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ABSTRACT: To study associations between long term and short term exposure to different work environmental conditions and the incidence of neck or shoulder pain. The results were obtained as part of the MUSIC-Norrtälje study, which is a population based case-control study conducted in Sweden in 1993-7.
The cases were people from the study base who sought medical care or treatment for neck or shoulder pain. Information on physical and psychosocial conditions in the work environment, currently and 5 years ago, and lifestyle factors, was obtained by self administered questionnaires from 310 cases and 1277 randomly selected referents.
Associations between both physical and psychosocial exposures in the work environment and seeking care for neck or shoulder pain were found. The risk patterns differed for the sexes, and risk ratios exceeding 1.5 were more often found among women than among men. Generally, subjects who had experienced a recent increase of exposure were more likely (relative risk (RR) 2.1-3.7) to seek care than those who had been exposed long term (RR 1.5-1.8). Among women, an increased amount of visual display terminal (VDT) work, work above shoulder level, and reduced opportunities to acquire new knowledge, and among men, an increased amount of seated work were associated with neck or shoulder pain. This might indicate short induction periods for neck or shoulder pain for these exposures. However, for repetitive work with the hands and hindrance at work among women, and possibly also local vibrations among men, the induction periods seem to be longer. Interactive effects between factors, both at work and in the family, were found, but only among women.
Associations between some exposures in the work environment and seeking care for neck or shoulder pain were found. The high RRs for short term exposure might indicate that for many factors the induction period for neck or shoulder pain is short.
Occupational and Environmental Medicine 04/2002; 59(3):182-8. · 3.02 Impact Factor
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ABSTRACT: The aim of this study was to assess the influence of work-related physical and psychosocial factors on seeking care for neck or shoulder disorders among men and women in a general working population. The study population comprised gainfully employed (>17 hours per week) men and women in the municipality of Norrtälje, altogether 392 cases and 1,511 controls. Cases were defined as persons seeking care because of neck or shoulder disorders by any caregiver in the region. The study began in 1994 and continued to 1997. We assessed physical and psychosocial exposures by questionnaires and interviews. The pattern of seeking care for neck or shoulder disorders differed between men and women. Among men, work with vibrating tools [relative risk (RR) = 1.6], not having a fixed salary (RR = 1.9), and low demands in relation to competence (RR = 1.5) were the strongest risk indicators obtained in analyses stratified for age and previous symptoms. Among women, repetitive hand or finger movements (RR = 1.6), constrained sitting (RR = 1.6), not having a fixed salary (RR = 2.0), and solitary work (RR = 1.8) were the strongest risk indicators. A large proportion of the general population was exposed to several of these moderately harmful conditions, and their concomitant effect may explain the high incidence of neck and shoulder disorders in the general working population.
Epidemiology 09/2001; 12(5):537-45. · 5.57 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
American Journal of Industrial Medicine 12/2000; 38(5):516-28. · 1.63 Impact Factor
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ABSTRACT: This study investigates changes in self-reported and expert-evaluated physical work loads between 1970 and 1993 in relation to calendar year, birth cohort, and gender in an urban and suburban population sample (232 men and 252 women) born between 1935 and 1952.
A self-administered questionnaire was answered in 1993 concerning different aspects of physical work loads between 1970 and 1993. With the use of a classification matrix, the objective physical work load on different body regions was also assessed.
Between 1970 and 1993 the fraction of subjects in blue-collar occupations and the physical work loads decreased among the men, but they both increased among the women. Physical work loads were, in general, higher among the men than among the women at younger ages (below 30 years), but less so at higher ages. Expert evaluations of the musculoskeletal load showed a pattern similar to that of self-reported work loads.
The gender difference in work load development with age may have implications for the development of musculoskeletal disorders.
Scandinavian journal of work, environment & health 05/2000; 26(2):161-8. · 3.12 Impact Factor
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ABSTRACT: A population-based case referent study.
To determine whether current and past physical and psychosocial occupational factors are associated with care-seeking for low back pain in working men and women.
The importance of physical and psychosocial workloads as causal factors of low back pain has mostly been investigated in special occupational groups and with a cross-sectional design, which makes generalizability and interpretations more difficult.
The study comprised 2118 working men and women 20 to 59 years old (695 cases, and 1423 referents). Cases were defined as persons seeking care by any caregiver for low back pain. The exposure assessments were made through questionnaires and interviews about current and past physical and psychosocial loads during work and leisure time.
