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: Aims : To identify the work factors that predict  intense low back pain ( LBP ) and LBP related sick leaves in nurses ’ aides . Methods : The sample comprised 4266 r and omly selected Norwegian nurses ’ aides , not bothered or only a little bothered by LBP during the previous three months , and not on sick leave when completing a mailed question naire in 1999 . Of these , 3808 ( 89.3 % ) completed a second question naire 3 months later and 3651 ( 85.6 % ) completed a third question naire 15 months later . Intensity of low back symptoms and certified sick leaves attributed to LBP during the observation period were assessed by self reports at the follow ups . Results : After adjustments for LBP during the three months prior to baseline , baseline health complaints , demographic and familial factors , and a series of physical , psychological , and social work factors , logistic regression analyses revealed the following associations : intense low back symptoms were predicted by frequent positioning of patients in bed , perceived lack of support from immediate superior , and perceived lack of pleasant and relaxing culture in the work unit . LBP related sick leaves were predicted by frequent h and ling of heavy objects , medium level of work dem and s , perceived lack of supportive and encouraging culture in the work unit , working night shifts , and working in a nursing home . Long term LBP related sick leaves were associated with changes of work or work tasks during the observation period that result ed in a perceived reduction of support and encouragement at work . Conclusions : Not only frequent mechanical exposures , but also organisational , psychological , and social work factors , such as night shift work , perceived lack of support from superior , and perceived lack of a pleasant and relaxing or supporting and encouraging culture in the work unit , are associated with an increased risk of intense low back symptoms and LBP related sick leaves in nurses ’ aides To investigate the associations between psychosocial factors and the development of  chronic disabling low back pain ( LBP ) in Japanese workers . A 1 yr prospect i ve cohort of the Japan Epidemiological Research of Occupation-related Back Pain ( JOB ) study was used . The participants were office workers , nurses , sales/marketing personnel , and manufacturing engineers . Self-administered question naires were distributed twice : at baseline and 1 yr after baseline . The outcome of interest was the development of chronic disabling LBP during the 1 yr follow-up period . Incidence was calculated for the participants who experienced disabling LBP during the month prior to baseline . Logistic regression was used to assess risk factors for chronic disabling LBP . Of 5,310 participants responding at baseline ( response rate : 86.5 % ) , 3,811 completed the question naire at follow-up . Among 171 eligible participants who experienced disabling back pain during the month prior to baseline , 29 ( 17.0 % ) developed chronic disabling LBP during the follow-up period . Multivariate logistic regression analysis implied reward to work ( not feeling rewarded , OR : 3.62 , 95%CI : 1.17–11.19 ) , anxiety ( anxious , OR : 2.89 , 95%CI : 0.97–8.57 ) , and daily-life satisfaction ( not satisfied , ORs : 4.14 , 95%CI : 1.18–14.58 ) were significant . Psychosocial factors are key to the development of chronic disabling LBP in Japanese workers .  Psychosocial interventions may reduce the impact of LBP in the workplace Objectives Studies from western countries show that dentists are vulnerable to work-related musculoskeletal disorders ( WMSDs ) of the neck and upper extremities , but little is known about their epidemiology among members of this rapidly growing profession in China . This study aims to investigate the prevalence of WMSDs and identify potential risk factors associated with their occurrence in the dental profession in China . Setting and participants A cross-sectional survey was carried out in 52 different hospitals in a large metropolitan city in China . A total of 304 question naires were distributed to respondents identified via stratified r and om sampling and 272 dentists ( 121 females and 151 males ) completed the survey . The response rate was 89.5 % . Outcomes Visual analogue score was used to record neck and upper limb musculoskeletal symptoms on a body chart . Work-related risk factors , including physical and psychosocial factors , were accounted for in the