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: Purpose Much research has been performed on physical exposures during work ( e.g. lifting , trunk flexion or body vibrations ) as risk factors for  low back pain ( LBP ) , however results are inconsistent . Information on the effect of doses ( e.g. spinal force or low back moments ) on LBP may be more reliable but is lacking yet . The aim of the present study was to investigate the prospect i ve relationship of cumulative low back loads ( CLBL ) with LBP and to compare the association of this mechanical load measure to exposure measures used previously . Methods The current study was part of the Study on Musculoskeletal disorders , Absenteeism and Health ( SMASH ) study in which 1,745 workers completed question naires .  Physical load at the workplace was assessed by video-observations and force measurements . These measures were used to calculate CLBL . Furthermore , a 3-year follow-up was conducted to assess the occurrence of LBP . Logistic regressions were performed to assess associations of CLBL and physical risk factors established earlier ( i.e. lifting and working in a flexed posture ) with LBP . Furthermore , CLBL and the risk factors combined were assessed as predictors in logistic regression analyses to assess the association with LBP . Results Results showed that CLBL is a significant risk factor for LBP ( OR : 2.06 ( 1.32–3.20 ) ) . Furthermore , CLBL had a more consistent association with LBP than two of the three risk factors reported earlier . Conclusions From these results it can be concluded that CLBL is a risk factor for the occurrence of LBP , having a more consistent association with LBP compared to most risk factors reported earlier BACKGROUND Job rotation might be an effective preventive measure to reduce the prevalence of musculoskeletal complaints , although its effect has not been yet established . The aim of the present study is to evaluate the effect of job rotation in refuse collecting on need for recovery , prevalence of musculoskeletal complaints , and sick leave due to musculoskeletal complaints .  METHODS A 1-year prospect i ve study among refuse collectors was performed , using st and ardized question naires . Job rotation was performed between collecting two-wheeled containers and driving a refuse truck . The experimental groups of rotating refuse collectors at t(0 ) and t(1 ) ( group R-R ) and non-rotating refuse collectors at t(0 ) and rotating refuse collectors at t(1 ) ( group NR-R ) were compared with a reference group of non-rotating refuse collectors at t(0 ) and t(1 ) ( group NR-NR ) . RESULTS The adjusted need for recovery of group R-R was marginally significantly lower than need for recovery of the reference group . Groups R-R and NR-R had a more than two times higher risk for complaints of the low back than the reference group . No other significant results were found . CONCLUSIONS Job rotation seemed to coincide with a reduced need for recovery and was associated with an increased risk of low back complaints . No effects were found on sick leave due to musculoskeletal complaints . The results might be influenced by the healthy worker selection effect in the reference group and its inverse in the rotating groups Purpose To help workers to stay at work in a healthy productive and sustainable way and for the development of interventions to improve work functioning , it is important to have insight in prognostic factors for successful work functioning . The aim of this study is to identify prognostic factors for successful work functioning in a general working population . Methods A longitudinal study ( 3 months follow-up ) was conducted among the working population ( N = 98 ) . Work functioning was assessed with the  Work Role Functioning Question naire 2.0 ( WRFQ ) . The total score was categorized as follows : 0–90 ; > 90 ≤95 ; and > 95–100 ( defined as ‘ successful work functioning ’ ) . Ordinal logistic regression analyses were performed to examine bivariate relationships between potential prognostic factors and the dependent variable ( successful work functioning ) to identify potential prognostic factors for the multivariate models ( p < 0.10 ) . A stepwise approach was used to introduce the variables in the multiple ordinal regression analyses . Results Baseline work functioning and work ability were significant prognostic factors for successful work functioning at 3 months follow-up . No prospect i ve associations were identified for psychological job dem and s and supervisor social support with successful work functioning . Conclusion To our knowledge this is the first longitudinal study to identify prognostic factors for successful work functioning in the general working population .  