Living in poverty or rural areas increases the odds of suffering from chronic pain, and one-fifth of adults in the U.S. live with the condition, according to a new study from the Centers for Disease Control and Prevention.

In 2016, 50 million adults, or 20.4 percent, had chronic pain, defined as pain on most days or every day in the past six months, the CDC estimates, based on self-reported data from the National Health Interview Survey. That same year, 19.6 million, or 8 percent, of adults had high-impact chronic pain, which frequently limits life or work activities.

Researchers found that in both categories, prevalence was higher for women, older adults, previously but not currently employed adults, adults living in poverty, adults with public health insurance and rural residents. They also found the rates of both types of pain were lower among adults with at least a bachelor's degree.

Pain can be debilitating and also challenging to treat, especially as opioids have come under scrutiny for their role in fueling a nationwide epidemic. It can also be costly, with chronic pain costing an estimated $560 billion annually between direct medical costs, lost productivity and disability, according to a 2011 report from the Institute of Medicine of the National Academies.