Abstract
Background
Little is known about the effect of region of origin on all‐cause mortality, cardiovascular mortality, and stroke mortality among Black individuals. We examined associations between nativity and mortality (all‐cause, cardiovascular, and stroke) in Black individuals in the United States.
Methods and Results
Using the National Health Interview Service 2000 to 2014 data and mortality‐linked files through 2015, we identified participants aged 25 to 74 years who self‐identified as Black (n=64 717). Using a Cox regression model, we examined the association between nativity and all‐cause, cardiovascular, and stroke mortality. We recorded 4329 deaths (205 stroke and 932 cardiovascular deaths). In the model adjusted for age and sex, compared with US‐born Black individuals, all‐cause (hazard ratio [HR], 0.44 [95% CI, 0.37–0.53]) and cardiovascular mortality (HR, 0.66 [95% CI, 0.44–0.87]) rates were lower among Black individuals born in the Caribbean, South America, and Central America, but stroke mortality rates were similar (HR, 1.01 [95% CI, 0.52–1.94]). African‐born Black individuals had lower all‐cause mortality (HR, 0.43 [95% CI, 0.27–0.69]) and lower cardiovascular mortality (HR, 0.42 [95% CI, 0.18–0.98]) but comparable stroke mortality (HR, 0.48 [95% CI, 0.11–2.05]). When the model was further adjusted for education, income, smoking, body mass index, hypertension, and diabetes, the difference in mortality between foreign‐born Black individuals and US‐born Black individuals was no longer significant. Time since migration did not significantly affect mortality outcomes among foreign‐born Black individuals.
Conclusions
In the United States, foreign‐born Black individuals had lower all‐cause mortality, a difference that was observed in recent and well‐established immigrants. Foreign‐born Black people had age‐ and sex‐adjusted lower cardiovascular mortality than US‐born Black people.
Keywords: African ancestry, migration, mortality, stroke, US
Subject Categories: Epidemiology, Cardiovascular Disease
Nonstandard Abbreviations and Acronyms
- NHIS
National Health Interview Survey
Clinical Perspective.
What Is New?
Our analysis demonstrates that in the United States, all‐cause mortality rate is lower among foreign‐born than US‐born Black individuals, a difference that was observed in recent and well‐established immigrants.
We also found that foreign‐born Black people had age‐ and sex‐adjusted lower cardiovascular mortality than US‐born Black people.
What Are the Clinical Implications?
We need to recognize that Black individuals in the United States may be a more heterogeneous group than previously thought and account for potential differences in region of origin in health outcome research.
The decline in all‐cause, cardiovascular, and stroke mortality observed over recent years has affected all racial and ethnic groups 1 , 2 ; however, Black people continue to die at a rate disproportionately higher than White people. 3
The foreign segment of Black individuals living in the United States has increased markedly over the past decades and may represent at least 8% of the Black population. 4 Those who have migrated to the United States may not share similar cardiovascular risk profiles with Black individuals who are born in the United States. For example, evidence from the National Health Interview Survey (NHIS) suggests that foreign‐born Black people have a similar odds of stroke compared with Non‐Hispanic White individuals, but US‐born Black people have higher odds. 5 Despite limited access to health care, immigrants to high‐income countries benefit from a phenomenon known as the healthy immigrant effect, translating to lower chronic noncommunicable disease incidence, including lower cancer and cardiovascular rates than the host population. 6 Similarly, death rates from cardiovascular diseases are lower in immigrants than in host populations. 7 The effect of migration and acculturation on all‐cause, cardiovascular, and stroke mortality among Black people has not been studied. Understanding potential differences in mortality between foreign‐born and US‐born Black people could inform clinicians and public health professionals to develop targeted interventions to curb mortality rates and reduce inequities.
Using the NHIS 2000 to 2014 data and mortality linked files through 2015, we examined the association between migration and time since migration, and mortality among Black people by region of origin. We hypothesized that Black immigrants would have lower mortality rates than US‐born Black individuals, and that this difference would dissipate with time since migration.
Methods
Data Source
All data and materials are publicly available at the NHIS and can be accessed at NHIS—National Health Interview Survey (cdc.gov) and NHIS—Data, Questionnaires and Related Documentation (cdc.gov). We used the NHIS 2000 to 2014 data and mortality‐linked files through 2015 to identify Black individuals. Details on the NHIS have been previously published. 8 Briefly, the NHIS is collected by the National Center for Health Statistics, overseen by the Centers for Disease Control and Prevention. It is a cross‐sectional household interview survey of the civilian noninstitutionalized population of the 50 US states and the District of Columbia conducted in a face‐to‐face computer‐assisted format. Health information is obtained from each sample household member. One member of the family is selected for further interview. Adults aged ≥65 years from racial and ethnic minority groups (Black, Hispanic) are oversampled. The NHIS uses geographically clustered sampling techniques to select the sample of dwelling units for the NHIS. The sample is designed in such a way that each month's sample is nationally representative. Data collection on the NHIS is continuous, that is, from January to December yearly.
