Article

Cumulative trauma, cumulative costs: Managing California’s growing WC exposure

Explore the growing cost of California cumulative trauma claims and practical strategies employers can use to manage litigation and losses.

A trend building for years

Cumulative trauma (CT) claims have long been a feature of California's workers' compensation system but have shifted in the past three years from a background concern to a front-line financial exposure. The Workers' Compensation Insurance Rating Bureau of California (WCIRB) reported in July 2026 that CT claims now account for 31.6% of all indemnity claims in the state, up from 26.6% in 2025. That share has more than doubled over 15 years.

Unlike an acute injury — a fall, crush, or laceration — a CT claim arises from repetitive stress or strain over time. The injury is gradual, the causation is contested, and the path to resolution is long. Back injuries, carpal tunnel syndrome, tendonitis, and increasingly psychological trauma attributed to workplace stress all qualify. The broadening of what counts as cumulative trauma is partly driving claim growth.

The geography of risk

There’s a frequency and pattern to CT claims, especially in California. The WCIRB’s 2025 State of the System report stated CT claims spiked between 2022 and 2024, accounting for nearly 24% of all indemnity claims in accident year 2024. WCIRB noted CT claims rose throughout California, but the Los Angeles Basin had the highest number, 20%, followed by San Diego with 16%.

California Workers’ Compensation Institute (CWCI) studies found:

Almost 50% of all litigated work-injury claims in the Los Angeles Basin in 2024 were CT claims.
Southern California applicant attorneys representing claimants in CT cases involving Northern California employers increased from 23% in 2019 to 79% in 2025.
The share of CT cases involving Northern California employers that were filed in Southern California venues jumped from 15% to 38% during the same period.

Applicant attorneys are pursuing multiple claims through new strategies, fueling the statewide expansion of cumulative trauma claims due increased electronic appearances, aggressive litigation advertising, and a claimant-friendly Workers’ Compensation Appeals Board.

Why these claims are disproportionately expensive

CT injuries arise from exposure over multiple years, can involve multiple employers, and often involve litigation as well as higher utilization of medical-legal services.

WCIRB data tells much of the story:

CT indemnity claims close much more slowly than non-CT indemnity claims. WCIRB found that at the first report level (18 months after policy inception), only 20% of CT claims close versus 45% of non-CT claims at the same point.
CT claims are likely to be litigated, driving increases in allocated loss adjustment expenses (ALAE), a WCIRB analysis found. In addition, these claims are more likely to involve medical-legal and interpreter services, contributing to higher medical costs for the workers’ comp system.
Pure premium for CT claims has more than doubled since 2020, versus 30% for non-CT claims. CT claims now account for about 25% of pure premium costs.

CT claims involve unique challenges for employers, including: claims filed months or years after symptom onset; ambiguous causation, making it difficult to distinguish work duties from gradual deterioration of a worker’s health; and the exposure period involving potentially several contributing employers.

What effective management looks like

At Marsh, we have engaged with our Claims Advocates and the Work Comp Excellence Council to discuss how they are helping clients navigate this complex litigation landscape. We also engaged in meaningful discussions with our carrier partners, third-party administrators, and leading California defense counsels to identify practical steps employers can take, including:

Training and ergonomics. Recurring training can minimize the risk of common repetitive trauma injuries.
Prompt reporting of claims. Employers should remain mindful of state laws regarding notification and compensability decisions. In California, claims administrators have 14 days from date of knowledge of injury to issue a notice of delay and 90 days to determine compensability.
Thorough documentation. Medical records, leaves of absence, work history, job duties and any change in work conditions should be documented and preserved.
Regular communication. Maintain open communication with the employee, the claims examiner, and legal representatives throughout the claims process.
Proactive investigation. During the claims investigation period, employers should work with the claims administrator to collect a comprehensive medical record, including diagnosis, treatment history, relevant imaging studies, and prior medical records. Information on outside activities or concurrent employment that may have contributed to the injury is also helpful.

An employee must prove his or her work contributed to the injury, through aggravation or exacerbation. The threshold for compensable claims is low — a medical professional only needs to find 1% of industrial causation in California.

Litigation Strategies

Employers have different risk tolerances and preferences for handling litigated claims. Therefore, it’s essential to discuss a coordinated approach with your claims administrator and defense attorney at the start of a claim to build a strategy that aligns with the case facts.

Upon notice of a claim or receipt of an application for adjudication, refer the claim promptly to defense counsel to start the discovery process.
Evaluate if early settlement is appropriate. Leverage analytics to identify claims that are prone for adverse development.
Consider length of employment, job duties, claimant age, and medical diagnosis when evaluating early settlement, as all these factors can affect case value.
Work with your defense attorney to develop a strong litigation strategy if early resolution is not an option. This can include:
- Workers’ Compensation Appeals Board venue selection
- Managing deposition – limit additional panels, cite initial medical report, and determine if complaints aligned with initial medical or in a prior deposition.
- Subpoena of prior medical records and any prior accidents related to the alleged body parts.
- Leverage apportionment:
  - Limit the exposure period based on the injury timeline and supporting medical evidence. Is there a companion specific claim to shift some of the exposure?
  - Identify potential concurrent employment or outside activities.
- Evaluate if a panel qualified medical examiner (PQME) is necessary. Limit the scope of PQME required to address primary body parts and initiate the panel request in a timely manner to secure the appropriate medical specialties.
- Review and limit the medical records sent to PQME.

Looking ahead

Cumulative trauma claims represent a significant and evolving challenge that require a strategic, multifaceted approach that considers regulatory nuances, medical evidence, and procedural tactics.

Because each organization’s risk profile, industry, jurisdiction, workforce patterns, and settlement philosophy are different, there is no one-size-fits-all solution. For the best results, work closely with your insurer, TPA, and Marsh consultant to develop a strategy aligned with your goals.

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Article

Cumulative trauma, cumulative costs: Managing California’s growing WC exposure

A trend building for years

31.6%

2×

58%

20%

The geography of risk

Why these claims are disproportionately expensive

What effective management looks like

Litigation Strategies

Looking ahead

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