Table 2 Potential pathways to inequity identified among eligible studies

Access to care

Underdiagnosis of asthma in the Alaska Native population related to a lack of health care providers [35].

Job requirements that may limit the ability to access health care services during normal business hours [36].

Access to transportation

The role of access to public or private transportation in influencing ambulance service and emergency room use for asthma [30, 36].

Discrimination

Potential variability in likelihood of asthma diagnosis due to different standards applied to different ethnic groups [15].

Environmental & occupational exposures

Association between lower educational level, poverty, visible minority status, ethnicity, and/or immigrant status and higher risk of developing asthma due to increased exposure to irritants and occupational risk factors [23, 27, 32].

Proximity of low-income urban neighborhoods to sources of pollutants (e.g. highways and truck routes) [39, 42]. Potential migration of high-risk populations to areas with lower pollutants [40], and potential reduced exposure to air pollutants in rural areas [41].

Housing & neighborhood environment

Poor housing conditions in low-income neighborhoods that may increase exposure to cockroach and rodent allergens, dampness, and mold [24, 39].

Increased stress related to community violence, and insufficient public services resulting in a poor physical environment in low-income neighborhoods [39, 42].

Insurance status

Association between lack of insurance or Medicaid and discharge against medical advice and worse asthma control [26, 31].

Emergency rooms as last resort for patients without health insurance in U.S. [28].

Race/ethnicity

Race/ethnicity as a marker for social disadvantage (e.g. low income, lack of insurance coverage) rather a risk factor itself [15, 28, 29].

Association between black race/ethnicity and increased emergency room visits [28].

Potential link between stress associated with multiple race identification and higher rates of asthma among adults who are both American Indian/Alaska Native and white [37].

Socioeconomic status

Relationship between race/ethnicity and discharge against medical advice neutralized when socioeconomic factors taken into account [31].

Association between low socioeconomic status or lack of employment and increased asthma symptoms, poor compliance, and worse asthma-related quality of life [29, 33, 34, 38].

Asthma as both a consequence and contributor to poverty by restricting ability to work and incurring medical expenses [23, 38].