Chronic pain is usually thought of as a problem affecting adults. But a new study shows that chronic pain is also highly prevalent in children and that more kids today suffer from pain compared to two decades ago.

Researchers in Nova Scotia analyzed data from 41 studies on pain in children published since 1991, which was the last time such an analysis was completed. They found that chronic pain conditions are more common in girls than boys and that pain problems tend to increase with age. Headache is the most common type of chronic pain in kids, with 23 percent of children age 7 to 18 reporting weekly headaches and 5 percent reporting daily headaches. But abdominal, back and musculoskeletal pain were common, too. Recurrent abdominal pain was reported by 12 percent of children. And, in two studies that looked at back pain, 21 percent of the children reported back pain for at least one month.

Understanding pain patterns in children may alleviate their suffering and help explain how and why adult chronic pain occurs, the authors said.

"(R)esults of this review indicate that persistent and recurrent chronic pain is overwhelmingly prevalent in children and adolescents and should be recognized as a major health concern in this population."

The study appears in the December issue of the journal Pain.