Diabetes as a “Confounding Condition” in Carpal Tunnel Claims: Deference to the Board’s Weighing of Medical Evidence

1. Introduction

In John Moore v. United Coal Company, LLC (W. Va. Apr. 24, 2026), the Supreme Court of Appeals of West Virginia affirmed—via memorandum decision—the Intermediate Court of Appeals of West Virginia (“ICA”), which had affirmed the Workers’ Compensation Board of Review (“BOR”) and the claim administrator’s denial of compensability for bilateral carpal tunnel syndrome (“CTS”).

Parties: John Moore (claimant/petitioner), an underground coal miner, alleged his CTS was caused by years of heavy, vibration-intensive tool use. United Coal Company, LLC (employer/respondent) maintained the evidence supported non-compensability, emphasizing an alternative causal factor—diabetes.

Core issue: Whether the ICA erred in affirming the BOR’s decision crediting the employer’s medical evidence (linking CTS to diabetes) over the claimant’s medical evidence (linking CTS to mining-related tool vibration and forceful wrist activity), and thus rejecting the claim as non-compensable.

2. Summary of the Opinion

The Court summarily affirmed the ICA under W. Va. R. App. P. 21, holding there was no reversible error in the BOR’s fact-finding or evidentiary weighing. Applying the Court’s standard of review—legal questions reviewed de novo, factual findings deferred to unless “clearly wrong”—the majority concluded the BOR permissibly found Dr. Austin Nabet’s report “more complete” because it addressed the claimant’s diabetes, a condition recognized in the workers’ compensation rules as one that can “produce or contribute to CTS.”

Dissent (Wooton, J.): The dissent would have found the claim compensable, reasoning that (i) the record contained credible evidence supporting both causation theories (work exposure and diabetes), (ii) the two medical opinions were of equal weight, and (iii) under W. Va. Code § 23-4-1g(a), an equal-evidence tie must be resolved in the claimant’s favor.

3. Analysis

3.1. Precedents Cited

  • Duff v. Kanawha Cnty. Comm'n, 250 W. Va. 510, 905 S.E.2d 528 (2024) (Syl. Pt. 3)
    The majority relied on Duff for the modern articulation of appellate review in workers’ compensation appeals: questions of law are reviewed de novo, while the BOR’s factual findings receive deference unless “clearly wrong.” This framework is outcome-determinative in close medical-causation disputes because it limits the Supreme Court’s role to correcting legal errors or clear factual mistakes, not reweighing competing expert reports.
  • Barnett v. State Workmens' Comp. Comm'r, 153 W. Va. 796, 172 S.E.2d 698 (1970) (Syl. Pt. 1)
    Cited in the dissent for the foundational compensability elements: (1) personal injury, (2) in the course of employment, and (3) resulting from employment. The dissent used Barnett to frame CTS as a compensable “personal injury” when the evidence establishes work-related causation.
  • Emmel v. State Comp. Dir., 150 W. Va. 277, 145 S.E.2d 29 (1965) (Syl. Pt. 3)
    Also cited by the dissent to emphasize that compensability requires a demonstrated causal connection between the injury and employment. The dissent’s key move was to argue that the claimant’s tool vibration and forceful wrist activity supplied a sufficient causal connection, even if diabetes was also a risk factor.
  • Moore v. United Coal Co., LLC, No. 25-ICA-137, 2025 WL 2781461 (W. Va. Ct. App. Sept. 30, 2025)
    The Supreme Court’s memorandum decision effectively adopts the ICA’s rationale: Dr. Nabet’s opinion was “more complete” because it addressed diabetes in a way consistent with the applicable regulations recognizing diabetes as a contributing condition for CTS.

