Trend Analysis Using NAMCS and NHAMCS Drug Data

The Ambulatory Care Drug Database underwent substantial revisions in 2002, as described in the 2002 NAMCS and NHAMCS Public Use Data File Documentation. As part of our annual data processing, we add new drugs and update the database as needed.  Because of these revisions to the file, and also because of the addition of a second and third therapeutic class for each drug beginning in 2004, trend analysis with survey data prior to 2002 becomes more problematic.  We recommend that researchers download the Drug Characteristics file (DRUGFILE-2004.DAT), which is updated annually. The characteristics from this file can be applied by matching on drug codes to previous years of data in order to get the most accurate results when doing analysis of drug trends.  We have also prepared a SAS program (which can be adapted for use with other software) (DRUGCHAR.SAS) to apply the new characteristics from the most current version of the drug database to previous years of data. This program will create a SAS dataset for you for each data year you run it for.  There is just one version of the Drug Characteristics file and one version of the SAS program, which can be used with both NAMCS and NHAMCS public use files.  For the convenience of data users, these have been placed in both the NAMCS and NHAMCS dataset documentation areas of the FTP server.  Please contact the Ambulatory Care Statistics Branch at 301-458-4600 if you have questions.