A cluster of reports of hypersensitivity reactions among patients who switched from carvedilol (immediate release formulation, referred to hereafter as carvedilol) to carvedilol extended release was received during the initial post-launch period of carvedilol extended release. In follow up to this observation, product labeling for both agents was updated and a nested case control study was subsequently conducted to examine the risk of serious hypersensitivity reactions i.e. anaphylactic reaction and/or angioedema among patients who used carvedilol extended release compared to carvedilol and separately compared to other long acting beta(β)-blockers. This proposed analysis is an update to the previously conducted analysis using the same database, LabRx, now containing 2 additional years of data, which should provide a larger number of carvedilol extended release exposed subjects.

Inclusion Criteria:

• At least one prescription claim for a β-blocker during follow-up time available in the database.
• At least one month of enrollment in the healthcare plan

Exclusion Criteria:

• None

Derived from the LabRx database from Oct. 1st 2004 to Sep. 30th 2009. The LabRx Database (referred to in publications as the "i3 InVision Data Mart") is provided by Ingenix Pharmaceutical Services, Inc. It is a comprehensive, de-identified U.S. healthcare claims database that contains the aggregated health claims experience of the covered lives managed by United Healthcare. It contains only those covered lives for which there exists a combined benefit structure including medical and prescription coverage. Overall, it is representative of the non-elderly, insurance-carrying population in the U.S., but it also contains information on several hundred thousand Managed Medicaid and Medicare Advantage members. It contains inpatient, outpatient and pharmacy claims, lab results and enrolment information on over 30.5 million lives from October 2004 through September 2009.