3.2. Legal Reasoning

The majority’s reasoning is procedural and deferential: it does not announce a new multi-factor causation test for CTS. Instead, it reinforces two practical propositions in CTS/occupational disease litigation:

  1. The sufficiency of medical reasoning is assessed against recognized “confounding conditions.”
    The ICA and Supreme Court highlighted W. Va. Code of State Rules § 85-20-41.4, which lists diabetes among medical conditions that “frequently produce or contribute to CTS.” The BOR viewed the claimant’s expert report as weaker because it did not engage with diabetes as an alternative or contributing cause. Thus, completeness—addressing confounders documented in the record—became a decisive credibility/reliability factor.
  2. Appellate review will not reweigh close medical disputes absent clear error.
    Under Duff, once the BOR chooses between plausible competing expert accounts, the Supreme Court will not substitute its judgment unless the factual findings are “clearly wrong.” The majority implicitly treated the BOR’s choice as within its factfinding discretion.

The dissent’s reasoning is substantive and claimant-protective. It accepts that both diabetes and workplace biomechanics can contribute to CTS, pointing also to W. Va. Code of State Rules § 85-20-41.5, which recognizes that “awkward wrist positioning, vibratory tools, significant grip force, and high force of repetitive manual movements” contribute to CTS. From that premise, the dissent concludes the evidence was at least evenly balanced and invokes the statutory tie-breaker in W. Va. Code § 23-4-1g(a) requiring that equal evidentiary weight be resolved consistent with the claimant’s position.

3.3. Impact

Although issued as a memorandum decision, the opinion’s practical impact for West Virginia workers’ compensation CTS claims is significant in three ways:

  • Medical reports must address documented comorbidities. Where diabetes (or other listed conditions) appears in the medical record, an expert causation opinion that ignores it risks being characterized as incomplete and therefore less persuasive.
  • Regulatory “confounding conditions” can drive the factfinder’s credibility assessment. The decision signals that the BOR may legitimately rely on W. Va. Code of State Rules § 85-20-41.4 to evaluate whether causation opinions adequately engage alternative explanations.
  • Future litigation may sharpen around the § 23-4-1g(a) “equal weight” rule. The dissent provides a roadmap for claimants to argue that, once both work-related biomechanical contributors (§ 85-20-41.5) and medical risk factors (§ 85-20-41.4) are supported, the evidentiary balance may be “equal,” requiring claimant-favorable resolution. Employers and administrators, conversely, will emphasize why one side is not truly equal—often by pointing to omissions or lack of differential diagnosis in the claimant’s medical proof.

4. Complex Concepts Simplified

  • Compensability (workers’ compensation): Whether an injury/disease is legally recognized as caused by work, entitling the claimant to benefits.
  • “In the course of” vs. “resulting from” employment: The injury must occur within the employment context and be causally connected to the job duties.
  • CTS (carpal tunnel syndrome): Compression of the median nerve at the wrist, often associated with numbness, tingling, and weakness.
  • EMG/NCS: Electromyography and nerve conduction studies—tests used to identify nerve dysfunction consistent with CTS.
  • Confounding condition: A separate medical condition (here, diabetes) that can independently cause or contribute to the same symptoms, complicating causation analysis.
  • Preponderance of the evidence: The more-likely-than-not standard.
  • “Clearly wrong” review: A deferential standard—an appellate court will not disturb factual findings simply because it might have weighed the evidence differently.
  • Memorandum decision: A streamlined disposition; it resolves the appeal without a full-length published opinion, often where the court views the governing law as settled and the outcome as controlled by the standard of review.

5. Conclusion

Moore reinforces that in West Virginia CTS claims, the BOR may credit medical causation opinions that explicitly address recognized “confounding conditions” such as diabetes (W. Va. Code of State Rules § 85-20-41.4), and appellate courts will generally defer to that weighing absent clear error under Duff v. Kanawha Cnty. Comm'n. The dissent highlights a competing statutory principle—W. Va. Code § 23-4-1g(a)—arguing that when evidence is truly in equipoise, the claimant should prevail. Together, the majority and dissent frame the next battleground in CTS litigation: not whether vibration and forceful wrist work can cause CTS (the rules recognize it), but whether the claimant’s medical proof persuasively performs a differential causation analysis in the face of comorbid risk factors.