Codes and Frequencies
MULTSCLERYRC indicates whether the person had chronic multiple sclerosis 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 MULTSCLERYRC) created from the pre-1997 condition records, see the User Note on Condition Records and Condition Variables.
Defining Multiple Sclerosis Records and Identifying Persons with Multiple Sclerosis
For all available years, persons who were asked a direct question about multiple sclerosis and who have a chronic multiple sclerosis condition record are given a "Yes" code for MULTSCLERYRC. Persons who were asked a direct question about multiple sclerosis but do not have a chronic multiple sclerosis record are given a code of "No." Persons who were not asked a direct question about multiple sclerosis, 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 multiple sclerosis record.
For 1973 and 1978-1981, multiple sclerosis records were defined as those condition records with a code of "340" ("Multiple sclerosis") in the variable DCICDCOD in the original NHIS public use files. This condition code value comes from the International Classification of Diseases (ICD). Additionally, to be considered "chronic," multiple sclerosis 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 multiple sclerosis records were defined as those condition records with a code of "415" ("Multiple sclerosis") 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.
For 1973, MULTSCLERYRC should be weighted with PERWEIGHT.
For 1978 to 1981, MULTSCLERYRC should be weighted with CONDWT3.
For 1982 to 1996, MULTSCLERYRC should be weighted with CONDWT4.
Related Multiple Sclerosis Variables
The nearest equivalent of MULTSCLERYRC available after 1996 is MULTSCLEREV (Ever told have multiple sclerosis). However, researchers should use caution when comparing prevalence estimates derived from these two variables, as both the manner of collecting information about multiple sclerosis and the reference period differ greatly between the two. MULTSCLERYRC 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 in the past year. MULTSCLEREV, by contrast, is based on a direct question about whether the person ever had the condition multiple sclerosis.
As with all of the person-level condition variables created by IHIS from condition records prior to 1997, the universe for MULTSCLERYRC 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 multiple sclerosis 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.
- 1973: All persons.
- 1978-1981: Persons living in 1/6 of households (who received Condition List 3).
- 1982-1996: Persons living in 1/6 of households (who received Condition List 4).
- 1973, 1978-1996