In a logistic regression analysis, physical load from forward bending in men (RR = 1.8) and high physical load, in general, in women (RR = 2.0) showed increased relative risks. Psychosocial factors alone seemed to be of less importance in women, but "poor job satisfaction" and "mostly routine work without possibilities of learning" increased the risk in men. Combined current and past exposures further increased the risks. A combination of high physical and psychosocial loads increased the risk substantially, but few were exposed to such loads. Adjustment for lifestyle and other loads outside work did not change the results.
Current and past physical and psychosocial occupational factors, both separately and combined, seem to be gender-specific, and to have a moderate impact on care-seeking for low back pain in a general working population.
Spine 03/2000; 25(4):493-500. · 2.08 Impact Factor
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ABSTRACT: A retrospective nested case-control study.
To identify occupational factors related to low back pain, and to study how interactions between psychosocial and physical factors, and between work-related and leisure-related factors affect low back pain in women and men.
A cohort of 484 subjects drawn from the general population was examined in 1969 and 1993, with a focus on occupational working conditions and musculoskeletal disorders.
Information about the physical and psychosocial working conditions and low back pain during the period 1970 to 1993 was collected retrospectively. Odds ratios and confidence intervals were calculated for different potential risk factors.
During the 24-year period, 46% of the subjects became patients with low back pain. Among women, heavy physical workload, sedentary work, smoking, and the combination of whole-body vibrations and low influence over work conditions were associated with an excess risk of low back pain. Among men, excess risk for low back pain was seen in heavy physical workload, sedentary work, high perceived load outside work, and the combination of poor social relations and overtime.
Factors at work were seen to be risk indicators for low back pain among both genders. Low influence over work conditions among women and poor social relations at work among men, in combination with other factors, seem to be of high relevance for the occurrence of low back pain.
Spine 03/2000; 25(3):369-74; discussion 375. · 2.08 Impact Factor
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ABSTRACT: The aim of the study was to validate interview data concerning the duration of four work postures (1) sitting, (2) standing/walking with hands above shoulder level, (3) standing/walking with hands between shoulder and knuckle level, and (4) standing/walking with hands below knuckle level. The self-reported time spent in each posture was tested in relation to observations and technical measurements in 20 subjects during two full working days. The linear relationships between self-reports and observations were strong for the three postures; sitting (r2 = 0.55), hands above shoulder level (r2 = 0.58) and hands below knuckle level (r2 = 0.69). Thus, using this interview technique, self-reports concerning time spent in (1) sitting, (2) standing/walking with hands above shoulder level and, (3) standing/walking with hands below knuckle level may be accurate enough for studying these work postures in epidemiological studies.
Applied Ergonomics 01/2000; 30(6):477-86. · 1.43 Impact Factor
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ABSTRACT: Retrospective exposure assessments are often performed in epidemiologic studies. The presence of an eventual misclassification, both nondifferential and differential, is debated but can rarely be investigated. The aim of this study was to compare self-reported information on the same physical and psychosocial work exposures with 25 years' difference.
In 1969-1970 a survey of randomly chosen men and women in Stockholm county, concerning, among other things, work exposures, was undertaken. During 1993-1994, 280 subjects participated in a reexamination, regarding psychosocial and physical factors at work and musculoskeletal disorders. The questions were all formulated in the same way as in 1969-1970.
When self-reported information on work exposures, collected with a 25-year interval, was compared, acceptable, although not high, agreement was found for 3 out of 4 physical factors and for 4 out of 10 physical environmental factors. Questions measuring psychosocial load had somewhat lower agreement. Current exposure status influenced the memory of past exposures. Study subjects who reported low-back disorders at the reexamination tended to show a better agreement in their assessments of retrospective exposures than those without current symptoms. When relative risks from original and retrospective data were calculated, hardly any influence on the estimates due to that differential misclassification could be found. For persons with and without neck or shoulder symptoms no apparent differences in assessments were found.
Retrospective assessments of exposures at the workplace showed misclassifications to a certain degree. However, the influence of the misclassifications on the risk estimates was limited.
Scandinavian journal of work, environment & health 11/1999; 25(5):410-4. · 3.12 Impact Factor
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ABSTRACT: The study aimed to determine the relationship between the physical magnitude and the subjective perception of applied pressure, and to determine discomfort and pain thresholds. Free modulus magnitude estimation of the subjective pressure level was made on three points: on the finger, the palm and the thenar area. The pressure was judged to be higher at the thenar point than at the finger and palm points. The slopes of the linear functions (log magnitude estimates as a function of log pressure) were 0.66, 0.78 and 0.76 for the finger, palm and thenar points respectively. The discomfort threshold was 38% of the pain pressure threshold at the finger point, 40% at the palm and 22% at the thenar point. The results are probably of importance in the performance of hand-intensive work, in particular in the design of hand tools.
