Work related and individual predictors for incident neck pain among office employees working with video display units.

AIMS: To investigate work related and individual factors as predictors for incident neck pain among office employees working with video display units (VDUs). METHODS: Employees in three administrative units of a medium sized city in Finland (n = 515) received mailed questionnaires in the baseline survey in 1998 and in the follow up survey in 1999. Response rate for the baseline was 81% (n = 416); respondents who reported neck pain for less than eight days during the preceding 12 months were included into the study cohort as healthy subjects (n = 232). The follow up questionnaire 12 months later was completed by 78% (n = 180). Incident neck cases were those reporting neck pain for at least eight days during the preceding 12 months. RESULTS: The annual incidence of neck pain was 34.4% (95% CI 25.5 to 41.3). Poor physical work environment and poor placement of the keyboard increased the risk of neck pain. Among the individual factors, female sex was a strong predictor. Smoking showed a tendency for an increased risk of neck pain. There was an interaction between mental stress and physical exercise, those with higher mental stress and less physical exercise having especially high risk. CONCLUSION: In the prevention of neck disorders in office work with a high frequency of VDU tasks, attention should be given to the work environment in general and to the more specific aspects of VDU workstation layout. Physical exercise may prevent neck disorders among sedentary employees.

Job experience, work load, and risk of musculoskeletal disorders.

OBJECTIVES: To investigate the effects of physical work load and job experience on morbidity from musculoskeletal disorders among trailer assembly workers. METHODS: A longitudinal study was carried out in a trailer assembly factory with many new workers employed during the follow up. The sickness absence of 532 workers (160 experienced and 372 new (separately for the first year of employment and from the second year on)) was followed up. Exposure was assessed by job titles, visits, task descriptions, and some direct measurements. The associations between the explanatory variables and sick leave were assessed by log linear models. RESULTS: A higher rate of sick leave due to disorders of the upper limbs was found for new workers compared with experienced ones, especially in the high work load group. Women had a higher rate than men. New male workers in physically strenuous tasks had a high rate of sick leave due to neck and shoulder disorders. CONCLUSIONS: As being unaccustomed to work seems to increase the risk of musculoskeletal disorders, special attention should be paid to newly employed workers.

Incidence of musculoskeletal disorders among newly employed manufacturing workers.

OBJECTIVES: The incidence of upper-limb, neck-shoulder, and low-back disorders and their induction times were investigated among new workers in tasks with various physical workloads. METHODS: New trailer assemblers (N=364) were followed prospectively for 45 months--the workers' health status via medical records and exposure to physical workload factors via job titles, walk-throughs, task descriptions, and some direct measurements. The incidence rate of first sick leave due to such disorders was calculated for different workload groups. The proportion of workers surviving without musculoskeletal disorders was estimated by the Kaplan-Maier product-limit estimator, and the effect of the exposure on the risk of incident disorders was estimated with the Cox proportional hazards model. RESULTS: The highest annual incidences were observed for strenuous tasks, the incidence rate for men being 16.8 per 100 person-years [95% confidence interval (95% CI) 8.0-30.9] for upper-limb disorders in strenuous tasks and 6.1 (95% CI 2.0-14.1) in nonstrenuous tasks and that for women being 32.0 (95% CI 11.7-69.7) and 9.9 (95% CI 0.2-54.9), respectively. The men's risk of contracting an upper-limb or neck-shoulder disorder in strenuous tasks was about threefold [hazard ratio (HR) 3.2 (95% CI 1.1-9.4) for upper-limb disorders and 2.7 (95% CI 0.9-8.1) for neck-shoulder disorders] that of nonstrenuous tasks, whereas workload seemed not to affect low-back disorders. The workers first sought medical advice for their disorders typically some months after employment began. CONCLUSIONS: Newly employed workers in hand-intensive tasks have a high risk of upper-limb and neck-shoulder disorders. An etiologic role for activities involving high force demands in upper-limb and neck-shoulder disorders is possible.

Assessment of duration and frequency of work tasks by telephone interview: reproducibility and validity.

Quantitative estimation of physical work load requires breakdown of jobs into smaller entities. The objective was to study the inter-rater reproducibility of the contents, frequency and duration of work tasks assessed by telephone interview. Two researchers interviewed 18 industrial workers with an interval of from 2 to 3 weeks in a balanced and blinded design. Altogether 114 tasks were identified, 68 of which were recorded by both interviewers. The tasks were classified into regularly occurring (n = 34) and occasional (n = 80). The outcome was the total duration of the tasks per day computed from the data on frequency and duration. Validity of the interview was studied against prestructured diaries filled in by nine workers. The interviewers' assessments of the overall contents of the tasks were rated as 'similar' or 'very similar' for 17 of the 18 workers. Both interviewers detected all 34 regularly occurring tasks. The intraclass correlation coefficient (ICC) of the total duration between the interviewers was 0.81 for regularly occurring tasks. ICCs of the total duration between the diary and the two interviewers were 0.90 and 0.91. However, in many cases the workers could not give a numerical value for duration or frequency. A telephone interview can be used as a first step in exposure assessment in epidemiological studies on risk factors of musculoskeletal disorders. These results show that a single telephone interview can give reproducible and valid information of the frequency and duration of tasks occurring daily. For occasional tasks interview methods should be developed further.

Effects of changes in work methods on musculoskeletal load. An intervention study in the trailer assembly.

The purpose of this case study was to identify the work cycles imposing high loads on the upper limb and low-back among trailer assembly workers for an ergonomic intervention. Several changes in work methods, tools and work organisation were implemented. The number of repetitions of fundamental work cycles and wrist posture were recorded from the video. Exposure imposed on the upper extremity in driving screws and drilling was computed based on experiments on force and time requirements. In lifting or carrying, the dose imposed on the low-back was computed based on the load moment on the L5/S1 disk and duration of the cycle. It was shown that after the intervention most workers worked less with deviated wrist and the cumulative exposure on the upper extremity was lower in furniture fixing tasks. Lifting with twisted torso was reduced. It was concluded that with relatively simple and low-cost solutions exposure to important risk factors of upper extremity and low-back disorders could be reduced.