Quantitative Assessment of Upper Extremity Capacity and Exposure

The classical ergonomics approach to workplace assessment includes consideration of the relevant task demands and characteristics of human capacity. In the case of the upper extremity, the primary exposure parameters measured often include force, posture, repetition, duration and environmental variables (i.e., vibration and temperature). Assessment is often best accomplished through direct measurement. The use of position, force and torque transducers, and electromyography electrodes provide the foundation for a direct measurement strategy that has been used to quantify these demands. The development and refinement of apparatus and approaches in our Research Center will be discussed, including specific laboratory and field applications. Similarly, methods for quantifying the typical capacity of the upper extremity, variations in capacity, and methods of relating capacity to performance requirements will be discussed.

The direct cost burden of 13years of disabling workplace injuries in the U.S. (1998-2010): Findings from the Liberty Mutual Workplace Safety Index

INTRODUCTION

Although occupational injuries are among the leading causes of death and disability around the world, the burden due to occupational injuries has historically been under-recognized, obscuring the need to address a major public health problem.

METHODS

We established the Liberty Mutual Workplace Safety Index (LMWSI) to provide a reliable annual metric of the leading causes of the most serious workplace injuries in the United States based on direct workers compensation (WC) costs.

RESULTS

More than $600 billion in direct WC costs were spent on the most disabling compensable non-fatal injuries and illnesses in the United States from 1998 to 2010. The burden in 2010 remained similar to the burden in 1998 in real terms. The categories of overexertion ($13.6B, 2010) and fall on same level ($8.6B, 2010) were consistently ranked 1st and 2nd.

PRACTICAL APPLICATION

The LMWSI was created to establish the relative burdens of events leading to work-related injury so they could be better recognized and prioritized. Such a ranking might be used to develop research goals and interventions to reduce the burden of workplace injury in the United States.

Geographic variation in opioid prescribing for acute, work-related, low back pain and associated factors: a multilevel analysis

BACKGROUND

Given reports about variation in opioid prescribing, concerns about increasing opioid use and its associated negative consequences make understanding the sources of variability important. The aims of the study were to assess the extent of and factors associated with geographic variation in early opioid prescribing for acute, work-related, low back pain (LBP).

METHODS

Cases were selected from workers compensation administrative data filed between January 1, 2002 and December 31, 2003 and included claims from states with more than 40 cases. Early opioid prescribing (one or more prescriptions within first 15 days) was the outcome. Weighted coefficient of variation (wCOV) estimated geographic variation, and multilevel models measured variability controlling for individual and contextual factors.

RESULTS

Of the 8,262 claimants, 21.3% received at least one early opioid prescription. Significant between-state variation was found (wCOV = 53%), from 5.7% (Massachusetts) to 52.9% (South Carolina). Seventy-nine percent of the between-state variation was explained by three contextual factors: state household income inequality (prevalence ratio [PR] 1.06, 95% confidence interval [CI] = 1.01, 1.12), number of physicians per capita (PR 0.99, 95% CI = 0.98, 0.99), and workers compensation cost containment effort score (PR 1.12, 95% CI = 1.02, 1.24). Individual-level factors, including severity, explained only a small portion of the geographic variability.

CONCLUSION

Geographic variation of early opioid prescribing for acute LBP is important and almost fully explained by state-level contextual factors. The study suggests that clinician and patient interaction and the subsequent decision to use opioids are substantially framed by social conditions and control systems. Am. J. Ind. Med. 52:162-171, 2009. (c) 2008 Wiley-Liss, Inc.

Relationship between early opioid prescribing for acute occupational low back pain and disability duration, medical costs, subsequent surgery and late opioid use

STUDY DESIGN

Retrospective cohort study of workers' compensation (WC) claims with acute disabling low back pain (LBP).

OBJECTIVE

To examine the association between early opioid use for acute LBP and outcomes: disability duration, medical costs, "late opioid" use (> or = 5 prescriptions from 30 to 730 days), and surgery in a 2-year period following LBP onset.

SUMMARY OF BACKGROUND DATA

Opioid analgesics have become more accepted for acute pain management. However, treatment guidelines recommend limited opioid use for acute LBP management. Little is known about the long-term impact on outcomes of opioid use for acute LBP.

METHODS

The sample consisted of 8443 claimants from a large WC database with new-onset, disabling LBP that occurred between January 1, 2002 and December 31, 2003. Based on morphine equivalent amount (MEA) in milligrams received in the first 15 days ("early opioids"), claimants were divided into 5 groups (0, 1-140, 141-225, 226-450, 450+). The associations between early opioids and outcomes were evaluated using multivariate linear and logistic regression models. Covariates included age, gender, job tenure, and low back injury severity. Injury severity was classified using ICD-9 codes.

RESULTS

Twenty-one percent of claimants received at least 1 early opioid prescription. After controlling for the covariates, mean disability duration, mean medical costs, and risk of surgery and late opioid use increased monotonically with increasing MEA. Those who received more than 450 mg MEA were, on average, disabled 69 days longer than those who received no early opioids (95% confidence interval [CI], 49.2-88.9). Compared with the lowest MEA group (0 mg opioid), the risk for surgery was 3 times greater (95% CI, 2.4-4.0) and the risk of receiving late opioids was 6 times greater (95% CI, 4.9-7.7) in the highest MEA group. Low back injury severity was a strong predictor of all the outcomes.

CONCLUSION

Given the negative association between receipt of early opioids for acute LBP and outcomes, it is suggested that the use of opioids for the management of acute LBP may be counterproductive to recovery.

Survey of Acute Low Back Pain Management by Specialty Group and Practice Experience

OBJECTIVE

The objective of this study was to explore concurrence with evidence-based management of acute back pain by primary care specialty and years in practice groups.

METHODS

Participants randomly selected from five American Medical Association physician groups were surveyed asking their initial care recommendations for case scenarios with and without sciatica. Response differences were compared among groups and with the Agency for Health Research Quality's guideline.

RESULTS

Response rate was 25%. Emergency physicians were least likely to order diagnostic studies for both cases but more often made recommendations likely to promote inactivity. Occupational physicians were less likely to order diagnostic studies and more likely choose treatments conducive to increasing activity. The longer physicians were in practice, the less likely they were to follow recommendations. All specialty groups selected more nonevidence-based interventions for the patient with sciatica. General practitioners were least likely to follow the guidelines in either case.

CONCLUSIONS

Despite widespread dissemination of acute low back pain guidelines, the study suggests a lack of adherence by certain primary care groups, physicians with more practice experience, and in specific areas of management.

Physicians' initial management of acute low back pain versus evidence-based guidelines. Influence of sciatica

BACKGROUND

Little information is available on physician characteristics and patient presentations that may influence compliance with evidence-based guidelines for acute low back pain.

OBJECTIVE

To assess whether physicians' management decisions are consistent with the Agency for Health Research Quality's guideline and whether responses varied with the presentation of sciatica or by physician characteristics.

DESIGN

Cross-sectional study using a mailed survey.

PARTICIPANTS

Participants were randomly selected from internal medicine, family practice, general practice, emergency medicine, and occupational medicine specialties.

MEASUREMENTS

A questionnaire asked for recommendations for 2 case scenarios, representing patients without and with sciatica, respectively.

RESULTS

Seven hundred and twenty surveys were completed (response rate=25%). In cases 1 (without sciatica) and 2 (with sciatica), 26.9% and 4.3% of physicians fully complied with the guideline, respectively. For each year in practice, the odds of guideline noncompliance increased 1.03 times (95% confidence interval [CI]=1.01 to 1.05) for case 1. With occupational medicine as the referent specialty, general practice had the greatest odds of noncompliance (3.60, 95% CI=1.75 to 7.40) in case 1, followed by internal medicine and emergency medicine. Results for case 2 reflected the influence of sciatica with internal medicine having substantially higher odds (vs case 1) and the greatest odds of noncompliance of any specialty (6.93, 95% CI=1.47 to 32.78), followed by family practice and emergency medicine.

CONCLUSIONS

A majority of primary care physicians continue to be noncompliant with evidence-based back pain guidelines. Sciatica dramatically influenced clinical decision-making, increasing the extent of noncompliance, particularly for internal medicine and family practice. Physicians' misunderstanding of sciatica's natural history and belief that more intensive initial management is indicated may be factors underlying the observed influence of sciatica.

Outcomes of workers' compensation claimants with low back pain undergoing intradiscal electrothermal therapy

STUDY DESIGN

Case series.

OBJECTIVE

To describe the outcomes of workers' compensation (WC) claimants who have had a lumbar intradiscal electrothermal therapy (IDET) procedure.

SUMMARY OF BACKGROUND DATA

IDET was developed as a less invasive treatment alternative to fusion after failure of conservative treatment for discogenic low back pain (LBP). Initial IDET case series from single practices have reported improved pain, function, and return to work outcomes. Little is known about results when performed by a variety of providers or in WC populations.

MATERIALS AND METHODS

LBP cases that underwent IDET between December 1, 1998 and February 29, 2000 were identified from WC records. Data sources included hardcopy claim files, administrative medical billing data, and computerized claim file narrative reports. Outcomes included narcotic use 6 months or more after IDET, additional invasive treatment after IDET (low back injections or surgery), and improved work status 24 months after IDET.

RESULTS

One hundred forty-two cases from 23 states were identified, with 97 different providers performing the procedure. Mean duration of symptoms before IDET was 26 months. Mean follow-up duration after IDET was 22 months. Ninety-six (68%) of the cases did not meet one or more of the published inclusion criteria. Seventy-eight cases (55%) received at least two narcotic prescriptions 6 months or more after IDET. Fifty-three (37%) had at least one lumbar injection and 32 (23%) had lumbar surgery after IDET. A total of 55 (39%) were working at 24 months after IDET; of these, 28 (20%) were not working and 27 (19%) were working before IDET. Narcotic use after IDET was associated with narcotic use before IDET, the same provider performing discography and IDET (provider self-referral), and positive signs of radiculopathy (C = 0.80). Need for invasive lumbar procedures after IDET were associated with provider self-referral, narcotic use before IDET, and older age (C = 0.73). Continued work absence after IDET was associated with provider self-referral, male gender, litigation, narcotic use before IDET, and older age (C = 0.83). Conformance with published selection criteria for IDET was not associated with provider self-referral or outcomes, nor was duration before IDET associated with outcomes.

CONCLUSION

The procedure may be less effective when performed by a variety of providers than suggested by initial case series performed by single providers or practices in work-related LBP cases. Provider self-referral and narcotic use before IDET are significant risk factors for poor outcomes. Randomized controlled trials are needed to determine whether there is a subset of patients with discogenic back pain who derive substantial and sustained benefit from this procedure.

Methodological challenges in studying recurrence of low back pain

Recurrences of low back pain (LBP) have been shown to be both frequent and costly, with reported recurrence rates ranging from 5 to 82%. Numerous methodological approaches have been developed to identify recurrence but there has been no standardized definition of LBP recurrence or required follow-up time. The objective of this study was to compare the methodological approaches used to analyze LBP recurrence in seminal contributions and to describe the differences in definitions of LBP recurrence and follow-up structure. Twelve seminal articles were identified for review during which four types of LBP recurrence definition and two types of follow-up structure were recognized. Definitional and follow-up differences considerably contributed to variations in computed recurrence rates due either to measurement or other methodological shortcomings, such as loss to follow-up and sick person effect. The results suggest that there is a need to develop a standardized definition of LBP recurrence and a standardized approach to follow-up to allow direct comparisons of published research findings. The use of alternative definitions is also likely to impact analyses of risk factors contributing to LBP recurrence and direct and indirect costs associated with treating LBP.

Disabling occupational injury in the US construction industry, 1996

In 1996 the US construction industry comprised 5.4% of the annual US employment but accounted for 7.8% of nonfatal occupational injuries and illness and 9.7% of cases involving at least a day away from work. Information in the published literature on the disability arising from construction injuries is limited. The construction claims experience (n = 35,790) of a large workers' compensation insurer with national coverage was examined. The leading types and sources of disabling occupational morbidity in 1996 in the US construction industry were identified. Disability duration was calculated from indemnity payments data using previously published methods. The average disability duration for an injured construction worker was 46 days with a median of 0 days. The most frequently occurring conditions were low back pain (14.8%), foreign body eye injuries (8.5%), and finger lacerations (4.8%). Back pain also accounted for the greatest percentage of construction claim costs (21.3%) and disability days (25.5%). However, the conditions with the longest disability durations were sudden-onset injuries, including fractures of the ankle (median = 55 days), foot (42 days), and wrist (38 days). Same-level and elevated falls were the principal exposures for fractures of the wrist and ankle, whereas elevated falls and struck by incidents accounted for the majority of foot fractures. Manual materials handling activities were most often associated with low back pain disability. The results suggest that these most disabling injuries can be addressed by increasing primary prevention resources in slips and falls and exposures related to injuries of sudden-onset as well as in reducing manual materials handling and other exposures associated with more gradual-onset injuries.

Maximal acceptable torques of highly repetitive screw driving, ulnar deviation, and handgrip tasks for 7-hour workdays

This study represents a continuation of a series of psychophysical studies on repetitive motions of the wrist and hand conducted at the Liberty Mutual Research Center for Safety and Health. The purpose of the study was to quantify maximum acceptable torques of six motions performed on separate days but within the context of the same experiment. The six motions were screw-driving clockwise with a 31-mm handle, a 40-mm handle, and a 39-mm yoke handle; screw-driving counterclockwise with a 31-mm handle; ulnar deviation with a power grip (similar to knife cutting), and a handgrip task (similar to a pliers task). A psychophysical methodology was used in which the subject adjusted the resistance on the handle, and the experimenter manipulated or controlled all other variables. Ten subjects performed the six tasks at repetition rates of 15, 20, and 25 motions per minute. Subjects performed the tasks for 7 hours per day, 5 days per week, for 4 weeks. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work they performed. Symptoms were recorded by the subjects during the last 5 min of each hour. The results revealed that mean maximum acceptable torques ranged from 0.33 to 0.65 Nm for screw driving, 1.08 to 1.13 Nm for ulnar deviation, and 4.80 to 4.85 Nm for the handgrip task. These values represent 14 to 24% (median of 17%) of maximum isometric torque depending on the frequency and motion. A table of maximum acceptable torques and forces of the six motions is presented for application in the field.