Ergonomics 11/1999; 42(10):1274-82. · 1.41 Impact Factor
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ABSTRACT: A negative association has previously been reported between long-lasting physically heavy work and some measures of physical capacity. This relationship was further investigated in a 24-year follow-up study of 484 middle-aged men and women from the general population.
A questionnaire was administered in 1993 concerning retrospective recall of physical work loads and physical training in the time span between 1970 and 1993. Laboratory tests performed in 1993 included tests of muscle function (maximal isometric strength and dynamic endurance) and aerobic power (submaximal ergometer test).
Consistent with the hypothesis, but mainly among the women, associations between long-lasting physically heavy demands and low trunk flexion strength, squatting endurance, and aerobic power were observed. In contrast, low isometric hand grip strength and low weight lifting endurance were seldom seen among those with high physical work loads, indicating a possible maintaining or training effect on the hand/arm/shoulder muscle groups.
Physically heavy work seems to have a different impact on different parts of the musculoskeletal system, an effect that is also different between men and women.
American Journal of Industrial Medicine 10/1999; 36(3):388-400. · 1.63 Impact Factor
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American Journal of Industrial Medicine 10/1999; Suppl 1:26-8. · 1.63 Impact Factor
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ABSTRACT: Information on psychosocial work conditions during a 24-year period for 484 participants was collected retrospectively. Analyses were made of the interrater reliability, stability, specificity, and aggregation of data. The main finding was that it is possible to collect reliable information about psychosocial work conditions retrospectively for a long period of years when using a time ruler in a structured interview when earlier conditions are compared with the present. Interrater agreement was satisfactory for the larger part of the studied retrospective psychosocial risk factors and excellent for some of them. For most of the studied risk factors, the risk of overreporting exposure was low. The aggregation of data resulted in 2 indexes: poor social relations at work and low influence over work conditions. In conclusion, an individual time ruler works satisfactorily as a method of collecting retrospective information about psychosocial risk factors.
Journal of Occupational Health Psychology 08/1999; 4(3):193-206. · 2.07 Impact Factor
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ABSTRACT: The principal aim of the present study was to evaluate questionnaire-based information on past physical work loads (6-year recall).
Effects of memory difficulties on reproducibility were evaluated for 82 subjects by comparing previously reported results on current work loads (test-retest procedure) with the same items recalled 6 years later. Validity was assessed by comparing self-reports in 1995, regarding work loads in 1989, with worksite measurements performed in 1989.
Six-year reproducibility, calculated as weighted kappa coefficients (k(w)), varied between 0.36 and 0.86, with the highest values for proportion of the workday spent sitting and for perceived general exertion and the lowest values for trunk and neck flexion. The six-year reproducibility results were similar to previously reported test-retest results for these items; this finding indicates that memory difficulties was a minor problem. The validity of the questionnaire responses, expressed as rank correlations (r(s)) between the questionnaire responses and workplace measurements, varied between -0.16 and 0.78. The highest values were obtained for the items sitting and repetitive work, and the lowest and "unacceptable" values were for head rotation and neck flexion. Misclassification of exposure did not appear to be differential with regard to musculoskeletal symptom status, as judged by the calculated risk estimates.
The validity of some of these self-administered questionnaire items appears sufficient for a crude assessment of physical work loads in the past in epidemiologic studies of the general population with predominantly low levels of exposure.
Scandinavian journal of work, environment & health 07/1999; 25(3):246-54. · 3.12 Impact Factor
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ABSTRACT: MUSIC-Norrtälje study is a case-referent study, the aim of which is to find risk and health factors for low back and neck/shoulder disorders. In this part of the study, the interview technique and the self-administered questionnaire used for assessment of physical loads are described and the inter-method reliability of parts of the self-administered questionnaire is estimated. The distribution of exposure levels in a general population is also described.
The study period was three years from November 1993 to November 1996, and the study subjects totaled 2,480 persons (813 female and 610 male referents, 380 female and 315 male low back cases, 252 female and 106 male neck/shoulder cases). The interview concerned "a typical working day" during the preceding 12 months and comprised assessment of energy expenditure, work postures, and manual materials handling for work and leisure time, including regular sport activities. The self-administered questionnaire comprised 18 questions, each covering 5 different points of time: right now, 5, 10, 15, 20 years ago. The answers to eight of the questions about current conditions were compared to corresponding interview responses. The interview was considered as the "gold standard."