Case Identification
We included participants aged 25 to 74 years who self‐identified as Black (n=64 717). We categorized Black race by self‐reported birth region, that is, foreign born (Caribbean, South and Central American, and African) versus US born. Additionally, time since migration was recorded, with early migration defined as ≤5 years since migration, intermediate migration as 5 to 14 years since migration, and late migration as ≥15 years since migration. The following variables were by self‐report: level of education, household income, and smoking status. Body mass index was measured and was categorized according to Centers for Disease Control and Prevention criteria into <18.5 kg/m2 (underweight), 18.5 to 24.9 kg/m2 (normal weight), 25.0 to 29.9 kg/m2 (overweight), 30.0 to 35.0 kg/m2 (obesity stage I), and 35.0 kg/m2 and above (obesity stage II/III).
Mortality Assessment
We assessed all‐cause mortality, cardiovascular mortality, and stroke mortality as reported by the Centers for Disease Control and Prevention, using cause of death groupings, based on the International Classification of Diseases, 10th Revision (ICD‐10) linked files through 2015. Since NHIS data are deidentified, there was no need for an Institutional Review Board of the study.
Statistical Analysis
We used SAS/STAT version 9.1 for Windows (SAS Institute Inc., Cary, NC) for statistical analyses. Results are presented as weighted counts and percentages, and weighted mean and SD. Differences between foreign‐born Black people and US‐born Black people were analyzed using the Rao‐Scott χ 2 tests 9 and t tests for categorical and continuous variables, respectively, adjusted for the complex survey design. Using survey‐adjusted multivariable Cox regression, we examined the association between nativity (US born versus African born and US born versus Caribbean, South American, and Central American born) and all‐cause, cardiovascular, and stroke mortality. Between‐group comparison was done without adjusting for any confounders (model 1), and subsequently after adjusting for sociodemographic and clinical variables. In the first adjusted (primary) model (model 2A), we adjusted for age and sex. In the second model (model 2B), we adjusted for age, sex, education, and income. In the third model (model 2C), we adjusted for age, sex, education, income, smoking, and body mass index (BMI). In the fourth model (model 2D), we adjusted for age, sex, education, income, smoking, BMI, hypertension, and diabetes. We applied the same model to each period of time (<5, 5–14, and >15 years) since migration to examine the effect of time since migration on the association between nativity (US born versus foreign born) and mortality, adjusting for the same variables. Additionally, we performed an exploratory stratified analysis of the association of nativity with mortality by sex applying the same model as for the whole cohort (model 1, model 2A to 2D). A P value of <0.05 was used to characterize statistical significance.
Results
General Characteristics
Our study included 64 717 individuals who self‐identified as Black, of whom 57 141 (88.3%) were born in the United States; 5205 (8%) were born in the Caribbean, South America, and Central America; and 2371 (3.7%) were born in Africa (Table 1). Black individuals born in Africa were younger than their counterparts born in the United States, Caribbean, and South and Central America. Compared with foreign‐born Black individuals, US‐born Black persons were more likely to be former smokers (United States, 15.4%; Caribbean, South America, and Central America, 9.3%; Africa, 8.3%; P<0.001) or current smokers (United States, 25.1%; Caribbean, South America, and Central America, 8.4%; Africa, 7.6%; P<0.001). They were also more likely to have hypertension (United States, 39.7%; Caribbean, South America, and Central America, 29.1%; Africa, 18.9%; P<0.001) and diabetes (United States, 12.4%; Caribbean, South America, and Central America, 10.7%; Africa, 6.5%; P<0.001). Similarly, obesity was more prevalent among US‐born Black individuals than foreign‐born Black individuals (eg, obesity stage II/III in United States, 18.9%; Caribbean, South America, and Central America, 8.5%; Africa, 5.4%; P<0.001). There were also differences in income between foreign‐born Black individuals and US‐born Black individuals (eg, there were >1.5 times more African‐born people earning $75 000 yearly than US‐born people). African‐born people were more likely to have graduated from college compared with US‐born Black people or those born in the Caribbean, South America, and Central America (United States, 30.0%; Caribbean, South America, and Central America, 34.3%; Africa, 57.1%; P<0.001).
Table 1.