The reduction of chronic, nonspecific low back pain through the control of early morning lumbar flexion: 3-year follow-up

Three years ago, an 18-month randomized controlled trial of chronic, nonspecific low back pain investigated the effectiveness of instructing subjects to restrict bending activities in the early morning, when the fluid content in the disc is increased. Pain days (as recorded by daily diaries) were reduced 23% in the treatment group, compared to a 2% reduction in the control (sham treatment) group. The purpose of the current follow-up study was to determine whether the results of that trial were maintained during the 3 years following completion of the trial. A questionnaire was mailed to the 60 subjects who completed the original trial. Fifty subjects completed the questionnaire for a response rate of 83%. Thirty-one subjects (62%) continued to restrict bending activities in the early morning, and experienced a further reduction of 10.1 pain days per month (51%) since the completion of the experiment. However, some of the subjects who did not continue to comply also improved. Several possible explanations for the improvement of noncompliant subjects are offered.

Antecedent factors and disabling occupational morbidity--insights from the new BLS data

Since 1992 the United States Bureau of Labor Statistics' (BLS) annual survey of occupational injuries and illnesses (SOII) has collected data on occupational injuries and illnesses involving 1 or more days away from work (DAW). However, to date, the BLS has not published a comprehensive set of cross-tabulated part of body (BP), nature of injury or illness (NOI), and exposure/event (EE) data. To improve the understanding of the causes of disabling occupational morbidity in the United States, the present study used a special data call and data reduction strategy to identify the leading BP-NOI-EE combinations for DAW cases by frequency, incidence rate, and severity (median DAW) for 1996. The results indicated that the majority of injury and illness morbidity reported by the BLS was related to musculoskeletal conditions of either gradual or sudden onset and traumatic injuries of sudden onset. In particular, traumatic injuries from sudden events such as falls resulted in the most disabling cases. The results indicate that the occupational morbidity identified in the SOII requires interventions focused on overexertion and falls, as well as more traditional injury prevention approaches. The BLS can improve the utility of the system by adding provisions for a second event code to the coding structure and by improving direct access to these data for occupational health and safety professionals.

Psychophysical study of six hand movements

This study represents a continuation of a series of psychophysical studies on repetitive motions of the wrist and hand conducted at the Liberty Mutual Research Center for Safety and Health. The purpose of the study was to quantify maximum acceptable forces of six motions performed on separate days but within the context of the same experiment. The six motions were wrist flexion with a power grip, wrist extension with a power grip, wrist flexion with a pinch grip, wrist extension with a pinch grip, ulnar deviation with a power grip, and a handgrip task (with a power grip). A psychophysical methodology was used in which the subject adjusted the resistance on the handle and the experimenter manipulated or controlled all other variables. Thirty-one subjects performed the six tasks at repetition rates of 15, 20 and 25 motions/min. Subjects performed the tasks for 7 h per day, 5 days per week, for 4 weeks. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work performed. Symptoms were recorded by the subjects during the last 5 min of each hour. The results revealed that maximum acceptable torques ranged from 11 to 19% of maximum isometric torque depending on frequency and motion. Maximum acceptable torques for the tasks that could be compared with previous studies showed the same patterns of response. However, the selected forces were substantially lower using the mixed protocol. A table of maximum acceptable torques and forces is presented for application in the field.

Clinical management and the duration of disability for work-related low back pain

Clinical practice guidelines recommend a conservative approach to management of acute low back pain (LBP). The present study sought to determine whether health care utilization and the physician's initial management of work-related LBP were associated with disability duration. Clinical management information was obtained for 98 randomly selected, workers' compensation claimants with acute, uncomplicated, disabling work-related LBP. Length of disability was based on indemnity (wage replacement) payments. Disability was significantly associated with increased utilization of specialty referrals (P = 0.013) and provider visits (P < 0.001), use of magnetic resonance imaging (P = 0.003), and use of opioids for more than 7 days (P = 0.013). Effects of early diagnostic imaging (first 30 days of care) on length of disability were observed (P = 0.001). Patients whose treatment course did not involve extended opioid use and early diagnostic testing were 3.78 times more likely (95% confidence interval, 1.6 to 8.9) to have gone off disability status by the end of the study. The nature of the association between these initial clinical management aspects and LBP disability duration merits further exploration.

The relation between pain intensity, disability, and the episodic nature of chronic and recurrent low back pain

STUDY DESIGN

An observational study on the course of chronic and recurrent low back pain and its relation to disability and medication use performed on the basis of daily diary recording.

