4223Income level and the prevalence of ischemic coronary heart disease in a low-mid-income country with high social inequalities. Influence of neighborhood walkability

Abstract

Background The greater burden of coronary heart disease (CHD) comes from low-middle income countries (LMIC). Socioeconomic status, environmental factors, poor access to healthcare, physical inactivity and excess consumption of carbohydrates, have explained part of this burden. However, the association between income level and CHD in LMIC with marked social inequalities is not fully understood, and whether there is influence of neighborhood walkability (walking-promoting potential of the residential built environment for daily activities) in this association requires further investigation. Purpose To investigate to what level income is associated with ischemic CHD in a LMIC with great social inequalities and to explore the potential role of neighborhood walkability in this association. Methods We evaluated patients referred for myocardial perfusion imaging with SPECT (SPECT-MPI) from February 2010 to August 2017 at a reference imaging center in our city, Brazil. Each patient was georeferenced and the exposure variable was the average income in Brazilian currency (Real) per month, from the patient's residential census block. Ischemic CHD was defined by an abnormal myocardial perfusion (summed stress score >3) during a SPECT-MPI study. Walkability was measured by a score combining street connectivity, residential density, commercial density and mixed land use. We used mixed effects models to evaluate the association between income level and ischemic CHD, adjusted for potential confounders, and performed a mediation analysis to measure the percentage of this association mediated by walkability. Results From 26,810 participants, those living in the lowest tertile income neighborhoods were younger (61±12 vs 63±13 vs 65±12 yrs old); with higher body mass index (28.4±5 vs 27.7±5 vs 27.4±4 kg/m2); more likely to be women (52 vs 49 vs 47%), current smokers (10 vs 9 vs 8%), sedentary (79 vs 76 vs 73%), having diabetes (27 vs 24 vs 23%), hypertension (65 vs 62 vs 60%) and with known CHD (21 vs 20 vs 19%) when compared to the second and the highest tertiles respectively, all with p<0.001. After adjusting for these potential confounders, income level was inversely associated with ischemic CAD (Figure). Neighborhoods with higher income levels were associated with better walkability scores (R = 0.34eta; p<0.001), but walkability did not mediate the association between income level and ischemic CHD (percent mediated = −0.3%). Figure 1. Association of income and CHD Conclusions In this large registry from a LMIC population, living in a lower-income neighborhood was associated with higher prevalence of ischemic CHD. Even though neighborhood walkability was directly associated with neighborhood income, it did not explain the association between income level and ischemic CHD.