Risk factors, incidence and persistence of symptoms from the eyes among professional computer users.

BACKGROUND: Symptoms from the eyes are common among computer users. Knowledge is scarce about these problems, however. OBJECTIVES: The aim was to study risk-factors, incidence and persistence of eye-symptoms among professionally active computer users. METHODS: This was a questionnaire based prospective study where 1283 males and females from different professions and companies answered a baseline questionnaire about individual factors and working conditions, e.g. duration of daily computer work, comfort of screen work, psychosocial factors. Subjects were at baseline and 10 follow-ups asked about the number of days with eye-symptoms during the preceding month. RESULTS: The incidence-rate of symptoms persisting minimum three days was 0.38/person-year. A multivariate Hazard-ratio model showed significant associations with extended continuous computer work, tasks with high demands on eye-hand coordination, low level of control, visual discomfort, female sex and nicotine use. Eye-symptoms at baseline was a strong risk factor for new symptoms. CONCLUSION: The incidence of eye-symptoms among professional computer users is high and related to both individual and work-related factors. The organization of computer work should secure frequent breaks from near-work at the computer screen. The severity of vision-related problems could in field studies be quantified by asking for the persistence of symptoms.

Incidence and risk factors for symptoms from the eyes among professional computer users.

Personal computers are used by a majority of the working population in their professions. Little is known about risk-factors for incident symptoms from the eyes among professional computer users. The aim was to study the incidence and risk-factors for symptoms from the eyes among professional computer users.This study is a part of a comprehensive prospective follow-up study of factors associated with the incidence of symptoms among professional computer users. 1531 computer users of different professions at 46 companies were invited, whereof 1283 answered a baseline questionnaire (498 men; 785 women) and 1246 at least one of 10 monthly follow-up questionnaires. The computer work-station and equipment were generally of a good standard. The majority used CRT displays.During the follow-up period 329 subjects reported eye symptoms. The overall incidence rate in the whole study group was 0.38 per person-year, 0.23 in the subgroup of subjects who were symptom free at baseline and 1.06 among subjects who reported eye symptoms at baseline. In the bivariate analyses significant associations were found with all explanatory variables, except BMI. The reduced multivariate model showed significant associations with extended computer work, visual discomfort (dose-response), eye symptoms at baseline (higher risk), sex (women=higher risk) and nicotine use.The incidence of eye problems among professional computer users is high and related to both individual and work-related factors.

Incidence of self-reported reduced productivity owing to musculoskeletal symptoms: association with workplace and individual factors among computer users.

UNLABELLED: The aim of the present study was to assess the incidence and identify possible risk factors for self-reported reduced productivity owing to musculoskeletal symptoms among computer users. DESIGN: a cohort study with a baseline questionnaire and monthly follow ups during 10 months. METHODS: the study base consisted of 1,283 computer users, 636 men and 896 women. Ergonomists observed workstation characteristics before entering the cohort. Cases were defined as subjects reporting reduced productivity or reporting being on sick leave owing to musculoskeletal symptoms. RESULTS: women had approximately two times the incidence of self-reported reduced productivity owing to symptoms in the neck, shoulder and in the forearm/hand than men. There was no difference in gender for the incidence of self-reported reduced productivity owing to back symptoms. Working overtime and job demands were risk factors for self-reported reduced productivity owing to neck and back symptoms. Physical exercise fewer than 8 times the last month was a risk factor for self-reported reduced productivity owing to neck, shoulder and forearm/hand symptoms. Computer mouse use for more than 0.5 h/day was a risk factor for self-reported reduced productivity owing to shoulder and forearm/hand symptoms. CONCLUSIONS: risk factors for self-reported reduced productivity owing to musculoskeletal symptoms included life style factors, such as overweight and low physical exercise, occupational factors, such as overtime, job demands and computer mouse operating time.

Predictors of leaving nursing care: a longitudinal study among Swedish nursing personnel.

