Sleep apnea research, including studies of sleep surgery, is moving forward around the world. On May 4-5, I will be the keynote speaker for the 94th Taiwan Otolaryngology–Head and Neck Surgery Congress in Tainan, Taiwan. I look forward to continued discussions with colleagues there about many topics, including the current knowledge of any racial and ethnic differences in the occurrence, consequences, and treatment outcomes for obstructive sleep apnea. This post considers a study just published in this area.
A number of studies have examined racial and ethnic factors associated with sleep apnea, revealing that certain racial and ethnic groups (as well as populations in different countries) are more or less likely to have obstructive sleep apnea. For a number of reasons, obstructive sleep apnea is more common among African-Americans, Asians, and Hispanic Caucasians than non-Hispanic Caucasians. Although of course there are wide variations within any racial or ethnic group, it is thought that higher body weight (or body mass index, which accounts for height) seen in some African-Americans and Hispanic Caucasians may explain the increased risk of sleep apnea. Certain craniofacial (facial structure) risk factors for sleep apnea are more common in Asians, and these might be the source of their higher prevalence of sleep apnea.
Maybe more severe sleep apnea but no clear increase in risk of death
Few studies have gone beyond this basic assessment of sleep apnea prevalence to examine the importance of various well-known sleep apnea risk factors or the disorder’s consequences in different racial and ethnic groups. This month’s issue of the Journal of Clinical Sleep Medicine is one of the first to do so. Researchers including Drs. Safwan Badr and James Rowley from the Wayne State University Division of Pulmonary & Critical Care and Sleep Medicine examined the records of over 500 patients who were diagnosed with sleep apnea during sleep studies performed from 1996-1999. The study compared patients who identified themselves as either African-American or Caucasian to determine if there were any differences in the severity of sleep apnea (measured by the apnea-hypopnea index) or the risk of dying over a 10-year period (before 2009).
The researchers used appropriate and sophisticated statistical analysis to separate the effect of various sleep apnea risks (age, gender, body mass index, other medical problems) from race (African-American vs. Caucasian, without distinguishing based on Hispanic ethnicity). There were 2 conclusions. The first was no difference in the risk of death associated with the severity of sleep apnea among the two groups, after correction for the other factors. Although a higher proportion of the African-American group (17%) died than among the Caucasians (12%), this seemed to be related to the fact that the African-American group was somewhat older, had more men, and had more heart disease and diabetes. They did not specifically evaluate the patients with severe sleep apnea (apnea-hypopnea index > 30 events/hour); it would have been interesting, given that the increased risk of death related to sleep apnea is almost exclusively seen among those with severe disease.
The second conclusion was somewhat misleading. The study showed that African-American men younger than 40 years of age and 50-59 years of age had a higher apnea-hypopnea index than similar Caucasians, and this was reported as such throughout the paper. However, the actual statistical results showed that this difference was relatively small (2.8 and 3.2 events/hour, respectively), likely not a difference that would affect patients at all. Instead of highlighting that there was a difference, it might have been better to indicate the small size of that difference.
The bottom line: sleep apnea risks may cut across these racial lines
As this is one of the first studies to address these critical issues related to race and ethnicity, more research clearly is needed. This era of personalized medicine and personalized sleep surgery requires an understanding of anything that distinguishes individuals in a meaningful way. However, if risk factors and consequences of sleep apnea are similar for African-Americans and Caucasians, many of the landmark studies in sleep apnea (that have been performed largely with Caucasian study subjects) may not need to be repeated in African-Americans. Instead, research efforts can focus more on possible differences in treatment outcomes, including for surgery.