High work ability is predictive for future successful work functioning , independent of baseline work functioning Purpose To investigate the Work Ability Index ( WAI ) as tool for identifying workers at risk of premature work exit in terms of disability pension , unemployment , or early retirement . Methods Prospect i ve cohort study of 11,537 male construction workers ( mean age 45.5 years ) , who completed the WAI at baseline and reported their work status ( employed , unemployed , disability pension , or retired ) after mean 2.3 years of follow-up . Associations between WAI scores and work status were investigated by multinomial logistic regression analysis . The ability of the WAI to discriminate between workers at high and low risk of premature work exit was analyzed by the area ( AUC ) under the receiver operating characteristic curve . Results 9,530 ( 83 % ) construction workers had complete data for analysis . At follow-up , 336 ( 4 % ) workers reported disability pension , 125 ( 1 % ) unemployment , and 255 ( 3 % ) retirement . WAI scores were prospect ively associated with the risk of disability pension at follow-up , but not with the risk of unemployment and early retirement . The WAI showed fair discrimination to identify workers at risk of disability pension [ AUC = 0.74 ; 95 % confidence interval ( CI ) 0.70–0.77 ] . The discriminative ability decreased with age from AUC = 0.78 in workers aged 30–39 years to AUC = 0.69 in workers ≥50 years of age . Discrimination failed for unemployment ( AUC = 0.51 ; 95 % CI 0.47–0.55 ) and early retirement ( AUC = 0.58 ; 95 % CI 0.53–0.61 ) . Conclusions The WAI can be used to identify construction workers < 50 years of age at increased risk of disability pension and invite them for preventive interventions OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity The effect of job rotation on the physical workload was investigated for male employees working at a refuse collecting department . Before the introduction of job rotation , an employee worked as a street sweeper , as a refuse collector or as a driver . After the introduction of job rotation , every employee was allowed to alternate between two of the three possible jobs during the day , i.e. refuse collecting/street sweeping , refuse collecting/driving or street sweeping/driving . Two non-rotation groups ( i.e. refuse collectors and street sweepers ) and two rotation groups ( i.e. refuse collectors/street sweepers and street sweepers/drivers ) were mutually compared . The physical workload was determined by measuring the perceived load , energetic load and postural load during a full working day . Job rotation result ed in a significant decrease of the perceived load and energetic load and a slight decrease of the postural load . The results indicate that the total amount of work performed by means of job rotation result ed in an overall reduced physical workload of the employees of the refuse collecting department Data on exposure variability is an important remedy for design ing and interpreting studies of occupational ergonomics . The present study aim ed at retrieving the within- and between-subjects variance of several mechanical exposure parameters in a repeated , short-cycle task . Seven experienced operators repeatedly secured joints using two types of h and -held nutrunners . The joints were placed in three different locations on a rack , simulating automotive assembly . Bilateral muscle activity from the upper trapezius and the lower arm extensors , as well as head and upper arm inclination was continuously monitored . Exposure levels and their variance components were assessed in several data subsets using ANOVA . The results were interpreted in terms of statistical precision and power , and discussed as markers of important ergonomic qualities . A substantial exposure variability was found within and between subjects in all joint locations and for both tools . For mixed work across tools and locations , the necessary number of subjects to arrive at a group mean exposure with 95 % confidence limits corresponding to ± 10 % of the mean ranged between 8 and 158 , with posture recordings tending to require smaller population s than muscle activity recordings . Within-subject variance increased 2- to 37-fold , depending on exposure parameter , when work was ‘ enlarged ’ from securings with a specified location and tool to a mix of all locations and tools . Systematic differences between subjects in variability and responsiveness to ‘ work enlargement ’ indicated individualized motor control strategies . The results illustrate the importance of exposure variability data to the design of proper measurement strategies . They also suggest that the sizes of exposure variability per se can be interpreted as operational indices of what is thought to be important ergonomic risk indicators , such as the ‘ sameness ’ of repeated operations and the allowance for flexible working techniques CONTEXT Common pain conditions appear to have an adverse effect on work , but no comprehensive estimates exist on the amount of productive time lost in the US workforce due to pain . OBJECTIVE To measure lost productive time ( absence and reduced performance due to common