Racial, ethnic disparities impact mortality rates among inborn errors of immunity
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Key takeaways:
- Black patients had the greatest odds for death before age 65 years.
- Hispanic vs. non-Hispanic patients had greater odds for death before age 24 years.
- Several causes may drive disparities.
Racial and ethnic disparities in mortality due to inborn errors of immunity indicate an urgent need to identify and remove barriers in care, according to a study published in The Journal of Allergy and Clinical Immunology.
“This study was prompted by the paucity of published data comparing the survival outcomes of different racial and ethnic groups of patients with inborn errors of immunity,” Mei-Sing Ong, PhD, assistant professor, department of population medicine, Harvard Pilgrim Health Care Institute, Harvard Medical School, told Healio.
Study results
Inborn errors of immunity (IEIs) were reported as underlying or contributing causes of death for 14,970 in the United States between 2003 and 2018.
“We found that IEI mortality rates, following adjustment for age and the racial composition of the U.S. population, showed stark disparities, with Black patients having the highest mortality rate,” Ong said.
These deaths predominantly comprised white (75.5%) and non-Hispanic (89.8%) patients. However, age-adjusted death rates per 1 million person-years included 4.25 for Black patients, 2.01 for white patients, 1.71 for American Indian/Alaska Native (AIAN) patients, 1.5 for Hispanic patients and 0.92 for Asian/Pacific Islander (API) patients.
The mortality gap between Black and white patients with IEIs was greater than the mortality gap between Black and white patients with cardiovascular diseases, the researchers said, which had age-adjusted death rates per million person-years of 2.1 for Black patients and 1.3 for white patients.
“Of note, the mortality gap between Black and white patients with IEI was greater than the documented mortality gap between Black and white patients with cardiovascular diseases — a condition for which racial disparities in survival outcome are well-established,” Ong said.
“We also found significant disparities in the age of death among historically marginalized groups,” she continued.
Odds ratios for death before age 65 years compared with white patients included 5.15 (95% CI, 4.61-5.76) for Black patients and 3.58 (95% CI, 2.3-5.82) for AIAN patients. Similarly, the odds ratio was 3.31 (95% CI, 2.88-3.82) for Hispanic patients compared with non-Hispanic patients.
Further, 85% of Black decedents, 57% of white decedents and 72% of decedents of other racial groups were aged younger than 65 years. Hispanic and API patients had the highest proportions of decedents aged younger than 24 years, followed by AIAN patients.
Hispanic decedents were 3.6 times more likely to die before age 24 years than non-Hispanic decedents, with 32% of Hispanic decedents and 12% of non-Hispanic decedents aged younger than 24 years.
Compared with white decedents, API decedents were three times more likely and AIAN decedents were twice as likely to die before age 24 years. Overall, 29% of API decedents, 27% of AIAN decedents, 14% of white decedents and 13% of Black decedents were aged younger than 24 years.
Black patients had excess mortality for all IEI diagnoses except for those diagnosed with several forms of predominantly antibody deficiency compared with white patients. These excess mortalities included complement deficiency, Wiskott-Aldrich syndrome, neutrophil defects, hypogammaglobulinemia and common variable immune deficiency.
These was a higher risk for early mortality for male patients compared with female patients, the researchers noted, possibly due to the male predominance in X-linked immunodeficiencies, which typically do not affect or cause less severe phenotypes in female individuals. This gap in mortality between the sexes was especially pronounced among Black men, the researchers added.
These disparities are probably driven by socioeconomic disadvantages, the researchers said, along with male tendencies to delay or avoid seeking medical care.
Additionally, white patients aged 65 years and older had a higher age-specific death rate than other racial groups, with significant excess mortality among white patients with other antibody defects compared with mortality among Black patients.
Although the later age of onset for these conditions may have contributed to these trends, the researchers said, further in-depth studies are necessary to understand the drivers behind these findings.
Conclusions, next steps
“Our study is the first to demonstrate racial and ethnic disparities in survival outcomes among patients with IEI in the U.S.,” Ong said. “These findings challenge the long-held belief that IEIs predominantly affect white individuals and highlight the unmet needs of minority patients with IEI.”
Overall, the researchers said that the causes of these racial disparities in IEI mortality are probably multifactorial, such as poor access to specialty care preventing timely diagnosis and treatment among historically marginalized racial groups.
Access to health insurance probably is another significant barrier, the researchers continued, along with discontinuity of care, which disproportionally impacts patients with lower socioeconomic status.
“Policies that address barriers to health care access, such as health insurance coverage, will be important to reduce disparities,” Ong said. “There is also a need to improve the capacity and number of providers skilled in recognizing IEIs in underserved communities.”
Historically marginalized racial groups face barriers in diagnosing certain classes of IEIs as well, the researchers said, with a need for greater awareness that IEIs may have different craniofacial and dermatologic manifestations across patient populations.
Genetic testing may mitigate some of these challenges, the researchers said, in addition to broad representation of patient populations in research and medical curricula.
Improved education may help the patients of primary care physicians and other providers who do not specialize in immunology, since they may face challenges in recognizing IEIs.
Finally, the researchers said that racial disparities in who receives the standard of care may persist, such as reported lower and disproportionate utilization of immunoglobulin replacement therapy among Black patients.
Based on these findings, the researchers said these disparities indicate an urgent need to further identify and remove barriers in care for historically marginalized patients with IEIs.
“We are actively conducting research to better understand the underlying causes of disparities and interventions that can reduce disparities,” Ong said.
Ong noted that previous studies have indicated that most primary care providers are not comfortable with diagnosing IEIs.
“We believe that there is a need to better equip primary care providers and non-specialists to recognize potential symptoms of IEIs, particularly those caring for underserved populations,” Ong said.
“We are currently piloting an educational initiative to raise awareness of disparities in IEIs among primary care providers in community health centers that primarily care for underserved communities,” she said.
For more information:
Mei-Sing Ong, PhD, can be reached at mei-sing_ong@hms.harvard.edu.
Perspective
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These results are significant but not surprising since racial and ethnic disparities have been documented for numerous chronic medical diseases.
This research also is important because IEIs are so rare that one physician’s or center’s patient experience may be skewed. Studying larger numbers of patients from national registries helps us better understand unmet needs for different racial and ethnic groups in orphan diseases such as IEIs.
Many IEIs first present in childhood. These results highlight the need for educational initiatives to better identify symptoms of IEIs, particularly for pediatricians caring for underserved populations.
Identification of disparities in health care is the first step. After identification of the problem, barriers can be identified to address within health system practices.
The authors discuss how newborn screening has identified IEIs that lead to severe combined immunodeficiency earlier in all racial and ethnic groups. It would be interesting to study whether earlier identification of IEIs through national newborn screening programs improves clinical outcomes for newborns of different races and ethnicities.
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