regression analysis . Results 88 % of the dentists reported at least one musculoskeletal disorder and 83.8 % suffered from neck pain . In the multivariate analyses , working hours per day were associated with neck pain ( OR=1.43 ; 95 % CI 1.03 to 1.98 ) . Inability to select the appropriate size of dental instrument was associated with shoulder ( OR=2.07 ; 95 % CI 1.00 to 4.32 ) and wrist/h and ( OR=2.47 ; 95 % CI 1.15 to 5.32 ) pain . As for psychosocial factors , high job dem and was associated with symptoms in the shoulder ( OR=1.09 ; 95 % CI 1.00 to 1.18 ) , elbow ( OR=1.11 ; 95 % CI 1.03 to 1.19 ) and wrist/h and ( OR=1.09 ; 95 % CI 1.02 to 1.17 ) . Regular physical exercise was associated with decreased neck pain ( OR=0.37 ; 95 % CI 0.14 to 1.00 ) . Conclusions The prevalence of WMSDs among Chinese dentists is high . Specifically , long working hours , inability to select the appropriate size of dental instrument and high job dem and are the most significant risk factors Study Design Two-year , prospect i ve cohort data from the Japan epidemiological research of occupation-related back pain study in urban setting s were used for this analysis . Objective To examine the association between aggravated low back pain and psychosocial factors among Japanese workers with mild low back pain . Summary of Background Data Although psychosocial factors are strongly indicated as yellow flags of low back pain ( LBP ) leading to disability , the association between aggravated LBP and psychosocial factors has not been well assessed in Japanese workers . Methods At baseline , 5,310 participants responded to a self-administered question naire including questions about individual characteristics , ergonomic work dem and s , and work-related psychosocial factors ( response rate : 86.5 % ) , with 3,811 respondents completing the 1-year follow-up question naire . The target outcome was aggravation of mild LBP into persistent LBP during the follow-up period . Incidence was calculated for the participants with mild LBP during the past year at baseline . Logistic regression was used to explore risk factors associated with persistent LBP . Results Of 1,675 participants who had mild LBP during the preceding year , 43 ( 2.6 % ) developed persistent LBP during the follow-up year . Multivariate analyses adjusted for individual factors and an ergonomic factor found statistically significant or almost significant associations of the following psychosocial factors with persistent LBP : interpersonal stress at work [ adjusted odds ratio ( OR ) : 1.96 and 95 % confidence interval ( 95%CI ) : 1.00–3.82 ] , job satisfaction ( OR : 2.34 , 95%CI : 1.21–4.54 ) , depression ( OR : 1.92 , 95%CI : 1.00–3.69 ) , somatic symptoms ( OR : 2.78 , 95%CI : 1.44–5.40 ) , support from supervisors ( OR : 2.01 , 95%CI : 1.05–3.85 ) , previous sick-leave due to LBP ( OR : 1.94 , 95%CI : 0.98–3.86 ) and family history of LBP with disability ( OR : 1.98 , 95%CI : 1.04–3.78 ) . Conclusions Psychosocial factors are important risk factors for persistent LBP in urban Japanese workers . It may be necessary to take psychosocial factors into account , along with physical work dem and s , to reduce LBP related disability Objectives To assess dental students ' posture on two different seats in order to determine if one seat predisposes to a difference in working posture . Design A between-subject experimental design was selected . Setting The study was undertaken at the University of Birmingham School of Dentistry in 2006 . Subjects ( material s ) and methods Sixty second year dental students at the University of Birmingham who were attending their fi rst classes in the phantom head laboratory were r and omly selected and allocated to two different seats ( 30 Bambach Saddle Seats and 30 conventional seats ) . Students were trained in the use of the seats . After ten weeks , the students were observed , photographs were taken by the research er and these were assessed using Rapid Upper Limb Assessment ( RULA ) . Main outcome measures The posture of the students was assessed using the RULA . Each student was given a risk score . A Mann Whitney test was used for statistical analysis . Results The results indicated that the students using the conventional seat recorded signifi cantly higher risk scores ( p < 0.05 ) when compared with the students using Bambach Saddle Seat , suggesting an improvement in posture when using the Bambach Saddle Seat . Conclusion RULA has identifi ed that dental students using a Bambach Saddle Seat were able to maintain an acceptable working posture during simulated dental treatment and this seating may reduce the development of work-related musculoskeletal disorders This article introduces the approach of GRADE to rating  quality of evidence .  