Abstract 16698: Variation in Systolic Blood Pressure Among Low-Socioeconomic Urban Dwellers is Associated With Travel Distance by Mode of Transportation

Abstract

Introduction: Hypertension affects one third of American adults and is especially common among low-socioeconomic urban dwellers. Studies suggest that poor access to a pharmacy is associated with elevated blood pressure (BP). Residents on the South Side of Chicago typically travel locally using three common modes of transportation - walking, riding the city bus, or driving - based on the distance of the trip. Based on previous literature, walking is preferred for distances less than 3 km, taking the city bus is preferred for distances 3-10 km, and driving is preferred if possible for distances greater than 10 km. Because distances from home to the pharmacy at thresholds between each mode of transportation (i.e. a long walk vs. a short bus ride) could cause logistical uncertainty for patients, we hypothesized that blood pressure is higher for patients living at threshold distances from the pharmacy they typically use. Methods: Medical records of adult South Side residents who received care at the University of Chicago’s outpatient clinics from 2012 through 2017 were reviewed. Blood pressure (BP) measurements for each patient were averaged and each patient’s home and pharmacy addresses were geocoded. We calculated the walking and driving distance from each patient’s home to his or her pharmacy. The relationship between BP and travel distance was compared using Spearman rank correlation and Fisher’s exact test. Results: 47,084 patients were included in the study. Mean systolic BP was significantly lower for patients living ≤1 km from their pharmacy than for patients living farther (p<0.0001). Mean systolic BP was highest at common distance thresholds for changing mode of transportation among urban dwellers (2-3 km and 10-20 km, Figure). Diastolic BP was not associated with distance from home to pharmacy. Conclusions: Among South Side Chicagoans, systolic BP is lowest for patients living ≤1 km from their pharmacy and highest at distance thresholds for walking, riding the city bus, or driving. Interventions to improve BP control among urban dwellers may benefit from targeting patients who live at threshold distances from their pharmacy.