pain conditions ) during a 2-week period . DESIGN AND SETTING Cross-sectional study using survey data from the American Productivity Audit ( a telephone survey that uses the Work and Health Interview ) of working adults between August 1 , 2001 , and July 30 , 2002 . PARTICIPANTS R and om sample of 28 902 working adults in the United States . MAIN OUTCOME MEASURES Lost productive time due to common pain conditions ( arthritis , back , headache , and other musculoskeletal ) expressed in hours per worker per week and calculated in US dollars . RESULTS Thirteen percent of the total workforce experienced a loss in productive time during a 2-week period due to a common pain condition . Headache was the most common ( 5.4 % ) pain condition result ing in lost productive time . It was followed by back pain ( 3.2 % ) , arthritis pain ( 2.0 % ) , and other musculoskeletal pain ( 2.0 % ) . Workers who experienced lost productive time from a pain condition lost a mean ( SE ) of 4.6 ( 0.09 ) h/wk . Workers who had a headache had a mean ( SE ) loss in productive time of 3.5 ( 0.1 ) h/wk . Workers who reported arthritis or back pain had mean ( SE ) lost productive times of 5.2 ( 0.25 ) h/wk . Other common pain conditions result ed in a mean ( SE ) loss in productive time of 5.5 ( 0.22 ) h/wk . Lost productive time from common pain conditions among active workers costs an estimated 61.2 billion dollars per year . The majority ( 76.6 % ) of the lost productive time was explained by reduced performance while at work and not work absence . CONCLUSIONS Pain is an inordinately common and disabling condition in the US workforce . Most of the pain-related lost productive time occurs while employees are at work and is in the form of reduced performance Objectives : A prospect i ve follow-up study of employees in Denmark was analyzed in order to investigate the association between physical and psychosocial exposures and musculoskeletal symptoms in the neck-shoulder and wrist-h and regions . Methods : Data were derived from a 5-year follow-up question naire study of a sample of employees in Denmark , aged between 18 and 59 years .  Occupational and individual background factors were assessed in 1990 , and the associations with symptoms in 1995 were analyzed using logistic regression . The analysis was restricted to comprise employees free of symptoms in 1990 . The neck-shoulder and wrist-h 
    Output:
    
agent
Practitioner 's Summary : Currently , there is inconsistent evidence for recommending job rotation as a strategy for preventing musculoskeletal complaints .
***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: Purpose Much research has been performed on physical exposures during work ( e.g. lifting , trunk flexion or body vibrations ) as risk factors for  low back pain ( LBP ) , however results are inconsistent . Information on the effect of doses ( e.g. spinal force or low back moments ) on LBP may be more reliable but is lacking yet . The aim of the present study was to investigate the prospect i ve relationship of cumulative low back loads ( CLBL ) with LBP and to compare the association of this mechanical load measure to exposure measures used previously . Methods The current study was part of the Study on Musculoskeletal disorders , Absenteeism and Health ( SMASH ) study in which 1,745 workers completed question naires .  Physical load at the workplace was assessed by video-observations and force measurements . These measures were used to calculate CLBL . Furthermore , a 3-year follow-up was conducted to assess the occurrence of LBP . Logistic regressions were performed to assess associations of CLBL and physical risk factors established earlier ( i.e. lifting and working in a flexed posture ) with LBP . Furthermore , CLBL and the risk factors combined were assessed as predictors in logistic regression analyses to assess the association with LBP . Results Results showed that CLBL is a significant risk factor for LBP ( OR : 2.06 ( 1.32–3.20 ) ) . Furthermore , CLBL had a more consistent association with LBP than two of the three risk factors reported earlier . Conclusions From these results it can be concluded that CLBL is a risk factor for the occurrence of LBP , having a more consistent association with LBP compared to most risk factors reported earlier BACKGROUND Job rotation might be an effective preventive measure to reduce the prevalence of musculoskeletal complaints , although its effect has not been yet established . The aim of the present study is to evaluate the effect of job rotation in refuse collecting on need for recovery , prevalence of musculoskeletal complaints , and sick leave due to musculoskeletal complaints .  