Prevalence of upper extremity symptoms and possible risk factors in workers handling paper currency

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1 Occup. Med. Vol. 48, No. 4, pp , 1998 Copyright 1998 Lippincott-Raven Publishers for SOM Printed in Great Britain. All rights reserved /98 INTRODUCTION Prevalence of upper extremity symptoms and possible risk factors in workers handling paper currency D. L. Holness,* D. Beaton* and R. A. House* *Department of Occupational and Environmental Health and * Upper Extremity Reconstructive Service, St Michael's Hospital and University of Toronto, Toronto, Ontario, Canada The prevalence of upper extremity symptoms in the workforce is high, particularly in industries characterized by forceful, repetitive or awkward movements. A study was undertaken to assess the prevalence of upper extremity symptoms in bank workers in a paper currency processing operation and to examine the role of possible risk factors for these complaints. Thirty-nine workers of a total workforce of 47 were assessed with a questionnaire and physical examination. The questionnaire collected information about demographics, health status, symptom reporting, psychosocial work stressors and other work exposure characteristics. Overall, 59% of the workers reported having significant work-related upper extremity musculoskeletal symptoms in the preceding year, including 49% with neck and shoulder symptoms and 49% with arm and wrist symptoms. In this study the key predictive factor for upper extremity musculoskeletal symptoms was psychological job demands. The workers had similar ergonomic stressors (with little gradient of exposure) and therefore our results do not contradict the importance of ergonomic factors in the development of upper extremity symptoms. However, the results do suggest that within a group exposed to similar ergonomic stressors, psychological job demands may be an important factor associated with musculoskeletal symptoms. Key words: Ergonomics; musculoskeletal; work organization. Occup. Med. Vol. 48, 2-236, 1998 There has been increasing recognition over the past decade of upper extremity problems in working populations. 1 " 9 While some of these problems represent specific diagnoses, such as carpal tunnel syndrome, the majority are labelled as tendonitis, sprains or strains, or more generally as repetitive strain injuries or cumulative trauma disorder. These labels are applied to a variety of specific and non-specific symptoms of the upper extremity. The problems are often ascribed to jobs involving repetitive movements or intensive use of the hand or Correspondence and reprint requests to: D. L. Holness, Department of Occupational & Environmental Health, St. Michael's Hospital, 30 Bond Street, Toronto, Ontario M5B 1W8, Canada. Tel: (+1) ; Fax: (+1) ; holnessl@smh.toronto.on.ca Received 21 January 1997; accepted in final form 26 January upper extremity, but in fact reflect a multifactorial aetiology which includes personal characteristics, environmental and sociocultural factors. 10 Ergonomic factors which are felt to be significant are high force and/or a high repetition rate. 1 " 12 There may be other task-related factors including posture, and personal risk factors such as pre-existing musculoskeletal problems and metabolic disease which contribute to the problem. Another group of factors which may influence workplace problems are psychosocial stressors related to how the work is organized, such as the amount of control the worker has of his or her job and how psychologically demanding the job is. 14 We report the results of a study designed to assess the prevalence of upper extremity symptoms in bank workers handling paper currency and to examine the role of possible risk factors for upper extremity syrnp toms in this group of workers. The study and its results are exploratory in nature.

2 232 Occup. Med. Vol. 48, 1998 MATERIALS AND METHODS The study was reviewed and approved by the Research Ethics Board of St Michael's Hospital in Toronto. The workers were provided with information about the study and indicated their willingness to participate in the study by signing a consent form. The study was a cross-sectional survey. The population of eligible workers included all currency handlers in a bank office. These workers had to rapidly evaluate large volumes of paper currency to determine which bills could re-enter circulation and which needed to be shredded. Of the 47 eligible workers, 39 (83%) were at work on the testing days and all of these 39 agreed to participate. Of the eight not assessed, six had short term absences with non-musculoskeletal problems (e.g., upper respiratory tract infection), one was on compensation for a non-musculoskeletal problem and one was on holiday. The currency handlers had job tasks which were split equally for each employee between preparing (prepping) the currency for processing and feeding and removing the currency from the processing machine. Both jobs required repetitive tasks at a rapid pace determined by the worker and his/her partner with an overall volume of work to be done established by the worksite. The tasks required in the two components of the jobs were repeated many times per hour. The movement patterns observed are outlined in Table 1. Questionnaire The questionnaire used was a compilation of components of other well-designed questionnaires which have been used in similar studies to investigate various workplace and non-workplace stressors and musculoskeletal symptoms with additional questions to collect information specific to this exposure setting and the workforce. The questionnaire was administered in the workplace by one of the investigators and it obtained information about demographics, health status, symptoms, psychosocial stressors and other work exposure characteristics. Most of the musculoskeletal questions were taken from a questionnaire developed by Silverstein. 15 Standard questions developed by Karasek relating to work organization and job content that allow determination of ordinal scores for several summary variables were used. 16 Several other questions were taken from the NIOSH General Job Stress Questionnaire 17 to allow investigation of other non-work stressors. Productivity measures In the questionnaire the workers were asked to rate their speed of work in comparison to others. This was a subjective rating and it was decided to try to obtain a more objective measure of speed of work. The work- Table 1. Description of job tasks Prepping (seated) Grasping bundles of paper currency in wide tripod pinch to remove from box Ipsilateral supination/pronation to visually inspect bundles Repeated wrist flexion using a small knife in a slicing motion with the contralateral hand to remove elastic bands Small pinch and pulling motions on currency wrappers with fingers and thumbs Replacing currency in box at shoulder height angled at about 60 s from horizontal Processing (standing) Grasping large bundles in wide tripod pinch Sustained grasp while fanning bundles to facilitate machine handling of currency Placing bundle in vertical waist-high feeder slot in processing machine requiring full forearm supination and wrist extension Removing bundles from processing machine and sealing in plastic bag with automatic sealer place collects productivity information for each worker for prepping and operation of the processing machine. After reviewing the available information two variables were created to characterize productivity. For the prepping value, the average of all the values obtained during a one month period was used (variable labelled 'prepping-average'). For the processing machine operation, the average of all values obtained during a one month period was used ('processing-average'). Outcome measures Definitions of significant and work-related upper extremity musculoskeletal symptoms similar to those described by Silverstein 15 were used in this study. Significant symptoms were defined as those occurring at least three times in the past year or lasting at least one week in the past year. Work-related symptoms were defined as those starting after the individual had been in his or her current job and which the worker related to some work activity. Symptoms described as significant and/or work-related were then evaluated in different locations including: (1) the neck or shoulder; (2) the arm or wrist and (3) any portion of the upper extremity [e.g., either (1) or (2)]. Data analysis Information was collected on standardized data collection forms. The information was entered into dbase IV files and converted into SAS files for analysis. The data were initially analyzed using univariate techniques to provide descriptive statistics including means, standard deviations and frequencies. Bivariate analyses were then carried out to compare possible risk factors between the groups with and without

3 D. L. Holness et al.: Upper extremity symptoms in workers handling paper currency 233 Table 2. Reporting of symptoms during past year Location Type of symptoms Significant* Significant + Work-related" Neck and shoulder Arm and wrist Any location in upper extremity % 51% 67% 49% 49% 59% Burning Stiffness Pain Cramping Tightness Aching Soreness Tingling Numbness As defined in Materials and methods section. As defined in Materials and methods section. significant work-related symptoms using either chi square tests (for proportions), Mests (for continuous outcomes) or Wilcoxon rank sum tests (for ordinal variables). The possible risk factors including demographic, exposure, past medical history and job content variables which were identified by bivariate statistics as possibly significantly different (p<0.1) between groups were assessed further with multiple logistic regression analysis to control for potential confounders. RESULTS Overall description of population The average age of the 39 workers assessed was 29 years with a range from 19-44; 62% were female. The workers had spent an average of 33 months with the study employer (range months) and had been in their current location for approximately 22 months (range 1-84 months). Thirty-six per cent worked on the night shift and 46% were contract employees. Sixty per cent thought they worked at average or belowaverage speed, whereas 40% thought they worked at above average speed. The workers took one to two 15 minute breaks per day and lunchtime ranged from minutes. The reporting of any significant symptoms in the upper extremity is summarized in Table 2. Sixty-seven per cent of the workers complained of any such symptoms with 51% reporting symptoms in the arm and wrist and % in the neck and shoulder. As indicated in Table 2 the majority of these significant symptoms were felt by the workers to also be work-related. Those who reported significant musculoskeletal symptoms as defined above had had their problem for Distribution Neck and shoulder 10% 41% 36% 10% 33% 46% 49% 8% 18% of significant symptoms by location Arm and wrist 5% 23% 41% 23% 18% 41% 38% 15% 21% an average of 14 months since the date of first onset. Eighty-six per cent noted that it was currently present. The majority reported that their symptoms occurred episodically and usually lasted between one and seven days. Eighteen per cent noted the problem started suddenly as opposed to 82% who reported a gradual onset. Seventy-six per cent reported that the problem was better on vacations. Work factors which were identified as being associated with the onset of the problem, included various tasks related to currency handling such as repetitive movements, lifting, rushing or awkward movements. Fatigue was recognized as aggravating the problem. In the past year workers had taken up to seven days off due to the musculoskeletal problems and had been on restricted work for up to 90 days. Some had received therapy during the past year for the problem, including 5% who had had medication, 18% who had had some bracing or splinting, and 9% who had had physiotherapy Seventy-eight per cent of those receiving treatment reported that it had been beneficial. Significant work-related upper extremity symptoms were reported by 59% of the workers including 49% with neck and shoulder and 49% with arm and wrist symptoms (Table 2). Workers with any significant work-related upper extremity problem were younger (p = 0.034) and smoked more (p = 0.035) than those without such problems and were more likely to always use hearing protection (p = 0.037) (Table 3). In the comparison of those with and without any upper extremity problem the key difference in job content was a higher rating of psychological job demands in those with problems (Table 4) {p = 0.033). Analysis of the specific components of the job content questionnaire related to psychological job demands revealed that the key item which was significantly different between those with and without symptoms

4 234 Occup. Med. Vol. 48, 1998 Table 3. Significant work-related upper extremity symptoms in past year; demographic and work characteristics (mean or % reporting) No (n = 16) Yes (n = 23) p-value Demographic characteristics Age Sex (% female) Smoke Married Schooling beyond high school Right-handed Work characteristics Months with current employer Months in current location Night shift Contract worker High speed of work (self-reported) Exercise Always uses hearing protection Prepping-average Processing-average ,461 63, ,324 63,960 Table 4. Perceptions of psychosocial stressors and the presence of significant work-related upper extremity symptoms in past year Gets along very well with work partner (% yes) Job content variables* (means) Skill discretion Create skills Decision authority Decision latitude Psychological job demands Job insecurity Physical exertion Co-worker support Supervisor support Non-work stressors (% yes) Have another job Have children at home Primary childcare responsibility Primary housework responsibility Going to school * Summary statistics as defined by Karasek. No symptoms (%) (n = 16) was freedom from conflicting demands from others. Other individual items on the job content questionnaire which tended to be different (0.05 < p < 0.1) between those with and without symptoms was having to work for long time periods with the