It’s long been known that morbidly obese patients with sleep apnea were at a high risk for non-alcoholic fatty liver disease (NAFLD). What wasn’t known was whether sleep apnea was an independent factor in causing NAFLD or whether they were both caused by obesity.
Now a new study shows that sleep apnea may increase your risk of NAFLD by seven times.
What Is NAFLD?
The liver is an important organ that helps your body utilize the energy and nutrients in your food as well as helping to filter your blood. In NAFLD, the cells of the liver accumulate additional fat, called steatosis. This causes the liver to swell and may lead to scarring of the liver, known as cirrhosis. Eventually, this can impair liver function and may lead to liver failure.
Initially, there are no symptoms, and by the time symptoms occur, such as fatigue, loss of appetite, abdominal pain, and others, the condition has usually become serious.
Sleep Apnea and NAFLD
In the new study, researchers looked at the incidence of NAFLD in patients who had indicators of sleep apnea, using the Berlin Questionnaire (BQ) and the Epworth Sleepiness Scale (ESS). They compared people who had daytime sleepiness to those who did not have daytime sleepiness, and found that those with daytime sleepiness were significantly more likely to have both steatosis and fibrosis, an early stage of scarring that can lead to cirrhosis.
They found the risk of developing NAFLD for sleep apnea sufferers with daytime sleepiness might be 7.1 times that for people without daytime sleepiness.
Limitations of the Study
Although this study points out a potentially important health risk of sleep apnea, its conclusions deserve a caveat. First, and most importantly, the researchers didn’t actually diagnose subjects with sleep apnea. Although the BQ and the ESS are respected measures of daytime sleepiness, it’s a long way from that to determining whether a person really has sleep apnea.
Second, the small sample size is worrying. Although the results show statistical significance, the 95% confidence interval (the interval where we are 95% sure the actual number can be found) ranges from 1.7 to 51. This huge interval shows us we don’t really have a good correlation here.
Still, NAFLD is another good reason you should talk to your doctor (or a sleep dentist) about sleep apnea.