There is moderate evidence of an association between duration of mouse use and hand-arm symptoms/disorders based on a systematic review of published longitudinal studies according to IJmker et al. A dose-response relationship was identified with, in general, greater hand-arm symptoms as the duration of mouse use increased.
Duration of computer use was more so related to hand-arm symptoms/disorders as opposed to neck-shoulder symptoms/disorders. However, there was insufficient evidence to claim an association for either exposure-outcome.
Seven databases were searched for articles published up to November 6, 2005. Criteria for inclusion of a research paper within the review were:
1) the study population included computer workers
2) the outcome measurement involved one or more syndromes, signs or symptoms related to pain or discomfort in hand, arm, shoulder or neck
3) a risk estimate of the association between the duration of computer use, mouse use or keyboard use and a relevant outcome measure was presented
4) the study had a longitudinal design with at least one follow up measurement after baseline assessment
5) the study was peer-reviewed and full text (experimental studies, letters and abstracts were excluded) written in English, Dutch or German
The search yielded 277 published articles which became reduced to nine papers once the selection criteria was applied.
Those research papers that met the inclusion criteria were then evaluated for methodological quality as defined by prior musculoskeletal disorder risk factor reviews (a prospective cohort study quality assessment list). High quality was defined as meeting greater than 50 percent of 11 benchmark values (i.e., was the statistical method used appropriate for the outcome studied and was a measure of association presented, including 95 percent CI or p value?).
Six of the studies were considered high quality.
The study data were stratified based on the measure of computer use (keyboard use, mouse use or total computer use) and body location of symptoms or disorders. If the study revealed a statistically significant risk estimate, a positive association was assigned.
The stratified study conclusions were summarized to produce levels of evidence:
· Strong evidence – consistent results of tested risk factor associations (at least 75 percent being positive) with at least two articles registering as high quality research
· Moderate evidence – consistent results of tested risk factor associations (at least 75 percent being positive) among three or more study findings regardless of quality level
consistent results of tested risk factor associations from two high quality studies regardless of the outcomes from medium quality studies
· Insufficient evidence – inconsistent results from tested associations
Less then three tested risk factor associations were identified for a given exposure/outcome category
A dose-response relationship was estimated when at least moderate evidence supported an association. Point estimates were plotted of reported exposure relative to outcome. Seeing greater risk relative to increased exposure duration was considered as evidence of a dose-response relationship. An average computer exposure level for a specific outcome was calculated by taking the middle value of a reported lower and upper time duration.
There was insufficient evidence to support an association between:
· Duration of keyboard use and hand-arm symptoms/disorders
· Duration of total computer use and hand-arm symptoms/disorders
· Duration of mouse use and neck-shoulder symptoms/disorders
· Duration of keyboard use and neck-shoulder symptoms/disorders
· Duration of total computer use and neck-shoulder symptoms/disorders
Reservations effecting of this research include:
· All studies determined duration of computer use through self-reporting
· Most studies only measured the duration of total computer use hence masking differentiation in duration of keyboard/duration of mouse use relative to symptoms/disorders
· The studies had varied case definitions (symptoms versus clinical diagnosis) and populations (newly hired employees, groups potentially effected by healthy worker effect)
· The total number of research articles found acceptable to assess was low
· Effect modifiers such as posture, force, mental demands were not considered during study review; duration was the only factor of concern
Article Title: Should office workers spend fewer hours at their computer? A systematic review of the literature
Publication: Occupational and Environmental Medicine 64: 211-222, 2007
Authors: S IJmker, M A Huysmans, B M Blatter, A J van der Beek, W van Mechelen and P M Bongers
This article originally appeared in The Ergonomics Report™ on 2007-06-06.