GRADE specifies four categories-high , moderate , low , and very low-that are applied to a body of evidence , not to individual studies . In the context of a systematic review , quality reflects our confidence that the estimates of the effect are correct . In the context of recommendations , quality reflects our confidence that the effect estimates are adequate to support a particular recommendation . R and omized trials begin as high- quality evidence , observational studies as low quality . " Quality " as used in GRADE means more than risk of bias and so may also be compromised by imprecision , inconsistency , indirectness of study results , and publication bias . In addition , several factors can increase our confidence in an estimate of effect . GRADE provides a systematic approach for considering and reporting each of these factors . GRADE separates the process of assessing quality of evidence from the process of making recommendations . Judgments about the strength of a recommendation depend on more than just the quality of evidence Activation of back musculature during work tasks leads to fatigue and potential injury . This is especially prevalent in dentists who perform much of their work from a seated position . We examined the use of an ergonomic dental stool with mid-sternum chest support for reducing lower back muscle activation . Electromyography of lower back extensors was assessed from 30 dental students for 20 s during three conditions in r and om order : ( a ) sitting upright at 90 ° of hip flexion on a st and ard stool , ( b ) leaning forward at 80 ° of hip flexion on a st and ard stool , and ( c ) leaning forward at 80 ° of hip flexion while sitting on an ergonomic stool . Muscular activity of the back extensors was reduced when using the ergonomic stool compared to the st and ard stool , by 33–50 % ( p < 0.01 ) . This suggests a potential musculoskeletal benefit with use of a dental stool with mid-sternum chest support BACKGROUND CONTEXT Sitting spinal alignment is increasingly recognized as a factor influencing strategy for deformity correction . Considering that most individuals sit for longer hours in a " slumped " rather than in an erect posture , greater underst and ing of the natural sitting posture is warranted . PURPOSE This study aim ed to investigate the differences in sagittal spinal alignment between two common sitting postures : a natural , patient-preferred posture ; and an erect , investigator-controlled posture that is commonly used in alignment studies . DESIGN / SETTING This is a r and omized , prospect i ve study of 28 young , healthy patients seen in a tertiary hospital over a 6-month period . PATIENT SAMPLE Twenty-eight patients ( 24 men , 4 women ) , with a mean age of 24 years ( range 19 - 38 ) , were recruited for this study . All patients with first episode of lower back pain of less than 3 months ' duration were included . The exclusion criteria consisted of previous spinal surgery , radicular symptoms , red flag symptoms , previous spinal trauma , obvious spinal deformity on forward bending test , significant personal or family history of malignancy , and current pregnancy . OUTCOME MEASURES Radiographic measurements included sagittal vertical axis ( SVA ) , lumbar lordosis ( LL ) , thoracolumbar angle ( TL ) , thoracic kyphosis ( TK ) , and cervical lordosis ( CL ) . St and ard spinopelvic parameters ( pelvic incidence , pelvic tilt [ PT ] , and sacral slope ) and sagittal apex and end vertebrae were also measured . METHODS Basic patient demographics ( age , gender , ethnicity ) were recorded . Lateral sitting whole spine radiographs were obtained using a slot scanner in the imposed erect and the natural sitting posture . Statistical analyses of the radiographical parameters were performed comparing the two sitting postures using chi-squared tests for categorical variables and paired t tests for continuous variables . RESULTS There was forward SVA shift between the two sitting postures by a mean of 2.9 cm ( p<.001 ) . There was a significant increase in CL by a mean of 11.62 ° ( p<.001 ) , and TL kyphosis by a mean of 11.48 ° ( p<.001 ) , as well as a loss of LL by a mean of 
    Output:
    
agent
