human
***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 Study Design . A r and omized controlled trial . Objective . To investigate feed-forward activation or timing of abdominal muscle activation in response to rapid shoulder flexion after 8 weeks with core stability exercises , sling exercises , or general exercises in chronic nonspecific low back pain ( LBP ) patients . Summary of Background Data . Delayed onset in abdominal muscles has been associated with LBP . Low load exercises to volitionally activate the transversus abdominis were introduced to restore trunk muscle activation deficits . More forceful co-contraction exercises have been advocated by others . This study explored whether abdominal muscle onset changed after low-load core stability exercises , high-load sling exercises , or general exercises . Methods . Subjects ( N = 109 ) with chronic nonspecific LBP of at least 3 months ' duration were r and omly assigned to 8 weekly treatments with low-load core stability exercises , high-load stabilizing exercises in slings , or general exercises in groups . Primary outcome was onset recorded bilaterally by m-mode ultrasound imaging in the deep abdominal muscles in response to rapid shoulder flexion . Results . No or small changes were found in onset after treatment . Baseline adjusted between group differences showed a 15 ms ( 95 % confidence interval [ CI ] , 1–28 ; P = 0.03 ) and a 19 ms ( 95 % CI , 5–33 ; P < 0.01 ) improvement with sling relative to core stability and general exercises , respectively , but on 1 side only . There was no association between changes in pain and onset over the intervention period ( R2 ⩽ 0.02 ) . Conclusion . Abdominal muscle onset was largely unaffected by 8 weeks of exercises in chronic LBP patients . There was no association between change in onset and LBP . Large individual variations in activation pattern of the deep abdominal muscles may justify exploration of differential effects in subgroups of LBP OBJECTIVE Our purpose was to measure the agreement , reliability , construct validity , and feasibility of a measurement tool to assess  systematic review s ( AMSTAR ) . STUDY DESIGN AND SETTING We r and omly selected 30 systematic review s from a data base . Each was assessed by two review ers using : ( 1 ) the enhanced quality assessment question naire ( Overview of Quality Assessment Question naire [ OQAQ ] ) ; ( 2 ) Sacks ' instrument ; and ( 3 ) our newly developed measurement tool ( AMSTAR ) . We report on reliability ( interobserver kappas of the 11 AMSTAR items ) , intraclass correlation coefficients ( ICCs ) of the sum scores , construct validity ( ICCs of the sum scores of AMSTAR compared with those of other instruments ) , and completion times . RESULTS The interrater agreement of the individual items of AMSTAR was substantial with a mean kappa of 0.70 ( 95 % confidence interval [ CI ] : 0.57 , 0.83 ) ( range : 0.38 - 1.0 ) . Kappas recorded for the other instruments were 0.63 ( 95 % CI : 0.38 , 0.78 ) for enhanced OQAQ and 0.40 ( 95 % CI : 0.29 , 0.50 ) for the Sacks ' instrument . The ICC of the total score for AMSTAR was 0.84 ( 95 % CI : 0.65 , 0.92 ) compared with 0.91 ( 95 % CI : 0.82 , 0.96 ) for OQAQ and 0.86 ( 95 % CI : 0.71 , 0.94 ) for the Sacks ' instrument . AMSTAR proved easy to apply , each review taking about 15 minutes to complete . CONCLUSIONS AMSTAR has good agreement , reliability , construct validity , and feasibility . These findings need confirmation by a broader range of assessors and a more diverse range of review Objectives Although motor control exercises have been shown to be effective in the management of  low back pain ( LBP ) the mechanism of action is unclear . The current study investigated the relationship between the ability to recruit transversus abdominis and clinical outcomes of participants in a clinical trial . Methods Ultrasonography was used to assess the ability to recruit transversus abdominis in a nested design : a sample of 34 participants with chronic LBP was recruited from participants in a r and omised controlled trial comparing the efficacy of motor control exercise , general exercise and spinal manipulative therapy .  Perceived recovery , function , disability and pain were also assessed . Results Participants with chronic LBP receiving motor control exercise had a greater improvement in recruitment of transversus abdominis ( 7.8 % ) than participants receiving general exercise ( 4.9 % reduction ) or spinal manipulative therapy ( 3.7 % reduction ) . The effect of motor control exercise on pain reduction was greater in participants who had a poor ability to recruit transversus abdominis at baseline . There was a significant , moderate correlation between improved recruitment of transversus abdominis and a reduction in disability ( r = −0.35 ; 95 % CI 0.02 to 0.62 ) . Conclusion These data provide some support for the hypothesised mechanism of action of motor control exercise and suggest that the treatment may be more effective in those with a poor ability to recruit transversus abdominis Many studies 
    Output:
    
agent
Evidence synthesis showed limited evidence supporting poor baseline transversus abdominis contraction thickness ratio as a treatment effect modifier favoring motor control exercise .
Limited evidence supported that high baseline transversus abdominis lateral slide was associated with higher pain intensity after various exercise interventions at 1-year follow-up .
However , there was limited evidence for the absence of relation between the contraction thickness ratio of transversus abdominis or anticipatory onset of lateral abdominal muscles at baseline and the short- or long-term LBP intensity after exercise interventions .
There was conflicting evidence for a relation between baseline percent thickness change of lumbar multifidus during contraction and the clinical outcomes of patients after various conservative treatments .
***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 Study Design . A r and omized controlled trial . Objective . To investigate feed-forward activation or timing of abdominal muscle activation in response to rapid shoulder flexion after 8 weeks with core stability exercises , sling exercises , or general exercises in chronic nonspecific low back pain ( LBP ) patients . Summary of Background Data . Delayed onset in abdominal muscles has been associated with LBP . Low load exercises to volitionally activate the transversus abdominis were introduced to restore trunk muscle activation deficits . More forceful co-contraction exercises have been advocated by others . This study explored whether abdominal muscle onset changed after low-load core stability exercises , high-load sling exercises , or general exercises . Methods . Subjects ( N = 109 ) with chronic nonspecific LBP of at least 3 months ' duration were r and omly assigned to 8 weekly treatments with low-load core stability exercises , high-load stabilizing exercises in slings , or general exercises in groups . Primary outcome was onset recorded bilaterally by m-mode ultrasound imaging in the deep abdominal muscles in response to rapid shoulder flexion . Results . No or small changes were found in onset after treatment . Baseline adjusted between group differences showed a 15 ms ( 95 % confidence interval [ CI ] , 1–28 ; P = 0.03 ) and a 19 ms ( 95 % CI , 5–33 ; P < 0.01 ) improvement with sling relative to core stability and general exercises , respectively , but on 1 side only . There was no association between changes in pain and onset over the intervention period ( R2 ⩽ 0.02 ) . Conclusion . Abdominal muscle onset was largely unaffected by 8 weeks of exercises in chronic LBP patients . There was no association between change in onset and LBP . Large individual variations in activation pattern of the deep abdominal muscles may justify exploration of differential effects in subgroups of LBP OBJECTIVE Our purpose was to measure the agreement , reliability , construct validity , and feasibility of a measurement tool to assess  systematic review s ( AMSTAR ) . STUDY DESIGN AND SETTING We r and omly selected 30 systematic review s from a data base . Each was assessed by two review ers using : ( 1 ) the enhanced quality assessment question naire ( Overview of Quality Assessment Question naire [ OQAQ ] ) ; ( 2 ) Sacks ' instrument ; and ( 3 ) our newly developed measurement tool ( AMSTAR ) . We report on reliability ( interobserver kappas of the 11 AMSTAR items ) , intraclass correlation coefficients ( ICCs ) of the sum scores , construct validity ( ICCs of the sum scores of AMSTAR compared with those of other instruments ) , and completion times . RESULTS The interrater agreement of the individual items of AMSTAR was substantial with a mean kappa of 0.70 ( 95 % confidence interval [ CI ] : 0.57 , 0.83 ) ( range : 0.38 - 1.0 ) . Kappas recorded for the other instruments were 0.63 ( 95 % CI : 0.38 , 0.78 ) for enhanced OQAQ and 0.40 ( 95 % CI : 0.29 , 0.50 ) for the Sacks ' instrument . The ICC of the total score for AMSTAR was 0.84 ( 95 % CI : 0.65 , 0.92 ) compared with 0.91 ( 95 % CI : 0.82 , 0.96 ) for OQAQ and 0.86 ( 95 % CI : 0.71 , 0.94 ) for the Sacks ' instrument . AMSTAR proved easy to apply , each review taking about 15 minutes to complete . CONCLUSIONS AMSTAR has good agreement , reliability , construct validity , and feasibility . These findings need confirmation by a broader range of assessors and a more diverse range of review Objectives Although motor control exercises have been shown to be effective in the management of  low back pain ( LBP ) the mechanism of action is unclear . The current study investigated the relationship between the ability to recruit transversus abdominis and clinical outcomes of participants in a clinical trial . Methods Ultrasonography was used to assess the ability to recruit transversus abdominis in a nested design : a sample of 34 participants with chronic LBP was recruited from participants in a r and omised controlled trial comparing the efficacy of motor control exercise , general exercise and spinal manipulative therapy .  Perceived recovery , function , disability and pain were also assessed . Results Participants with chronic LBP receiving motor control exercise had a greater improvement in recruitment of transversus abdominis ( 7.8 % ) than participants receiving general exercise ( 4.9 % reduction ) or spinal manipulative therapy ( 3.7 % reduction ) . The effect of motor control exercise on pain reduction was greater in participants who had a poor ability to recruit transversus abdominis at baseline . There was a significant , moderate correlation between improved recruitment of transversus abdominis and a reduction in disability ( r = −0.35 ; 95 % CI 0.02 to 0.62 ) . Conclusion These data provide some support for the hypothesised mechanism of action of motor control exercise and suggest that the treatment may be more effective in those with a poor ability to recruit transversus abdominis Many studies 
    Output:
    