title: A Longitudinal Study of Industrial and Clerical Workers: Incidence of Carpal Tunnel Syndrome and Assessment of Risk Factors A prospective study of computer users: I. Study design and incidence of musculoskeletal symptoms and disorders. Prolonged median sensory latency as a predictor of future carpal tunnel syndrome. The context of a study influences the reporting of symptoms Prevalence of carpal tunnel syndrome in a general population. Vibration sense in the upper limb in patients with repetitive strain injury and a group of at-risk office workers Computer Professionals and Carpal Tunnel Syndrome (CTS) Carpal tunnel syndrome: prevalence in the general population. Use of keyboards and symptoms in the neck and arm: evidence from a national survey.
abstract: This study followed workers over an extended period of time to identify factors which may influence the onset of  Carpal Tunnel Syndrome ( CTS ) . The purpose was to evaluate incidence of CTS and to create a predictive model of factors that play a role in the development of CTS . This prospect i ve study followed 432 industrial and clerical workers over 5.4 years . Incident cases were defined as workers who had no prior history of CTS at baseline testing and were diagnosed with CTS during the follow-up period or at the follow-up screening . On the basis of logistic regression , significant predictors for CTS include baseline median-ulnar peak latency difference , a history of wrist/h and /finger tendonitis , a history of numbness , tingling , burning , and /or pain in the h and , and work above the action level of the peak force and h and activity level threshold limit value . This longitudinal study supports findings from previous cross-sectional studies identifying both work related ergonomic stressors and physical factors as independent risk factors for CTS BACKGROUND A prospect i ve study of computer users was performed to determine the occurrence of and evaluate risk factors for  neck or shoulder ( N/S ) and h and or arm ( H/A ) musculoskeletal symptoms ( MSS ) and disorders ( MSD ) . METHODS Individuals ( n = 632 ) newly hired into jobs requiring > or = 15 hr/week of computer use were followed for up to 3 years . At study entry , workstation dimensions and worker postures were measured and medical and psychosocial risk factors were assessed . Daily diaries were used to document work practice s and incident MSS . Those reporting MSS were examined for specific MSD . Incidence rates of MSS and MSD were estimated with survival analysis . Cox regression models were used to evaluate associations between participant characteristics at entry and MSS and MSD . RESULTS The annual incidence of N/S MSS was 58 cases/100 person-years and of N/S MSD was 35 cases/100 person-years . The most common N/S MSD was somatic pain syndrome . The annual incidence of H/A MSS was 39 cases/100 person-years and of H/A MSD was 21 cases/100 person-years . The most common H/A disorder was deQuervain 's tendonitis . Forty-six percent of N/S and 32 % of H/A MSS occurred during the first month of follow-up . Gender , age , ethnicity , and prior history of N/S pain were associated with N/S MSS and MSD . Gender , prior history of H/A pain , prior computer use , and children at home were associated with either H/A MSS or MSD . CONCLUSIONS H/A and N/S MSS and MSD were common among computer users . More than 50 % of computer users reported MSS during the first year after starting a new job The purpose of the study was to determine whether abnormal median sensory nerve conduction among asymptomatic workers was predictive of future symptoms suggestive of carpal tunnel syndrome ( CTS ) . This was a prospect i ve study involving 77 workers who were identified as asymptomatic cases with electrodiagnostic findings of median mononeuropathy compared to an age- and sex-matched control group . Follow-up was completed an average of 70 months later , and subjects who reported pain , numbness , tingling , or burning in the distribution of the median nerve , based upon a h and diagram , were classified as having CTS symptoms . The follow-up participation rate was 70 % . Among subjects with abnormal median sensory latencies , 23 % went on to develop symptoms consistent with CTS within the follow-up period , compared with 6 % in the control group ( P= .010 ) . Age and h and repetition were also risk factors for CTS , but the majority of asymptomatic workers with a median mononeuropathy do not become symptomatic over an extended time Objectives To study whether different information on a study may influence the reporting of symptoms suspected to be related to poor indoor climate at the workplace or at home . Methods A question naire was mailed to a r and om sample ( n=4,000 ) of the general population in Denmark . The participants were r and omly allocated to two study groups , each group receiving a slightly different information letter . There were 2,710 subjects ( 67.8 % ) who completed the question naire , and 2,164 subjects , who were in employment , were included in the study . All subjects were informed that the purpose of the study was to assess the prevalence of non-specific symptoms related to the indoor climate at work and in dwellings . However , in the letter to one study group it was stated that knowledge was especially lacking about health effects related to the indoor climate at work ( n=1,468 ) . To the other study group the words at work were replaced with at home ( n=696 ) . The question naires were similar for each study group . Results The prevalence rates of symptoms were similar , but reporting of work-relatedness and home-relatedness differed considerably between the two study groups . If the information letter focused slightly more on the workplace than the home , the subjects were more likely to report that their symptoms were work-related ( significant unadjusted odds ratios ( ORs ) between 1.8 and 5.5 ) . We found that adjusting the results for several confounders mainly led to higher estimates of ORs . Likewise , the subjects reported more home-related symptoms if focus was on the environment at home ( significant unadjusted ORs between 5.7 and 20.6 ) . Conclusions The information about a study may play an important role in the reporting of symptoms CONTEXT Carpal tunnel syndrome ( CTS ) is a cause of pain , numbness , and tingling in the h and s and is an important cause of work disability . Although high prevalence rates of CTS in certain occupations have been reported , little is known about its prevalence in the general population . OBJECTIVE To estimate the prevalence of CTS in a general population . DESIGN General health mail survey sent in February 1997 , inquiring about symptoms of pain , numbness , and tingling in any part of the body , followed 2 months later by clinical examination and nerve conduction testing of responders reporting symptoms in the median nerve distribution in the h and s , as well as of a sample of those not reporting these symptoms ( controls ) . SETTING A region in southern Sweden with a population of 170000 . PARTICIPANTS A sex- and age-stratified sample of 3000 subjects ( age range , 25 - 74 years ) was r and omly selected from the general population register and sent the survey , with a response rate of 83 % ( n = 2466 ; 46 % men ) . Of the symptomatic responders , 81 % underwent clinical examination . MAIN OUTCOME MEASURES Population prevalence rates , calculated as the number of symptomatic responders diagnosed on examination as having clinical ly certain CTS and /or electrophysiological median neuropathy divided by the total number of responders . RESULTS Of the 2466 responders , 354 reported pain , numbness , and /or tingling in the median nerve distribution in the h and s ( prevalence , 14.4 % ; 95 % confidence interval [ CI ] , 13.0%-15.8 % ) . On clinical examination , 94 symptomatic subjects were diagnosed as having clinical ly certain CTS ( prevalence , 3.8 % ; 95 % CI , 3.1%-4.6 % ) . Nerve conduction testing showed median neuropathy at the carpal tunnel in 120 symptomatic subjects ( prevalence , 4.9 % ; 95 % CI , 4.1%-5.8 % ) . Sixty-six symptomatic subjects had clinical ly and electrophysiologically confirmed CTS ( prevalence , 2.7 % ; 95 % CI , 2.1%-3.4 % ) . Of 125 control subjects clinical ly examined , electrophysiological median neuropathy was found in 23 ( 18.4 % ; 95 % CI , 12.0%-26.3 % ) . CONCLUSION Symptoms of pain , numbness , and tingling in the h and s are common in the general population . Based on our data , 1 in 5 symptomatic subjects would be expected to have CTS based on clinical examination and  electrophysiologic testing Abstract Objectives : To investigate in patients with repetitive strain injury ( RSI ) and in office workers using computer keyboard equipment  ( a ) whether the vibration threshold in the h and was altered , ( b ) the immediate effects of keyboard use on vibration thresholds and ( c ) whether the tolerance of suprathreshold vibration was normal . Method : A vibrametre ( Somedic Ab , Stockholm Sweden ) was used to obtain threshold vibration measurements , by the method of limits , for all peripheral-nerve cutaneous distributions in the h and . Tolerance of suprathreshold stimulation was obtained by stimulation of the soft tissues of the forearm by increasing the amplitude of vibration . Results : Thresholds for vibration were significantly raised for the median nerve in both the patient and office-worker groups . The patient group additionally had raised thresholds for the ulnar nerve . Following use of the keyboard , thresholds for the median nerve were further elevated in the patient group , but not in the other groups , demonstrating a work-related exacerbation . At suprathreshold stimulation , 14 members ( 82 % ) of the patient group experienced an allodynic response to vibration , indicating possible changes in the central processing of non-noxious sensory information . This changed sensory response was not seen in either the office-worker or control groups . Conclusion : Patients may have a minor polyneuropathy , whereas the office workers demonstrate early signs of the condition . Quantitative measurement of vibration perception may prove useful in patient assessment and for detection of the early onset of RSI in the work environment Carpal Tunnel Syndrome ( CTS ) is an important problem among computer professionals . Hence the prevalence of CTS among computer professionals and risk factors were studied . 648 subjects were selected from 4,276 computer professionals from 21 companies with a simple r and om sampling method . CTS was diagnosed based on clinical features . The prevalence of CTS was found to be 13.1 % ( 95 % CI 10.5–15.7 % ) . Subjects with over 8 years of computer work , over 12 hrs of work per day and system administrators were at a higher risk for CTS ( OR 3.3 , 4.9 and 2.5 respectively ) . Flexed or extended h and position had higher risk for CTS . Higher risk for CTS was found with higher exposure to computer work . Ergonomic considerations are important in facilitating proper positioning of h and while working with a computer . Further studies on CTS risk factors among computer professionals are essential for planning prevention To study the prevalence of  carpal tunnel syndrome ( CTS ) in the general population and the value of brachialgia paraesthetica nocturna ( BPN ) in diagnosing CTS , an age and sex stratified r and om sample of 715 subjects was taken from the population register of Maastricht ( The Netherl and s ) and surrounding villages , between September 1983 and July 1985 . The response rate was 70 % . Of these , 12 CTS cases had already been diagnosed . Of the remaining subjects , 64 ( 13 men , 51 women ) woke up because of BPN . Among these subjects 1 man and 23 women were found to have CTS . The prevalence rate of undetected CTS was 5.8 % [ 95 % confidence interval ( CI ) : 3.5 - 8.1 % ] in adult women ; 3.4 percent ( 95 % CI : 1.5 - 5.3 % ) had already been diagnosed as CTS . The overall prevalence rate for men was 0.6 % ( 95 % CI 0.02 - 3.4 % ) . These figures have to be regarded as minimal estimates . The overall diagnostic value of BPN for CTS was 38 % , while for women only this was 45 % ( 95 % CI : 31 - 60 % ) The objective of this study was to examine the relationship between upper limb symptoms and keyboard use in a population survey . A question naire was mailed to 21,201 subjects aged 16 - 64 years , selected at r and om from the registers of 34 British general practice s. Information was collected on occupation and on regular use of keyboards ( for > 4 h in an average working day ) , pain in the upper limbs and neck , numbness or tingling in the upper limbs , headaches , and feelings of tiredness or stress . Associations were explored by logistic regression , with the result ant odds ratios converted into prevalence ratios ( PRs ) . Among 12,262 respondents , 4899 held non-manual occupations . These included 1871 regular users of keyboards ( e.g. computer operators , data processors , clerks , administrators , secretaries and typists ) .  Pain in the neck or upper limbs and sensory symptoms were common in the non-manual workers overall ( with 1 week period prevalences of 30 and 15 % , respectively ) , and were associated with older age , smoking , headaches and tiredness or stress . After adjustment for these factors , regular keyboard use was significantly associated with pain in the past week in the shoulders ( PRs 1.2 - 1.4 ) and the wrists or h and s ( PR 1.4 ) , but not with elbow pain or sensory symptoms over the same period , or with neck or upper limb pain that prevented normal activities in the past year . Disabling symptoms were somewhat less prevalent among symptomatic keyboard users than among other symptomatic workers . We conclude that use of keyboards was associated with discomfort at the shoulder and wrist or h and , but risk estimates were lower than generally reported in workplace surveys . Previous estimates of risk in the occupational setting may have been biased by shared expectations , concerns , or other aspects of illness behaviour
target: Conclusion There is insufficient epidemiological evidence that computer work causes CTS
background: Background This review examines evidence for an association between  computer work and carpal tunnel syndrome ( CTS ) .