The two eligible studies for this review provide moderate evidence that saddle seats provided lower ergonomic risk than conventional seats in the examined population of dental students
***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: Aims : To identify the work factors that predict  intense low back pain ( LBP ) and LBP related sick leaves in nurses ’ aides . Methods : The sample comprised 4266 r and omly selected Norwegian nurses ’ aides , not bothered or only a little bothered by LBP during the previous three months , and not on sick leave when completing a mailed question naire in 1999 . Of these , 3808 ( 89.3 % ) completed a second question naire 3 months later and 3651 ( 85.6 % ) completed a third question naire 15 months later . Intensity of low back symptoms and certified sick leaves attributed to LBP during the observation period were assessed by self reports at the follow ups . Results : After adjustments for LBP during the three months prior to baseline , baseline health complaints , demographic and familial factors , and a series of physical , psychological , and social work factors , logistic regression analyses revealed the following associations : intense low back symptoms were predicted by frequent positioning of patients in bed , perceived lack of support from immediate superior , and perceived lack of pleasant and relaxing culture in the work unit . LBP related sick leaves were predicted by frequent h and ling of heavy objects , medium level of work dem and s , perceived lack of supportive and encouraging culture in the work unit , working night shifts , and working in a nursing home . Long term LBP related sick leaves were associated with changes of work or work tasks during the observation period that result ed in a perceived reduction of support and encouragement at work . Conclusions : Not only frequent mechanical exposures , but also organisational , psychological , and social work factors , such as night shift work , perceived lack of support from superior , and perceived lack of a pleasant and relaxing or supporting and encouraging culture in the work unit , are associated with an increased risk of intense low back symptoms and LBP related sick leaves in nurses ’ aides To investigate the associations between psychosocial factors and the development of  chronic disabling low back pain ( LBP ) in Japanese workers . A 1 yr prospect i ve cohort of the Japan Epidemiological Research of Occupation-related Back Pain ( JOB ) study was used . The participants were office workers , nurses , sales/marketing personnel , and manufacturing engineers . Self-administered question naires were distributed twice : at baseline and 1 yr after baseline . The outcome of interest was the development of chronic disabling LBP during the 1 yr follow-up period . Incidence was calculated for the participants who experienced disabling LBP during the month prior to baseline . Logistic regression was used to assess risk factors for chronic disabling LBP . Of 5,310 participants responding at baseline ( response rate : 86.5 % ) , 3,811 completed the question naire at follow-up . Among 171 eligible participants who experienced disabling back pain during the month prior to baseline , 29 ( 17.0 % ) developed chronic disabling LBP during the follow-up period . Multivariate logistic regression analysis implied reward to work ( not feeling rewarded , OR : 3.62 , 95%CI : 1.17–11.19 ) , anxiety ( anxious , OR : 2.89 , 95%CI : 0.97–8.57 ) , and daily-life satisfaction ( not satisfied , ORs : 4.14 , 95%CI : 1.18–14.58 ) were significant . Psychosocial factors are key to the development of chronic disabling LBP in Japanese workers .  Psychosocial interventions may reduce the impact of LBP in the workplace Objectives Studies from western countries show that dentists are vulnerable to work-related musculoskeletal disorders ( WMSDs ) of the neck and upper extremities , but little is known about their epidemiology among members of this rapidly growing profession in China . This study aims to investigate the prevalence of WMSDs and identify potential risk factors associated with their occurrence in the dental profession in China . Setting and participants A cross-sectional survey was carried out in 52 different hospitals in a large metropolitan city in China . A total of 304 question naires were distributed to respondents identified via stratified r and om sampling and 272 dentists ( 121 females and 151 males ) completed the survey . The response rate was 89.5 % . Outcomes Visual analogue score was used to record neck and upper limb musculoskeletal symptoms on a body chart . Work-related risk factors , including physical and psychosocial factors , were accounted for in the regression analysis . Results 88 % of the dentists reported at least one musculoskeletal disorder and 83.8 % suffered from neck pain . In the multivariate analyses , working hours per day were associated with neck pain ( OR=1.43 ; 95 % CI 1.03 to 1.98 ) . Inability to select the appropriate size of dental instrument was associated with shoulder ( OR=2.07 ; 95 % CI 1.00 to 4.32 ) and wrist/h and ( OR=2.47 ; 95 % CI 1.15 to 5.32 ) pain . As for psychosocial factors , high job dem and was associated with symptoms in the shoulder ( OR=1.09 ; 95 % CI 1.00 to 1.18 ) , elbow ( OR=1.11 ; 95 % CI 1.03 to 1.19 ) and wrist/h and ( OR=1.09 ; 95 % CI 1.02 to 1.17 ) . Regular physical exercise was associated with decreased neck pain ( OR=0.37 ; 95 % CI 0.14 to 1.00 ) . Conclusions The prevalence of WMSDs among Chinese dentists is high . Specifically , long working hours , inability to select the appropriate size of dental instrument and high job dem and are the most significant risk factors Study Design Two-year , prospect i ve cohort data from the Japan epidemiological research of occupation-related back pain study in urban setting s were used for this analysis . Objective To examine the association between aggravated low back pain and psychosocial factors among Japanese workers with mild low back pain . Summary of Background Data Although psychosocial factors are strongly indicated as yellow flags of low back pain ( LBP ) leading to disability , the association between aggravated LBP and psychosocial factors has not been well assessed in Japanese workers . Methods At baseline , 5,310 participants responded to a self-administered question naire including questions about individual characteristics , ergonomic work dem and s , and work-related psychosocial factors ( response rate : 86.5 % ) , with 3,811 respondents completing the 1-year follow-up question naire . The target outcome was aggravation of mild LBP into persistent LBP during the follow-up period . Incidence was calculated for the participants with mild LBP during the past year at baseline . Logistic regression was used to explore risk factors associated with persistent LBP . Results Of 1,675 participants who had mild LBP during the preceding year , 43 ( 2.6 % ) developed persistent LBP during the follow-up year . Multivariate analyses adjusted for individual factors and an ergonomic factor found statistically significant or almost significant associations of the following psychosocial factors with persistent LBP : interpersonal stress at work [ adjusted odds ratio ( OR ) : 1.96 and 95 % confidence interval ( 95%CI ) : 1.00–3.82 ] , job satisfaction ( OR : 2.34 , 95%CI : 1.21–4.54 ) , depression ( OR : 1.92 , 95%CI : 1.00–3.69 ) , somatic symptoms ( OR : 2.78 , 95%CI : 1.44–5.40 ) , support from supervisors ( OR : 2.01 , 95%CI : 1.05–3.85 ) , previous sick-leave due to LBP ( OR : 1.94 , 95%CI : 0.98–3.86 ) and family history of LBP with disability ( OR : 1.98 , 95%CI : 1.04–3.78 ) . Conclusions Psychosocial factors are important risk factors for persistent LBP in urban Japanese workers . It may be necessary to take psychosocial factors into account , along with physical work dem and s , to reduce LBP related disability Objectives To assess dental students ' posture on two different seats in order to determine if one seat predisposes to a difference in working posture . Design A between-subject experimental design was selected . Setting The study was undertaken at the University of Birmingham School of Dentistry in 2006 . Subjects ( material s ) and methods Sixty second year dental students at the University of Birmingham who were attending their fi rst classes in the phantom head laboratory were r and omly selected and allocated to two different seats ( 30 Bambach Saddle Seats and 30 conventional seats ) . Students were trained in the use of the seats . After ten weeks , the students were observed , photographs were taken by the research er and these were assessed using Rapid Upper Limb Assessment ( RULA ) . Main outcome measures The posture of the students was assessed using the RULA . Each student was given a risk score . A Mann Whitney test was used for statistical analysis . Results The results indicated that the students using the conventional seat recorded signifi cantly higher risk scores ( p < 0.05 ) when compared with the students using Bambach Saddle Seat , suggesting an improvement in posture when using the Bambach Saddle Seat . Conclusion RULA has identifi ed that dental students using a Bambach Saddle Seat were able to maintain an acceptable working posture during simulated dental treatment and this seating may reduce the development of work-related musculoskeletal disorders This article introduces the approach of GRADE to rating  quality of evidence .  