A novel measure of socioeconomic status using individual housing data to assess the association of SES with rheumatoid arthritis and its mortality: a population-based case-control study.
OBJECTIVE
To assess whether HOUSES (HOUsing-based index of socioeconomic status (SES)) is associated with risk of and mortality after rheumatoid arthritis (RA).


METHODS
We conducted a population-based case-control study which enrolled population-based RA cases and their controls without RA.


METHODS
The study was performed in Olmsted County, Minnesota.


METHODS
Study participants were all residents of Olmsted County, Minnesota, with RA identified using the 1987 American College of Rheumatology criteria for RA from 1 January 1988, to 31 December 2007, using the auspices of the Rochester Epidemiology Project. For each patient with RA, one control was randomly selected from Olmsted County residents of similar age and gender without RA.


METHODS
The disease status was RA cases and their matched controls in relation to HOUSES as an exposure. As a secondary aim, post-RA mortality among only RA cases was an outcome event. The associations of SES measured by HOUSES with the study outcomes were assessed using logistic regression and Cox models. HOUSES, as a composite index, was formulated based on a summed z-score for housing value, square footage and number of bedrooms and bathrooms.


RESULTS
Of the eligible 604 participants, 418 (69%) were female; the mean age was 56±15.6 years. Lower SES, as measured by HOUSES, was associated with the risk of developing RA (0.5±3.8 for controls vs -0.2±3.1 for RA cases, p=0.003), adjusting for age, gender, calendar year of RA index date, smoking status and BMI. The lowest quartile of HOUSES was significantly associated with increased post-RA mortality compared to higher quartiles of HOUSES (HR 1.74; 95% CI 1.10 to 2.74; p=0.017) in multivariate analysis.


CONCLUSIONS
Lower SES, as measured by HOUSES, is associated with increased risk of RA and mortality after RA. HOUSES may be a useful tool for health disparities research concerning rheumatological outcomes when conventional SES measures are unavailable.
Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA.
Husam
H
Ghawi
Division of Rheumatology, Department of Health Sciences Research and Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
Cynthia S
http://orcid.org/0000-0001-5847-7475
CS
Crowson
Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA.
Jennifer
J
Rand-Weaver
Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA.
Elizabeth
E
Krusemark
Division of Rheumatology, Department of Health Sciences Research and Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
Sherine E
SE
Gabriel
Department of Pediatric and Adolescent Medicine and Internal Medicine, Mayo Clinic, Rochester, Minnesota, USA.
Young J
YJ
Juhn
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000401:mortality*; D016022:Case-Control Studies; D005260:Female; D006798:Housing / Q000706:statistics & numerical data*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D016016:Proportional Hazards Models; D012307:Risk Factors; D012959:Socioeconomic Factors
EPIDEMIOLOGY; RHEUMATOLOGY