Confounding by drug formulary restriction in pharmacoepidemiologic research.

ABSTRACT:

Purpose

The potential consequences of confounding due to drug formulary restrictions in pharmacoepidemiologic research remain incompletely understood. Our objective was to illustrate this potential bias using the example of fluticasone/salmeterol combination therapy, an oral inhaler used to treat asthma and chronic obstructive pulmonary disease, whose use is restricted in the province of Quebec, Canada.

Methods

We identified all new users of fluticasone/salmeterol in Quebec's administrative databases and classified those who received their initial dispensing of fluticasone/salmeterol between 1 September 1999 and 30 September 2003 as users from the liberal period and those who received it between 1 January 2004 and 31 October 2006 as users from the restricted period. The prim

SUBMITTER: Filion KB 

PROVIDER: S-EPMC5770206 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature