Physiological responses, trunk posture, and work pace in commercial building cleaning in Washington State: An observational field study.

INTRODUCTION: This study aimed to investigate whether work pace is a critical indicator for predicting a janitor's risk of work-related musculoskeletal disorders (WMSDs). METHOD: Field measurements were obtained from commercial building janitors as well as the determination of work pace. Physiological responses collected were heart rate, energy expenditure (calories), activity level (METs), steps, trunk posture. Data were obtained using direct measurements, along with a time study, which was performed by shadowing 13 janitors in Washington State. The measured values were summarized descriptively, and five of the most common janitorial tasks were compared. The relationships between work pace and the physiological response variables were determined by calculating the Pearson product-moment correlation coefficients. RESULTS: The highest average percent heart rate reserve (47.4%) was reported during restroom cleaning, while the highest activity and energy expenditure levels (3.6 METs and 217.1 calories/h) were reported for mopping. The top 90% of trunk flexion angles and the highest percentage of time in trunk flexion from 20° to 60° were recorded during restroom cleaning. Restroom cleaning showed the highest correlation between all the physiological response variables and work pace. In most of the tasks, a high work pace may have increased the degree and duration of severe trunk flexion. CONCLUSION: Overall, when several tasks were considered, the extent of physiological responses, trunk joint angles, and exposure time to awkward postures tended to increase with an increase in work pace. PRACTICAL APPLICATIONS: This study showed the feasibility of using the work pace measured from time studies as a predictive indicator of WMSDs risks. Using this information, managers may compose a schedule that can minimize WMSDs risks while considering actual work pace deviations that may impact a janitor's ability to complete assigned tasks properly within a shift.

The job demand-control-support model and work-related musculoskeletal complaints in daytime and nighttime janitors: The mediating effect of burnout.

Janitors' jobs require repetitive work with low control (skill discretion, decision authority) and social support. Previous studies have found this constellation of work conditions leads to high stress levels. This study investigated the relationships among job demand-control-support, burnout, and musculoskeletal symptoms for commercial janitors in Washington State. Structural equation modeling was performed using data from 208 participants with analyses comparing models of daytime and nighttime janitors. Burnout fully mediated the relationship between job demands and musculoskeletal complaints among daytime janitors. Among nighttime janitors, burnout mediated between job demands, job control, and social support, and musculoskeletal complaints. The nighttime janitors' model was more fully supported compared to the daytime model. This study is one of a small number that examine and bring attention to the importance of janitors' burnout. Recommendations to improve the psychosocial work environment toward mitigating burnout and reducing musculoskeletal complaints are provided.

Comparison of BRFSS Data Between Home-Based Care Providers and Health Care Support Workers in Clinical Environments in Washington State.

Background: The demand for home-based health care support providers (HB providers) is growing as the locus of care shifts to private homes. However, industry representative data of these workers are limited. Methods: Washington Behavioral Risk Factor Surveillance System (WA BRFSS) data from 2011 to 2016 were analyzed to compare HB providers (n = 385) with health care support occupations not based in the home, non-HB providers (n = 229), and all other occupations (n = 32,011). Findings: More HB providers were overweight (4.2%, 95% confidence interval [CI] = [3.3%, 5.2%]) than non-HB providers and all other occupations. Significantly more HB providers had arthritis (33.2%, 95% CI = [27.0%, 39.4%]) and diabetes (9.4%, 95% CI = [5.7%, 13.2%]) than non-HB providers. Nearly twice as many HB providers currently smoked (31.3%, 95% CI = [24.2%, 38.4%]) than non-HB providers. Significantly more HB providers reported serious mental illness (6.8%, 95% CI = [2.8%, 10.7%]) than all other occupations (2.2%). Conclusion/Application to Practice: It is imperative to maintain good health in this home-based health care population as these workers are aging and their professional time becomes limited.

Are Work-Related Musculoskeletal Disorders Claims Related to Risk Factors in Workplaces of the Manufacturing Industry?

OBJECTIVES: Varied work-related musculoskeletal disorders (WMSDs) claim rates were found between companies even when they were in the same sectors with similar sizes. This study aimed to (i) identify common risk factors for back, shoulder, hand/wrist, and knee WMSDs among manufacturing jobs, and (ii) characterize the biomechanical exposures in jobs and work organizational practices between high and low WMSD claim rate companies so that more focused, industry-specific intervention strategies may be developed. METHODS: Using historical workers' compensation data, manufacturing companies were divided into two paired groups (low and high in the lower 25%ile and higher 75%ile, respectively). On-site job evaluations were conducted in 16 companies to determine job biomechanical risk levels. Management and workers' representatives in 32 paired companies were interviewed to identify possible differences between management strategies and management/worker relationships. A total of 39 injured workers were also interviewed to gather information of self-reported injury causes and suggested preventive measures. RESULTS: Analyses of 432 job evaluations showed that more jobs had higher risk levels of prolonged standing and heavy lifting in the high back WMSD claim rate companies than the low claim rate ones. No high biomechanical risk factors were found to be associated with jobs in high shoulder claim rate companies. High repetition, pinch force, and Strain Index were associated with high hand/wrist WMSD claim rate companies. High work pace and job stress were common among high knee WMSD claim rate companies. There were no statistically significant differences for the organizational factors between high and low WMSD claim rate companies. Heavy lifting, fast work pace, high hand/wrist repetition, high hand force, and awkward shoulder postures were identified as major contributing factors by the injured workers. CONCLUSIONS: High WMSD claim rate companies appeared to have more high biomechanical exposure jobs than low WMSD claim rate companies. Available job evaluation methods for the low back and hand/wrists are satisfactory in quantifying job risk levels in the manufacturing industry. Research into more sensitive job evaluation methods for the shoulder and knee are needed.

Bringing a structural perspective to work: Framing occupational safety and health disparities for nursing assistants with work-related musculoskeletal disorders.

BACKGROUND: Certified Nursing Assistants (CNAs) experience a high risk of work-related musculoskeletal disorders (WMSDs) and are further made vulnerable by their situation in low levels of workplace and societal hierarchies of power and privilege. OBJECTIVE: This study applies structural vulnerability theory to CNA WMSD experiences in order to identify structural factors that may influence such injuries. METHODS: A sample of CNAs (n = 26) working in Nursing and Residential Care Facilities (NRCFs) was selected from workers who filed a claim during 2011-2014 for a WMSD of the back, shoulder, knee, or hand/wrist in the Washington State Department of Labor & Industries workers' compensation system. Interviews included questions about workers' injury experiences and work contexts. Qualitative data was analyzed for themes related to structural vulnerability theory and occupational safety and health (OSH) models. RESULTS: Themes illustrate a work environment in NRCFs with major organizational deficiencies for CNA safety and a broader structural environment that appears to mediate them. CNAs described policies and practices that result from management priorities being diverted away from worker safety. These difficulties are compounded by several aspects of CNAs' socio-economic vulnerability. CONCLUSIONS: This study demonstrates the utility of a structural perspective for OSH disparities research and points to the need for occupational health intervention on a structural level.

Predicting work-related incidence of lateral and medial epicondylitis using the strain index.

BACKGROUND: The Strain Index (SI) has been developed to evaluate the risk for developing a distal upper extremity disorder. The objective of this study is to determine if the SI predicts incidence cases of work-related lateral, medial, or any epicondylities (LEPI, MEPI, and EPI). METHODS: Six hundred seven workers were followed for up to 3.5 years, 70 developed EPI on the dominant side (44 LEPI, 13 MEPI, and 13 both). Survival analyses were conducted adjusting for demographic, psychosocial, and work organizational factors, with the SI as time-dependent variable. RESULTS: High exposure (SI > 5), older age, and self-perceived poor general health were associated with incidence of LEPI and EPI, but not MEPI. There was a significant relationship between higher scores of SI and LEPI, hazard ratio (HR) 2.00 (95% CI 1.04-3.87) for SI 5.1-12, HR 2.12 (95% CI 1.11-4.05) for SI > 12. CONCLUSIONS: The SI can effectively identify jobs with increased risk of developing incidence of LEPI.

The association between combination of hand force and forearm posture and incidence of lateral epicondylitis in a working population.

OBJECTIVE: The objective of this prospective study is to investigate the exposure-response relationships between various workplace physical exposures of force, repetition, and their combination assessed at an individual level with lateral epicondylitis (LE). BACKGROUND: Workplace upper extremity musculoskeletal disorders (UEMSDs) are prevalent, disabling, and expensive. LE is one of the major UEMSDs in active workers. METHOD: We used detailed health history, symptoms, and physical examination for identifying incidence and detailed exposure assessment to capture work tasks of each worker and to measure quantitative mechanical workload. We used counting process style input of proportional hazards regression for modeling cumulative incidence that accounts for changed exposure estimates during the follow-up period when respondents change jobs. RESULTS: The incidence rate of LE on the dominant side was 4.91 per 100 person-years. Adjusted for age and gender, the combined effect of forearm pronation > or = 45 degrees for > or = 40% of time and time spent with forceful exertion, including any power grip (hazard ratio [HR] = 2.8, 95% confidence interval [CI] = [1.35-5.77]), lifting for > or = 3% of time (HR = 2.50, 95% CI = [1.19-5.24]), and duty cycle for forceful exertion for > or = 10% (HR = 2.25, 95% CI = [1.09-4.66]), were significant predictors of dominant side LE, whereas neither the awkward posture nor the forceful exertion alone was significant. Older workers with jobs requiring a high percentage of time working with force in combination with awkward postures of forearm were more likely to predict LE. CONCLUSION: This study shows the evidence of the etiologic role of strenuous manual tasks in the occurrence of LE.

Comparison of two different methods for performing combination analysis of force and posture risk factors in an epidemiological study.

OBJECTIVES: This study aimed to introduce a method of simultaneous combination analysis of multiple exposure parameters for large epidemiological studies of work-related upper-extremity musculoskeletal disorders (MSD) and compare this analysis method with the conventionally used job-level combination analysis method when applied in exposure-response analysis of work-related upper-extremity MSD. METHODS: Health outcome [carpal tunnel syndrome (CTS)] and physical exposure (forceful exertion and hand/wrist postures) data for 733 subjects were obtained from the baseline period of a 3-year work-related upper-extremity MSD study. Determinations of CTS cases were done based on a set of defined criteria. Physical exposure variables of several different types of forceful exertions and three different hand/wrist postures were collected onsite, processed, and analyzed using both a simultaneous combination and job-level combination analysis method. RESULTS: The commonly used job-level combination analysis method resulted in significantly different combination exposure distributions compared to the simultaneous combination analysis method, although the absolute differences were small. Both methods showed some significantly higher combined force-posture exposures among CTS cases than non-cases. CONCLUSIONS: The simultaneous combination method provides more realistic distribution information on combined exposure parameters compared to the job-level combination method that has been commonly used in epidemiological studies. The newly developed simultaneous combination analysis method needs to be used in larger scale work-related upper-extremity MSD epidemiological studies to test its predictive power compared to the job-level combination analysis method.

An analysis of injuries among home health care workers using the Washington state workers' compensation claims database.

An examination of the Washington State workers' compensation claims for home health care workers was conducted. Some comparisons were made with nursing homes, acute care hospitals, and all other industries in the state. Between 1998 and 2007, the average claims rate for home health care workers was 1,375 claims/10,000 full-time equivalents (FTEs) compared to 862 claims/10,000 FTEs for all other industries. The proportion of home health care workers' injuries resulting from interactions with another person (89.6%) was comparable to those for nursing homes and hospitals. Although this industry has important economic and social value, risks are poorly characterized. Continued research is necessary.

The natural course of carpal tunnel syndrome in a working population.

OBJECTIVE: The aim of this study was to assess prevalence, incidence, and persistence of carpal tunnel syndrome (CTS) and associated symptoms over a one-year period in a working population. METHODS: We conducted a one-year prospective study of 418 active workers in 12 worksites. Detailed health interviews, psychosocial questionnaires, and electrophysiological studies [ie, nerve conduction velocity (NCV) tests] were conducted at baseline and one-year follow-up. Individual-observed exposure assessments of wrist posture, hand activity, and hand forces were conducted. RESULTS: Prevalence of CTS cases at baseline was 10.8% [95% confidence interval (95% CI) 7.8-13.7%] on the dominant side and 6.0% (95% CI 3.7-87.3%) on the non-dominant side; CTS symptoms were 14.1% (95% CI 10.8-17.5%) and 11.0% (95% CI 8.0-14.0%), respectively. Incidence of CTS cases were 7.5% (95% CI 4.8-10.2%) and 5.6% (95% CI 3.3-7.9%), respectively. Higher proportions of subjects with current symptoms or positive electrophysiological test findings at baseline became CTS cases at one year compared to those with neither (28.6% and 13.9%, respectively, versus 0.5%). One-year persistence of CTS case status was 44.4% (95% CI 29.9-59.0%) for the dominant hand and 52.0% (95% CI 32.4-71.6) for non-dominant hand. There were significant differences at baseline between asymptomatic subjects and CTS cases with respect to higher job demands (P=0.027), lower job satisfaction (P=0.036), lower general health (P=0.0009), higher exposure to vibrating hand tool use (P=0.039), and greater time using a forceful power grip (P=0.035) among cases. CONCLUSIONS: CTS symptoms more than positive NCV test results alone appear to predict CTS at one year. Persistence of CTS at one year is high.

Interrater reliability of posture observations.

OBJECTIVE: The aims of this research were (a) to study the interrater reliability of a posture observation method, (b) to test the impact of different posture categorization systems on interrater reliability, and (c) to provide guidelines for improving interrater reliability. BACKGROUND: Estimation of posture through observation is challenging. Previous studies have shown varying degrees of validity and reliability, providing little information about conditions necessary to achieve acceptable reliability. METHOD: Seven raters estimated posture angles from video recordings. Different measures of interrater reliability, including percentage agreement, precision, expression as interrater standard deviation, and intraclass correlation coefficients (ICC), were computed. RESULTS: Some posture parameters, such as the upper arm flexion and extension, had ICCs > or = 0.50. Most posture parameters had a precision around the 10 degrees range. The predefined categorization and 300 posture categorization strategies showed substantially better agreement among the raters than did the 10 degrees strategy. CONCLUSIONS: Different interrater reliability measures described different aspects of agreement for the posture observation tool. The level of agreement differed substantially between the agreement measures used. Observation of large body parts generally resulted in better reliability. Wider width angle intervals resulted in better percentage agreement compared with narrower intervals. For most postures, 30 degrees-angle intervals are appropriate. Training aimed at using a properly designed data entry system, and clear posture definitions with relevant examples, including definitions of the neutral positions of the various body parts, will help improve interrater reliability. APPLICATION: The results provide ergonomics practitioners with information about the interrater reliability ofa postural observation method and guidelines for improving interrater reliability for video-recorded field data.

Quantitative exposure-response relations between physical workload and prevalence of lateral epicondylitis in a working population.

BACKGROUND: Lateral epicondylitis is a common work-related musculoskeletal disorder. The objective of this study was to identify risk factors associated with lateral epicondylitis among active workers. METHODS: Seven-hundred thirty-three workers in 12 Washington worksites participated in structured interviews, physical examinations, and individual exposure assessments of biomechanical and psychosocial factors. Multivariable logistic modeling was used. RESULTS: Thirty-eight subjects (5.2%) had lateral epicondylitis. Age (36-50 years-old), being female, and low social support at work were significant risk factors. Frequency of forceful exertion (> or =5 vs. < 1 times/min (OR 5.17, 95%CI 1.78-15.02), and > or =1 to <5 vs. <1 (OR 4.47, 95%CI 1.57-13.71)) and forearm supination at > or =45 degrees for > or =5% of the time with high lifting force (OR = 2.98, 95% CI 1.18-7.55) were significant physical load factors. CONCLUSIONS: Frequency of forceful exertion or a combination of forearm supination and forceful lifting were significant physical factors and should be considered for prevention strategies.

Gender adjustment or stratification in discerning upper extremity musculoskeletal disorder risk?

OBJECTIVES: The aim was to explore whether "adjustment" for gender masks important exposure differences between men and women in a study of rotator cuff syndrome (RCS) and carpal tunnel syndrome (CTS) and work exposures. METHODS: This cross-sectional study of 733 subjects in 12 health care and manufacturing workplaces used detailed individual health and work exposure assessment methods. Multiple logistic regression analysis was used to compare gender stratified and adjusted models. RESULTS: Prevalence of RCS and CTS among women was 7.1% and 11.3% respectively, and among men 7.8% and 6.4%. In adjusted (gender, age, body mass index) multivariate analyses of RCS and CTS, gender was not statistically significantly different. For RCS, upper arm flexion >/=45 degrees and forceful pinch increased the odds in the gender-adjusted model (OR 2.66, 95% CI 1.26-5.59) but primarily among women in the stratified analysis (OR 6.68, 95% CI 1.81-24.66 versus OR 1.45, 95% CI 0.53-4.00). For CTS, wrist radial/ulnar deviation >/=4% time and lifting >/=4.5kg >3% time, the adjusted OR was higher for women (OR 4.85, 95% CI 2.12-11.11) and in the gender stratified analyses, the odds were increased for both genders (women OR 5.18, 95% CI 1.70-15.81 and men OR 3.63, 95% CI 1.08-12.18). CONCLUSIONS: Gender differences in response to physical work exposures may reflect gender segregation in work and potential differences in pinch and lifting capacity. Reduction in these exposures may reduce prevalence of upper extremity disorders for all workers.

Application of the Strain Index in multiple task jobs.

Six different methods to calculate the Strain Index (SI) scores for jobs with multiple forces/tasks were developed. Exposure data of 733 subjects from 12 different worksites were used to calculate these SI scores. Results show that using different SI computation methods could result in different SI scores, hence different risk level classifications. However, some simpler methods generated SI scores were comparable to the more complicated composite SI method. Despite differences in the scores between the six different SI computation methods, Spearman rank-order correlation coefficients of 0.61-0.97 were found between the methods. With some confidence, ergonomic practitioners may use simpler methods, depending on their specificity requirement in job evaluations and available resources. Some SI computation methods may tend to over-estimate job risk levels, while others may tend to under-estimate job risk levels, due to different ways used in obtaining the various SI parameters and computations.

Assessment of perceived injury risks and priorities among truck drivers and trucking companies in Washington State.

PROBLEM: The trucking industry experiences one of the highest work-related injury rates. Little work has been conducted previously in the United States to assess the hazards, needs, and injury prevention priorities in trucking. METHOD: Two separate industry-wide surveys of 359 trucking companies and 397 commercial truck drivers were conducted in Washington State. RESULTS: Trucking companies and drivers both ranked musculoskeletal and slip, trip, fall injuries as the top two priorities. Controlling heavy lifting, using appropriate equipment, and addressing slippery surfaces were frequently listed as solutions. There appears to be a gap in safety climate perception between workers and employers. However, driver and company priorities agreed with industry workers' compensation claims. There is room for safety program management improvement in the industry. The study findings detail opportunities for prioritizing and reducing injuries. IMPACT ON INDUSTRY: This information can be used to focus and design interventions for the prevention of work-related injuries while improving industry competitiveness.

