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A lung mural in Berkeley, California.

A lung mural in Berkeley, California.

Quinn Dombrowski/Flickr (CC BY-SA 2.0)

Lung research survey highlights lack of minority subjects in many biomedical studies

Fewer than 5% of lung disease studies funded by the National Institutes of Health (NIH) over the past 2 decades have included a statistically meaningful number of participants from racial or ethnic minorities, concludes a new analysis. The finding highlights the continuing difficulty of adequately representing minorities in biomedical research, the authors say, but they argue the problem could be remedied through a number of steps.

NIH officials don’t dispute the results, but note the survey’s focus on published results may understate the agency’s ongoing efforts to improve minority representation in clinical research and other studies.

The new survey, published online last month in the American Journal of Respiratory and Critical Care Medicine, examined respiratory disease studies published between 1993 and 2013. A search of PubMed found 58,160 studies that reported NIH funding. Of these, 2534 studies—just 4.4%—reported that minorities made up 25% or more of the study population. Below the 25% participation threshold, it can be difficult for statistical analyses to detect racial or ethnic differences in risk factors or disease effects, write the authors, led by physician-scientist Esteban Burchard of the University of California, San Francisco.

Over the 20-year period, minority inclusion increased slightly, from just over 2% of studies in 1993 to nearly 5% in 2013, the study found. Over the same time period, the authors note, the proportion of people in the United States who identified as part of a racial or ethnic minority group increased from 26.5% to 38.9%.

“The findings are disturbing given that we know many lung diseases disproportionately impact underrepresented minorities,” says Patricia Finn, a pulmonologist at the University of Illinois, Chicago, and immediate past president of the American Thoracic Society. (Finn was not involved in the study.)

The study is the latest in a long line to put the spotlight on minority representation in clinical research. Last year, for example, a similar review of cancer studies funded by the National Cancer Institute found that fewer than 2% focused on minorities. In 1993, Congress ordered NIH to step up its effort to recruit more minorities into federally funded studies, and the agency has since launched an array of efforts, including programs aimed at recruiting Latinos and African-Americans into asthma studies.

The new survey may not fully capture those efforts, NIH officials say, because not all studies have published results. “Analyses that focus on selected publications may not … completely reflect the inclusion of all individuals enrolled in studies supported by NIH,” wrote a representative for NIH’s Office of Extramural Research to ScienceInsider in an e-mail. The agency says that, in 2013, about 30% of all clinical research it funded included some minority participation.

Efforts to fully represent minority populations in biomedical research are becoming increasingly important as new “personalized” or “precision” approaches expand, researchers say. The approaches aim to use each person’s specific genetic and other traits to develop tailored treatments, and “in order to harness the power of this science, we need to include everyone,” Finn says.

Better representation also helps researchers understand disparities in disease rates among different ethnic groups, said the study authors. Studies have shown that African-Americans may be more likely to develop some forms of chronic obstructive pulmonary disease after smoking than whites, for instance. They are also more likely to die of lung cancer.

Health disparities are especially glaring in asthma, according to Burchard. Asthma is the most common chronic disease of childhood, affecting about 26 million people in the United States. Prevalence is higher among Puerto Ricans and African-Americans than non-Hispanic whites, other Hispanic groups, or Asians. Black children with asthma are four times more likely to die of the disease than white children with asthma, according to studies.

Environmental and socioeconomic factors play a role, but so does ancestry. In a previous study, Burchard and colleagues found that one genetic mutation linked to asthma severity was about 40% more common in African-Americans.

Even the effectiveness of treatments may vary by race or ethnicity. For instance, albuterol, the most commonly prescribed asthma medication, is less likely to work in African-Americans and Puerto Ricans than in whites. “Ethnic background is the single strongest predictor of response to albuterol,” says Burchard, who has helped start two large gene-environment studies of asthma among minority children in the United States. (The studies are known as GALA, or Genetics of Asthma in Latino Americans, and SAGE, or Study of African Americans, Asthma, Genes, & Environments.)

Burchard and his team say a number of factors contribute to the underrepresentation of minorities in NIH-funded studies. They include a lack of training on how to run inclusive studies, a lack of incentives to run inclusive studies, the relatively low numbers of minority scientists, and “a dearth of successful partnerships between academic medical centers and under-represented communities.” Addressing those problems systematically, they suggest, could help shift the numbers.