head and arms in awkward positions and having an excessive amount of work. Multiple logistic regression analysis was then used to determine which of the factors identified in the bivariate comparisons were most strongly associated with the various outcomes. In Table 5, the results are presented for the outcome of any significant workrelated musculoskeletal upper extremity problem in 13 Symptoms present (%) (n = 23) p-value the past year. The two key factors which emerged from this multivariate analysis were age and psychological job demands. No other variable or interaction terms were found to be significantly associated with upper extremity symptoms in the multivariate model including the measurements of individual productivity. Younger age and greater psychological job demands were associated with increased upper extremity symptoms. The larger standardized parameter for the psychological job demands variable indicates that this variable was more important than age in the prediction of musculoskeletal symptoms. The psychological job demands composite variable

5 D. L. Holness e( al.: Upper extremity symptoms in workers handling paper currency 235 Table 5. Results of logistic regression analyses* Variable Model containing psychological job demands and age Regression co-efficient SE(B) p value Standardized parameter Intercept Age Psychological job demands Model containing conflict and age Intercept Age Conflicting demands Regression co-efficient SE(B) * Dependent variable = significant work-related upper extremity symptoms consists of five components. When the logistic regression was repeated after replacing the composite psychological job demands variable with its five component variables, the new model was found to contain age and conflicting demands from others as indicated in Table 5. This second model had an R 2 of in comparison to an R 2 of in the model containing age and psychological job demands. Consequently the second model was a better overall model for predicting upper extremity symptoms. The higher standardized parameter for conflict in the second model indicates that conflict was a better predictor than age for upper extremity musculoskeletal symptoms. DISCUSSION The present study was exploratory in nature, designed to provide information on current status of the workforce with respect to upper extremity problems and to generate hypotheses regarding possible risk factors. One problem in this area of study relates to the nosology. Only a small number of workers with symptoms had conditions which, based on clinical examination and questionnaire would be categorized as a 'diagnosis' such as carpal tunnel disease or dequervain's tenosynovitis. Classification of workrelated neck and upper limb disorders is an ongoing challenge. We elected to apply a classification system that did not imply aetiology (i.e., repetitive strain) nor pathology as this information was not available to us based on the information collected. Another issue relates to the difference between symptoms and problems. In a study such as this, information is obtained about symptoms. However, these symptoms may not be perceived as problems by some of the affected individuals. The prevalence of symptoms found in this study is high but similar to other studies that have embarked on similar surveillance activities. 1.18,19 Greater than 50% of the workers we studied reported p value Standardized parameter some upper extremity musculoskeletal symptoms, though only 13% had findings (suggestive symptoms and a positive Phalen's or Tinel's test) which might be consistent with carpal tunnel syndrome. Morganstern etal. examined 1,058 female grocery checkers and found that 63% had at least one upper extremity related complaint and 12% had four symptoms consistent with carpal tunnel syndrome. 5 Punnett et al. studied 162 garment workers and found that 42% had upper limb and trunk symptoms. 18 Hunting et al. evaluated 308 electricians and found that 47% had hand and wrist symptoms. 20 McCormack et al., studying workers in a textile plant with varying ergonomic exposures found the overall prevalence of complaints that were diagnosable to be 27%. 2 Silverstein et al. in a study examining workers in six different plants with a variety of exposures (from low force, low repetition to high force, high repetition) found overall that 18.3% had complaints on interview. 1 In summary there is wide variation in the reporting of musculoskeletal complaints in various studies. Generally the reporting of any musculoskeletal problem is higher than the reporting of symptoms consistent with carpal tunnel syndrome or other specific diagnoses. We were interested in exploring the possible factors that may be associated with reporting of symptoms within a group with exposure to similar ergonomic stressors. The reporting of upper extremity symptoms was higher in younger workers which may reflect both work hardening and/or selection out of the job. 21 Alternatively younger workers may be more likely to complain about their symptoms. Another factor which was significantly associated with upper extremity symptom reporting in the bivariate analysis was the use of hearing protection. The use of hearing protection was, however, correlated with psychological job demands and may be some proxy for concern about potential hazards in the work environment. The key risk factor for reporting symptoms within this group with similar ergonomic stressors was psychological job demands. These job content variables reflect the actual job demands and/or the worker's

