The far-reaching effects of chronic pain may be worse for black women than they are for white women.

That's the conclusion of a new study that found black women with chronic pain were more likely to be physically impaired by their pain, and more likely to suffer from depression and post-traumatic stress disorder (PTSD).

Why these differences exist is unclear, according to study author Dr. Carmen Green, an associate professor of anesthesiology at the University of Michigan Health System in Ann Arbor.

There are many factors that could account for the differences, Green said. "There may be differences in the way black women cope with pain. There may be cultural differences. Do they have less access to pain medications or physician services? Are minority women less likely to have their pain assessed or is it under-treated? Or is it something about the way women communicate their pain complaints?" she asked.

Dr. Paru Pandya, director of pain management at Mount Sinai Medical Center in New York City, said, "The cause of pain is multi-factorial. The definition is that it's a sensory and emotional experience, and every person's perception of pain is completely different. It's subjective."

"There's no cookie-cutter answer" to why these differences might exist, she said, but added that it would be interesting to examine whether different cultures experience pain differently.

What is clear is that many Americans suffer from chronic pain. According to Green, about one in five people in the United States has chronic pain. Since past studies have shown that chronic pain affects more women than men, and that it affects women differently, Green and her colleagues wanted to learn if there were racial differences in the effects of chronic pain.

To answer that question, the researchers reviewed questionnaires completed by 1,192 women suffering from chronic pain. Most (1,088) were white, while 104 were black. Two-thirds of the women were married and three-quarters had at least a high school education. Twenty percent of the women were involved in a legal action due to the cause of their pain. The study didn't look at what caused the women's pain symptoms, according to Green.

Forty-four percent of black women reported physical disability due to their pain, compared to 37 percent of white women.

On a scale of zero through 36, with a higher score indicating more PTSD, black women scored an average of 12.9 while white women scored 8.1. And, on another scale, this one with a range of zero through 63, with a higher score indicating more depression, black women scored 19.4, compared to 16.9 for white women.

"Black women had more physical disability, more depression, more anxiety, more PTSD and increased pain scores," Green said.

Results of the study appear in the October issue of the Journal of the National Medical Association.

"Pain is not just physiological. There's a strong emotional component," said Dr. Doris K. Cope, director of the pain medicine program at the University of Pittsburgh Medical Center. "Different cultural groups have different ways of expressing the grief and stress that can come with pain."

She said it's important when seeking treatment for chronic pain to treat the whole person, and not just depend on pain medications.

Green said an important message from this study is the need to advocate for quality pain care. "You don't have to live with pain. Be adamant, and make sure your pain complaints are taken seriously," she said.

Pandya agreed and added, "It's never normal to have pain. It almost always is an indication of something going on in the body. You can treat pain. It's better to come in sooner for pain treatment, rather than later."