摘要：Objectives. To determine whether non-US citizens have a higher mortality risk of heat-related deaths than do US citizens. Methods. We used place of residence reported in mortality data from the National Vital Statistics System from 2005 to 2014 as a proxy for citizenship to examine differences in heat-related deaths between non-US and US citizens. Estimates from the US Census Bureau American Community Survey of self-reported citizenship status and place of birth provided the numbers for the study population. We calculated the standardized mortality ratio and relative risk for heat-related deaths between non-US and US citizens nationally. Results. Heat-related deaths accounted for 2.23% (n = 999) of deaths among non-US citizens and 0.02% (n = 4196) of deaths among US citizens. The age-adjusted standardized mortality ratio for non-US citizens compared with US citizens was 3.4 (95% confidence ratio [CI] = 3.2, 3.6). This risk was higher for Hispanic non-US citizens (risk ratio [RR] = 3.6; 95% CI = 3.2, 3.9) and non-US citizens aged 18 to 24 years (RR = 20.6; 95% CI = 16.5, 25.7). Conclusions. We found an increased mortality risk among non-US citizens compared with US citizens for heat-related deaths, especially those younger and of Hispanic ethnicity. A recent Centers for Disease Control and Prevention (CDC) Health Disparities and Inequality Report highlighted health disparities among racial, ethnic, geographic, and socioeconomic groups for several health outcomes and called for increased efforts to identify and measure these disparities so that barriers to health equity can be removed. 1 One study discussed in the CDC report documented a higher risk of work-related fatal injuries among Hispanic and foreign-born workers, with rates among Hispanics more than 1.5 times the US rate for work place–related fatalities resulting from exposure to harmful substances or environs, including exposure to extreme temperatures causing hyper- or hypothermia. 1 In the United States, an average of 658 people died from exposure to excessive natural heat annually from 1999 to 2009, 2 and heat-related deaths are a leading cause of death from natural weather or environmental events. 3 These deaths are preventable, and numerous studies have described risk factors for increased mortality, including young or old age; minority race and ethnicity, particularly non-Hispanic Black 3 ; low socioeconomic status; presence of comorbid conditions such as high blood pressure, heart disease, and mental illness; and lack of access to air conditioning. 3–5 Differences in mortality among US immigrant populations are not routinely examined because of challenges in characterizing deaths among immigrants and difficulties in obtaining relevant population denominator data. 6 Previous studies, which have focused mainly on deaths among foreign-born individuals (defined as anyone who is not a US citizen at birth), found that foreign-born individuals have lower mortality rates than do US-born individuals 6,7 ; in particular, foreign-born Hispanic young adults have lower mortality rates than do US-born White young adults. 8 Only a few studies looked at differences in health outcomes by citizenship status 9,10 ; however, non-US citizens of working age are 52% less likely to have health insurance than are US citizens. 6 Current interventions in the United States to prevent heat-related deaths are based largely on risk factors identified following extreme heat events in urban areas. To determine whether a mortality differential exists for deaths associated with extreme heat among immigrants who may be at higher risk because of occupation, we compared heat-related deaths among non-US and US citizens from 2005 to 2014.
