ObjectivesTo assess whether HOUSES (HOUsing-based index of socioeconomic status (SES)) is associated with risk of and mortality after rheumatoid arthritis (RA).DesignWe conducted a population-based case–control study which enrolled population-based RA cases and their controls without RA.SettingThe study was performed in Olmsted County, Minnesota.ParticipantsStudy 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.Primary and secondary outcome measureThe 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.ResultsOf 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.ConclusionsLower 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.

Objective To assess whether asthma is associated with risk of appendicitis in children. Methods We used a population-based case-control study design utilizing a comprehensive medical record review and predetermined criteria for appendicitis and asthma. All children (age<18 years) who resided in Olmsted County, Minnesota, and developed appendicitis between 2006 and 2012 were matched to controls (1:1) with regard to birthday, gender, registration date, and index date. Asthma status was ascertained using predetermined criteria. Active (current) asthma was defined as the presence of asthma symptoms or asthma-related events (eg, medication use, clinic visits, emergency department, or hospitalization) within one year prior to the index date. Inactive asthma was defined as subjects without these events. A conditional logistic regression model was used. Results Among the 309 appendicitis cases identified, when stratified by asthma status, active asthma was associated with significantly increased risk of appendicitis when compared to inactive asthma (OR=2.48; 95% CI, 1.22–5.03) and to no asthma (OR=1.88; 95% CI, 1.07–3.27) (overall p-value=0.035). When controlling for potential confounders such as gender, age, and smoking status, active asthma was associated with a higher odds of developing appendicitis compared to non-asthmatics (adjusted OR=1.75, 95% CI 0.99–3.11) whereas inactive asthma was not (overall p-value=0.049). Tobacco smoke exposure within three months was associated with an increased risk of appendicitis (adjusted OR=1.66; 95% CI, 1.02, 2.69). Among asthma medications, leukotriene receptor antagonists reduced the risk of appendicitis (OR=0.18; 95% CI, 0.04–0.74). Conclusions Active asthma may be an unrecognized risk factor for appendicitis in children while a history of inactive asthma does not pose such risk. Further investigation exploring the underlying mechanisms is warranted.