OBJECTIVES

To provide a description of daily pain reporting by individuals with self-reported chronic and recurrent low back pain, to study how the intensity and episodic nature of low back pain is related to disability and medication use, and to classify subjects according to Von Korff's categories of chronic low back pain.

SUMMARY OF BACKGROUND DATA

The natural history of low back pain has been described, and some classification schemes have been proposed, but little has been reported on pain characteristics and their relation to self-report of disability.

METHODS

Daily self-reports of pain intensity, social and work disability, and medication use were collected from 94 participants with self-reported chronic or recurrent low back pain over a 6-month period. A metric for describing the episodic nature of chronic low back pain was developed.

RESULTS

A significant effect of pain intensity on disability was found. During an episode, participants had significantly greater disability and medication use. Work-related disability and medication use was significantly greater in the latter half of an episode.

CONCLUSIONS

Pain intensity can affect disability, but the episodic nature of low back pain also affects the ability to function in both work and personal life. Intermittent increases in pain can markedly alter disability. Chronic low back pain should not be treated as a static phenomenon.

Clinical practices in the management of new-onset, uncomplicated, low back workers' compensation disability claims

Recent consensus guidelines delineate what appears to be the most successful and cost-effective management of low back pain (LBP), and some recent studies have suggested that better outcomes occur with the least aggressive forms of medical intervention. The purpose of this study was to describe how practitioners manage new-onset, uncomplicated low back workers' compensation (WC) disability cases. A sample of cases was randomly selected from a large insurance carrier's national data source. An effort was made to select only uncomplicated cases, which would be expected to have relatively minimal need for medical intervention. There was an apparent overuse of diagnostic and treatment modalities. Diagnostic imaging was overutilized, not only in terms of the number of studies done (65% had plain films, 22% had magnetic resonance imaging scans) but also in the time frame in which they were performed (38% had plain films on the first clinic visit). Ninety percent received at least one medication, and 38% received more than one prescription for opioid analgesics. Expensive non-steroidal anti-inflammatory drugs were prescribed more often than acetaminophen (61% versus 6%, respectively). Sixty-two percent received physical therapy that often included modalities with as yet unproven efficacy. Overutilization of either diagnostic or treatment procedures increases the likelihood of iatrogenic complications, is not cost-effective, and may adversely impact clinical and occupational outcomes.

Disabling occupational morbidity in the United States. An alternative way of seeing the Bureau of Labor Statistics' data

The United States Bureau of Labor Statistics' (BLS) annual survey of occupational injuries and illnesses (ASOII) is one of the most frequently utilized sources of data on national occupational morbidity. In 1992 the BLS introduced a new and expanded survey method that collects more detailed data on cases with days-away-from-work (DAW). However, to date, the BLS has not released any official publication that contains a comprehensive set of crosstabulated part-of-body (BP) and nature-of-injury (NOI) data. To improve the understanding of national DAW case morbidity estimates, the study presented here utilized a special data-call and data-reduction strategy to identify the leading ASOII BP-NOI combinations for DAW cases by frequency, incidence rate, and severity (median DAW) for 1994. The results indicated the significance of disability associated with discrete trauma (ie, resulting from instantaneous or sudden events) in the US workplace. While morbidity associated with back pain clearly continued as the most frequent type of disabling case, fractures at critical anatomical sites (eg, pelvic region, leg, shoulder) were responsible for the most lengthy disability absences from work in 1994. In some instances these findings were contrary to conclusions typically inferred from BLS publications.

The reduction of chronic nonspecific low back pain through the control of early morning lumbar flexion. A randomized controlled trial

STUDY DESIGN

Eighteen-month, randomized controlled trial with partial crossover.

OBJECTIVES

To test the hypothesis that the control of lumbar flexion in the early morning will significantly reduce chronic, nonspecific low back pain.

SUMMARY OF BACKGROUND DATA

Previous studies have indicated an increased risk of low back pain with bending forward in the early morning, primarily because of increased fluid content in the intervertebral discs at that time.

METHODS

After 6 months of recording baseline data, 85 subjects with persistent or recurring low back pain were randomly assigned to treatment and control groups. The treatment group received instruction in the control of early morning lumbar flexion. The control group received a sham treatment of six exercises shown to be ineffective in reducing low back pain. Six months later, the control group received the experimental treatment, Diaries were used to record daily levels of pain intensity, disability, impairment, and medication usage.

RESULTS

Significant reductions in pain intensity (P < 0.01) were recorded for the treatment group, but not for the control group (point estimate, 33%; 95% confidence interval, 11-55%). After receiving the experimental treatment, the control group responded with similar reductions (P < 0.05). Significant reductions also were observed in total days in pain, disability, impairment, and medication usage.

CONCLUSIONS

Controlling lumbar flexion in the early morning is a form of self-care with potential for reducing pain and costs associated with chronic, nonspecific low back pain.

