NIOSH Urges Adherence to Updated Guidelines to Prevent CTS

Nancy Grover

Sarasota FL (WorkersCompensation.com) – Carpal Tunnel Syndrome is one of the most common and costly musculoskeletal disorders affecting workers. The estimated median care and total direct workers’ costs for CTS in 2013 dollars were $10,000 and $18,000, according to researchers. And yet, many workers in hand-intensive occupations are still exposed to limit above those recommended.

Guidelines established in 2001 were proven to be less than adequate to reduce the incidence of CTS and were modified in 2018. The resulting Threshold Limit Value (TLV) for Hand Activity developed by the American Conference of Governmental Industrial Hygienists (ACGHI) holds great promise for reducing the rates of CTS, thus protecting workers and saving money for employers and payers. Researchers at the National Institute for Occupational Safety and Health are pressing public health professionals to ensure the newest guidelines are used and encouraging employers to reduce hand intensive exposures to prevent CTS.

The Problem
The direct costs for hand, wrist and elbow MSDs among workers were estimated at more than $2 billion, with 11.8 million lost work days from 1999- 2013, in the state of Washington alone. CTS accounted for about half of these costs associated with 28 percent of the claims, according to researchers.

CTS is an MSD caused by frequent, forceful hand exertions. In addition to being a common and costly workers’ compensation injury, it has the second highest rate of opioid prescribing by injury type, according to NIOSH.
The 2001 voluntary guidelines set limits to help prevent CTS and other MSDs of the hand, wrist and elbow. TLV considers applied hand force as well as repetition of hand exertions. It is a limit within which a worker can be repeatedly exposed without adverse health effects. If the limit is exceeded, the risk of injury is heightened and control measures – such as engineering or administrative – should be implemented. A lower limit, called the Action Limit, constitutes a moderate risk level and should trigger monitoring or surveillance to protect workers.

Studies subsequently showed that far too many workers were exposed to harmful hand activity levels, despite the 2001 limits. That led to the 2018 TLV, described as a “proven, easy-to-use tool” to reduce the risk of CTS.

“Basically, the ratio of observed force to recommended force should be < 1.0 for a specific hand activity level score. The TLV® formulas are used to calculate a recommended force limit for any hand activity level score,” according to NIOSH. “In contrast, for the 2001 TLV®, practitioners categorized the ratio of hand activity level to normalized peak force into three distinct ranges: 1) below the Action Limit, 2) above the Action Limit but below the TLV®, or 3) at or above the TLV®.”

The Study
Researchers compared the effectiveness of the 2018 vs. the 2001 guidelines. Their findings were published in the Journal of Occupational and Environmental Hygiene.

More than 4,000 workers were studied. All were adults employed in jobs involving hand-intensive, often repetitive and forceful activities in industries such as manufacturing, healthcare and social assistance, services and construction. The researchers wanted to see how effective the 2001 and 2018 TLV and Action Limits could have been at preventing CTS if the workers’ exposures had been reduced.

“The study found that the 2018 revision of the TLV® better protects workers from CTS,” the researchers wrote. “The results showed that eliminating exposure above the TLV® for all workers would have prevented 21 cases of CTS (11% of all cases in the cohort) using the 2001 limit, and 47 cases (25% of cases) using the 2018 TLV®. For both the 2001 and 2018 recommendations, further reductions would be achieved by eliminating exposures above the Action Limit.”
Specifically, the workers exposed to limits above the 2001 Action Limit had “significant excess risk of CTS,” the researchers wrote. The 2018 TLV showed significant excess risk “only above the RLV,” rather than the Action Limit. “Of 186 total cases of CTS, 52 cases occurred among workers exposed above the 2001 TLV vs. 100 among those exposed above the 2018 value.”

“The 2018 revision of the TLV better protects workers from CTS,” the researchers concluded.

Despite the evidence, many workers are exposed to forceful repetitive hand activity above the guidelines. NIOSH is seeking input from organizations that have used the new TLV for Hand Activity. “A substantial number of workers in this study were exposed above both the 2001 and 2018 TLV®s recommended by ACGIH®,” NIOSH wrote. “This indicates an ongoing need to reduce exposures to prevent CTS and other upper extremity MSDs among workers in hand-intensive jobs.”

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