***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Prognosis studies are investigations of future events or the evaluation of associations between risk factors and health outcomes in population s of patients ( 1 ) . The results of such studies improve our underst and ing of the clinical course of a disease and assist clinicians in making informed decisions about how best to manage patients . Prognostic research also informs the design of intervention studies by helping define subgroups of patients who may benefit from a new treatment and by providing necessary information about the natural history of a disorder ( 2 ) . There has recently been a rapid increase in the use of systematic review methods to synthesize the evidence on research questions related to prognosis . It is essential that investigators conducting systematic review s thoroughly appraise the method ologic quality of included studies to be confident that a study 's design , conduct , analysis , and interpretation have adequately reduced the opportunity for bias ( 3 , 4 ) . Caution is warranted , however , because inclusion of method ologically weak studies can threaten the internal validity of a systematic review ( 4 ) . This follows abundant empirical evidence that inadequate attention to biases can cause invalid results and inferences ( 5 - 9 ) . However , there is limited consensus on how to appraise the quality of prognosis studies ( 1 ) . A useful framework to assess bias in such studies follows the basic principles of epidemiologic research ( 10 , 11 ) . We focus on 6 areas of potential bias : study participation , study attrition , prognostic factor measurement , confounding measurement and account , outcome measurement , and analysis . The main objectives of our review of review s are to describe methods used to assess the quality of prognosis studies and to describe how well current practice s assess potential biases . Our secondary objective is to develop recommendations to guide future quality appraisal , both within single studies of prognostic factors and within systematic review s of the evidence . We hope this work facilitates future discussion and research on biases in prognosis studies and systematic review s. Methods Literature Search and Study Selection We identified systematic review s of prognosis studies by search ing MEDLINE ( 1966 to October 2005 ) using the search strategy recommended by McKibbon and colleagues ( 12 ) . This strategy combines broad search terms for systematic review s ( systematic review .mp ; meta- analysis .mp ) and a sensitive search strategy for prognosis studies ( cohort , incidence , mortality , follow-up studies , prognos * , predict * , or course ) . We also search ed the reference lists of included review s and method ologic papers to identify other relevant publications . We restricted our search to English- language publications . One review er conducted the search and selected the studies . Systematic review s , defined as review s of published studies with a comprehensive search and systematic selection , were included if they assessed the method ologic quality of the included studies by using 1 or more explicit criteria . We excluded studies if they were meta-analyses of independent patient data only , if their primary goal was to investigate the effectiveness of an intervention or specific diagnostic or screening tests , or if they included studies that were not done on humans . Data Extraction and Synthesis Individual items included in the quality assessment of the systematic review s were recorded as they were reported in the publication ( that is , the information that would be available to readers and future review ers ) . We review ed journal Web sites and contacted the authors of the systematic review s for additional information when authors made such an offer in their original papers . When review s assessed different study design s by using different sets of quality items , we extracted only those items used to assess cohort studies . We constructed a comprehensive list of distinct items that the review s used to assess the quality of their included studies . The full text of each review was screened . All items used by the review authors to assess the quality of studies were extracted into a computerized spreadsheet by 1 review er . Two experienced review ers , a clinical epidemiologist and an epidemiologist , independently synthesized the quality items extracted from the prognosis review s to determine how well the systematic review s assessed potential biases . We did this in 3 steps : 1 ) identified distinct concepts or domains addressed by the quality items ; 2 ) grouped each extracted quality item into the appropriate domain or domains ; and 3 ) identified the domains necessary to assess potential biases in prognosis studies . We then used this information to assess how well the review s ' quality assessment included items from the domains necessary to assess potential biases . After completing each of the first 3 steps , the review ers met to attempt to reach a consensus . The consensus process involved each review er presenting his or her observations and results , followed by discussion and debate . A third review er was available in cases of persistent disagreement or uncertainty . In the first step , all domains addressed by the quality items were identified . The first review er iteratively and progressively defined the domains as items were extracted from the included review s. The second review er defined domains from a r and om list of all extracted quality items . Limited guidance was provided to the review ers so that their assessment s and definitions of domains would be independent . The review ers agreed on a final set of domains that adequately and completely defined all of the extracted items . In the second step , review ers independently grouped each extracted item into the appropriate domains . Review ers considered each extracted item by asking , What is each particular quality item addressing ? or What are the review 's authors getting at with the particular quality assessment item ? . Items were grouped into the domain or domains that best represented the concepts being addressed . For example , the extracted items at least 80 % of the group originally identified was located for follow-up and follow-up was sufficiently complete or does n't jeopardize validity were each independently classified by both review ers as assessing the domain completeness of follow-up adequate , whereas the extracted item quantification and description of all subjects lost to follow-up was classified as assessing the domain completeness of follow-up described . In the third step , we identified the domains necessary to assess potential biases . Each review er considered the ability of the identified domains to adequately address , at least in part , 1 of the following 6 potential biases : 1 ) study participation , 2 ) study attrition , 3 ) prognostic factor measurement , 4 ) confounding measurement and account , 5 ) outcome measurement , and 6 ) analysis . Domains were considered to adequately address part of the framework if information garnered from that domain would inform the assessment of potential bias . For example , both review ers judged that the identified domain study population represents source population or population of interest assessed potential bias in a prognosis study , whereas the domain research question definition did not , although the latter is an important consideration in assessing the inclusion of studies in a systematic review . Finally , on the basis of our previous ratings , we looked at whether each review included items from the domains necessary to assess the 6 potential biases . We calculated the frequency of systematic review s by assessing each potential bias and the number of review s that adequately assessed bias overall . From this systematic synthesis , we developed recommendations for improving quality appraisal in future systematic review s of prognosis studies . We used Microsoft Access and Excel 2002 ( Microsoft Corp. , Redmond , Washington ) for data management and SAS for Windows , version 9.1 ( SAS Institute , Inc. , Cary , North Carolina ) for descriptive statistics . Role of the Funding Sources The funding sources , the Canadian Institutes of Health Research , the Canadian Chiropractic Research Foundation , the Ontario Chiropractic Association , and the Ontario Ministry of Health and Long Term Care , did not have a role in the collection , analysis , or interpretation of the data or in the decision to su bmi t the manuscript for publication . Results We identified 1384 potentially relevant articles . Figure 1 shows a flow chart of studies that were included and excluded . Figure 2 shows the number of review s identified by year of publication . We excluded 131 systematic review s of prognosis studies that did not seem to include any quality assessment of the included studies ; this represented 44 % of prognosis review s. We included 163 review s of prognosis studies in our analysis ( 13 - 175 ) . The most common topics were cancer ( 15 % ) , musculoskeletal disorders and rheumatology ( 13 % ) , cardiovascular ( 10 % ) , neurology ( 10 % ) , and obstetrics ( 10 % ) . Other review s included a wide range of health and health care topics . Sixty-three percent of the review s investigated the association between a specific prognostic factor and a particular outcome ; the remainder investigated multiple prognostic factors or models . The number of primary studies included in each systematic review ranged from 3 to 167 ( median , 18 [ interquartile range , 12 to 31 ] ) . A complete description of the included review s is available from the authors on request . Figure 1 . Flow diagram of inclusion and exclusion criteria of systematic review s. Figure 2 . Number of systematic review s of prognosis studies identified over time . Quality Items One hundred fifty-three review s provided adequate detail to allow extraction of quality items . Eight hundred eighty-two distinct quality items were extracted from the review s. Most review s developed their own set of quality items , with only a few applying criteria from previous review s. Most quality items BACKGROUND CONTEXT Evidence demonstrating the biomechanical effects of the Hueter-Volkmann principle on vertebral body growth in spinal deformities is lacking . Bracing a scoliotic curve should , in theory , unload the growth plates on the concave side of the vertebral bodies near the curve 's apex . Growth stimulation , leading to structural remodeling of the vertebral bodies , on the curve 's concave side may explain the improvement or lack of curve progression , as measured by Cobb angles , reported with successful brace management of adolescent idiopathic scoliosis ( AIS ) . PURPOSE To determine whether brace treatment stimulated asymmetric chondrogenesis in the apical three vertebral bodies . STUDY DESIGN A prospect i ve cohort of patients with AIS receiving brace treatment were followed from the initiation of brace treatment until skeletal maturity . Patients were then retrospectively divided into those with and without radiographic progression . This post hoc analysis was included to determine risk factors for curve progression . PATIENT SAMPLE Forty-one skeletally immature patients with AIS meeting criteria for brace treatment were followed until skeletal maturity . All patients were treated with thoracolumbosacral orthotics ( TLSOs ) . OUTCOME MEASURES The positional derotation of the TLSO on the spine was measured by comparing the initial radiograph with the first radiograph in a brace . The long-term structural changes of the vertebral bodies were determined by comparing the initial and final radiographs . Differences in initial radiographic parameters between the groups of patients with AIS with and without curve progression indicated predictive factors for successful brace treatment . METHODS Initial radiographic measurements were compared with those observed in a brace and those observed at final follow-up . The same analysis was retrospectively repeated comparing patients with AIS with and without radiographic progression . RESULTS Cobb measurements ( p=.0001 ) and concave-to-convex height ratios of the apical three vertebral bodies improved when the brace was initially applied ( p=.0035 ) . Structural remodeling or a rotational correction of the apical three vertebral bodies was appreciated only in patients with flexible curves ( p=.01 ) . CONCLUSION Brace application results in immediate positional derotations of the spine in patients with AIS . These positional derotations were maintained only in patients with flexible curves , at final follow-up . Brace treatment was not recommended in patients whose curves did not correct at least 20 % in a TLSO Background : Curve magnitude and skeletal maturity are important factors in determining the efficacy of bracing for the treatment of adolescent idiopathic scoliosis , but curve morphology may also affect brace success . The purpose of this study was to determine the influence of curve morphology on the response to bracing with a thoracolumbosacral orthosis ( TLSO ) . Methods : A retrospective review of patients managed with an orthosis for the treatment of adolescent idiopathic scoliosis who were prospect ively enrolled at the initiation of brace wear and followed through completion of bracing or surgery was performed . Inclusion criteria were main curves of 25 ° to 45 ° and a Risser stage of 0 , 1 , or 2 at the time of brace prescription . Compliance with bracing was measured with Maxim Integrated Thermochrons . Radiographs made at brace initiation , brace cessation , and final follow-up were used to retrospectively categorize curves with use of the modified Lenke ( mLenke ) classification system and more broadly to categorize them as main thoracic or main lumbar . The effect of morphology on outcome was evaluated using chi-square and Fisher exact tests . Results : One hundred and sixty-eight patients were included . There was no difference in curve magnitude at the time of brace initiation ( p = 0.798 ) or in average hours of daily brace wear ( p = 0.146 ) between groups . The rate of surgery or progression of the curve to ≥50 ° was 34.5 % ( 29 of 84 ) in mLenke-I curves , 54.5 % ( 6 of 11 ) in mLenke-II curves , 29.4 % ( 10 of 34 ) in mLenke-III curves , 17.6 % ( 3 of 17 ) in mLenke-V curves , and 13.6 % ( 3 of 22 ) in mLenke-VI curves . There were no mLenke-IV curves at the time of brace initiation . The rate of surgery or progression to ≥50 ° was 34.1 % ( 44 of 129 ) in the combined thoracic group and 15.4 % ( 6 of 39 ) in the combined lumbar group ( p = 0.0277 ) . In brace-compliant patients ( > 12.9 hours/day ) , the rate of surgery or progression to ≥50 ° was 30.3 % ( 20 of 66 ) in main thoracic curves and 5.3 % ( 1 of 19 ) in main lumbar curves ( p = 0.0239 ) . One-tenth of curves changed morphology during bracing . The rate of surgery or progression to ≥50 ° was 35.8 % ( 43 of 120 ) in persistent main thoracic curves , 20.0 % ( 6 of 30 ) in persistent main lumbar curves , 12 
    Output:
    
Strong evidence was found that lack of initial in-brace correction is associated with treatment failure .
Moderate evidence suggests that brace wear time is associated with failure and success , whereas initial curve magnitude and curve type are not .
Conclusion The results of this review suggest that lack of initial in-brace correction is strongly associated with brace treatment failure .