METHODS A 1-year prospect i ve study among refuse collectors was performed , using st and ardized question naires . Job rotation was performed between collecting two-wheeled containers and driving a refuse truck . The experimental groups of rotating refuse collectors at t(0 ) and t(1 ) ( group R-R ) and non-rotating refuse collectors at t(0 ) and rotating refuse collectors at t(1 ) ( group NR-R ) were compared with a reference group of non-rotating refuse collectors at t(0 ) and t(1 ) ( group NR-NR ) . RESULTS The adjusted need for recovery of group R-R was marginally significantly lower than need for recovery of the reference group . Groups R-R and NR-R had a more than two times higher risk for complaints of the low back than the reference group . No other significant results were found . CONCLUSIONS Job rotation seemed to coincide with a reduced need for recovery and was associated with an increased risk of low back complaints . No effects were found on sick leave due to musculoskeletal complaints . The results might be influenced by the healthy worker selection effect in the reference group and its inverse in the rotating groups Purpose To help workers to stay at work in a healthy productive and sustainable way and for the development of interventions to improve work functioning , it is important to have insight in prognostic factors for successful work functioning . The aim of this study is to identify prognostic factors for successful work functioning in a general working population . Methods A longitudinal study ( 3 months follow-up ) was conducted among the working population ( N = 98 ) . Work functioning was assessed with the  Work Role Functioning Question naire 2.0 ( WRFQ ) . The total score was categorized as follows : 0–90 ; > 90 ≤95 ; and > 95–100 ( defined as ‘ successful work functioning ’ ) . Ordinal logistic regression analyses were performed to examine bivariate relationships between potential prognostic factors and the dependent variable ( successful work functioning ) to identify potential prognostic factors for the multivariate models ( p < 0.10 ) . A stepwise approach was used to introduce the variables in the multiple ordinal regression analyses . Results Baseline work functioning and work ability were significant prognostic factors for successful work functioning at 3 months follow-up . No prospect i ve associations were identified for psychological job dem and s and supervisor social support with successful work functioning . Conclusion To our knowledge this is the first longitudinal study to identify prognostic factors for successful work functioning in the general working population .  High work ability is predictive for future successful work functioning , independent of baseline work functioning Purpose To investigate the Work Ability Index ( WAI ) as tool for identifying workers at risk of premature work exit in terms of disability pension , unemployment , or early retirement . Methods Prospect i ve cohort study of 11,537 male construction workers ( mean age 45.5 years ) , who completed the WAI at baseline and reported their work status ( employed , unemployed , disability pension , or retired ) after mean 2.3 years of follow-up . Associations between WAI scores and work status were investigated by multinomial logistic regression analysis . The ability of the WAI to discriminate between workers at high and low risk of premature work exit was analyzed by the area ( AUC ) under the receiver operating characteristic curve . Results 9,530 ( 83 % ) construction workers had complete data for analysis . At follow-up , 336 ( 4 % ) workers reported disability pension , 125 ( 1 % ) unemployment , and 255 ( 3 % ) retirement . WAI scores were prospect ively associated with the risk of disability pension at follow-up , but not with the risk of unemployment and early retirement . The WAI showed fair discrimination to identify workers at risk of disability pension [ AUC = 0.74 ; 95 % confidence interval ( CI ) 0.70–0.77 ] . The discriminative ability decreased with age from AUC = 0.78 in workers aged 30–39 years to AUC = 0.69 in workers ≥50 years of age . Discrimination failed for unemployment ( AUC = 0.51 ; 95 % CI 0.47–0.55 ) and early retirement ( AUC = 0.58 ; 95 % CI 0.53–0.61 ) . Conclusions The WAI can be used to identify construction workers < 50 years of age at increased risk of disability pension and invite them for preventive interventions OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity The effect of job rotation on the physical workload was investigated for male employees working at a refuse collecting department . Before the introduction of job rotation , an employee worked as a street sweeper , as a refuse collector or as a driver . After the introduction of job rotation , every employee was allowed to alternate between two of the three possible jobs during the day , i.e. refuse collecting/street sweeping , refuse collecting/driving or street sweeping/driving . Two non-rotation groups ( i.e. refuse collectors and street sweepers ) and two rotation groups ( i.e. refuse collectors/street sweepers and street sweepers/drivers ) were mutually compared . The physical workload was determined by measuring the perceived load , energetic load and postural load during a full working day . Job rotation