Baseline Characteristics of Black Adults in the United States, NHIS 2000 to 2014
| Variables | US born, N (n), % 11 462 006 (57141), 88.3% | Caribbean, South and Central America 1 040 464 (5205), 8.0% | Africa 480 703 (2371), 3.7% | P value |
|---|---|---|---|---|
| Sex, n (%) | ||||
| Male | 22 194 (42.1) | 2139 (44.0) | 1252 (55.6) | <0.0001 |
| Female | 34 996 (57.9) | 3067 (56.0) | 1119 (44.4) | |
| Age categories, n (%) | ||||
| 25–44 y | 25 642 (49.1) | 2382 (47.1) | 1555 (67.5) | <0.0001 |
| 45–64 y | 23 788 (39.6) | 2179 (42.1) | 723 (28.9) | |
| 65–74 y | 7760 (11.3) | 645 (10.8) | 93 (3.6) | |
| Smoking history, n (%) | ||||
| Never | 33 437 (60.2) | 4213 (82.2) | 1989 (84.1) | <0.0001 |
| Former | 9350 (15.9) | 502 (9.3) | 196 (8.3) | |
| Current | 13 807 (23.9) | 457 (8.4) | 175 (7.6) | |
| BMI categories, n (%) | ||||
| Normal | 13 438 (25.1) | 1550 (31.5) | 842 (37.1) | <0.0001 |
| Overweight | 18 397 (34.0) | 2101 (41.8) | 951 (42.4) | |
| Obesity stage I | 12 141 (22.0) | 927 (18.3) | 355 (15.1) | |
| Obesity stage II/III | 10 781 (18.9) | 448 (8.5) | 122 (5.4) | |
| Hypertension, n (%) | 24 450 (39.7) | 1582 (29.1) | 476 (18.9) | <0.0001 |
| Diabetes, n (%) | 7662 (12.4) | 608 (10.7) | 152 (6.5) | <0.0001 |
| Income categories, n (%) | ||||
| $0–34 999 | 18 688 (60.1) | 1885 (60.9) | 948 (56.8) | 0.0001 |
| $35 000–74 999 | 9826 (33.1) | 957 (32.4) | 498 (32.3) | |
| ≥$75 000 | 2073 (6.7) | 204 (6.7) | 162 (10.9) | |
| Level of education, n (%) | ||||
| <High school | 10 478 (17.7) | 1219 (21.1) | 267 (9.4) | <0.0001 |
| High school diploma | 29 615 (52.3) | 2242 (44.6) | 801 (33.6) | |
| ≥College degree | 16 632 (30.0) | 1653 (34.3) | 1286 (57.1) | |
BMI indicates body mass index; N, weighted number of participants; n, unweighted number of participants; and NHIS, National Health Interview Survey.
All‐Cause, Cardiovascular, and Stroke Mortality in US‐Born and Foreign‐Born Black Individuals
Overall, 4329 deaths (including 205 stroke and 932 cardiovascular deaths) were recorded in Black individuals during the study period. Weighted cumulative incidence of all‐cause, cardiovascular, and stroke mortality at 10 years were 12.6%, 2.8%, and 0.6% for those born in the United States; 6.1%, 1.6% and 0.5% for those born in the Caribbean, South America, and Central America; and 3.1%, 0.5%, and 0.1% for those born in Africa, respectively. In the unadjusted model (Model 1; Table 2), mortality rates were lower in Black individuals born in the Caribbean, South America, and Central America compared with US‐born Black individuals (all‐cause mortality: hazard ratio [HR], 0.44 [95% CI: 0.36–0.52]; and cardiovascular mortality: HR, 0.56 [95% CI, 0.38–0.84]), but rates of stroke mortality were not different (HR, 0.98 [95% CI, 0.51–1.88]). Compared with US‐born people, the unadjusted mortality rates were lower in Black people born in Africa for all‐cause mortality (HR, 0.27 [95% CI, 0.17–0.43]), cardiovascular mortality (HR, 0.24 [95% CI, 0.10–0.55]), and stroke mortality (HR, 0.24 [95% CI, 0.06–0.95]).
Table 2.
Univariate and Multivariable Models for Mortality Outcomes by Nativity Category Among Black Individuals Aged 25 to 74 Years, NHIS 2000 to 2014
| Birth region | All‐cause mortality | P value | CV mortality | P value | Stroke mortality | P value |
|---|---|---|---|---|---|---|
| OR* (95% CI) | OR* (95% CI) | OR* (95% CI) | ||||
| Model 1: unadjusted | ||||||
| Caribbean, South and Central America | 0.43 (0.36–0.54) | <0.0001 | 0.56 (0.38–0.84) | 0.005 | 0.98 (0.51–1.88) | 0.942 |
| Africa | 0.27 (0.17–0.437) | <0.0001 | 0.24 (0.10–0.55) | 0.001 | 0.24 (0.06–0.95) | 0.043 |
| United States (reference) | 1.00 | 1.00 | 1.00 | |||
| Model 2A: adjusted for age and sex | ||||||
| Caribbean, South and Central America | 0.44 (0.37–0.53) | <0.0001 | 0.58 (0.39–0.87) | 0.008 | 1.01 (0.52–1.94) | 0.981 |
| Africa | 0.43 (0.27–0.69) | <0.0001 | 0.42 (0.18–0.98) | 0.045 | 0.48 (0.11–2.05) | 0.320 |
| United States (reference) | 1.00 | 1.00 | 1.00 | |||
| Model 2B: adjusted for age, sex, education, and income | ||||||
| Caribbean, South and Central America | 0.46 (0.38–0.55) | <0.0001 | 0.60 (0.40–0.91) | 0.012 | 1.09 (0.52–1.11) | 0.899 |
| Africa | 0.50 (0.32–0.80) | 0.003 | 0.47 (0.20–1.13) | 0.092 | 0.57 (0.13–2.49) | 0.456 |
| United States (reference) | 1.00 | 1.00 | 1.00 | |||
| Model 2C: adjusted for age, sex, education, income, smoking, and BMI | ||||||
| Caribbean, South and Central America | 0.53 (0.44–0.64) | <0.001 | 0.71 (0.48–1.07) | 0.101 | 1.02 (0.53–1.99) | 0.945 |
| Africa | 0.57 (0.36–0.91) | 0.018 | 0.56 (0.24–1.35) | 0.198 | 0.57 (0.13–2.44) | 0.436 |
| United States (reference) | 1.00 | 1.00 | 1.00 | |||
| Model 2D: adjusted for age, sex, education, income, smoking, BMI, hypertension, and diabetes | ||||||
| Caribbean, South and Central America | 0.54 (0.45–0.66) | <0.001 | 0.75 (0.5–1.13) | 0.168 | 1.1 (0.56–2.17) | 0.795 |
| Africa | 0.59 (0.37–0.93) | 0.023 | 0. 60 (0.25–1.43) | 0.247 | 0.60 (0.14–2.65) | 0.503 |
| United States (reference) | 1.00 | 1.00 | 1.00 | |||
BMI indicates body mass index; NHIS, National Health Interview Survey; and OR, odds ratio.
Odds ratio.
In model 2A (adjusted for age and sex), compared with US‐born Black individuals, Black individuals born in the Caribbean, South America, and Central America had lower all‐cause mortality (HR, 0.44 [95% CI, 0.37–0.53]) and cardiovascular mortality (HR, 0.58 [95% CI, 0.39–0.87]), but stroke mortality was similar (HR, 1.01 [95% CI, 0.52–1.94]). Similarly, compared with US‐born individuals, African‐born Black individuals had lower all‐cause mortality (HR, 0.43 [95% CI, 0.27–0.69]) and lower cardiovascular mortality (HR, 0.42 [95% CI, 0.18–0.98]), but stroke mortality was not significantly different (HR, 0.48 [95% CI, 0.11–2.05]).
In general, further adjustment for education and income in model 2B did not significantly change the association between nativity and all‐cause, cardiovascular, and stroke mortality. The only exception was that the difference in cardiovascular mortality was no longer significant for those born in Africa versus those born in the United States.
Subsequent adjustment for medical factors (smoking and BMI in model 2C; and smoking, BMI, hypertension, and diabetes in model 2D), showed similar results to previous models for all‐cause mortality; however, in those models, there was no difference between US‐born and foreign‐born Black individuals for both cardiovascular and stroke mortality (Table 2).
In all models, time since migration did not significantly affect mortality differences between US‐born and foreign‐born Black individuals (Table 3).
Table 3.
Univariate and Multivariable Models of Mortality Outcomes by Nativity Category and Time Spent in the United States Among Black Individuals Aged 25 to 74 Years in the United States, NHIS 2000 to 2014
| All‐cause mortality | P value | Cardiovascular mortality | P value | Stroke mortality | P value | |
|---|---|---|---|---|---|---|
| OR* (95% CI) | OR* (95% CI) | OR* (95% CI) | ||||
| Model 1: unadjusted | ||||||
| Birth region | ||||||
| Foreign born, <5 y | 0.20 (0.10–0.42) | <0.0001 | 0.35 (0.10–1.16) | 0.085 | 0.76 (0.10–5.52) | 0.783 |
| Foreign born, 5–14 y | 0.25 (0.18–0.36) | <0.0001 | 0.27 (0.15–0.49) | <0.0001 | 0.16 (0.03–0.71) | 0.016 |
| Foreign born, ≥15 y | 0.52 (0.43–64) | <0.001 | 0.66 (0.44–1.00) | 0.050 | 1.22 (0.62–2.42) | 0.575 |
| United States (reference) | 1.00 | 1.00 | 1.00 | |||
| Model 2A: adjusted for age and sex | ||||||
| Birth region | ||||||
| Foreign born, <5 y | 0.41 (0.20–0.82) | 0.012 | 0.81 (0.25–2.7) | 0.731 | 1.90 (0.28–14.11) | 0.491 |
| Foreign born, 5–14 y | 0.47 (0.29–0.60) | <0.001 | 0.49 (0.27–89) | 0.019 | 0.32 (0.07–1.40) | 0.131 |
| Foreign born, ≥15 y | 0.45 (0.44–0.55) | <0.0001 | 0.56 (0.37–0.86) | 0.007 | 1.05 (0.53–2.07) | 0.895 |
| United States (reference) | 1.00 | 1.00 | ||||
| Model 2B: adjusted for age, sex, education, and income | ||||||
| Birth region | ||||||
| Foreign born, <5 y | 0.38 (0.19–0.77) | 0.007 | 0.76 (0.23–2.50) | 0.649 | 1.90 (0.27–13.63) | 0.523 |
| Foreign born, 5–14 y | 0.41 (0.29–0.60) | <0.001 | 0.49 (0.27–0.89) | 0.019 | 0.32 (0.07–1.38) | 0.126 |
| Foreign born, ≥15 y | 0.50 (0.41–0.61) | <0.0001 | 0.61 (0.40–0.93) | 0.022 | 1.14 (0.58–2.25) | 0.711C |
| United States (reference) | 1.00 | 1.00 | ||||
| Model 2C: adjusted for age, sex, education, income, smoking, BMI | ||||||
| Birth region | ||||||
| Foreign born, <5 y | 0.43 (0.21–0.88) | 0.021 | 0.92 (0.28–3.00) | 0.885 | 1.87 (0.26–13.69) | 0.537 |
| Foreign born, 5–14 y | 0.48 (0.33–0.769) | <0.0001 | 0.59 (0.33–1.08) | 0.085 | 0.31 (0.07–1.38) | 0.124 |
| Foreign born, ≥15 y | 0.57 (0.46–0.70) | <0.0001 | 0.72 (0.47–1.10) | 0.132 | 1.11 (0.55–2.22) | 0.764 |
| United States (reference) | 1.00 | 1.00 | ||||
| Model 2D: adjusted for age, sex, education, income, smoking, BMI, hypertension, and diabetes | ||||||
| Birth region | ||||||
| Foreign born, <5 y | 0.45 (0.22–0.93) | 0.031 | 1.02 (0.31–3.35) | 0.978 | 2.09 (0.28–15.43) | 0.468 |
| Foreign born, 5–14 y | 0.49 (0.34–0.71) | <0.0001 | 0.63 (0.34–1.16) | 0.137 | 0.34 (0.08–1.48) | 0.150 |
| Foreign born, ≥15 y | 0.58 (0.47–0.71) | <0.0001 | 0.75 (0.49–1.15) | 0.189 | 1.18 (0.58–2.39) | 0.644 |
| United States (reference) | 1.00 | 1.00 | ||||
BMI indicates body mass index; NHIS, National Health Interview Survey; and OR, odds ratio.