OBJECTIVES: Despite extensive research on turnover among nursing personnel very little is known about the impact of physical workload and health on leaving. The aim of this study was to find predictors for leaving nursing care with special reference to physical working conditions and musculoskeletal problems. METHODS: This study is based on longitudinal data from a survey of nursing personnel who were employed at various county hospitals in Sweden from 1992-95. A self administrated follow up questionnaire was used to identify their present position in the labour market. The response rate was 73% (n = 1095). RESULTS: The results showed that nursing personnel reporting musculoskeletal problems of the neck/shoulder or knees and those who had limited use of transfer devices were more likely to leave nursing care. CONCLUSIONS: The study highlights the importance of taking musculoskeletal problems and use of transfer devices into consideration in order to retain nursing personnel.

Concordance between VDU-users' ratings of comfort and perceived exertion with experts' observations of workplace layout and working postures.

The aim of the present study was to evaluate the concordance (agreement) between VDU-users' ratings of comfort and ergonomists' observations of workplace layout, and the concordance between VDU-users' ratings of perceived exertion and ergonomists' observations of working postures during VDU-work. The study population consisted of 853 symptom free subjects. Data on perceived comfort in different dimensions and data regarding perceived exertion in different body locations were collected by means of a questionnaire. Data concerning workplace layout and working postures were collected with an observation protocol, by an ergonomist. Concordance between ratings of comfort and observations of workplace layout was reasonably good for the chair and the keyboard (0.60, 0.58) and good regarding the screen and the input device (0.72, 0.61). Concordance between ratings of perceived exertion and observations of working postures indicated good agreement (0.63-0.77) for all measured body locations (neck, shoulder, wrist and trunk). In conclusion ratings of comfort and perceived exertion could be used as cost-efficient and user-friendly methods for practitioners to identify high exposure to poor workplace layout and poor working postures.

Perceived muscular tension, job strain, physical exposure, and associations with neck pain among VDU users; a prospective cohort study.

AIMS: To determine whether perceived muscular tension, job strain, or physical exposure are associated with increased risk of developing neck pain among VDU users. METHODS: A baseline questionnaire was answered by 1283 respondents, of whom 671 were free from neck pain at baseline. Perceived muscular tension, job strain, and physical exposure were assessed at baseline. Information about newly developed neck pain was collected in 10 follow up questionnaires and the case definition was the first report of such pain in any of the follow up questionnaires. Median follow up time was 10.9 months. RESULTS: Both men and women who perceived muscular tension at least a few times per week, compared to those who had not perceived muscular tension the preceding month, had an incidence rate ratio (IRR) of 1.9 (95% CI 1.25 to 2.93) for developing neck pain, when stratifying for sex. High perceived muscular tension was associated with an increased risk (IRR 1.6, 95% CI 1.02 to 1.91), even when controlling for job strain, physical exposure, and age in the model stratified by sex. CONCLUSIONS: Perceived muscular tension was associated with an increased risk of developing neck pain among VDU users. The combination of high job strain and high perceived muscular tension was associated with higher risk of developing neck pain than the combination of high physical exposure and high perceived muscular tension. There was an indication of an excess risk due to interaction between high physical exposure and high job strain.

Risk factors for neck and shoulder disorders: a nested case-control study covering a 24-year period.

BACKGROUND: In 1969 a population-based study was conducted in the Stockholm region. From the 2,579 randomly selected participants (18-65 years of age in 1969), the youngest subset were asked to participate in a reexamination in 1993. Information regarding working conditions, conditions outside work, and neck and shoulder disorders was collected retrospectively for the period 1970-1993. METHODS: Of 783 eligible subjects (42-59 years of age in 1993), 484 responded. Cases of neck/shoulder disorders were defined by past sick leave or medical attention or recent symptoms, depending on available information. For each case (n = 271) two controls were randomly selected, matched by age and gender. Variables regarding both physical and psychosocial conditions were included in the matched analyses. RESULTS: Among women mainly psychosocial factors and among men mainly physical factors were associated with neck/shoulder disorders. The only gender common risk indicator found was repetitive hand work (OR approximately 1.5). Interactive effects were also observed. CONCLUSIONS: The impact on neck/shoulder disorders from separate factors was moderate but combinations of physical and psychosocial factors, as well as of work-related and non-work-related factors, produced relative risks above 2.

Risk factors for neck and upper limb disorders: results from 24 years of follow up.

OBJECTIVES: To investigate associations between different potential risk factors, related and not related to work, and disorders of the neck and upper extremities occurring up to 24 years later. METHODS: The study comprised 252 women and 232 men, Swedish citizens, 42-59 years of age and in a broad range of occupations. Information about potential risk factors was available from a former study conducted in 1969. Data on disorders of the neck, shoulder, and hand-wrist disorders were obtained retrospectively for the period 1970-93. RESULTS: Risk factors were found to differ between the sexes. Among women over-time work, high mental workload, and unsatisfactory leisure time were associated with disorders in the neck-shoulder region. Interaction was found between high mental workload and unsatisfactory leisure time. Neck symptoms earlier in life were associated with recurrent disorders. Hand and wrist disorders were associated mainly with physical demands at work. Among men blue collar work and a simultaneous presence of high mental workload and additional domestic workload predicted disorders in the neck-shoulder region. CONCLUSIONS: Factors related and not related to work were associated with disorders of the neck, shoulders, and hands and wrist up to 24 years later in life. These included factors related to working hours which previously have not been noted in this context. Interactions between risk factors both related and not related to work were commonly found.

Characteristics of pain drawings in the neck-shoulder region among the working population.

OBJECTIVES: The aim was to study the characteristics of pain drawings in the neck, shoulders, and upper-back regions among the general working population. METHODS: Pain drawings of the rear view of the neck, shoulders, and upper back were made by 125 middle-aged subjects from the general working population suffering from symptoms, mainly ache and pain, in the neck or shoulder regions. The locations of the markings in each pain drawing were coded to computer files using a transparent grid (878 pixels). The total area, the number of separate loci, and the left-right symmetry were recorded. Symptoms and signs were assessed at a medical examination. RESULTS: The most frequently marked locations in the resulting aggregated topographical diagram covered two palm-sized areas in the neck-shoulder angles, with a symmetrical and even distribution occurring between the left and right sides. Subjects with more chronic or severe symptoms made pain drawings with larger areas. The presence of tenderness in the neck-trapezius region was associated with larger areas and more bilateral and multiple loci. Larger areas with multiple bilateral loci and a more symmetric distribution characterized pain drawings made by women as compared with those made by men. No substantial difference was noted in connection with age or educational level. CONCLUSIONS: Pain drawings of neck and shoulder symptoms among the middle-aged general working population most usually focused on the neck-shoulder angles with a symmetrical left-right distribution. The number of separate symptom loci and their total area, left-right distribution, and symmetry were characteristics associated with symptom chronicity and severity or signs of tenderness in the neck-trapezius region.

Predictive aspects of the abduction external rotation test among male industrial and office workers.

BACKGROUND: Nerve compression of the brachial plexus can be provoked by the Abduction External Rotation (AER) test where the arms are held in a "hands-up" position. METHODS: The AER test was conducted among 137 male industrial and office workers at baseline and after 5 years follow-up, together with a medical examination/history and exposure analysis. Nerve conduction measurements in the wrist regions were also made. RESULTS: The cumulated incidence of neurological signs during the AER test, was estimated to be 2/100 person-years. Factors related to work-conditions, constitution, disease, and neck trauma were associated with AER signs. Subjects with AER signs exhibited a slowing of the nerve conduction velocities in the wrist region. The AER test predicted future neck and upper extremity symptoms and signs of nerve compression. CONCLUSIONS: The results of this study gave support to the "double or multiple crush" theory of nerve compression. Prevention, evaluation, and management of neck and upper extremity nerve compression diseases should, therefore, attend to all probable locations of such compression, even when a specific location is in focus. The AER test can be a supplementary tool in such work, both in epidemiological and occupational health settings.

Validity and reliability of self-reported retrospectively collected data on sick leave related to musculoskeletal diseases.

OBJECTIVES: The aim was to study the reliability and validity of retrospective data, collected by self-report, on sick leave related to musculoskeletal diseases. METHODS: The study groups consisted of 66 and 306 subjects, for the reliability and validity studies, respectively. They were all part of a wider study of risk factors for musculoskeletal disorders, the REBUS study, conducted in Stockholm in 1993. Reliability was tested using a test-retest design regarding self-reported sick leave related to musculoskeletal diseases in 1970-1993. The validity study comprised the period 1990-1994. Self-reported and registered sick-leave data related to musculoskeletal diseases were collected and analyzed regarding concordance. Data about current musculoskeletal disorders and different work-related conditions were collected and analyzed regarding possible effect- and exposure-dependent misclassification. RESULTS: The test-retest reliability study showed the percentage of agreement to be between 0.88 and 0.97, and the kappa values were between 0.73 and 0.93. The validity study of the concordance between the self-reported and registered data showed high agreement and specificity, but the sensitivity was sometimes lower. All the kappa values exceeded 0.50. No effect- or exposure-dependent misclassification was found. CONCLUSIONS: The validity of retrospectively collected self-reported sick-leave data was sufficient for use as a measure of musculoskeletal morbidity in the analyses of associations with work-related conditions. Because of the relatively low sensitivity, such data will underestimate the prevalence of sick leave and should not be used for surveys of morbidity.

Possible bias from rating behavior when subjects rate both exposure and outcome.

OBJECTIVES: In many epidemiologic studies the subjects rate both the exposure and the outcome, assigning numerical values to the variables according to their perceptions and judgments. Hypothetically, subjects who tend to overestimate, exaggerate, or use high numerical values in rating tasks would rate both exposure and outcome higher than subjects who tend to underestimate, dissimulate, or use low numerical values. A range of such rating behaviors among the subjects would introduce uncontrollable bias to relative risk estimates, in most cases an overestimation. The aim of this study was to assess the possible presence of and effects on relative risk estimates of such high and low rating behavior among subjects in an epidemiologic study of musculoskeletal disorders. METHODS: Rating behavior was analyzed by intercorrelating the ratings of 19 different stimuli. High positive correlations would indicate the presence of high and low rating behavior. RESULTS: The correlations were, however, both positive and negative and close to zero. Adjusting for rating behavior did not affect relative risk estimates, based on subjective ratings of both exposure and outcome. CONCLUSION: There is no support in this study for the existence of a range of high and low rating behavior among subjects who rate neutral and nonaffective stimuli, such as time, weight, number and physical exposure, as well as pain and other symptoms. There is therefore no support for the idea of a bias to relative risk estimates from such rating behavior in studies where subjects rate both exposure and outcome variables of this kind.

Associations between self-rated psychosocial work conditions and musculoskeletal symptoms and signs. Stockholm MUSIC I Study Group.

OBJECTIVES: The aim was to study the associations between self-rated psychosocial work conditions and the characteristics and location of musculoskeletal symptoms, signs, and syndromes. METHODS: Perceived psychosocial work conditions were recorded in a cross-sectional study with 358 men and women in various occupations. Symptoms were recorded from the musculoskeletal system with a questionnaire, and signs were detected in a medical examination of all body regions. The analyses of statistical associations between the psychosocial factors and musculoskeletal disorders were performed with control for age, gender, and physical load. RESULTS: The most consistent and pronounced associations were mainly seen between poor psychosocial work conditions and coexisting symptoms and signs of the neck and back regions. Poor psychosocial work conditions were more consistently and strongly associated with signs of muscular (soft tissue) tenderness than with signs of tenderness in the joints, tendons, or muscular insertions or signs in nerve compression tests. Mainly low social support at work, but also high psychological demands and high job strain, were associated with such symptoms and signs, whereas decision latitude at work showed few associations with musculoskeletal disorders. CONCLUSIONS: Perceived poor psychosocial work conditions are statistically associated mainly with symptoms and signs of muscular tenderness in the central body regions. Studies on associations between psychosocial work conditions and musculoskeletal disorders should separate effect measures of different clinical signs and different body regions in order to avoid attenuation of the risk estimates.

Provocation of the electromagnetic distress syndrome.

BACKGROUND: Many patients in Sweden are today distressed by fears of "electric fields." This phenomenon was almost unknown to occupational health clinics 10 years ago. CASE HISTORY AND EXAMINATION: A 35-year-old male plumber complained of fatigue, headache, lack of concentration, numbness and paresthesia in his arms, and a greasy feeling in his palms, where he observed tiny shiny spots. These symptoms made him unable to work. It all started after a period of high strain at the work. He feared negative influences, mainly from electric fields. Signs indicating nerve entrapment in the upper extremities were found in a clinical examination. PROVOCATION STUDY: The patient was blindly provocated in a whole-body electromagnetic coil at 34 or 100 microT randomly mixed with sham exposures. After being blinded against irrelevant external cues, he was not able to detect the existence of or any symptoms at either field intensity. He was informed about the results and was later able to return to his previous work. CONCLUSIONS: No sensitivity to electromagnetic fields could be objectively verified for this patient, who was suspected to suffer from a thoracic outlet syndrome.

Self-administered examination versus conventional medical examination of the musculoskeletal system in the neck, shoulders, and upper limbs. The Stockholm MUSIC I Study Group.

A self-administered examination protocol of the musculoskeletal system in the neck, shoulders, and upper limbs was mailed to 350 subjects and the results were compared to those of a subsequent medical examination. The prevalences of reported positive findings were higher than in the medical examination. Validity ranged between poor and good. Acceptable validity was noted for items measuring tenderness. No systematic substantial exposure-related misclassification was noted. Self-administered examination of the musculoskeletal system is not suitable to replace a traditional medical examination in epidemiological studies. Self-administered examination of tenderness could, however, be used as a screening method in analytical studies of relations between exposure and disorders in the musculoskeletal system. Subjects reporting such findings at a self-administered examination could be further examined by professional examiners for definite diagnostic appraisal. Substantial savings in medical examination resources could thereby be obtained.

Irritation effects from experimental exposure to n-butyl acetate.

The irritation produced by acute exposure to n-butyl acetate in human subjects without any history of occupational solvent exposure was studied in three experiments. Exposure levels tested in the different experiments were 350, 700, 1,050, and 1,400 mg/m3 in 20 min sessions, 70 and 1,400 mg/m3 in 20 min sessions, and 70 and 700 mg/m3 in 4 h sessions. Rating scales, various measures of eye irritation, and pulmonary functions were used to evaluate the irritation produced by the exposures in different parts of the study. The results indicate only very slight irritation from the exposures as revealed by categorical ratings, magnitude estimation, and some of the clinical measures of eye irritation and pulmonary functions, such as eye redness, lipid layer thickness, and bronchial responsiveness. These essentially negative results indicate the need to explore and develop the utility of new/different methods of quantifying irritative effects of exposure to various substances.

Outcome of the abduction external rotation test among manual and office workers.

Reactions during the Abduction External Rotation (AER) test were studied among 71 platers and 70 assemblers exposed to vibratory tools and manual work and 45 unexposed white collar workers. The frequency of positive neurological reactions was 31% among the platers, 6% among the assemblers, and 16% among the white collar workers. Platers reported the highest fatigue rates in the shoulder regions during the test. A positive association was noted between a pathological AER test and current problems in the neck/scapula or shoulder/upper arm regions, day- or night-time numbness in the hands, tension neck, and carpal tunnel syndrome. Age, length of daily vibration exposure, and vibration acceleration level were also positively associated with a positive AER test outcome. The results indicate that the outcome of the AER test is sensitive to neck and shoulder disorders but also, to some extent, to the carpal tunnel syndrome.