Our Method
Most nexus letters end where ours begin. A sentence of professional judgment carries no data behind it, and a C&P examiner or VA rater can discount it in a line. Every opinion we author is a structured, literature-backed causation argument — Hill’s criteria applied point by point, AMA Guides–based causation methodology, and cited peer-reviewed research establishing mechanism, plausibility, and clinical consistency.
Opinion-only letter
Our method
Framework One
Sir Austin Bradford Hill’s criteria are the recognized epidemiological framework for reasoning from association to causation. We do not gesture at them — each applicable criterion is addressed against the veteran’s own record and the published literature.
01
How strongly the exposure or in-service event is associated with the diagnosed condition in the published literature, not merely in impression.
02
Whether the same association has been observed repeatedly across independent studies, populations, and clinical settings.
03
Whether the exposure produces a recognizable pattern of injury consistent with the veteran's documented presentation.
04
Whether the exposure clearly preceded onset — reconstructed from service treatment records, post-service care, and the veteran's clinical course.
05
Whether greater duration, load, or intensity of exposure corresponds to greater risk or severity — highly relevant to cumulative spine and joint loading.
06
Whether a credible anatomic and physiologic mechanism explains the injury, supported by cited peer-reviewed research.
07
Whether the causal explanation fits what is already known about the natural history and pathophysiology of the condition.
08
Whether intervention data, biomechanical studies, or closely analogous exposures reinforce the causal inference.
Framework Two
The AMA Guides set out a disciplined sequence for causation analysis. It forces the reasoning into the open and requires that competing explanations be confronted rather than avoided.
Confirm the specific spine, nerve, or joint diagnosis with objective support — imaging, electrodiagnostics, examination findings, and treating-provider documentation.
Document the in-service event or cumulative exposure in detail: mechanism, load, frequency, duration, protective equipment, and duty requirements.
Identify peer-reviewed literature and population-level incidence data addressing that exposure-condition relationship, and weigh its quality.
Rule competing causes in or out on the record — age-related degeneration, post-service occupation, prior injury, comorbidity — rather than ignoring them.
Reach the 'at least as likely as not' standard explicitly, with the reasoning, criteria, and citations that support it laid out in writing.
Framework Three
Biological plausibility and clinical consistency are not assertions — they are claims that the literature either supports or does not. We cite established research on injury mechanism, population-level incidence in service members, and the natural history of the condition.
The result is a letter that can be checked. A rater who wants to test the reasoning can follow the citations rather than take a clinician’s word for it.
C&P examiners and VA raters are evaluating the strength of the evidence, not just the opinion itself. A letter that says “I believe this is connected” is easy to discount.
A letter that says “this is connected, and here is the peer-reviewed literature establishing the mechanism, the population-level incidence data, and the causation framework applied” is much harder to dismiss.
Who applies it
Our opinions are authored by a Chiropractic Physician and university professor with a PhD in Health Sciences, an MS in Neuroscience, and advanced training in clinical neurology, who teaches pain physiology, neurological examination, and pathophysiology at the graduate and undergraduate levels. Doctoral-level academic training matters here: a nexus letter is a written argument, and it has to be structured, cited, and reasoned to survive scrutiny.
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