Date Completed 31.08.2021

Date Revised 23.12.2021

published: Print

CommentIn: Am J Epidemiol. 2021 Jul 1;190(7):1349-1352. - PMID 33350439

Citation Status MEDLINE

doi:

10.1093/aje/kwaa283

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM319150437