Trends in disability duration and cost of workers' compensation low back pain claims (1988-1996)

Previously published epidemiologic studies of low back pain (LBP) have reported that the prevalence of low back disability has increased dramatically. These studies based their findings on either the number of disability claims filed, the disability duration, or both. This information was from countries other than the United States or from the US Social Security Disability Insurance data, with findings reported only to the early 1980s. More recent studies of US workers' compensation LBP claims reported a decrease in the incidence rate from the late 1980s to the mid-1990s. No studies have been found that report on the trends of disability duration for workers' compensation LBP claims. This study examined recent trends in the length of disability (LOD) for LBP claims and associated costs, using a large sample of claims from the privately insured US workers' compensation market. LOD and cost information were derived for injuries from 1988, 1990, 1992, 1994, and 1996. For each year, the distributions of LOD and cost were skewed, with the small percentage of claims that lasted more than one year (4.6%-8.8%, depending on the year) accounting for a large percentage of the total disability days (77.6%-90.1%) and cost (64.9%-84.7%). From 1988 to 1996, the average LOD decreased 60.9%, from 156 days to 61 days. The probability of being on disability for a long period of time has decreased over the years. Over the study period, the average cost of a claim decreased 41.4%, while the median cost increased 19.7%. The most influential change in the LOD and cost distributions was a reduction in expensive claims with a long disability duration. The evolution of LOD and cost is also detailed for different disability durations for the study period.

Healthcare utilization and referral patterns in the initial management of new-onset, uncomplicated, low back workers' compensation disability claims

Most episodes of low back pain are considered non-specific in nature, with the vast majority resolving within 2 weeks and almost all resolving within 6 weeks regardless of the medical intervention. Recently published clinical guidelines have clearly delineated a limited set of circumstances that would indicate the need for specialist referral. The purpose of this study was to describe the healthcare utilization and physician referral patterns for new-onset, uncomplicated, low back workers' compensation disability cases randomly selected from a large insurance carrier data source. The provision of care in urgent care centers and emergency departments for both initial and main sources of care occurred more frequently than was probably indicated. For this selected group of uncomplicated low back pain cases, specialist care was provided more commonly than would be expected or indicated (36% of the sample was seen by a surgeon, while only 2% received surgery). In addition, referral to specialists (other than occupational medicine specialists) was often made sooner than would be expected or indicated, with a median of 13 days for such referrals. Such overutilization of resources can reasonably be expected to increase overall medical costs.

Non-fatal workplace violence workers' compensation claims (1993-1996)

More is known about fatal workplace violence than non-fatal workplace violence (NFWV). This study provides descriptive information on the number and cost of NFWV claims filed with a large workers' compensation carrier. NFWV claims from 51 US jurisdictions were selected either by cause codes or by word search from the accident-description narrative. Claims reported in 1993 through 1996 were analyzed to report the frequency, cost, gender, age, industry, and nature of injury. An analysis of a random sample of 600 claims provided information on perpetrator type, cause of events, and injury mechanism. A total of 28,692 NFWV claims were filed during the study period. No cost was incurred for 32.5% of the claims, and 15.5% received payments for lost work. As a percentage of all claims filed by industry, schools had the highest percentage (11.4%) of NFWV claims, and banking had the highest percentage (11.5%) of cost. The majority of claims in the banking random sample group (93%) were due to stress. In the random sample, 90.3% of claims were caused by criminals (51.8%) or by patients, clients, or customers (38.5%). Only 9.7% were caused by an employee (9.2%) or a personal acquaintance of the employee (0.5%). Employers should acknowledge that NFWV incidents occur, recognize that the majority of perpetrators are criminals or clients rather than employees, and develop appropriate prevention and intervention programs.

Length of disability and cost of work-related musculoskeletal disorders of the upper extremity

There is little information on the length of disability (LOD) reported for work-related musculoskeletal disorders of the upper extremity (WMSDUE). For this study, LOD, cost, and the relationship between LOD and cost were derived from a large workers' compensation company's claims data for 1994 WMSDUE (n = 21,338). The average LOD was 87 days, with a median of zero days. For those claims with at least one day of compensable disability (25.2%), the average and median LOD were 294 and 99 days, respectively. The distribution of cost was skewed, with the average cost of a claim being 13 times higher than its median. Approximately 60% of the claims cost $1000 or less. Additionally, the 6.8% of the claims with an LOD greater than one year accounted for 59.9% of the cost and 75% of the total disability days. The majority of WMSDUE claimants did not lose sufficient time to qualify for indemnity. For those who did receive lost time wages, a disability duration of more than three months was typical.