Odds ratio.
When stratified by sex in the exploratory analyses, adjusting for age (model 2A), Black men and women born in the Caribbean, South America, and Central America had lower all‐cause mortality than those born in the United States (HR, 0.44 [95% CI, 0.32–0.59]; and HR, 0.45 [95% CI, 0.36–0.57]). Similarly, Black men and women born in Africa had lower all‐cause mortality than those born in the United States (HR, 0.50 [95% CI, 0.29–0.87]; and HR, 0.30 [95% CI, 0.13–0.71]). For cardiovascular mortality, Black women born in the Caribbean, South America, and Central America had lower cardiovascular mortality than those born in the United States (HR, 0.50 [95% CI, 0.30–0.84]); however, there was no difference in Black men. Adjusting the model for education and income did not change this association. When smoking and BMI (model 2C), and then hypertension and diabetes (model 2D) were added to the model, cardiovascular mortality was no longer different between Black women born in the Caribbean, South America, and Central America and Black women born in the United States. There was no difference in stroke mortality when assessed separately in men and in women for all models (Table 4). Time since migration did not affect the association between nativity and mortality when assessed separately in men and women (Table 5).
Table 4.
Multivariable Models of Mortality Outcomes Stratified by Sex Among Black Individuals Aged 25 to 74 Years in the United States, NHIS 2000 to 2014
| Variables | All‐cause mortality | P value | Cardovascular mortality | P value | Stroke mortality | P value | |
|---|---|---|---|---|---|---|---|
| OR* (95% CI) | OR* (95% CI) | OR* (95% CI) | |||||
| Model 2A: adjusted for age | |||||||
| Men | Birth region | ||||||
| Caribbean, South and Central America | 0.44 (0.32–0.59) | <0.0001 | 0.64 (0.36–1.12) | 0.116 | 1.349 (0.53–3.44) | 0.530 | |
| Africa | 0.50 (0.29–0.87) | 0.014 | 0.35 (0.11–1.12) | 0.076 | |||
| United States (reference) | 1.00 | 1.00 | 1.00 | ||||
| Women | Caribbean, South and Central America | 0.45 (0.36–0.57) | <0.0001 | 0.50 (0.30–0.840) | 0.009 | 0.77 (0.33–1.84) | 0.559 |
| Africa | 0.30 (0.13–0.71) | 0.006 | 0.56 (0.16–2.00) | 0.374 | 10.3 (0.24–4.50) | 0.965 | |
| United States (reference) | 1.00 | 1.00 | 1.00 | ||||
| Model 2B: adjusted for age, education, and income | |||||||
| Men | Caribbean, South and Central America | 0.46 (0.34–0.61) | <0.0001 | 0.65 (0.38–1.14) | 0.131 | 1.44 (0.57–3.63) | 0.437 |
| Africa | 0.65 (0.38–1.1) | 0.107 | 0.39 (0.12–1.26) | 0.115 | |||
| United States (reference) | 1.00 | 1.00 | 1.00 | ||||
| Women | Caribbean, South and Central America | 0.46 (0.37–0.59) | <0.0001 | 0.52 (0.31–0.87) | 0.013 | 0.78 (0.33–1.83) | 0.563 |
| Africa | 0.31 (0.13–0.73) | 0.007 | 0.60 (0.17–2.12) | 0.424 | 1.15 (0.26–5.06) | 0.854 | |
| United States (reference) | 1.00 | 1.00 | 1.00 | ||||
| Model 2C: adjusted for age, education, income, smoking, and BMI | |||||||
| Birth region | |||||||
| Men | Caribbean, South and Central America | 0.52 (0.39–0.71) | <0.001 | 0.80 (0.46–1.38) | 0.417 | 1.40 (0.56–3.50) | 0.469 |
| Africa | 0.71 (0.42–1.22) | 0.215 | 0.46 (0.14–1.51) | 0.202 | … | … | |
| United States (reference) | 1.00 | 1.00 | 1.00 | … | … | ||
| Women | Caribbean, South and Central America | 0.53 (0.42–0.68) | <0.001 | 0.61 (0.36–1.04) | 0.07 | 0.77 (0.32–1.86) | 0. 558 |
| Africa | 0.36 (0.15–0.86) | 0.021 | 0.72 (0.20–2.58) | 0.614 | 1.15 (0.26–5.10) | 0.851 | |
| United States (reference) | 1.00 | 1.00 | 1.00 | ||||
| Model 2D: adjusted for age, sex, education, income, smoking, BMI, hypertension, and diabetes | |||||||
| Birth region | |||||||
| Men | Caribbean, South and Central America | 0.54 (0.40–0.73) | <0.001 | 0.84 (0.49–1.43) | 0.510 | 1.49 (0.59–3.75) | 0.398 |
| Africa | 0.72 (0.42–1.22) | 0.228 | 0.48 (0.15–1.57) | 0.224 | … | ||
| United States (reference) | 1.00 | 1.00 | 1.00 | ||||
| Women | Caribbean, South and Central America | 0.55 (0.43–0.70) | <0.001 | 0.65 (0.38–1.11) | 0.113 | 0.82 (0.33–2.07) | 0.680 |
| Africa | 0.38 (0.16–0.92) | 0.031 | 0.83 (0.23–2.97) | 0.772 | 1.33 (0.30–5.89) | 0.710 | |
| United States (reference) | 1.00 | 1.00 | 1.00 | ||||
BMI indicates body mass index; NHIS, National Health Interview Survey; and OR, odds ratio.
