Description

MIGRAINEYRC indicates whether the person had chronic migraines 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 MIGRAINEYRC) created from the pre-1997 condition records, see the User Note on Condition Records and Condition Variables.

Defining Migraine Records and Identifying Persons with Migraines

For all available years, persons who were asked a direct question about having migraines and who have a chronic migraines condition record are given a "Yes" code for MIGRAINEYRC. Persons who were asked a direct question about having migraines but do not have a chronic migraine record are given a code of "No." Persons who were not asked a direct question about migraines, 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 migraine record.

For 1973 and 1978-1981, chronic migraine records were defined as those condition records with a code of "111" ("Migraine") 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," migraine records must have a code of "1" ("Chronic") in the variable CACODE in the original NHIS public use files.

For 1982-1996, chronic migraine records were defined as those condition records with a code of "406" ("Migraine headache") in the variable C1CONDRC in the original NHIS public use files. This condition code value comes from NCHS's Diagnostic Recode C: Chronic Conditions and Impairments.

Weights
For 1973, MIGRAINEYRC should be weighted with PERWEIGHT.

For 1978 to 1981, MIGRAINEYRC should be weighted with CONDWT3.

For 1982 to 1996, MIGRAINEYRC should be weighted with CONDWT4.

Related Migraine Variables
The nearest equivalent of MIGRAINEYRC available for 1997 forward is FHEADYR (Had frequent headaches/migraines, past 12 months). However, researchers should use caution when comparing prevalence estimates derived from these two variables, as the manner of collecting information about migraines differs greatly between the two. MIGRAINEYRC 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. FHEADYR, by contrast, is based on a direct question about whether the person had the condition migraines.

Comparability

As with all of the person-level condition variables created by IHIS from condition records prior to 1997, the universe for MIGRAINEYRC 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 migraines in the past year. There is also a minor universe change between the sets of years 1978-1981 and 1982-1996. These changes require 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.

Universe

Availability

• 1973, 1978-1996

Weights

• 1973 : PERWEIGHT
• 1978-1981 : CONDWT3
• 1983-1996 : CONDWT4
• 1982 : CONDWT5