6 236 Occup. Med. Vol. 48, 1998 perception of the demands. Significant associations with psychological job demands were found in those with any upper extremity problem (p = 0.033) and in those with arm or wrist problems {p = 0.019) and neck or shoulder problems (p = 0.013). The key component within the psychological job demands was the conflicting demands of others at work. In general, measures to decrease the psychological job demands, particularly related to the pace of work, and to increase the workers' control of their work would appear appropriate to reduce the psychosocial stress in the workplace. The study was exploratory in nature and had some important limitations. Cross sectional studies which attempt to evaluate premorbid, etiologic factors after the problem occurs may blur the temporality of cause and effect and introduce the possibility of significant recall bias. Therefore it is possible that the reporting of increased psychological job demands was a consequence rather than a cause of the musculoskeletal symptoms. The study was further limited by the small sample size which reduced the power to detect risk factors and might have contributed to the small number of significant risk factors identified in the multivariate analysis. Also the small gradient of exposure to ergonomic factors reduced the likelihood of detecting an ergonomic contribution to the reporting of symptoms. Workers rotated each half-shift in the prepping and processing activities and therefore variation in ergonomic stress was probably related mainly to anthropometric factors and personal work habits and experience. However the relative homogeneity of ergonomic stressors may be considered a strength of this study rather than a weakness. Given similar ergonomic exposures it is of interest to compare perception of work stress and its association with musculoskeletal symptoms. In summary, the study provides information on factors affecting symptom reporting within a group exposed to ergonomic stressors. The results demonstrate the importance of evaluating job content and psychological stressors in future studies evaluating upper extremity symptoms in workers. REFERENCES 1. Silverstein BA, Fine LJ, Armstrong TJ. Hand-wrist cumulative trauma disorders in industry. BrJIndMed 1986; 43: McCormack RR, Inman RD, Wells A, Berntsen C, Imbus HR. Prevalence of tendinitis and related disorders of the upper extremity in a manufacturing facility. J Rheumatol 1990; 17: Harber P, Pena L, Bland G, Beck J. Upper extremity symptoms in supermarket workers. Am JInd Med 1992; 22: Hagberg M, Wegman DH. Prevalence rates and odds ratios of shoulder-neck diseases in different occupational groups. BrJ Ind Med 1987; 44: Morganstern H, Kelsh M, Kraus J, Margolis W. A cross-sectional study of hand/wrist symptoms in female grocery checkers. Am J Ind Med 1991; 20: Feldman RG, Goldman R, Keyserling WM. Peripheral nerve entrapment syndromes and ergonomic factors. Am J Ind Med 1983; 4: Chatterjee DS. Repetition strain injury a recent review. J Soc Occup Med 1987; 37: Silverstein BA, Fine LJ, Armstrong TJ. Occupational factors and carpal tunnel syndrome. Am J Ind Med 1987; 11: Barton NJ, Hooper G, Noble J, Steel WM. Occupational causes of disorders in the upper limb. Br Med J1992; 304: Armstrong TJ, Buckle P, Fine LJ, et al. A conceptual model for work-related neck and upper limb musculoskeletal disorders. Scan J Vhrk Environ Health 1993; 19: Stock S. Workplace ergonomic factors and the development of musculoskeletal disorders of the neck and upper limbs: a metaanalysis. Am J Ind Med 1991; 19: Hagberg M, Silverstein B, Wells R, et at. Work related musculoskeletal disorders (WMSDs): a reference book for prevention. Kuorinka I, Forcier L, eds. London, UK: Taylor and Francis, Karasek R, Theorell T. Health work. Stress, productivity, and the reconstruction of working life. Basic Books, Bongers PM, Kompier MAJ, Hildebrandt VH. Psychosocial factors at work and musculoskeletal disease. ScanJ W>rk Environ Health 1993; 19: Silverstein BA, Fine LJ. Evaluation of upper extremity and low back cumulative trauma disorders: a screening manual. Ann Arbor, MI (USA) The University of Michigan School of Public Health, Karasek R. Job content questionnaire and user's guide NIOSH. NIOSH general job stress questionnaire Punnett L, Robins JM, Wegman DH, Keyserling WM. Soft tissue disorders in the upper limbs of female garment workers. Scand J Wark Environ Health 1985; 11: Buckle P. Musculoskeletal disorders of the upper extremities: the use of epidemiologic approaches in industrial setting. J HandSurg 1987; 12(A): Hunting KL, Welch LS, Cuccherini BA, Seiger LA. Musculoskeletal symptoms among electricians. Am J Ind Med 1994; 25: Thorslund M, Waneryd B, Ostlin R The work-relatedness of disease: workers own assessment. SociolHealth Illness 1992; 14: