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Abstract from the SRS 2004 Annual Meeting
Purpose: To establish consistent parameters for future AIS bracing studies
so that valid and reliable comparisons can be made. As prior literature lacks
consistency for both inclusion criteria and brace effectiveness, clinicians
are currently unable to draw valid conclusions from existing data.
Methods: A thorough review of published natural history studies was
performed to determine the AIS patient population most at-risk for curve progression
(and the subsequent possible need for surgery). Then, 31 bracing articles including
the current BrAIST proposal were analyzed to determine 1) inclusion criteria
that will best identify those patients most at-risk for progression 2) the most
appropriate definitions for bracing effectiveness, and 3) identification of
additional variables which would provide valuable information.
Results: S: Early studies either lacked inclusion criteria or were quite
varied in age at brace prescription (4- 18.9 years), skeletal maturity (Risser
0-4), and curve magnitude (120-680). In more recent studies, inclusion criteria
narrowed considerably; specifically, Risser 0-2, age e” 10 years at brace prescription,
and primary curves between 250-450 (250-390 in the current BrAIST proposal).
Curves 200-250 were included in some studies if progression had been documented.
Brace effectiveness was usually defined as the prevention of curve progression
d”50 at maturity. However, maturity was variably defined as the end of growth,
Risser 4, or two years post-menarchal. Most commonly, bracing was described
as ineffective when curve progression was e”60 or if surgical intervention was
recommended. Less frequently, bracing was described as ineffective when progression
was e”100, if the curve progressed to > 450, or if there was change to another
brace. In those studies with follow-up e”2 years beyond maturity, additional
curve progression (ultimately leading to surgical intervention) was not unusual.
Potentially useful additional variables included: curve patterns, curve grouping
(250-350, 300-400, 350-450), brace type, in-brace correction, and amount of
daily time in brace.
Conclusions: I. Inconsistent selection criteria in many older bracing
studies prevent clinicians from drawing valid conclusions about the effectiveness
of bracing in AIS. II. Optimal inclusion criteria for future AIS brace studies
consist of age e”10 years old when brace is prescribed, Risser 0-2, primary
curve angles between 250 and 390, and no prior treatment. III. Assessment of
brace effectiveness should include: 1) the percentage of patients who have d”50
curve progression and the percentage who have e”60 progression at maturity 2)
the percentage of patients who have had surgery recommended/undertaken at maturity
(surgical indications must be documented), and 3) two-year follow-up beyond
maturity to determine the percentage of patients who subsequently undergo surgery
(again, surgical indications must be documented). IV. All patients, regardless
of subjective reports on compliance, should be included in results (intent to
treat). Whenever possible, compliance should be measured objectively. V. All
studies should provide results stratified by curve type and size grouping.
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