Stubborn cases of chronic constipation in childhood may become an adulthood problem for a significant percentage of kids, a new study suggests.

Dutch researchers found that among 401 children and teens treated for chronic constipation at their center, one-quarter were still having symptoms 11 years later, as young adults.

The odds of long-lasting constipation were greater when the problem arose later in childhood or when years passed between a child’s first bouts of constipation and his or her referral for specialized treatment.

The findings, reported in the journal Pediatrics, are based on a group of children and teens with symptoms serious enough that they were referred to a specialist clinic.

So they may not be representative of kids treated for less-serious constipation by their primary care doctors, note the researchers, led by Dr. Marc A. Benninga of Emma Children’s Hospital in Amsterdam.

Experts generally recommend that children see their doctor if they have constipation problems that last more than two weeks. Typically, treatment involves diet changes – such as eating more fiber-rich grains, fruits and vegetables – and, with a doctor’s approval, stool softeners or laxatives.

The new findings suggest that children whose symptoms do not improve with initial treatment might benefit from earlier referral to a specialist, according to Benninga and his colleagues.

It’s estimated that functional constipation – constipation not caused by an underlying health condition or medication side effects – accounts for about 3 percent of all visits to the pediatrician. But there has been little research into how often those problems persist into adulthood.

The current study included 401 children and teenagers who were treated for chronic constipation at the researchers’ center in the 1990s. All had at least two symptoms of chronic constipation – such as having fewer than three bowel movements a week and two or more bouts of fecal incontinence per week – and had not improved after using laxatives for at least two months.

After six to eight weeks of “intensive” treatment that included medication and behavioral therapy, the children were followed, through yearly surveys, to track their long-term progress.

After 11 years, the researchers found, three-quarters of the study participants were showing a “good” outcome – defined as having had at least three bowel movements per week in the past month, and fewer than two bouts of incontinence.

That left one-quarter who were still suffering symptoms. For comparison, that rate is much higher than studies have found among adults in the general population; in the U.S., for example, it is estimated that between 4 and 5 million Americans have frequent constipation – with older adults accounting for a large portion, according to the National Institute of Diabetes and Digestive and Kidney Diseases.

Benninga’s team also found that certain factors – including constipation problems starting later in childhood, and longer gaps between a child’s first symptoms and treatment referral – seemed to increase the likelihood of persistent constipation.

For example, they say, a boy whose symptoms began at age 3, and included only two bowel movements and multiple bouts of incontinence each week, would have a 7 percent chance of adulthood constipation if there were a one-year gap between the onset of his symptoms and his referral for specialist treatment.

Those odds increased to 31 percent with a 9-year delay before referral.

The findings, according to Benninga’s team, suggest that referring kids for specialist care earlier on might cut the risk of long-lasting problems.

“Referral to a specialized clinic should be considered at an early stage for children who are unresponsive to first-line treatment,” they conclude.