The Ambulatory Care Drug Database System

Guidance on Search Criteria

NOTE: The Ambulatory Care Drug Database made the switch to a Multum-based system of drug classification with the 2006 data year. As we work more with this system, we are identifying some issues which may affect data users. Specifically, in developing the new online drug database application, we discovered that Multum assigns certain drug characteristics differently than NCHS had done in the past. This was first noticed with aspirin, which Multum classifies as a prescription drug. The reason for this appears to be that there are certain strengths of aspirin that are only available by prescription, and Multum appears to code up to the highest level rather than differentiating prescription and non-prescription forms of drugs. This was also noticed with the DEA Status variable. Some drugs, such as codeine, may have multiple DEA statuses, depending on their dosage and route of administration. Multum codes such drugs up to their highest DEA status. Beginning with the 2008 drug data, we have worked with Multum to reclassify drugs within our own database to reflect multiple statuses. We wish to bring such issues to the attention of our data users so that they can be aware of any seeming contradictions with regard to these characteristics.

Drug Entry Code: A unique, NCHS-assigned 5-digit code, applied to each drug reported in the NAMCS and NHAMCS.

Drug Entry Name: The specific drug identifier entered by the survey respondent. It corresponds with the entry made in the medical record, prescription, or medical order, and may be a trade/brand/proprietary or generic name. It should not be a drug class, although sometimes respondents will enter specific therapeutic effects, like allergy relief or antidepressant, in lieu of names, and these will also receive codes.

Generic-Equivalent Code: A 6-digit code based on the Multum classification. If a match could not be found within Multum, NCHS developed its own code. These codes, unlike NCHS generic codes prior to 2006, can encompass up to 6 ingredients for each drug. Multum codes begin with the letter "d", and NCHS codes begin with the letters "a", "c" or "n". The generic-equivalent code is the same as the ingredient code for single-ingredient products, but not for combination products. See "Ingredient Code" below for more information. Information about Multum is also available in the NAMCS and NHAMCS Public Use Data File Documentation.

Generic-Equivalent Name: This is a listing of ingredient names (up to 6) comprising the component(s) of a given drug.

Ingredient Code: A 6-digit code based on the Multum classification, used to identify the active ingredients of drugs. A maximum of 6 ingredients can be identified for each drug in the NAMCS and NHAMCS. Note that the ingredient code and the generic-equivalent code will be the same for single-ingredient products, but not for combination products. For example, the antibiotic drug Augmentin is "generically equivalent" to the Multum code for amoxicillin-clavulanate (d00089). But those ingredients also have their own unique codes in the Multum classification (amoxicillin, d00088 and clavulanate, d04405).

Ingredient Name: The names of the active ingredients used in drugs.

Therapeutic Class (Multum's "Drug Category"): Beginning with the 2006 data year, therapeutic class is being assigned using Multum's drug categories. (Prior to this time, the National Drug Code Directory was used to assign therapeutic class.). The Multum Lexicon provides a 3-level nested category system that assigns a therapeutic class to each drug and each ingredient of the drug (e.g., for naproxen: the broadest category is central nervous system agents [level 1]; the more detailed category is analgesics [level 2]; and the most detailed category is nonsteroidal anti-inflammatory agents [level 3]). Not all drugs have three classification levels; some may only have two [e.g. for digoxin: cardiovascular agents [level 1]; inotropic agents [level 2]), others only have one. Each drug may have up to four therapeutic categories in the ambulatory care drug database. Note that Multum uses a “combination” category for some multiple ingredient drugs. These include antihypertensive combinations, antiasthmatic combinations, upper respiratory combinations, psychotherapeutic combinations, bronchodilator combinations, sex hormone combinations, skeletal muscle relaxant combinations, and narcotic analgesic combinations. This categorization may be sufficient for certain analyses but not for others because it lacks information about the therapeutic effect of the individual ingredients that make up the combination. For example, the drug HYDROCHLOROTHIAZIDE; LOSARTAN is identified as an antihypertensive combination. Therefore, we know that this drug has an antihypertensive drug effect. However, based on this combination category we do not know that the drug’s single ingredients have the therapeutic effects of a diuretic and angiotensin II inhibitor, which is relevant for some analyses. As a result, NCHS decided that, in addition to assigning therapeutic categories to each drug, a separate file would be provided that could be merged with the public use file, and that listed up to 6 ingredients for each drug along with up to 3 therapeutic categories for each ingredient.

Prescription Status: A code designed to identify the federal legal status (prescription or nonprescription) of the drug entered.

Composition Status: A code used to distinguish between drug products made up of a single ingredient versus a fixed active ingredient combination. Fixed active ingredient combination drug products are referred to as a combination drugs in NAMCS and NHAMCS.

DEA Status: Controlled medications, because of their significant potential for dependence or abuse and their possible diversion into illicit channels, are regulated under Federal law by the Department of Justice, Drug Enforcement Agency (DEA). The Controlled Substance Act of 1970 identifies each controlled drug as one of five schedules. Schedule I drugs, like heroin and LSD, have a higher potential for abuse and no current accepted medical usefulness for treatment in the United States. Each successive schedule, II through V, reflects a decreasing degree of dependence and potential for abuse.

Drug Search Results

The Drug Search Results screen displays search results by drug entry code, drug entry name, generic-equivalent name, and number of drug mentions (defined below) for the most recent year of data. Note that, for 2022, the data only include hospital emergency department visits from NHAMCS. If number of mentions is blank, there were no recorded entries for the drug that year. By clicking on any of the underlined text in the Drug Search Results, information will be displayed on the drug's characteristics, number of mentions, and mention rate.

Drug Mention: The estimate of drug mentions for each drug reported in the most recently available NAMCS and NHAMCS datasets is provided. For 2022, only NHAMCS emergency department data are available. A drug mention is the entry on the survey collection form of a pharmaceutical agent--by any route of administration--for prevention, diagnosis, or treatment. Generic as well as brand-name drugs are included, as are nonprescription and prescription drugs. Along with all new drugs, the survey respondent also records continued medications if the patient was specifically instructed or expected to continue the medication. For 2022, as many as 30 drugs can be reported per emergency department visit. If no figure is displayed, there were no mentions of that drug in the current year of data. Figures are presented as one would generate them from public use data and can be used to make sure one’s analysis is yielding the correct result. The figures shown here do not include standard errors and may not be statistically reliable. They are presented only to show the relative frequency of their occurrence in the current year of data.

Drug Mention Rate: The drug mention rate is the number of mentions in the 2022 NHAMCS emergency department data for a particular drug code per 10,000 people per year. The mention rate is based on the July 1, 2022, estimate of the U.S. civilian noninstitutionalized population as developed by the U.S. Census Bureau, Population Division. If a number of mentions is displayed without a mention rate, the mention rate was less than 1 per 10,000 people.