Rotator cuff syndrome: personal, work-related psychosocial and physical load factors.

OBJECTIVE: To identify factors associated with rotator cuff syndrome (RCS) among active workers. METHODS: Seven hundred thirty-three workers in 12 worksites participated in a cross-sectional study with individual structured physical and psychosocial health interviews, physical examinations, and exposure assessments of biomechanical factors. Work organization, including job content or structural constraints, was assessed at the departmental level. Multivariable logistic modeling was used. RESULTS: Fifty-five subjects (7.5%) had RCS. Cases were more likely to report low job security (P < 0.04) and to have very high job structural constraints (P < 0.03). Age and body mass index were marginally significant. Upper arm flexion >or= 45 degrees >or= 15% of time and either duty cycle of forceful exertions >or=9% time (odds ratio = 2.43, 95% CI = 1.04 to 5.68) or forceful pinch >0% [odds ratio = 2.66, 95% CI = 1.26 to 5.59] were significant risk factors. CONCLUSIONS: Long duration of shoulder flexion and forceful exertion (especially pinch) in a job are significant risk factors for RCS. Work organization may impact physical and psychosocial exposures and should be further explored.

Reliability and validity assessment of the hand activity level threshold limit value and strain index using expert ratings of mono-task jobs.

This study evaluated two subjective assessment methods for physical work-related musculoskeletal disorder (WMSD) risk factors. A total of 567 participants from 12 companies in the manufacturing and health care industries were evaluated using the hand activity level (HAL) threshold limit value (TLV) and the Strain Index. Inter-rater reliability comparisons were performed on 125 selected cyclic tasks, with one novice and three experienced raters. Predictive validity was assessed by evaluation of relationships between measured exposure parameters and diagnosed WMSDs of the hand/wrist and elbow. HAL hand repetition ratings had a Spearman r value of 0.65 and a kappa value of 0.44 between raters. Subjective force (0-10 scale) estimates had a Spearman r = 0.28 and were not significantly different between raters (p > .05). The rating comparison for the four subjective components of the Strain Index had Spearman r correlations of 0.37-0.62 and kappa values of 0.25-0.44. The Strain Index and HAL TLV agreed on exposure categorization 56% of the time. Logistic regression showed, after adjustment for age, gender, and body mass index, that higher peak hand force estimates (odds ratio [OR] 1.14, confidence interval (CI) 1.02-1.27), most common force estimates (OR 1.14, CI 1.02-1.28), hand/wrist posture rating (OR 1.71, CI 1.15-2.56), and Strain Index scores >/= 7 (OR 1.82, CI 1.04-3.18) were associated with distal upper extremity disorders in the dominant hand. HAL repetition ratings >/= 4 (OR 2.81, CI 1.40-5.62) and hand/wrist posture ratings (OR 1.59, CI 1.01-2.49) were associated with disorders in the nondominant hand. These findings show moderate to good inter-rater agreement and significant relationships to health outcomes for the identified measures.

Field evaluation of a new grocery checkstand design.

A novel express checkstand with basket cut-out was developed and evaluated in a small grocery store chain. Eight checkers performed three trials of simulated grocery checkout work with actor customers using both old and new checkstand designs. Usability was assessed by survey, structured interview and observation. Time-motion video analysis was used to evaluate differences in body postures, motions, and productivity. The new express checkstand design, which lowered and angled the presentation of the grocery basket, significantly (p<0.05) reduced right wrist flexion duration and repetition, and right arm elevation repetition. No significant differences were found in job cycle time between designs. These results demonstrate the utility of a new express checkstand design that could reduce extreme postures and motions with no loss in productivity.