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Outcome of Spinal Screening

As many of our readers know, the Scoliosis Research Society, the American Academy of Orthopaedic Surgeons, and over 23 states suggest or require school screening for abnormal spinal curvatures. In September of 1992, Dr. William P. Bunnell, Professor and Chairperson, Loma Linda University Medical Center, presented his paper, "Outcome of Spinal Screening" to members of the Scoliosis Research Society; his findings will also be published in an upcoming issue of Spine. Dr. Bunnell is a developer of the Scoliometer, a hand-held device used in assisting spinal screening programs across the country. What follows are excerpts from an interview that the NSF conducted with Dr. Bunnell about his study:

Q: Dr. Bunnell, would you start by giving us some background information about spinal screening as it pertains to your study?
A: The major criticism of spinal screening, as it is being practiced today, is that schools are referring too many students who do not require treatment. The primary cause of over-referral is lack of objective screening criterion; in the state of California, for example, any amount of asymmetry of the thoracic ribs or the lumbar area is an indication for referral. As a result of over-referral, many screening programs are cost ineffective. Youngsters who are referred--whether they need treatment or not--will be sent to a doctor for a medical consultation; they may have several x-rays taken; and then they'll be asked to return to the doctor six months or a year later for another consultation. All of this adds up to skyrocketing costs.

Q: What were some of the goals you wanted to achieve by undertaking this study?
A: One of my many goals was to determine the prevalence of scoliosis--i.e., how many in the general population presently have it. Another was to use the data on prevalence in combination with previous studies to determine what is a reasonable level orcriterion for recommending referrals.

Q: What were some of your findings?
A: In our study of 1,000 physically mature high school students--in which we used the Scoliometer as the screening device--we found that only 16 out of 1,000 students (1.6%) had a clinically straight spine. Eighty percent had three or more degrees of rotation at one or more levels of the spine. We also learned that within this population, if "any degree of deformity" (i.e. one degree) is used as the criterion, then 98.4 % of students will be referred.

Q: Would you explain the criterion--the degree of deformity--that screeners currently look for, and tell us why you feel this criterion should be changed?
A: When I first started out in practice, everybody thought we should treat 20 degree curves with low profile braces. There is a direct correlation between 20 degree curve and a 5 degree Angle of Trunk Rotation (ATR), so screeners referred anybody with 5 degrees of ATR or greater, and they're sill using 5 ATR as the criterion. Today, we know that at least 4 out of 5 kids with 20-degree idiopathic (causes unknown) curves will never get any worse. In fact, most doctors wait until a youngster with this type of curvature reaches 30 degrees before starting treatment. So it's clear that we should be screening for these children in the 30 degree and above category.

Q: Based on the data from your study, what are some of your recommendations?
A: We know that spinal screening programs must have defined referral criteria and "treatment-eligible" degrees of scoliosis in order to judge their effectiveness. The ideal criteria will minimize both the number of referrals and the number of false-negative examinations. In view of the new prevalence data from my study and the current recommendations to wait until scoliosis approaches 30 degrees (Cobb angle) before starting brace treatment, I am recommending changing the screening referral criterion to seven degrees ATR at any level of the spine and changing the definition of false-negative (treatment-eligible curves that are missed) to 30 degrees Cobb angle for the purposes of spinal screening.

Q: If it is implemented in screening programs across the country, what will your new recommendation accomplish?
A: It will accomplish a referral rate of 3% and detect 95% of all "treatment eligible" curvatures, thus preserving an acceptably low false-negative rate and helping maintain cost effectiveness of spinal screening programs.

Q: What about youngsters whose curves are below that "treatment eligible" line--let's say, between 20 and 25?
A: Those youngsters should be rescreened within six months or a year. Rescreening would take place at school, which would keep it a public health issue.

Q: In light of your findings, how do you now view the importance of screening for spinal deformity?
A: Screening is vitally important, but we do not want to screen out a whole bunch of people who don't need medical attention because it's very costly. We're not looking for the cheapest way to screen--we're looking for a better quality outcome for our patients.


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