Codes and Frequencies
BRONYRC indicates whether the person had chronic bronchitis in the past year. This variable is created with supplemental programming by the IPUMS NHIS staff from the pre-1997 condition records. For general information about IHIS variables (such as BRONYRC) created from the pre-1997 condition records, see the User Note on Condition Records and Condition Variables.
Defining Bronchitis Records and Identifying Persons with Bronchitis
For all available years, persons who were asked a direct question about bronchitis and who have a chronic bronchitis condition record are given a "Yes" code for BRONYRC. Persons who were asked a direct question about bronchitis but do not have a chronic bronchitis record are given a code of "No." Persons who were not asked a direct question about bronchitis, or for whom it is unknown whether they were asked such a question, are given a code of "NIU" (not in universe), regardless of whether they have a chronic bronchitis record.
For 1970 and 1978-1981, bronchitis records were defined as those condition records with a code of "151" ("Chronic bronchitis [nonallergic]") in the variable DIAGR1 in the original NHIS public use files. This condition code value comes from NCHS's Diagnostic Recode #1: Diseases, Injuries, and Impairments, not from the International Classification of Diseases (ICD) codes. Additionally, to be considered "chronic," bronchitis condition records must have a code of "1" ("Chronic") in the variable CACODE in the original NHIS public use files.
For 1982 to 1996, chronic bronchitis records were defined as those condition records with any of the following codes in the variable DCICDCOD in the original NHIS public use files:
- "4910" ("Simple chronic bronchitis")
- "4911" ("Mucopurulent chronic bronchitis")
- "4912" ("Obstructive chronic bronchitis")
- "4918" ("Other chronic bronchitis")
- "4919" ("Unspecified chronic bronchitis")
These condition code values come from ICD Revision 9.
For 1970, BRONYRC should be weighted with PERWEIGHT.
For 1978 to 1996, BRONYRC should be weighted with CONDWT6.
Related Bronchitis Variables
The nearest equivalent of BRONYRC for 1997 forward is CRONBRONYR (Told had chronic bronchitis, past 12 months). However, researchers should use caution when comparing prevalence estimates derived from these two variables, as the manner of collecting information about bronchitis differs greatly between the two. BRONYRC was created by recoding condition records that were generated in response to several different survey questions about health problems underlying disability, sick days, or contacts with health care practitioners. CRONBRONYR, by contrast, is based on a direct question about whether the person had the condition bronchitis.
As with all of the person-level condition variables created by IHIS from condition records prior to 1997, the universe for BRONYRC is substantially different for 1978 forward than it is for years prior to 1978. Beginning in 1978, only persons living in 1/6 of households, rather than all persons, were asked a direct question about having bronchitis in the past year. This change requires that different weight variables be used depending on which years of data are analyzed. See the "Description" tab for details.
Additionally, there is a change in the way "Yes" responses are coded over time. See the User Note on Condition Records and Condition Variables for details about the composite coding scheme employed by IHIS.
- 1970: All persons.
- 1978-1996: Persons living in 1/6 of households (who received Condition List 6).
- 1970, 1978-1996