GRADE specifies four categories-high , moderate , low , and very low-that are applied to a body of evidence , not to individual studies . In the context of a systematic review , quality reflects our confidence that the estimates of the effect are correct . In the context of recommendations , quality reflects our confidence that the effect estimates are adequate to support a particular recommendation . R and omized trials begin as high- quality evidence , observational studies as low quality . " Quality " as used in GRADE means more than risk of bias and so may also be compromised by imprecision , inconsistency , indirectness of study results , and publication bias . In addition , several factors can increase our confidence in an estimate of effect . GRADE provides a systematic approach for considering and reporting each of these factors . GRADE separates the process of assessing quality of evidence from the process of making recommendations . Judgments about the strength of a recommendation depend on more than just the quality of evidence Activation of back musculature during work tasks leads to fatigue and potential injury . This is especially prevalent in dentists who perform much of their work from a seated position . We examined the use of an ergonomic dental stool with mid-sternum chest support for reducing lower back muscle activation . Electromyography of lower back extensors was assessed from 30 dental students for 20 s during three conditions in r and om order : ( a ) sitting upright at 90 ° of hip flexion on a st and ard stool , ( b ) leaning forward at 80 ° of hip flexion on a st and ard stool , and ( c ) leaning forward at 80 ° of hip flexion while sitting on an ergonomic stool . Muscular activity of the back extensors was reduced when using the ergonomic stool compared to the st and ard stool , by 33–50 % ( p < 0.01 ) . This suggests a potential musculoskeletal benefit with use of a dental stool with mid-sternum chest support BACKGROUND CONTEXT Sitting spinal alignment is increasingly recognized as a factor influencing strategy for deformity correction . Considering that most individuals sit for longer hours in a " slumped " rather than in an erect posture , greater underst and ing of the natural sitting posture is warranted . PURPOSE This study aim ed to investigate the differences in sagittal spinal alignment between two common sitting postures : a natural , patient-preferred posture ; and an erect , investigator-controlled posture that is commonly used in alignment studies . DESIGN / SETTING This is a r and omized , prospect i ve study of 28 young , healthy patients seen in a tertiary hospital over a 6-month period . PATIENT SAMPLE Twenty-eight patients ( 24 men , 4 women ) , with a mean age of 24 years ( range 19 - 38 ) , were recruited for this study . All patients with first episode of lower back pain of less than 3 months ' duration were included . The exclusion criteria consisted of previous spinal surgery , radicular symptoms , red flag symptoms , previous spinal trauma , obvious spinal deformity on forward bending test , significant personal or family history of malignancy , and current pregnancy . OUTCOME MEASURES Radiographic measurements included sagittal vertical axis ( SVA ) , lumbar lordosis ( LL ) , thoracolumbar angle ( TL ) , thoracic kyphosis ( TK ) , and cervical lordosis ( CL ) . St and ard spinopelvic parameters ( pelvic incidence , pelvic tilt [ PT ] , and sacral slope ) and sagittal apex and end vertebrae were also measured . METHODS Basic patient demographics ( age , gender , ethnicity ) were recorded . Lateral sitting whole spine radiographs were obtained using a slot scanner in the imposed erect and the natural sitting posture . Statistical analyses of the radiographical parameters were performed comparing the two sitting postures using chi-squared tests for categorical variables and paired t tests for continuous variables . RESULTS There was forward SVA shift between the two sitting postures by a mean of 2.9 cm ( p<.001 ) . There was a significant increase in CL by a mean of 11.62 ° ( p<.001 ) , and TL kyphosis by a mean of 11.48 ° ( p<.001 ) , as well as a loss of LL by a mean of 
    Output:
    