Ninety-eight percent of the subjects completed the interview without any great difficulties. According to the interview, the distributions of different exposure levels were generally positively skewed, i.e., the frequency of highly exposed subjects was low in the study base. The correlation between interview and questionnaire responses among the referents was high for time spent "sitting at work" (r = 0.82), "VDU work" (r = 0.87), and work related "motor vehicle driving" (r = 0.80). The correlation was moderate for work-related "hands above shoulder level" (rs = 0.63), and "hands below knee level (trunk flexion)" (rs = 0.66). The correlation was lower for leisure time activities such as "domestic work" (r = 0.55), "time for own activities" (r = 0.39), and "sitting during leisure time" (r = 0.38). Subjects seeking care for low back or neck/shoulder disorder estimated equally correctly or not, as had the referents. However, non-differential misclassification was present in all questions, which will attenuate observed estimates of the relative risk.
Even though interview data are preferable, questionnaire data may be useful for assessing well-defined work tasks and for "sitting at work."
American Journal of Industrial Medicine 06/1999; 35(5):441-55. · 1.63 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Occupational and Environmental Medicine 02/1999; 56(1):59-66. · 3.02 Impact Factor
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ABSTRACT: Blood flow changes in the brachial artery of seven subjects during and after submaximal static handgrip contractions were measured by duplex Doppler ultrasound technique. These measurements were compared with the results of occlusion plethysmography, measured immediately (2-3 heartbeats) after. For the combined data from all measurements, a common calibration line could be drawn (linear regression, r=0.92). The flow measurements from the two methods were tested by a four-way analysis of variance and there was no significant difference between the methods during (static) exercise, indicating acceptable coherence. Occlusion plethysmography may well be used for monitoring forearm blood flow during conditions of static exercise. In addition, the cuff occlusion pressure of the plethysmograph (50 mmHg) decreased the blood flow of the brachial artery by approximately 28% as measured by duplex Doppler ultrasound.
Scandinavian Journal of Clinical and Laboratory Investigation 12/1998; 58(7):569-76. · 1.38 Impact Factor
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ABSTRACT: The aim was to study the reliability and validity of retrospective data, collected by self-report, on sick leave related to musculoskeletal diseases.
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.
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.
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.
Scandinavian journal of work, environment & health 11/1998; 24(5):425-31. · 3.12 Impact Factor
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ABSTRACT: To investigate the relation between psychosocial and physical factors at work, as well as conditions during leisure time, and low back pain (LBP) over 24 years.
The study group consisted of 252 women and 232 men. From a previous study conducted in 1969, data on psychosocial and physical conditions and LBP were available. Data on LBP for 1971-93 were obtained retrospectively in 1993.
The prevalence of LBP in 1969 among women and men were 34% and 24%, the cumulative incidences of LBP during 1970-92 were 38% and 43%, and the prevalences in 1993 of having had LBP during the past 12 months were 44% and 39%, respectively. Monotonous work and few or unsatisfactory social contacts outside work were risk factors for LBP in 1969 among women. LBP in 1969 and dissatisfaction with leisure time were risk factors among both sexes for LBP in 1970-92. LBP in 1969 was a risk factor for LBP in 1993 among women and dissatisfaction with leisure time a risk factor among men. Interactions between few or unsatisfactory social contacts outside work, as well as dissatisfaction with leisure time, and several factors related to work were found to increase the risk of LBP among both sexes during the studied periods.
Conditions in leisure time exert a long term influence on LBP. In this study factors related to work had a long term effect only in interaction with leisure time factors.
Occupational and Environmental Medicine 03/1998; 55(2):84-90. · 3.02 Impact Factor
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ABSTRACT: 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.
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.
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.
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.
Scandinavian journal of work, environment & health 11/1997; 23(5):370-7. · 3.12 Impact Factor
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ABSTRACT: In 1949, 27 female and 26 male physical education students were studied at a mean age of 22 and 25 yr, respectively. They were restudied in 1970 and 1982. Measurements included oxygen uptake, heart rate, and pulmonary ventilation during submaximal and maximal exercise on a cycle ergometer and treadmill. After 21 yr, peak aerobic power was significantly reduced, from 2.90 to 2.18 l/min and from 4.09 to 3.28 l/min for women and men, respectively. After another 12 yr, the 1970 maxima were not reduced further. From 1949 to 1982 there was a decrease in peak heart rate from 196 to 177 beats/min in women and from 190 to 175 beats/min in men (P < 0.05). Highest pulmonary ventilation did not change significantly. At an oxygen uptake of 1.5 l/min, the heart rate was the same in 1949 as in 1982. In conclusion, the physical fitness level of the subjects was well above average for these ages. From 1970 to 1982 there was no decline in the average peak aerobic power, a finding possibly related to increased habitual physical activity.
Journal of Applied Physiology 06/1997; 82(6):1844-52. · 3.75 Impact Factor
