***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 RATIONALE Low back pain ( LBP ) remains a common and costly problem among the nursing profession . Several studies have indicated that LBP is attributed to mentally straining or dem and ing work , fatigue or exhaustion or general work satisfaction . AIMS This study aims to measure the magnitude of LBP among Hong Kong nurses and its association with the work-related psychological strain and patients h and ling activities . RESEARCH METHODS AND MEASURES : A cross-sectional study of Hong Kong hospital nurses was conducted . Three hundred and seventy-seven nurses were recruited from six district hospitals . They were registered nurses or enrolled nurses working full-time for at least 1 month in the current ward . One hundred and seventy-eight ( 47.2 % ) study subjects were r and omly selected from two district hospitals and 199 ( 52.8 % ) study nurses made up the convenience sample . Possible bias from psychological distress , socio-demographics and lifestyle factors was controlled for . Data were collected by face-to-face interviews . The data included work factors ( both psychological stress and patient h and ling activities related to work ) , demographics , psychological distress and lifestyle factors and the occurrence of LBP . RESULTS Of the 377 nurses interviewed , 153 ( 40.6 % ) reported having LBP within the last 12 months . With symptoms of LBP as the outcome , risks were increased where nurses self-reported that they only occasionally or never enjoyed their work [ adjusted odds ratio ( OR ) 2.07 ] , where frequent manual repositioning of patients on the bed was required ( adjusted OR 1.84 ) and where they were required to assist patients while walking ( adjusted OR 2.11 ) after adjustment for other potential confounders . CONCLUSION The results indicate that an association exists between work stress , manual lifting and LBP prevalence . The main route to prevention of LBP among nurses is likely to lie in improved ergonomics and psychological health in their work place . Good posture and correct transferring techniques in ward situations should be reinforced with h and s-on practice performed on nurses ' common types of clients Data from a community-based four-year prospect i ve study were used to test the hypothesis that heavy physical work is a stronger predictor of  low back pain in smokers than in non-smokers . Of 708 working responders without low back pain during the entire year prior to 1990 , 562 ( 79 % ) completed a question naire four years later in 1994 . A job involving heavy lifting and much st and ing in 1990 was a strong predictor of low back pain in smokers four years later [ odds ratio ( OR ) = 5.53 , 95 % confidence interval ( CI ) = 1.93 - 15.84 , p < 0.01 ) after having adjusted for other job characteristics , demographic factors , emotional symptoms , physical exercise and musculoskeletal pain elsewhere . In non-smokers , having a job with heavy lifting and much st and ing was not associated with low back pain . One explanation may be that smoking leads to reduced perfusion and malnutrition of tissues in or around the spine and causes these tissues to respond inefficiently to mechanical stress Study Design . A prospect i ve , population ‐based cohort study of working adults . Objectives . To determine whether work‐related psychosocial factors and social status predict the occurrence of new episodes of low back pain and influence consultation behavior . Summary and Background Data . Dissatisfaction with work and social status has been associated with low back pain in several studies ; few of these studies have been prospect i ve or population based . Methods . An initial postal survey  was returned by 4,501 ( 59 % ) adults ( 18‐75 years old ) registered with two primary care practice s. From this , a cohort of 1,412 people currently in employment and free of low back pain was identified , and baseline information on work‐related psychosocial factors and psychologic distress was obtained . Social class was derived from current occupation using a st and ardized classification . New episodes of low back pain occurring in the next 12 months were identified by continuous monitoring of primary care consulters and by mailing a second question naire a year later to identify occurrences of low back pain for which no consultation was sought . Results . The baseline cross‐sectional survey showed modest but significant associations between low back pain and perceived inadequacy of income ( risk ratio 1.3 ) , dissatisfaction with work ( risk ratio 1.4 ) and social class IV/V ( risk ratio 1.2 ) . In the follow‐up year , the risk of reporting low back pain for which no consultation was sought doubled in those dissatisfied with their work . Both perceived inadequacy of income ( odds ratio 3.6 ) and social class IV/V ( odds ratio 4.8 ) were strongly associated with consulting with a new episode of low back pain during the follow‐up year , an association more marked in women . The associations with work dissatisfaction and perceived adequacy of income were not explained by general psychologic distress or social status . Conclusion . People dissatisfied with work are more likely to report low back pain for which they do not consult a physician , whereas lower social status and perceived inadequacy of income are independent risks for working people to seek consultation because of low back pain STUDY DESIGN A systematic review of r and omized and nonr and omized controlled trials . SUMMARY OF BACKGROUND DATA Lumbar supports are used in the treatment of low back pain , but also to prevent the onset ( primary prevention ) or recurrences of a low back pain episode ( secondary prevention ) . OBJECTIVES To assess the effects of lumbar sup-ports for prevention and treatment of nonspecific low back pain .  