Computer use and carpal tunnel syndrome: a 1-year follow-up study

Context  Computer use is increasingly common among many working populations, and concern exists about possible adverse effects of computer use, such as carpal tunnel syndrome (CTS). Objectives  To estimate the prevalence and incidence of possible CTS and to evaluate the contribution of use of mouse devices and keyboards to the risk of possible CTS. Design and Setting  A 1-year follow-up study with questionnaires conducted in 2000 and 2001 at 3500 workplaces in Denmark, followed on each of the 2 occasions by a clinical interview on symptom distribution and frequency. Participants  The questionnaire was sent to 9480 members of a trade union, with an initial response rate of 73% (n = 6943), and 82% (n = 5658) at follow-up. Main Outcome Measures  At baseline, there were 3 outcome measures: tingling/numbness in the right hand once a week or more as reported in the questionnaire; tingling, numbness, and pain in the median nerve in the right hand confirmed by clinical interview; and tingling, numbness, and pain in the median nerve in the right hand at night confirmed by clinical interview. At 1 year of follow-up the main outcome of interest was onset of symptoms among participants who had no or minor symptoms at baseline. Results  The overall self-reported prevalence of tingling/numbness in the right hand at baseline was 10.9%. The interview confirmed that prevalence of tingling/numbness in the median nerve was 4.8%, of which about one third, corresponding to a prevalence of 1.4%, experienced symptoms at night. Onset of new symptoms in the 1-year follow-up was 5.5%. In the cross-sectional comparisons and in the follow-up analyses, there was an association between use of a mouse device for more than 20 h/wk and risk of possible CTS but no statistically significant association with keyboard use. Conclusions  The occurrence of possible CTS in the right hand was low. The study emphasizes that computer use does not pose a severe occupational hazard for developing symptoms of CTS.      

A combination study design to examine mycophenolate mofetil (MMF) and PTLD in renal transplant patients

Renal transplant recipients who are chronically immunosuppressed by drugs are at a higher risk of developing malignancies. Commonly observed malignancies are several forms of posttransplant lymphoproliferative disorders (PTLD), skin, lip and gynaecological cancers. The risk is associated with many risk factors including the extent of immunosuppression. Mycophenolate mofetil (MMF) is an immunosuppressant, indicated for the prophylaxis of organ rejection in patients receiving allogenic renal and heart transplants. During the European approval of MMF for renal transplantation, the question was raised as to whether the use of MMF was associated with an increased risk of PTLD in comparison with alternate immunosuppressive regimens. In response, F. Hoffman-La Roche Ltd set up a prospective observational cohort study with a companion case-control study. This paper describes the objectives and the methods of these studies along with the rationale of the methodology.     

The role of physical examinations in studies of musculoskeletal disorders of the elbow

Objectives

To present data on pain and physical findings from the elbow region, and to discuss the role of diagnostic criteria in epidemiological studies of epicondylitis.

Methods

From a cohort of computer workers a subgroup of 1369 participants, who reported at least moderate pain in the neck and upper extremities, were invited to a standardised physical examination. Two independent physical examinations were performed—one blinded and one not blinded to the medical history. Information concerning musculoskeletal symptoms was obtained by a baseline questionnaire and a similar questionnaire completed on the day of examination.

Results

349 participants met the authors'' criteria for being an arm case and 249 were elbow cases. Among the 1369 participants the prevalence of at least mild palpation tenderness and indirect tenderness at the lateral epicondyle was 5.8%. The occurrence of physical findings increased markedly by level of pain score. Only about one half with physical findings fulfilled the authors'' pain criteria for having lateral epicondylitis. A large part with physical findings reported no pain at all in the elbow in any of the two questionnaires, 28% and 22%, respectively. Inter‐examiner reliability between blinded and not blinded examination was found to be low (kappa value (0.34–0.40)).

