Meeting News CoveragePerspectivePublication Exclusive

Elevated BMI poses lower mortality risk for blacks than whites

The link between elevated BMI and mortality was found to be weaker among blacks compared with whites in the United States, especially among women, according to data presented at The Obesity Society 30th Annual Scientific Meeting.

“Current BMI recommendations are largely based on data from white americans and Europeans, and the vast majority of the studies investigating the risk of death for increasing BMI with a sufficient number of Black participants also found a weaker risk of death with increasing levels of BMI among African Americans compared to whites,” researcher Chandra Jackson, PhD, MS, a postdoctoral fellow at Harvard University, told Endocrine Today

Researchers collected a series of cross-sectional surveys from the National Health Interview Survey (NHIS, 1997-2002) that have been linked to the National Death Index with mortality follow-up to 2006, which included 4,815 non-Hispanic blacks and 27,160 non-Hispanic whites. All participants were never-smokers, aged 35 to 75 years, with no history of cardiovascular disease or cancer at the start of the study.

According to the data, average BMI was 27 for whites and for blacks. Through 9 years of follow-up 1,205 participants who never smoked died. After adjustments, absolute mortality rates were higher in blacks compared with whites across all levels of BMI quintiles, but showed no increase at higher levels of BMI.

The HR for death from all causes in men rose across upper BMI quintiles among whites and in black men. However, BMI was positively linked to mortality risk in white women but inversely linked in black women (P=.01).

Black women had an adjusted mortality HR of 1.11 for quintile one; 0.44 for quintile three; 0.78 for quintile four; and 0.64 for quintile five, according to data.

According to researchers, these data indicate the relationship of elevated BMI to mortality appears weaker among US blacks, especially women. They suggest that recommendations for BMI be re-evaluated or modified, as researchers and clinicians may not wish to hold blacks to the same clinical intervention standard of <25, which could free limited resources to focus on other risk factors, like hypertension, that are more clearly and strongly associated with mortality risk.

“The BMI-mortality relationship appears weaker in African Americans compared to whites, especially in women. Current recommendations for a BMI <25 might not apply to blacks. However, additional studies are needed to address the methodological limitations related to the bi-directionality of obesity and ill health that may have influenced our study,” Jackson said.

For more information:

Jackson C. 97-OR. Presented at: The Obesity Society 30th Annual Scientific Meeting; Sept. 20-24, 2012; San Antonio.

Disclosure: Jackson reports no relevant financial disclosures.

The link between elevated BMI and mortality was found to be weaker among blacks compared with whites in the United States, especially among women, according to data presented at The Obesity Society 30th Annual Scientific Meeting.

“Current BMI recommendations are largely based on data from white americans and Europeans, and the vast majority of the studies investigating the risk of death for increasing BMI with a sufficient number of Black participants also found a weaker risk of death with increasing levels of BMI among African Americans compared to whites,” researcher Chandra Jackson, PhD, MS, a postdoctoral fellow at Harvard University, told Endocrine Today

Researchers collected a series of cross-sectional surveys from the National Health Interview Survey (NHIS, 1997-2002) that have been linked to the National Death Index with mortality follow-up to 2006, which included 4,815 non-Hispanic blacks and 27,160 non-Hispanic whites. All participants were never-smokers, aged 35 to 75 years, with no history of cardiovascular disease or cancer at the start of the study.

According to the data, average BMI was 27 for whites and for blacks. Through 9 years of follow-up 1,205 participants who never smoked died. After adjustments, absolute mortality rates were higher in blacks compared with whites across all levels of BMI quintiles, but showed no increase at higher levels of BMI.

The HR for death from all causes in men rose across upper BMI quintiles among whites and in black men. However, BMI was positively linked to mortality risk in white women but inversely linked in black women (P=.01).

Black women had an adjusted mortality HR of 1.11 for quintile one; 0.44 for quintile three; 0.78 for quintile four; and 0.64 for quintile five, according to data.

According to researchers, these data indicate the relationship of elevated BMI to mortality appears weaker among US blacks, especially women. They suggest that recommendations for BMI be re-evaluated or modified, as researchers and clinicians may not wish to hold blacks to the same clinical intervention standard of <25, which could free limited resources to focus on other risk factors, like hypertension, that are more clearly and strongly associated with mortality risk.

“The BMI-mortality relationship appears weaker in African Americans compared to whites, especially in women. Current recommendations for a BMI <25 might not apply to blacks. However, additional studies are needed to address the methodological limitations related to the bi-directionality of obesity and ill health that may have influenced our study,” Jackson said.

For more information:

Jackson C. 97-OR. Presented at: The Obesity Society 30th Annual Scientific Meeting; Sept. 20-24, 2012; San Antonio.

Disclosure: Jackson reports no relevant financial disclosures.

    Perspective

    The findings are generally consistent with most of the previous research studies on this topic that have found a weaker association between BMI and all-cause mortality among blacks, especially women, compared with whites. From a research point-of-view, this observed difference leads to many questions that remain to be answered including the optimal measure of obesity (BMI versus some other measure, perhaps of central adiposity), the likely complex role of genetic factors, and the relevance of socioeconomic status and how it should be addressed in comparison to different race/ethnic groups.

    While I am not a clinician myself, my interpretation of the existing research, including Dr. Jackson’s study, relevant to clinicians is that obesity, regardless of race, is one the most pressing health concerns due to the strong associations between obesity and many common, chronic diseases including diabetes, cardiovascular disease, and several cancers. Until further research can tease out the many unknown factors that may lead to differing associations between body mass index and mortality in black versus white populations, clinical focus should remain on the identification and evaluation of obesity in all patients, regardless of race, and to help patients identify and adhere to effective strategies to reach and maintain a healthy body size.

    • Sarah S. Cohen, PhD
    • Biostatistical Epidemiologist at the International Epidemiology Institute Rockville, MD

    Disclosures: Cohen has no relevant financial disclosures.

    See more from ObesityWeek