Length of disability and cost of workers' compensation low back pain claims

Although information exists on the cost of workers' compensation low back pain (LBP), there is limited information on the duration of lost work time as well as the association between cost and duration. For this study, cost and duration of lost work time information were derived from a large workers' compensation company's database for 1992 LBP claims (n = 106,961). The distribution of cost was skewed, with an average cost of a claim being 20 times higher than its median. A disproportionately small percentage of the costliest LBP claims (10%) were responsible for a large percentage of the total cost (86%). The distribution of length of disability (LOD) was also skewed, with an average of 102 days and a median of zero. The average and median LOD for those claims with at least one day of compensable disability was 303 and 39 days, respectively. As a "rule of thumb," it was found that of those claimants who remain on disability at the end of n weeks, approximately 50% will be off disability at the end of 6.n weeks. Additionally, the 7% of the claims with an LOD greater than one year accounted for 75.1% of the cost and 84.2% of the total disability days. Disability days that were accrued after one year of disability accounted for 59.3% of the total number of disability days. This result suggests that other LOD estimation techniques, which may not account for disability days beyond one calendar year (e.g., the Bureau of Labor Statistics Annual Survey of Occupational Injuries and Illnesses), may result in a marked underestimation of LOD.

The influence of personal variables on work-related low-back disorders and implications for future research

Work-related low-back disorders (LBDs) continue to be one of the single largest sources of compensation costs. The relative contributions of personal, workplace, organizational, and environmental variables to the development and severity of LBDs are not completely understood. The inclusion of personal variables in epidemiologic studies of LBDs has been inconsistent, and different authors have different opinions concerning the importance of such variables. Personal variables either known or suspected to influence outcomes are discussed to elucidate the importance of these variables with respect to understanding LBDs and conducting epidemiological studies in industry. The authors suggest that age, gender, injury history, relative strength, smoking, and psychosocial variables be studied further, and that height, weight, pathologies, genetic factors, maximum oxygen uptake, and absolute strength are unlikely to produce significant effects in industrial populations.

Maximum acceptable forces for repetitive ulnar deviation of the wrist

The purpose of this experiment was to quantify maximum acceptable forces for ulnar deviation motions of the wrist at various repetition rates. Subjects grasped a handle with a power grip and moved it through a 1.40 rad (80 degrees) ulnar deviation wrist motion (similar to a knife cutting task). A psychophysical methodology was used in which the subject adjusted the resistance on the handle and the experiment manipulated or controlled all other variables. Two series of experiments were conducted. Thirteen subjects completed the first series, which investigated repetition rates of 15 and 20 motions per minute. Eleven subjects completed the second series, which investigated 15, 20, and 25 motions per minute. Subjects performed for 7 hours per day, 5 days per week, for 4 weeks in the first series and 5 weeks in the second series. The subjects were instructed to work as if they were on an incentive basis, getting paid for the amount of work they performed. Symptoms were recorded by the subjects during the last 5 minutes of each hour. The results are presented and compared with maximum acceptable forces for wrist flexion and extension.

Injury and illness in the American workplace: a comparison of data sources

Setting priorities for workplace health and safety research depends upon accurate and reliable injury and illness data. All occupational health databases have limitations when used to summarize the national scope of workplace hazards. The comparison of data from multiple sources may produce more credible estimates of the leading occupational injuries and illnesses. The purpose of this paper is to describe the strengths and weaknesses of six data collection systems that record occupational injuries and illnesses on a national level and to compare the leading estimates from these systems for 1990. The six systems are: 1) National Traumatic Occupational Fatalities database, 2) the Bureau of Labor Statistics Census of Fatal Occupational Injuries, 3) The Bureau of Labor Statistics Annual Survey data, 4) a large workers' compensation database, 5) the National Council on Compensation Insurance data, and 6) The National Electronic Injury Surveillance System. Occupational injuries, as defined herein, predominate over illnesses in terms of the number of cases and the overall costs. Databases that provide information on the antecedents of injuries suggest how these injuries may be prevented and warrant more attention and refinement.

Recent trends in work-related cumulative trauma disorders of the upper extremities in the United States: an evaluation of possible reasons

The increasing trends of cumulative trauma disorders of the upper extremities (CTDUEs) in US industry is well established; however, systematic examination of potential reasons for these trends has been lacking. Data from the United States Bureau of Labor Statistics and from Liberty Mutual Group workers' compensation claims were used to count CTDUEs. The proportions of all Bureau of Labor Statistics' cases and Liberty Mutual Group workers' compensation claims that resulted from CTDUEs were estimated for the years 1986 to 1993. The proportions by occupation (job classification code), gender, potential video display unit use, and in the meat-packing industry are described. Both data systems show a steady increase in cases and claims from less than 1% in 1986 to about 4% in 1993. Women and specific occupational categories are over-represented with respect to CTDUEs. A shift to service industry work and video display unit use do not appear to be strongly related to the increased reporting of CTDUEs, whereas increased productivity, an increased number of women in the work force and general awareness of CTDUEs in the media and health care system may be related. Coding and definition problems still limit these conclusions, however.