result ed in a significant decrease of the perceived load and energetic load and a slight decrease of the postural load . The results indicate that the total amount of work performed by means of job rotation result ed in an overall reduced physical workload of the employees of the refuse collecting department Data on exposure variability is an important remedy for design ing and interpreting studies of occupational ergonomics . The present study aim ed at retrieving the within- and between-subjects variance of several mechanical exposure parameters in a repeated , short-cycle task . Seven experienced operators repeatedly secured joints using two types of h and -held nutrunners . The joints were placed in three different locations on a rack , simulating automotive assembly . Bilateral muscle activity from the upper trapezius and the lower arm extensors , as well as head and upper arm inclination was continuously monitored . Exposure levels and their variance components were assessed in several data subsets using ANOVA . The results were interpreted in terms of statistical precision and power , and discussed as markers of important ergonomic qualities . A substantial exposure variability was found within and between subjects in all joint locations and for both tools . For mixed work across tools and locations , the necessary number of subjects to arrive at a group mean exposure with 95 % confidence limits corresponding to ± 10 % of the mean ranged between 8 and 158 , with posture recordings tending to require smaller population s than muscle activity recordings . Within-subject variance increased 2- to 37-fold , depending on exposure parameter , when work was ‘ enlarged ’ from securings with a specified location and tool to a mix of all locations and tools . Systematic differences between subjects in variability and responsiveness to ‘ work enlargement ’ indicated individualized motor control strategies . The results illustrate the importance of exposure variability data to the design of proper measurement strategies . They also suggest that the sizes of exposure variability per se can be interpreted as operational indices of what is thought to be important ergonomic risk indicators , such as the ‘ sameness ’ of repeated operations and the allowance for flexible working techniques CONTEXT Common pain conditions appear to have an adverse effect on work , but no comprehensive estimates exist on the amount of productive time lost in the US workforce due to pain . OBJECTIVE To measure lost productive time ( absence and reduced performance due to common pain conditions ) during a 2-week period . DESIGN AND SETTING Cross-sectional study using survey data from the American Productivity Audit ( a telephone survey that uses the Work and Health Interview ) of working adults between August 1 , 2001 , and July 30 , 2002 . PARTICIPANTS R and om sample of 28 902 working adults in the United States . MAIN OUTCOME MEASURES Lost productive time due to common pain conditions ( arthritis , back , headache , and other musculoskeletal ) expressed in hours per worker per week and calculated in US dollars . RESULTS Thirteen percent of the total workforce experienced a loss in productive time during a 2-week period due to a common pain condition . Headache was the most common ( 5.4 % ) pain condition result ing in lost productive time . It was followed by back pain ( 3.2 % ) , arthritis pain ( 2.0 % ) , and other musculoskeletal pain ( 2.0 % ) . Workers who experienced lost productive time from a pain condition lost a mean ( SE ) of 4.6 ( 0.09 ) h/wk . Workers who had a headache had a mean ( SE ) loss in productive time of 3.5 ( 0.1 ) h/wk . Workers who reported arthritis or back pain had mean ( SE ) lost productive times of 5.2 ( 0.25 ) h/wk . Other common pain conditions result ed in a mean ( SE ) loss in productive time of 5.5 ( 0.22 ) h/wk . Lost productive time from common pain conditions among active workers costs an estimated 61.2 billion dollars per year . The majority ( 76.6 % ) of the lost productive time was explained by reduced performance while at work and not work absence . CONCLUSIONS Pain is an inordinately common and disabling condition in the US workforce . Most of the pain-related lost productive time occurs while employees are at work and is in the form of reduced performance Objectives : A prospect i ve follow-up study of employees in Denmark was analyzed in order to investigate the association between physical and psychosocial exposures and musculoskeletal symptoms in the neck-shoulder and wrist-h and regions . Methods : Data were derived from a 5-year follow-up question naire study of a sample of employees in Denmark , aged between 18 and 59 years .  Occupational and individual background factors were assessed in 1990 , and the associations with symptoms in 1995 were analyzed using logistic regression . The analysis was restricted to comprise employees free of symptoms in 1990 . The neck-shoulder and wrist-h 
    Output:
    