Work-related Musculoskeletal Disorders of the Neck, Back, and Upper Extremity in Washington State, 1990-1998

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Washington State Department of Labor and Industries , Safety and Health Assessment Research for Prevention (SHARP) Program

Summary Statement

An in-depth research study of work-related musculoskeletal disorders in Washington state from 1990-1998 based on worker’s compensation claims.
May 2000


This study examines the frequency, incidence rate, severity rate, cost and industry distribution of non-traumatic soft tissue musculoskeletal disorders in Washington State in order to help focus prevention efforts by business, labor and government.

Methods: In the current study we examined State Fund workers compensation claims for general and selected specific hand/wrist, elbow, shoulder and back disorders in 1990- 1998. We examined the Self-Insured compensable (four or more lost workdays) claims data for general categories because diagnostic codes (ICD-9) were unavailable and calculated rates for 1992-1998 because hours for the Self-Insured were unavailable prior to 1992. We used a prevention index (PI) to rank industries by averaging the ranks of their number of claims and their claims incidence rate. The focus was on nontraumatic soft tissue musculoskeletal disorders (NTST-MSDs). In previous reports, we referred to these as gradual onset MSDs. These NTST-MSDs, when caused or aggravated by work activities, (for example exposures to frequent or heavy manual handling, awkward postures, forceful or repetitive exertions) are referred to as Work-related MSDs or WMSDs. There were some changes in the coding criteria (see methods section) from earlier reports. The lower extremity is not included in this report.

Results: Between 1990-1998, there were 392,925 State Fund accepted claims for non-traumatic soft tissue (NTST) musculoskeletal disorders (MSD) of the neck, back and upper extremity resulting in:

  • $2.6 billion in direct costs
  • 20.5 million lost workdays
  • 26.4% of all State Fund accepted claims
  • More than 36% were compensable (four or more lost workdays) compared to 23.5% of all claims
  • Average claims incidence rate (CIR) of 355 per 10,000 full-time equivalent employees (FTEs)
  • Average compensable claims incidence rate of 129 per 10,000 FTEs
  • 54.4% were claims for back disorders, 34% were for upper extremity disorders

The average number of State Fund NTST-MSD claims for the neck, back and upper extremity was 43,658 per year.

  • Average of $5,923 per claim
  • 146 lost workdays per compensable claim
Although the claims incidence rate for NTST-MSDs decreased over the study period (approximately 5% per year), it decreased significantly less than for all other claims (p=0.05). The CIR for upper extremity NTST-MSDs did not significantly decrease over the study period.

For the Self-Insured, coded data was available only for compensable Self-Insured accepted closed claims. While the number of claims was available from 1990-1998, data on hours worked were only available since 1992 so rates reflect 1992-1998. Therefore the analysis is limited to compensable claims (four or more lost workdays). There were 80,230 compensable closed NTST-MSD claims resulting in estimated:
  • $572 million in costs
  • Approximately 46.5% of all<> compensable claims
  • Average compensable CIR of 164.1 per 10,000 FTEs
  • 53% were back disorders and 33.4% were upper extremity disorders

The compensable claims incidence rate for the Self-Insured decreased only slightly, averaging 2.3% per year.

We looked at several specific diagnostic codes (ICD-9) for NTST-MSDs in the State Fund and found:

For sciatica there were 5,468 accepted claims and while infrequent (608 per year, CIR of 4.9 per 10,000 FTEs), they were extremely costly:

  • $39,371 per claim on average
  • 421 lost work days on average
  • 80% were compensable
  • The CIR did not significantly change over the study period
For rotator cuff syndrome, there were 17,030 accepted claims (1,898 per year) with:
  • An average CIR of 15.3 per 10,000 FTEs
  • Severity rate of 1,436 lost work days per 10,000 FTEs
  • Average cost of $15,226 per claim
  • 59% were compensable, averaging 236 lost workdays
  • The CIR did not change over the study period
For epicondylitis, there were 11,897 claims (1,322 per year) with:
  • An average CIR of 10.6 per 10,000 FTEs
  • Severity rate of 499 lost work days per 10,000 FTEs
  • Average cost of $6,959 per claim
  • 43% were compensable, averaging 208 lost workdays
  • A significant increase in the CIR over the study period.
For carpal tunnel syndrome, there were 27,148 claims (3,016 per year) with:
  • An average CIR of 24.5 per 10,000 FTEs
  • Severity rate of 2,524 lost work days per 10,000 FTEs
  • Average direct cost of $12,627 per claim
  • 66% were compensable, averaging 209 lost workdays
  • A significant decrease in the CIR over the study period

