That's the conclusion of a study spanning 50 years, the results of which appear in the Feb. 5 issue of the Journal of the American Medical Association.

The individuals in the study all had LIS, or late-onset idiopathic scoliosis, a condition that is usually diagnosed after age 10 and has no known cause. LIS affects some 1 percent to 3 percent of children between the ages of 8 and 16, or about 60,000 adolescents in the United States, according to the study authors. It tends to run in families, and strikes girls more often than boys. The severity of the condition varies widely and not all cases merit treatment.

According to the researchers, previous studies of the condition had lumped LIS in with other, more severe forms of scoliosis. As a result, the prognosis for all patients appeared grim and failed to take into account differences within the patient population.

This study sets itself apart by distinguishing LIS patients from other scoliosis patients. "It puts things in perspective and gives physicians treating scoliosis a benchmark to make intelligent treatment decisions," says study author Dr. Stuart L. Weinstein, a professor of orthopaedic surgery at the University of Iowa in Iowa City.

"What they're hinting at is, if this doesn't cause a problem 50 years later, why are we operating on it in young teenagers? That's the question they're posing," says Dr. Andrew Casden, associate director of the Spine Institute at Beth Israel Medical Center in New York City.

Surgery was not available 50 years ago, but today it's common and largely successful in more severe cases.

The study surveyed patients who were originally diagnosed with LIS between 1932 and 1948, at a time when no treatments were available. Weinstein says it took him two years just to locate the patients who would form this part of the follow-up, which began in 1992.

Ultimately, Weinstein and his team compared 117 of the original 444 participants with LIS with normal volunteers. For the most part, the individuals with untreated LIS were as healthy as the controls. Certainly they did not have the high rates of respiratory failure and early death cited by earlier studies.

Twenty-two percent the patients (mostly those with a greater angle of curvature) complained of shortness of breath during daily activities compared with 15 percent of the controls. The cumulative death rate was about 54 percent, not higher than what would be expected in the population at large.

Not surprisingly, those with the scoliosis had more body-image concerns and more back pain. Almost double (61 percent) reported chronic back pain compared with controls (35 percent).

However, neither the cosmetic concerns nor the back pain seemed disabling, Weinstein says.

One question is what happened to the original participants who did not appear in this follow-up. "They only have about one-third of the people who started in the study," Casden says. "How many ended up with surgery?"

Also, it's unclear whether these results are applicable to people, especially adolescents, of today. "What's acceptable in terms of a spinal deformity may be very different," Casden says.

"Medicine is different and perceptions are different today," Weinstein agrees. "Kids born in 1970, you don't know how they'd perceive any cosmetic issues."

More information

For more on idiopathic scoliosis, visit the Scoliosis Research Society, the American Academy of Orthopaedic Surgeons, or the Scoliosis Association.