Psychophysical studies of repetitive wrist flexion and extension

The purpose of this experiment was to investigate the feasibility of using psychophysical methods to determine maximum acceptable forces for various types and frequencies of repetitive wrist motion. Four adjustable work stations were built to simulate repetitive wrist flexion with a power grip, wrist flexion with a pinch grip, and wrist extension with a power grip. The study consisted of two separate experiments. Subjects worked for two days per week during the first experiment, and five days per week during the second experiment. Fifteen women completed the first experiment, working seven hours each day, two days per week, for 20 days. Repetition rates of 2, 5, 10, 15 and 20 motions per minute were used with each flexion and extension task. Maximum acceptable torques were determined for the various motions, grips, and repetition rates without dramatic changes in wrist strength, tactile sensitivity, or number of symptoms. Fourteen different women completed the second experiment, performing a wrist flexion motion (power grip) fifteen times per minute, seven hours per day, five days per week, for 23 days. There were no significant differences in maximum acceptable torque from day to day. However, the average maximum acceptable torque for a five days per week exposure was 36.3% lower than for the same task performed two days per week. Assuming that maximum acceptable torques decrease 36.3% for other repetition rates and motions, tables of maximum acceptable force were developed for female wrist flexion (power grip), female wrist flexion (pinch grip), and female wrist extension (power grip).

The cost of compensable upper extremity cumulative trauma disorders

There is little information available of the costs of upper extremity cumulative trauma disorders. Cost data were collected from computerized records of the Liberty Mutual Insurance Company for upper extremity cumulative trauma disorder workers' compensation claims (N = 6,067) and for all claims (N = 731,087) initiated from 45 states during 1989. The data were not analyzed until July 1992, allowing more accurate "closing cost" data to be used in the analysis. Upper extremity cumulative trauma disorder cases represented 0.83% of all claims and 1.64% of all claims costs. The mean cost per case for upper extremity cumulative trauma disorders was $8070; median cost per case was $824. Medical costs represented 32.9% of the total costs; indemnity costs were 65.1%. The total compensable cost for upper extremity cumulative trauma disorders in the United States was estimated to be $563 million.

The cost of 1989 workers' compensation low back pain claims

STUDY DESIGN

Cost data were gathered from computerized records of the Liberty Mutual Insurance Company for low back pain workers' compensation claims (N = 119,107) and for all claims (N = 731,087) initiated from 45 jurisdictions (states) during 1989.

OBJECTIVE

This study provided more current, accurate, and additional information to estimate the costs and incidence associated with compensable low back pain compared with all compensation claims.

METHODS

The first group of data included all compensable low back claims selected by specific codes: body part codes consisted of low back area, sacrum and coccyx, disc, and multiple trunk; injury codes consisted of strain, sprain, inflammation, rupture, hernia, fracture, and contusion. The second sample included all compensable claims, including both occupational injuries and illnesses.

RESULTS

Low back pain cases represented 16% of all claims but 33% of all claims costs; 55.4% of the low back pain cases received medical payments only (i.e., did not receive indemnity payments for lost time). The mean cost per case for low back pain was $8321; median cost per case was $396. Medical costs represented 32.4% of the total costs; indemnity costs (i.e., payment for lost time) represented 65.8%.

CONCLUSIONS

Since indemnity costs represent the greatest percentage of workers' compensation expenditure, the primary goal of low back pain management should be the prevention or reduction of prolonged disability.

The cost of compensable low back pain

Cost data were retrieved from all claims of low back pain initiated during 1986 (N = 98,999) from computerized records of the Liberty Mutual Insurance Company. The mean cost per case was $6807; median cost, $391. Medical costs represented 31.5% of the total costs; indemnity costs, 67.2%. The total compensable cost for all low back pain in the United States was estimated to be $11.1 billion. Large variations were found to exist among different states in cost per case and percentage of costs for indemnity and medical payments.

The cost of disability

Approximately 16.5% of the adult population in the United States is disabled. About half of the disabled are severely limited and unable to work regularly. Musculoskeletal disorders are the most frequent type of disability. In the United States, there are three major types of disability insurance: Social Security Disability Insurance (a federal program), Workers' Compensation Insurance (usually a state-regulated program), and private health insurance. Recent years have seen a greater demand for private long-term disability insurance, as the trend increases toward less than total reliance on public programs to support disabled workers. The most recent statistics available indicate that Social Security Disability Insurance benefits are currently about $16.8 billion per year; workers' compensation benefits, $16.1 billion; and private disability income protection benefits, $5.2 billion. These figures add up to almost $40 billion in insurance costs. However, insurance costs are only part of the total cost because not everyone is covered by insurance, and insurance does not cover all disabilities. Disability can never be totally prevented or eliminated, but disability and its costs can be substantially reduced through more effective treatment and rehabilitation, including patient education and vocational rehabilitation.