Conclusion

Very few with at least moderate pain in the elbow region met common specific criteria for lateral epicondylitis. The occurrence of physical findings increased markedly by level of pain score and the associations were strongest with pain intensity scores given just before the examination. Physical signs were commonly found in subjects with no pain complaints. No further impact was achieved if the physical examination was not blinded to the medical history. Furthermore, the authors propose that pain, clinical signs and disability are studied as separate outcomes, and that the diagnoses of lateral epicondylitis should be used only for cases with classical signs of inflammation reflected by severe pain, which for example conveys some disability.Musculoskeletal symptoms of the neck and upper limb are common complaints among computer workers, and a large epidemiological literature exists on the relation between computer work and upper extremity symptoms and disorders.^1,2,3,4,5,6 Physical examination is a basic diagnostic tool but a considerable resource‐demanding outcome measurement in some of these studies.^3,5,7 The examination is used primarily to identify the occurrence and severity of impairments and to diagnose clinically relevant conditions. To reduce subjective elements and in an attempt to reduce potential bias of the results, the examination is often blinded to information about the medical history.^3,6,8,9The results of an examination are however of limited value if the inter‐examiner reliability is poor. This is particularly a problem for upper extremity disorders, where a clear‐cut golden diagnostic standard is missing.^10,11,12,13 The diagnoses are mainly based on symptoms and physical findings, which may not necessarily be explained on the basis of the underlying pathophysiology. This means that the reliability of the individual test is crucial in terms of ensuring that we are in fact measuring the same phenomenon, because the true “approach” is difficult to define. In the epidemiological setting diagnoses are furthermore mainly based on symptoms recorded in questionnaires that are completed days or weeks before the physical examination, based on the assumption that pain level is relatively constant, but this does not necessary seem to be the case.⁵ Moreover, the low prevalence and generally mild nature of upper extremity disorders in computer workers have been found to lead to unstable reliability of any physical examination.^10,11 In a study of reliability of physical examination among keyboard operators, Salerno et al reported that more reliable results could probably be achieved if the physical examination was not blinded to the medical history. A recent study of primary healthcare patients with neck and/or shoulder problems found that the history had no or only little impact on the reliability of the test, but the prevalence of the findings increased when history was known.¹⁴Most often questionnaires are used as a screening method to identify the occurrence of musculoskeletal complaints and only a subgroup is invited to the physical examination.^3,4 In an ideal scenario, the selection criteria used to identify these participants should be sensitive enough to include the majority of possible musculoskeletal disorders, and should be specific enough to diagnose the relevant cases and reduce the number of resource‐demanding physical investigations. In recent years there have been several attempts to standardise diagnostic criteria for work‐related musculoskeletal disorders in epidemiological studies,^15,16 and lateral epicondylitis represents one of the conditions, where a reasonable consensus exists on the diagnostic criteria.¹⁰In this paper, we present data from an epidemiological study: the NUDATA study (Neck and Upper limb Disorders Among Technical Assistants), which may contribute to the discussion and clarification of diagnostic criteria for studying epicondylitis in an epidemiological context.     

Soluble HLA-I (s-HLA-I) synthesis in systemic lupus erythematosus

Our objective was to study a possible contribution of major histocompatibility complex (MHC) genes to soluble HLA-I synthesis in patients with systemic lupus erythematosus (SLE). Solid-phase enzyme-linked immunoassay (ELISA) was used to measure sHLA-I in the sera of 20 patients with SLE and 76 normal controls with known HLA phenotypes. Serial serum samples (n=108) from the above group of patients (n=19) were further investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Soluble HLA-I levels were abnormally higher in patients with SLE than normal controls (P<0.0002). No complete HLA haplotype has been identified to be correlated with high or low sHLA-I secretion. Only the sera of HLA-A23- or -A24- (splits of HLA-A9) positive individuals were found to contain high sHLA-I concentrations in both populations studied. The difference between sHLA-I of HLA-A24 patients (n=7) and HLA-A24 normal controls (n=19) was statistically highly significant (P<0.0079). The results suggest that HLA-A24 may confer additional risk of more severe disease expression in female patients with SLE. The data imply that SLE patients carrying 39-kDa sHLA-I have increased risk of developing renal disease. A higher prevalence of 35–37 kDa was observed in patients with mild disease. Interestingly, 44–46 kDa was the predominant molecular form of sHLA-I in SLE patients with lymphocytosis with no evidence of organ involvement. Notably, all these variations were not reflected by differences in HLA phenotypes, with the exception of HLA-A24-positive patients, in whom the 44–46-kDa form occurs consistently but not exclusively. In summary, the results show a genetic heterogeneity of SLE with MHC control of the expression of sHLA-I concentrations and possible involvement of disease-associated factors that might potentiate a specific sHLA-I molecule synthesis.     

Patient attitudes following participation in a health outcome survey.

A study was conducted to assess attitudes of women with breast cancer following their participation in a health outcome interview survey. The majority of the sample indicated that the interview was easier than expected and one reported being inconvenienced by the interview; 94 percent indicated they were glad to have participated and 58 percent felt they have received some personal benefit. There was no evidence of distress resulting from participation.