Study population and design
The Hispanic Community Health Study/Study of Latinos (HCHS/SOL) is a community-based prospective cohort study of 16,415 self-identified Hispanic/Latino persons aged 18–74 years at screening from randomly selected households in four U.S. field centers (Chicago, IL; Miami, FL; Bronx, NY; San Diego, CA) with baseline examination (2008 to 2011) and yearly telephone follow-up assessment. The goals of the HCHS/SOL, sample design, and cohort selection have been previously described [16, 17]. The baseline clinical examination included comprehensive biological (e.g., anthropometrics, blood draw), behavioral (e.g., tobacco use assessed by self-report), and socio-demographic (e.g., socioeconomic status, nativity) assessments. The Institutional Review Board at each field center approved the study. All participants gave written informed consent in either English or Spanish.
Exposures of interest
Mortgage foreclosure risk
In 2008, the U.S. Department of Housing and Urban Development (HUD) created a novel mortgage foreclosure risk metric which estimates mortgage foreclosure risk for the year 2007 and the first six months of 2008 as a function of area decline in home values as of June 2008; unemployment rate as of June 2008; and high cost mortgage loans between 2004 and 2006. The mortgage foreclosure risk metric is estimated at the census tract level and reflects areas in the country that have started or could potentially become areas of abandonment and disinvestment. This measure was used to inform where state and local resources should be targeted to stabilize neighborhoods and stem the decline of house values of homes in these areas. More details on the methodology HUD used to calculate mortgage foreclosure risk is available on the HUD website [18].
Homeownership
Homeownership was determined by a question asked during the baseline HCHS/SOL visit: Is your house, apartment, or mobile home… (1) “Owned by you or someone in the household free and clear --- without a mortgage or loan”; (2) “Owned by you or someone in the household--- with a mortgage or loan”; (3) “Rented”; or (4) occupied without rent. In order to be consistent with other studies that do not distinguish between mortgage status among owners, both of the ‘owned’ categories were combined into one category and compared with renters. [19, 20]
Cardiovascular disease risk factors
Each cardiovascular disease risk factor was measured during the baseline clinic visit of HCHS/SOL participants. Three seated blood pressure measurements were obtained after a 5-min rest period using an automatic sphygmanometer. The average of the second and third measurement was used in analysis. Hypertension was defined as a systolic blood pressure ≥ 140 mmHg, diastolic blood pressure ≥ 90 mmHg, and/or receiving antihypertensive medication. Hypercholesterolemia was defined as total cholesterol ≥240 mg/gL, LDL cholesterol ≥160 mg/ dL, or HDL cholesterol < 40 mg/ dL or receiving cholesterol lowering medications. Cigarette smoking was categorized as never, former, and current use.
Covariates
Participants’ height was measured to the nearest centimeter and body weight to the nearest 0.1 kg. BMI was calculated as weight in kilograms divided by height in meters squared. BMI categories were defined as underweight (< 18.5 kg/m2), normal weight (18.5–24.9 kg/m2), overweight (25.0–29.9 kg/m2), and obese (≥ 30.0 kg/m2). Potential confounders. Socio-demographic characteristics self-reported during the baseline exam included: age, sex, household income, education, employment, nativity (foreign-born vs. US-born), and Hispanic/Latino background. Neighborhood percent poverty was defined as the percentage of families per census tract (CT) whose income in the past 12 months was below the poverty line, based on data from 2007 to 2011 American Community Survey 5-year estimates [21, 22].
Statistical analyses
All participants of the HCHS/SOL cohort with complete information for study variables were included in the current analysis (n = 13,856) with several specific exceptions. Residents indicating that they occupy their home without paying rent were excluded from analysis (n = 422). Since we were interested in examining risk factor for cardiovascular disease and to reduce the likelihood of reverse causation of residents with pre-existing cardiovascular disease preferentially residing in high foreclosure areas, participants with preexisting cardiovascular disease at the baseline interview were also excluded from analysis (n = 1166). Preexisting cardiovascular disease included prevalent coronary heart disease, defined as self-report of history of heart attack or procedure (angioplasty, stent, bypass) or electrocardiogram showing old myocardial infarction; or cerebrovascular disease, defined as self-reported medical history of stroke, mini-stroke or transient ischemic attack, or carotid revascularization or balloon angioplasty or surgery to the arteries in the neck at baseline assessment.
A mortgage foreclosure risk value was attributed to each participant based on his or her residential census tract. The mortgage foreclosure risk variable was linked based on 2000 census tract boundaries, whereas the percent poverty variable was linked to each participant’s census tract based on 2010 census tract boundaries. In this study, 97% of addresses were successfully geocoded. Participants not able to be geocoded were dropped from the analysis (n = 551).
We computed descriptive statistics (e.g. proportions) across all study variables. We initially compared all study variables including homeownership across tertiles of mortgage foreclosure risk. Poisson regression models were used to estimate prevalence ratios (PR) with 95% confidence intervals (95% CI) for hypertension, hypercholesterolemia, and smoking by homeownership status and mortgage foreclosure risk, with robust variance estimation used to account for clustering by census tract. Additional stratified analyses were done to examine the association of mortgage foreclosure risk with cardiovascular disease risk factors by homeownership status. Analyses were primarily adjusted for age, sex, education level, employment status, income level, nativity, Hispanic/Latino group, and percent poverty level.
All reported values (means, prevalences, and prevalence ratios) were weighted to account for the disproportionate selection of the sample and to partially adjust for any bias due to differential nonresponse in the selected sample at the household and individual levels. The adjusted weights were also trimmed to limit precision losses due to the variability of the adjusted weights, and calibrated to the 2010 Census characteristics by age, sex, and Hispanic/Latino background in each field site’s target population. All analyses also account for cluster sampling and the use of stratification in sample selection.
Statistical significance was determined at the P < 0.05 level. All analyses were performed using SAS 9.4 software (SAS Institute, Cary, NC) and SUDAAN software Release 11.0 (RTI International, Research Triangle Park, NC).