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Thread: Interesting but preliminary study on a predictive model of brace curve progression

  1. #1
    Join Date
    Aug 2009

    Interesting but preliminary study on a predictive model of brace curve progression

    Summary: Using a patient's individual risk of progressing (I'm guessing through some combination of Risser/Cobb angle, but the abstract doesn't say) and then recording after a month how well the brace fit and how many hours a day it was worn allowed the research to predict within +/- 3.5 degrees what the final curve size would be.

    Preliminary validation of curve progression model for brace treatment.

    Brace treatment is the most commonly used non-surgical treatment for adolescent idiopathic scoliosis (AIS). A brace compliance monitoring system consisting of a microcomputer and a force transducer was used to monitor how brace candidates used their braces during daily activates. A prediction model of the brace treatment outcome was developed based on 20 AIS subjects. Six subjects (1M, 5F) with AIS who had worn their braces for six weeks participated into this study. One month data was recorded during the study period. Knowing the risk progression at the beginning of brace treatment plus how brace subjects used their braces in terms of brace tightness and wear time during brace treatment yielded a predicted outcome which was compared to the final treatment outcomes with 2 years followed-up. This preliminary result demonstrated that the prediction model was able to predict the treatment outcome within +/-3.5 degrees.

  2. #2
    Join Date
    Jan 2008
    Hi hdugger,

    I tried to view to full-page article but didn't want to pay $ for it…What I am wondering is how they determined with certainty what an individual child's curve progression risk IS. I know with Leah we were told early on that 70% progress and 30% don't, but they didn't have any way to tell which group she would fall into other than waiting for time to tell (while going ahead with treatment of course). I think this is an important part of the over-bracing conundrum, where many kids are braced needlessly because no one knows their true, personal risk. So many parents have come on here asking for a crystal ball…(myself included!).

    I would love to read the full article as it sounds very interesting. Curiously it is published in an Informatics journal, so I wonder how much of it is clinically based and how much of it is based on computations or computer analysis of some sort.

    Lastly, they say they studied 20 subjects, then in the very next sentence go on to say they studied 5 goes and one boy, so I am confused…is it 20 subjects or 6 subjects? I would like to read their standards in regards to what criteria are required of the brace (such as amount of correction in brace, etc) so that all of the blame for curve progression is not being assigned to the child if they don't wear their brace enough. In other words, how are they removing the variables from the brace treatment itself and being so certain that the only variable is time in brace. I am always a little leery when I read these types of studies because I fear the researchers are using it as a way to blame kids for curve progression if they don't wear their brace enough or tight enough, when in reality there are many other factors that contribute to curve progression or lack thereof. Interesting food for thought...
    Gayle, age 49
    Oct 2010 fusion T8-sacrum w/ pelvic fixation
    Feb 2012 lumbar revision for broken rods @ L2-3-4
    Sept 2015 major lumbar A/P revision for broken rods @ L5-S1

    mom of Leah, 15 y/o, Diagnosed '08 with 26* T JIS (age 6)
    5/10 VBS Dr Luhmann Shriners St Louis
    5/16 6 yrs post-op, 24*T/ 22* L, mild increase in curves, watching

    also mom of Torrey, 12 y/o son, 16* T, stable

  3. #3
    Join Date
    Aug 2009
    I found the earlier article which (I believe) includes their risk progression method:
    "Peterson's risk of progression (Risser sign, age, apex of curve and imbalance of curve)"

    They're referring back to this study when they talk about the 20 kids. So, this is the preliminary study where they develop they model, then they write a second paper (with 6 kids) where they test it out.

    What's been interesting to me about both this and the BrAIST study is how much brace use seems to predict outcome. I'd had the idea with Scoliscore that there were other inherent factors at play (other than the simple risk model based on age, curve, etc). But, if you can predict outcome based solely on basic risk criteria and brace wear, then where do the genetic factors come in? Or, are the genetic factors just duplicating what we can see - like an 11 year old with a 30 degree curve just has a different genetic profile then a 12 year old with a 20 degree curve.

    Anyway, yes, it's interesting (in it's very preliminary form)

  4. #4
    Join Date
    Aug 2009

    Break out your calculators

    I found the whole equation

    Here are the factors:

    Peterson's risk progression: risk of progression at the time when the brace was prescribed was calculated based on 4 variables: Risser sign, apex of the curve, age, and imbalance
    Flexibility: (Initial Cobb - in-brace Cobb)/Initial Cobb (I think they're calling this in-brace correction in the formula)
    Quantity: percent of wear time relative to the prescribed wear (22 hours a day is the prescribed wear)
    Quality: percent of wear tightness relative to the prescribed tightness level

    and the equation

    curve Progression (in degrees) = 33 + 0.11*Peterson Risk (%) - 0.07 in-brace correction (%) - 0.45*Quality (%) - 0.48*Quantity (%) + 0.62*Quantity*Quality

    I'm not sure where that constant (33) is coming from, though. Is that just their best guess of average correction after brace wear? Or do they plug in a different number for each kid based on the curve size when they started?

    From the equation - time in brace and tightness are the big factors. Far more important then the starting risk or in-brace correction.

  5. #5
    Join Date
    Aug 2009
    Quote Originally Posted by hdugger View Post
    Or, are the genetic factors just duplicating what we can see - like an 11 year old with a 30 degree curve just has a different genetic profile then a 12 year old with a 20 degree curve.
    Partially answering my own question, yes, Lenke finds that 1/3 of Scoliscore's prediction is accounted for by Cobb angle. Not age or Risser - just Cobb angle.

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