Unintended consequences of a quality measure for acute bronchitis.

Objectives: To determine whether diagnostic coding shifts might undermine apparent improvements resulting from the 2007 Healthcare Effectiveness Data and Information Set (HEDIS) measure on avoidance of antibiotics for the treatment of adults with acute bronchitis (International Classification of Diseases, Ninth Revision, Clinical Modification code 466.0).

Study Design: Time series analysis within a primary care network for 3 successive winter seasons from 2006 to 2009.