Use of a rigid back brace was significantly more effective than observation alone in preventing the progression of idiopathic scoliosis among adolescents who were at high risk of progressing to the point at which surgery would be warranted, according to a report in the Oct. 17 issue of the New England Journal of Medicine.
Moreover, this benefit increased as the average daily hours of wearing the back brace increased, indicating a significant dose-response effect, said Dr. Stuart L. Weinstein of the department of orthopedics and rehabilitation, University of Iowa, Iowa City, and his associates.
Although rigid bracing (thoracolumbosacral orthosis) is common in adolescent idiopathic scoliosis, there are little data supporting this practice. Until now, most studies of the issue have been observational and have yielded inconsistent results; only one prospective study has compared patients who wore back braces with patients who did not, the investigators said.
"Our findings have direct clinical applicability because they are derived from assessment of a group of patients for whom bracing would have been recommended in a typical orthopedic practice but in the absence of rigorous supporting data," they noted (N. Engl. J. Med. 2013;369:1512-21).
Dr. Weinstein and his colleagues performed the Bracing in Adolescent Idiopathic Scoliosis Trial (BRAIST) to compare bracing against observation alone in preventing the progression of scoliosis to 50 degrees or more, a common indication for surgery. They assessed 383 treatment-naive patients aged 10-15 years who attended 25 medical centers across the United States and Canada in 2007-2011.
In all the study subjects, the Cobb angle for the largest curve was 20-40 degrees at baseline.
Enrollment in the randomized trial proved difficult because so many families were unwilling to assign a patient to one group or the other, so one portion of the trial involving 155 patients was randomized (the randomized cohort), while another portion involving 228 patients was allowed to choose group assignment (the preference cohort).
Patients in the bracing groups were instructed to wear their rigid thoracolumbosacral braces for a minimum of 18 hours a day until they reached skeletal maturity. Adherence was measured by the use of a temperature sensor imbedded in the device, which indicated by the presence or absence of body heat how long the brace was worn.
The study could not be blinded because both patients and physicians were aware of treatment assignment; however, all radiographic evaluations and the final determination of patient outcomes were done by a musculoskeletal radiologist and a research associate who were blinded to treatment assignment.
The trial was terminated early when an interim analysis demonstrated a clear benefit in favor of bracing, with an odds ratio of 2.03.
The primary outcome was progression of the curvature to 50 degrees or more, which signaled treatment failure, or attainment of skeletal maturity without progression to 50 degrees or more of curvature, which signaled treatment success.
A total of 242 patients were included in the primary analysis: 51 patients assigned to back bracing, 65 assigned to observation, 88 who chose back bracing, and 38 who chose observation. After an average follow-up of 21-23 months, the rate of treatment success was 72% with bracing and 48% with observation alone in this analysis, Dr. Weinstein and his associates said.
In the intention-to-treat analysis, the rate of treatment success was 75% in patients randomly assigned to bracing, compared with 42% in those randomly assigned to observation only. This represents a relative risk reduction of 56% with bracing.
The number needed to treat to prevent a single case of curve progression warranting surgery was 3.
Duration of brace wear positively correlated with treatment success. Patients in the lowest quartile of brace wear (mean of 0-6 hours of wear daily) had a treatment success rate of 41%, very similar to that in the observation groups. In contrast, patients who wore their braces for an average of at least 13 hours per day had a treatment success rate of 90%-93%.
Scores on measures of general quality of life were not significantly different between the bracing and observation groups at baseline or at the final follow-up assessment.
The number of adverse events also was no different between the two study groups, and the same percentage of patients in both groups reported the most common adverse event (back pain). Eight percent of patients who wore a brace reported skin problems related to the device. The only serious adverse event occurred in a patient who wore a brace, who sought hospitalization for anxiety and depression.
BRAIST was supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases, Children’s Miracle Network, Canadian Institutes of Health Research, Shriners Hospitals for Children, the University of Rochester, and Children’s Mercy Hospitals and Clinics. Dr. James G. Wright reported other support as the R.B. Salter Chair in Surgical Research during the conduct of the study. No financial conflicts of interest were reported.