Work exposure and cumulative trauma disorders among visual display terminal (VDT) users in Hong Kong

Abstract

This study was to investigate the exposure of VDT work and musculoskeletal health among a group of VDT workers in Hong Kong. An attempt was made to quantify the VDT work exposure in terms of repetitiveness of work tasks, work demands and associating postures sustained at work. The relationships between musculoskeletal discomforts and the VDT exposure factors were explored to shed light on the likelihood of developing cumulative trauma disorders by VDT work. A cross sectional pilot survey was conducted to cover the majority of VDT workers in Hong Kong. Feedback from the 688 office workers revealed the common sites of musculoskeletal discomforts (neck, shoulder and back) and helped to confirm the focus of quantifying VDT work exposure on repetitiveness of work demands and awkward postures sustained at work. In the main study, three groups of VDT workers were recruited from the service centers (Credit Card Center, Network Support Center, Phone Banking Center) of a local banking corporation. Forty-nine female VDT workers (age = 28.6 +-6.4) were invited to participate in a 30-minute questionnaire interview in order to solicit information on the perceived work demands and severity of musculoskeletal discomforts. Eleven VDT workers further participated in the on-site surveillance study for the purpose of quantifying working postures and confirming the major VDT work demands. Results from the questionnaire revealed a high prevalence of musculoskeletal discomforts among the workers in the neck (63.3% at 7-day prevalence; 73.5% at 12-month prevalence), shoulder (36.7% at 7-day prevalence; 63.3% at 12-month prevalence) and back regions (73.5% at 7-day prevalence; 79.6% at 12-month prevalence). The major work demands identified from the work were keying (highest mean percentage of time duration among the three groups = 43.6%), finger picking/pinching (40.6%), sustained attention for verifying (21.8%); whilst a lesser extent was found in writing (7.4%), stamping (0.5%) and talking. No significant differences were revealed in the musculoskeletal discomforts on the common sites among the three groups of VDT workers. Trunk postures extracted from video playback revealed that all of the participating workers had within the neutral range of movement (+-20o inclined with vertical axis). The majority of them also worked with shoulders flexed within the acceptable range (flexion <= 30o). However, awkward and sustained neck postures (flexion >= 20o) were identified as common for most of the workers. Significantly more work demands were revealed in the credit card and network support center groups (F=3.42 to 190.56, df=2, p<.05). Moreover, workers from the Credit Card Center, as well as Network Support Center, were more prone to work with sustained awkward neck posture than workers from the Phone Banking Center. It was concluded that the general profile of VDT work required at credit card and network support centers was similar and was found to bid with more physical demands in keying, finger picking/pinching, and sustained attention. Video-display terminal work required at the phone banking center was found to be relatively less physically demanding. Findings from this study revealed that high repetitiveness and awkward postures were contributing factors to the development of musculoskeletal discomforts among the workers. However, the small sample size and non-experimental research design adopted in this study did not allow more confirmative conclusions to be drawn on the causal relationships between work exposure and cumulative trauma disorders. Further studies with larger sample size and manipulation on the work exposure factors are therefore recommended.