METHODS The Medline , Cinahl , and Current Contents data bases ; the Cochrane Controlled Trials Register up to September 1999 ; and the Embase data base up to September 1998 were all search ed . References of identified trials and systematic review s were review ed and the Science Citation Index used to identify additional trials . Method ologic quality assessment and data extraction were performed by two review ers independently . A quantitative analysis was performed in which the strength of evidence was classified as strong , moderate , limited or conflicting , and no evidence . RESULTS Five r and omized and two nonr and omized preventive trials and six r and omized therapeutic trials were included in the review . Only 4 of the 13 studies were of high quality . There was moderate evidence that lumbar supports are not effective for primary prevention . No evidence was found on the effectiveness of lumbar supports for secondary prevention . The systematic review of therapeutic trials showed that there is limited evidence that lumbar supports are more effective than no treatment , whereas it is still unclear whether lumbar supports are more effective than other interventions for treatment of low back pain . CONCLUSIONS There continues to be a need for high quality r and omized trials on the effectiveness of lumbar supports . One of the most essential issues to tackle in these future trials seems to be the realization of adequate compliance Study Design . Prospect i ve cohort study of twins . Objectives . To investigate associations between physical activity , physical function , and incident low back pain ( LBP ) in an elderly population . Summary of Background Data . The relationship between an active lifestyle and LBP in seniors is unknown . Methods . Participants in the population -based Longitudinal Study of Aging Danish Twins free from LBP at baseline ( no LBP during the past month ) were included , and interview data on physical activity , overall physical function , and LBP at baseline and follow-up were obtained . Associations between levels of  physical activity and LBP were estimated using logistic regression for the entire cohort , and using a matched case-control design for twin pairs discordant for physical activity . Absolute risk and relative risks for incident LBP in relation to physical activity were calculated for participants with higher or lower than average physical function at baseline . Absolute risk for LBP was also calculated for participants based on whether they remained active or inactive between baseline and follow-up or changed activity level . Results . A total of 1387 persons aged 70–100 at baseline were included in the analyses , including 86 twin pairs discordant for physical activity at baseline . In the total sample , 83 % were engaged in light physical activity  , and 42 % of men and 35 % of women were engaged in strenuous  physical activity  at least weekly . Being engaged in strenuous physical activity at baseline was strongly protective in relation to both having had any LBP ( odds ratio 0.21 , 95 % confidence interval 0.12–0.37 for intra-pair analysis ) and having had LBP lasting more than 30 days altogether during the past year at follow-up ( odds ratio 0.08 , 95 % confidence interval 0.03–0.18 for intra-pair analysis ) . Statistically significant dose-response associations between increasing frequency of strenuous physical activity and magnitude of this protective effect were found . Participants with poor initial physical function experienced the strongest protective effect of strenuous physical activity . Finally , LBP does not appear to be an important factor affecting whether participants remained engaged in strenuous physical activity at baseline and follow-up or vice versa . Conclusions . Strenuous physical activity at least once a week is protective for incident LBP in seniors We investigated muscle strength , aerobic power , and occupational and leisure-time physical loading as predictors of  back pain  in a 5-year follow-up study . A cohort of 456 adults aged 25 , 35 , 45 and 55 years , free of back pain , participated in measurements of anthropometric characteristics , aerobic power and muscle strength characteristics at baseline . The subjects ' levels and types of physical activity and occupational physical loading were also determined . At 5 years after the baseline examinations 356 of these subjects ( 78.1 % ) were reached by mail , and 262 of them ( 73.6 % ) properly completed and returned a question naire including a detailed back pain history for the 5 years following the baseline measurements . Of this number 56 subjects ( 21 % ) who reported back pain ( > 30 on a scale from 0 to 100 ) and functional impairment during the 5-year follow-up composed the marked back pain group . Other subjects ( n = 71 , 27 % ) noting lesser symptoms were included in the mild back pain group ; 135 subjects ( 52 % ) reported having had no back pain . The subjects with marked back pain were on average taller than the subjects without back pain , while no such difference was found in body mass . Heavy occupational musculoskeletal loading ( P = 0.005 ) and high general occupational physical dem and s ( P = 0.036 ) predicted future back pain . Leisuretime physical activity , aerobic power or muscle strength characteristics were not predictive of future back pain STUDY DESIGN A prospect i ve population -based cohort study performed in South Manchester , United Kingdom . OBJECTIVES To determine whether nonoccupational physical activity and indicators of physical stress on the spine predict low back pain in the short term . SUMMARY OF BACKGROUND DATA There is evidence that physical activity outside the workplace helps to protect against low back pain in the long term . However , such activity may injure or stress the spine in the short term . METHODS A baseline survey question naire identified 2715 adults , aged 18 - 75 years , with no low back pain at the time of the survey . Information on potential predictors of low back pain also was obtained . New episodes of back pain were identified during the subsequent year . RESULTS A new low back pain episode occurred in 34 % of men and 37 % of women . Poor general health at baseline was the strongest predictor of a new episode of pain ( men : relative risk ( RR ) 1.5 , 95 % confidence intervals ( CI ) 0.8 , 2.7 ; women : RR 2.2 , 95 % CI 1.2 , 4.0 ) . High weight was associated with subsequent low back pain in women ( RR 1.4 ; 95 % CI 1.0 , 2.0 ) , but neither height nor weight predicted low back pain in men . A self-rated low level of physical activity  was not consistently linked with subsequent low back pain , nor were specific nonoccupational physical activities , apart from 
    Output:
    
CONCLUSION We found strong evidence that leisure time sport or exercises , sitting , and prolonged st and ing/walking are not associated with LBP .
Evidence for associations in leisure time activities ( e.g. , do-it-yourself home repair , gardening ) , whole-body vibration , nursing tasks , heavy physical work , and working with ones trunk in a bent and /or twisted position and LBP was conflicting .
We found no studies , thus no evidence , for an association between sleeping or sporting on a professional level and LBP