Methods: We retrospectively analyzed OFC data collected at Tufts Medical Center and Massachusetts General Hospital between March 2008-April 2015. Household income (HHI, ≤$50,000/yr or >$50,000/yr) was estimated using median income of the patient home zip code. We used uni- and multivariable logistic regression to analyze for associations to outcome.
Results: Analysis of 1252 OFCs in 831 patients was performed. Most were male (57%) and white (79%), with an average age of 10 years (0.7-77.8). OFCs for major allergens (milk, egg, peanut, tree nuts, soy, wheat, fish and shellfish) accounted for 89% of the total. Ninety-three percent of the families were in the high HHI bracket. OFC outcomes were 26% positive, 69% negative, and 5% indeterminate. OFC outcome was associated with HHI (p=0.008) and allergen (major vs. non-major, p=0.039), but not with age (p=0.15), gender (p=0.08), race (p=0.30) or facility (p=0.52). We found that the low HHI group was 2.7 times more likely to have a negative OFC (CI=1.2-5.9, p=0.015), after controlling for allergen type, facility, age, gender, and race.
Conclusions: Patients from families with low HHI (≤$50,000/yr) are 2.7 times more likely to have a negative OFC compared with high HHI group (>$50,000/yr). Further studies are needed to determine the causality.