We used the Prevention Index to identify industries with the greatest impact of WMSDs. Industries are listed in rank order by the number of claims and by the rate of claims. The Prevention Index is the average of the two ranks for each industry. An industry therefore is high on the prevention Index if it has a relatively high number of claims and a relatively high claims rate. In the State Fund, Construction, Manufacturing and Transportation sectors ranked first, second and third on the Prevention Index. Among the Self-Insured, Transportation ranked first, followed by Retail Trade and Manufacturing, whereas construction ranked 8th. The CIR for Transportation appears to have increased over the study period among the Self-Insured.

We calculated the Prevention Index for industries classified by their 3-digit SIC codes. We also calculated a rate ratio for each industry by comparing the CIR for each industry with the overall state CIR. A rate ratio of 3 for example, means that the rate for that industry is 3 times the overall state rate. The top 10 industries for combined State Fund and Self-Insured Compensable NTST-MSDs were:

  1. Trucking and Courier Services (SIC 421) RR=3.0
  2. Nursing and Personal Care Services (SIC 805) RR=3.0
  3. Masonry, Stonework, Tile Setting and Plastering (SIC 174) RR=3.4
  4. Air Transportation Scheduled, and Air Courier Services (SIC 451) RR=2.8
  5. General Building Contractors-Residential Buildings (SIC 152) RR=2.1
  6. Roofing, Siding and Sheet Metal Work (SIC 176) RR=3.3
  7. Carpentry & Floor Work (SIC 175) RR=2.4
  8. Residential Care (SIC 836) RR=2.2
  9. Grocery Stores (SIC 541) RR=1.8
  10. Concrete Work (SIC 177) RR=2.9

We also looked at industry by using the Washington Industrial Risk Classification (WIC) codes. These codes are used for industrial insurance purposes and they code industries by similar processes and exposures. While in general the results are similar to the SIC analysis, there are some high risk industries that do not show up in the SIC analysis.

Top 10 Industries for NTST-MSDs by
Prevention Index and Washington Industrial Risk Classification (WIC)

Rank State Fund WIC Rate Ratio Self Insured Compensable WIC Rate Ratio
Nursing Homes
Parcel Package Delivery
Wood Frame Building Construction
Bus Companies
Wood Products Manufacturing
Airlines, Groud Crew
Wallboard Installation
Schools, All Other Employees
Warehouses NOC
Cities-All Other Employees
Building Construction NOC
Airlines, Flight Crews
Garbage Collection
Temporary Help-Administrative Staff*
Moving Companies
Wholesale Stores

Note: NOC=Not otherwise classified, All Other Employees=groundskeeping, maintenance, etc. *Temp Help Administrative in Self Insured also has temporary assembly and machine operator claims

As the report details, temporary help workers were at increased risk compared to overall industry for all NTST-MSDs, back and upper extremity NTST-MSDs, particularly temporary workers in assembly, vehicle operation, construction and machine operation (and in food processing for upper extremity NTSTs) and for the Self-Insured, temporary help-administrative.

Conclusions: Non-traumatic soft tissue musculoskeletal disorders continue to be a large and costly problem in Washington State. While the incidence rates for some NTST-MSDs are decreasing, the overall rate is not decreasing as fast as the rate for all other claims. In some cases, the rate is stable (sciatica, rotator cuff syndrome) or increasing (epicondylitis). The highest risks are in industries characterized by manual handling and forceful repetitive exertions. The contingent workforce appears to be at particularly high risk. These overall estimates of the burden of NTST-MSDs are most likely an underestimate because the lower extremity is not included, there is evidence of under-reporting of these kinds of disorders in the literature and the indirect costs to the employer, employee and society are not included.