Odds ratio.
Table 5.
Multivariable Models of Mortality Outcomes by Sex, Nativity Category, and Time Spent in the United States Among Black Individuals Aged 25 to 74 Years in the United States, NHIS 2000 to 2014
| Variables | All‐cause mortality | P value | Cardiovascular mortality | P value | Stroke mortality | P value | |
|---|---|---|---|---|---|---|---|
| OR* (95% CI) | OR* (95% CI) | OR* (95% CI) | |||||
| Model 2A: adjusted for age | |||||||
| Men | Foreign born, <5 y | 0.11 (0.02–0.52) | 0.005 | ||||
| Foreign born, 5–14 y | 0.40 (0.23–0.67) | 0.001 | 0.57 (0.25–1.31) | 0.188 | 0.91 (0.20–4.14) | 0.906 | |
| Foreign born, ≥15 y | 0.49 (0.36–0.66) | <0.0001 | 0.64 (0.37–1.13) | 0.124 | 1.26 (0.44–3.61) | 0.670 | |
| United States (reference) | 1.00 | 1.00 | … | … | … | ||
| Women | Foreign born, <5 y | 0.77 (0.36–1.64) | 0.499 | 1.91 (0. 58–6.27) | 0.28 | 3.22 (0.45–22.87) | 0.242 |
| Foreign born, 5–14 y | 0.45 (0.27–0.74) | 0.002 | 0.40 (0.16–1.04) | 0.060 | NA | <0.0001 | |
| Foreign born, ≥15 y | 0.40 (0.30–0.54) | <0.0001 | 0.44 (0.22–0.86) | 0.016 | 0.88 (0.39–2.01) | 0.760 | |
| United States (reference) | 1.00 | 1.00 | |||||
| Model 2B: adjusted for age, sex, education, and income | |||||||
| Men | Foreign born, <5 y | 0.11 (0.02–0.49) | 0.004 | … | … | … | … |
| Foreign born, 5–14 y | 0.40 (0.24–0.68) | 0.001 | 0.57 (0.24–1.33) | 0.193 | 0.99 (0.21–4.60) | 0.990 | |
| Foreign born, ≥15 y | 0.55 (0.41–0.75) | <0.0001 | 0.70 (0.39–1.22) | 0. 203 | 1.43 (0.49–4.2) | 0.510 | |
| United States (reference) | 1.00 | 1.00 | |||||
| Women | Foreign born, 5–14 y | 0.43 (0.26–0.72) | 0.001 | 0.40 (0.15–1.02) | 0.056 | NA | |
| Foreign born, <5 y | 0.70 (0.32–1.53) | 0.371 | 1.78 (0.53–5.91) | 0.347 | 3.04 (0.43–21.73) | 0.267 | |
| Foreign born, ≥15 y | 0.43 (0.32–0.58) | <0.0001 | 0.47 (0.24–0.914) | 0. 026 | 0.91 (0.40–2.05) | 0.814 | |
| United States (reference) | 1.00 | 1.00 | |||||
| Model 2C: adjusted for age, sex, education, income, smoking, BMI | |||||||
| Men | Foreign born, <5 y | 0.12 (0.02–0.55) | 0.007 | … | … | … | … |
| Foreign born, 5–14 y | 0.46 (0.27–0.78) | 0.004 | 0.70 (0.30–1.62) | 0.400 | 0.93 (0.20–4.43) | 0.930 | |
| Foreign born, ≥15 y | 0.63 (0.46–0.85) | 0.003 | 0.83 (0.48–1.46) | 0.525 | 1.41 (0.49–4.02) | 0.930 | |
| United States (reference) | 1.00 | 1.00 | |||||
| Women | Foreign born, <5 y | 0.82 (0.37–1.80) | 0.620 | 2.12 (0.64–7.05) | 0.219 | 3.07 (0.42–22.49) | 0.270 |
| Foreign born, 5–14 y | 0.50 (0.30–0.84) | 0.008 | 0.47 (0.18–1.22) | 0.121 | 0.00 (0.00–0.00) | <0.0001 | |
| Foreign born, ≥15 y | 0.49 (0.36–0.66) | <0.0001 | 0.55 (0.27–1.10) | 0.088 | 0.89 (0.38–2.07) | 0.789 | |
| United States (reference) | 1.00 | 1.00 | |||||
| Model 2D: adjusted for age, sex, education, income, smoking, BMI, hypertension, and diabetes | |||||||
| Men | Foreign born, <5 y | 0.12 (0.03–0.58) | 0.008 | … | … | … | … |
| Foreign born, 5–14 y | 0.47 (0.28–0.80) | 0.005 | 0.73 (0.3–1.69) | 0.464 | 1.02 (0.21–4.95) | 0.981 | |
| Foreign born, ≥15 y | 0.64 (0.47–0.86) | 0.004 | 0.87 (0.50–1.51) | 0.608 | 1.47 (0.51–4.24) | 0.475 | |
| United States (reference) | 1.00 | 1.00 | |||||
| Women | Foreign born, <5 y | 0.86 (0.38–1.92) | 0.710 | 2.32 (0.67–8.00) | 0.182 | 3.27 (0.44–24.50) | 0.249 |
| Foreign born, 5–14 y | 0.52 (0.31–0.86) | 0.012 | 0.50 (0.19–1.32) | 0.163 | NA | ||
| Foreign born, ≥15 y | 0.51 (0.38–0.68) | <0.0001 | 0.58 (0.30–1.15) | 0.119 | 0.96 (0.41–2.26) | 0.932 | |
| United States (reference) | 1.00 | 1.00 | |||||
BMI indicates body mass index; NA, not available due to the small number of events; NHIS, National Health Interview Survey; and OR, odds ratio.
Odds ratio.
Discussion
In this nationally representative survey of Black individuals, we found that after adjusting for age and sex, foreign‐born Black individuals had an overall and cardiovascular survival advantage over US‐born Black individuals, but stroke mortality was not different by birth region. This difference was observed among early and late migrants.
A potential major contributor to the differences in mortality between foreign‐born and US‐born Black people is a combination of factors grouped under the umbrella term healthy immigrant effect. These factors include purported healthier lifestyle of foreign‐born people in their home country, better health than nonimmigrants, and greater ability to endure stressors. In Canada, for example, where mortality rate is in general lower than in the United States, 10 evidence for a survival advantage of immigrants was found in several studies, which has been partly attributed to the healthy immigrant effect. 11 Similar to our findings, this advantage was noted for cause‐specific mortality, including cardiovascular mortality. The current study focused specifically on Black individuals, a racial group that has historically had higher stroke incidence and higher all‐cause and cardiovascular mortality rates than White individuals. While studies on cardiovascular and stroke mortality abound, our study is another step forward in understanding the excess death in Black individuals by assessing deaths by region of birth. The differences observed in the current analysis are in line with previous observations among immigrants to Northern America. 10
Socioeconomic status 12 , 13 and clinical factors such as smoking and obesity 14 , 15 have been associated with excess all‐cause, cardiovascular, and stroke mortality in general and contributed to race inequities in mortality. In our study, the differences in cardiovascular mortality by nativity dissipated once we adjusted for sociodemographic factors such as education and income and clinical factors such as smoking, BMI, hypertension, and diabetes. The survival advantage for all‐cause mortality persisted after adjusting for these factors, possibly as a result of other confounding factors. After adjusting for age, education, income, smoking, and BMI, foreign‐born Black women had lower cardiovascular mortality rates than their US‐born counterparts. It remains unclear why Black immigrant women are at a lower risk of death than US‐born Black women.
The survival (all‐cause mortality) advantage of foreign‐born Black individuals was sustained among more established Black migrants, suggesting a persistent healthy immigrant effect or long‐term better access to health care compared with US‐born Black individuals as higher prevalence of surrogates of health care access such as level of education and income were higher among foreign‐born Black individuals.
The unadjusted stroke mortality was lower in African‐born individuals but faded after adjusting for sociodemographic factors, which may suggest that addressing sociodemographic inequalities may be a path toward closing the stroke mortality gap between foreign‐born Black and US‐born Black individuals and perhaps more generally between racial and ethnic groups. Additionally, the absence of association between nativity and stroke mortality in the adjusted model could reflect the small sample size among foreign‐born Black individuals, particularly from Africa, rather than a true absence of association.
Limitations
The current study has limitations. The relatively small number of outcomes of interest (all‐cause mortality, cardiovascular mortality, and stroke mortality) could explain why we did not observe a difference in a specific mortality cause type such as stroke mortality. Nativity and some of the variables were by self‐report, which could have led to misclassification biases. Additionally, due to the small number of events, we were not able to assess the impact of time since migration on mortality in subgroups of foreign‐born individuals. Finally, the possibility of multiple comparisons could have arisen from performing several analyses, including stratified analyses by sex; however, these were exploratory analyses, and future confirmatory studies will need to be performed.
Conclusions
Foreign‐born Black individuals (from Africa, Caribbean, and South and Central America) have lower all‐cause mortality, a difference that was observed in recent and established migrants. Foreign‐born Black people (from Africa, Caribbean, and South and Central America) had age‐ and sex‐adjusted lower cardiovascular mortality than US‐born Black individuals; however, after adjusting for income, education, and further for clinical variables, the difference persisted only among women. The findings of this study support the concept that Black individuals are a heterogeneous population and that region of origin should be accounted for when examining racial disparities, including in stroke.
Sources of Funding
This work was supported by the James and Dorothy Williams Stroke Scholarship.
Disclosures
None.
This article was sent to Meng Lee, MD, Guest Editor, for review by expert referees, editorial decision, and final disposition.
For Sources of Funding and Disclosures, see page 9.
References
- 1. Lackland DT, Roccella EJ, Deutsch AF, Fornage M, George MG, Howard G, Kissela BM, Kittner SJ, Lichtman JH, Lisabeth LD, et al. Factors influencing the decline in stroke mortality: a statement from the American Heart Association/American Stroke Association. Stroke. 2014;45:315–353. doi: 10.1161/01.str.0000437068.30550.cf [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2. Hummer RA, Chinn JJ. Race/ethnicity and U.S. adult mortality: progress, prospects, and new analyses. Du Bois Rev. 2011;8:5–24. doi: 10.1017/S1742058X11000051 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 3. Howard G. Ancel Keys Lecture: adventures (and misadventures) in understanding (and reducing) disparities in stroke mortality. Stroke. 2013;44:3254–3259. doi: 10.1161/STROKEAHA.113.002113 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4. Kent M. Immigration and America’s Black population. Popul Bull. 2007;62:1–20. [Google Scholar]
- 5. Wirth LS, Tobo BB, Hinyard L, Vaughn MG. Foreign‐born blacks no different from whites for odds of stroke. J Epidemiol Community Health. 2017;71:786–793. doi: 10.1136/jech-2016-208125 [DOI] [PubMed] [Google Scholar]
- 6. Lu C, Ng E. Healthy immigrant effect by immigrant category in Canada. Health Rep. 2019;30:3–11. doi: 10.25318/82-003-x201900400001-eng [DOI] [PubMed] [Google Scholar]
- 7. Vyas MV, Austin PC, Fang J, Laupacis A, Silver FL, Kapral MK. Immigration status, ethnicity, and long‐term outcomes following ischemic stroke. Neurology. 2021;96:e1145–e1155. doi: 10.1212/WNL.0000000000011451 [DOI] [PubMed] [Google Scholar]
- 8. Centers for Disease Control and Prevention . 2021. https://www.cdc.gov/nchs/nhis/about_nhis.htm
- 9. Rao JN, Scott AJ. The analysis of categorical data from complex sample surveys: chi‐squared tests for goodness of fit and independence in two‐way tables. J Am Stat Assoc. 1981;76:221–230. doi: 10.1080/01621459.1981.10477633 [DOI] [Google Scholar]
- 10. Guyatt GH, Devereaux P, Lexchin J, Stone SB, Yalnizyan A, Himmelstein D, Woolhandler S, Zhou Q, Goldsmith LJ, Cook DJ, et al. A systematic review of studies comparing health outcomes in Canada and the United States. Open Med. 2007;1:e27–e36. [PMC free article] [PubMed] [Google Scholar]
- 11. Vang ZM, Sigouin J, Flenon A, Gagnon A. Are immigrants healthier than native‐born canadians? A systematic review of the healthy immigrant effect in Canada. Ethn Health. 2017;22:209–241. doi: 10.1080/13557858.2016.1246518 [DOI] [PubMed] [Google Scholar]
- 12. Beydoun MA, Beydoun HA, Mode N, Dore GA, Canas JA, Eid SM. Racial disparities in adult all‐cause and cause‐specific mortality among US adults: mediating and moderating factors. BMC Public Health. 2016;16:1113. doi: 10.1186/s12889-016-3744-z [DOI] [PMC free article] [PubMed] [Google Scholar]
- 13. Sautter JM, Thomas PA, Dupre ME, George LK. Socioeconomic status and the black‐white mortality crossover. Am J Public Health. 2012;102:1566–1571. doi: 10.2105/AJPH.2011.300518 [DOI] [PMC free article] [PubMed] [Google Scholar]
- 14. Banack HR, Kaufman JS. The obesity paradox: understanding the effect of obesity on mortality among individuals with cardiovascular disease. Prev Med. 2014;62:96–102. doi: 10.1016/j.ypmed.2014.02.003 [DOI] [PubMed] [Google Scholar]
- 15. Munro HM, Tarone RE, Wang TJ, Blot WJ. Menthol and nonmenthol cigarette smoking: all‐cause deaths, cardiovascular disease deaths, and other causes of death among blacks and whites. Circulation. 2016;133:1861–1866. doi: 10.1161/CIRCULATIONAHA.115.020536 [DOI] [PMC free article] [PubMed] [Google Scholar]