What Is the Difference Between Causation and Aggravation in a VA Secondary Claim?

Quick Answer

When seeking secondary service connection, VA recognizes two distinct legal theories under 38 CFR § 3.310: causation and aggravation. Causation means that an established, service-connected disability directly brought about or produced a new, separate disability. Aggravation means that a pre-existing or non-service-connected condition became worse due to the effects of an established service-connected disability, beyond its natural progression.

Many secondary claim denials occur because the claim and medical evidence were evaluated under causation when the medical facts actually supported aggravation, or vice versa. Causation requires competent medical evidence showing that Condition A caused Condition B. Aggravation requires evidence establishing a baseline level of severity before the aggravation occurred, followed by clinical proof that the service-connected disability caused an increase in severity beyond natural progression.

If VA denied your secondary claim because the examiner concluded the primary condition did not cause your secondary diagnosis, review your decision narrative carefully. An accredited representative can help determine whether the medical evidence supports a theory of secondary aggravation that was not adequately developed or evaluated.

You May Have Seen Language Like This

What Does This Mean?

When VA adjudicators evaluate a secondary claim, they must assess the evidence under the specific legal theory presented by the evidence:

1. Causation (`38 CFR § 3.310(a)`): Applies when the secondary condition is proximately due to, or the result of, a service-connected condition. The medical question is whether the primary condition directly produced the secondary condition. For example, if service-connected knee instability causes a veteran to fall and suffer a shoulder injury, the shoulder injury was caused by the knee condition.
2. Aggravation (`38 CFR § 3.310(b)`): Applies when a veteran already had a non-service-connected condition, and an established service-connected disability caused that condition to worsen. The medical question is not whether the primary condition caused the initial illness or injury, but whether it caused an increase in disability beyond what would have occurred naturally.
3. The Baseline Requirement: For aggravation claims under 38 CFR § 3.310(b), adjudicators must be able to ascertain the baseline severity of the non-service-connected condition prior to the alleged aggravation. Without evidence establishing how severe the condition was before the service-connected condition affected it, adjudicators may find it impossible to measure whether an increase beyond natural progression occurred.

Open Your VA Decision and Check These Things

• The Theory Evaluated: Does the decision narrative evaluate your claim under causation (38 CFR § 3.310(a)), aggravation (38 CFR § 3.310(b)), or both?
• The Medical Question Put to the Examiner: Check whether the C&P examiner was asked only whether the primary condition caused the secondary condition, or whether the examiner was also asked to consider aggravation.
• Pre-Existing Diagnosis: Did your records show that the secondary condition existed before the claimed worsening occurred?
• Baseline Severity: Does the record contain medical evidence establishing the severity of the secondary condition prior to the claimed worsening?
• Natural Progression Analysis: Did the examiner discuss whether the worsening was due to the natural progression of the underlying disease or was worsened by the service-connected disability?
• Favorable Findings: Check the Favorable Findings section to see whether VA conceded the diagnosis of the secondary condition and the service connection of the primary condition.

Questions to Consider

• Did the medical evidence frame your claim as causation when the clinical reality was that an established condition aggravated an existing issue?
• Did the C&P examination address whether the service-connected disability contributed to or aggravated the claimed condition?
• Is there medical documentation in the record establishing what the secondary condition was like before the primary condition affected it?
• Did the examiner explain whether the increased severity exceeded the expected natural progression of the secondary condition?

What Authoritative Sources Say

• 38 U.S.C. § 1110: Authorizes disability compensation for disabilities resulting from personal injury suffered or disease contracted in line of duty, providing the basic statutory foundation for service connection.
• 38 CFR § 3.310(a): Establishes secondary service connection for any disability that is proximately due to or the result of a verified service-connected condition.
• 38 CFR § 3.310(b): Establishes that any increase in severity of a non-service-connected disease or injury that is proximately due to or the result of a service-connected disability will be service connected, with compensation based on the degree of increase beyond natural progression measured against an established baseline level of severity.
• Allen v. Brown, 7 Vet. App. 439 (1995): Landmark en banc decision of the U.S. Court of Appeals for Veterans Claims holding that disability resulting from aggravation of a non-service-connected condition by a service-connected condition is compensable under 38 CFR § 3.310.
• Ward v. Wilkie, 31 Vet. App. 233 (2019): The Court rejected a permanent worsening requirement in the secondary-service-connection context, recognizing that the relevant inquiry concerns an increase in severity attributable to the service-connected condition, subject to the requirements of 38 CFR § 3.310(b), including natural progression and baseline severity.

What This Does Not Necessarily Mean

• It does not mean a secondary denial under causation bars an aggravation claim. If VA evaluated your claim only under causation, the record may still be open to development under an aggravation theory through appropriate review procedures.
• It does not mean you must prove the primary condition was the only factor. Under secondary aggravation, the primary condition need not be the sole cause of the worsening, but it must have proximately caused an increase in disability beyond natural progression.
• It does not mean baseline severity requires formal disability ratings. A baseline can often be established through medical records, clinical treatment notes, diagnostic imaging, or competent medical statements documenting the veteran's condition prior to the aggravation.

When This May Be a Medical Question

Distinguishing between causation and aggravation, and measuring an increase beyond natural progression, are clinical and medical determinations:

• Clinical Etiology: Whether Condition A produced Condition B, or whether Condition B existed independently and was made worse by Condition A, is a medical judgment requiring knowledge of disease pathology.
• Natural Progression vs. Accelerated Worsening: Determining how a disease normally progresses over time compared to how it progressed in an individual patient requires clinical expertise.
• Baseline Ascertainment: Clinicians must review historical records to establish a clinical baseline against which subsequent deterioration can be objectively measured.

Is More Medical Evidence Actually Needed?

More medical evidence may be helpful if:

• The previous medical opinion only addressed causation and never analyzed whether the primary disability aggravated the claimed condition.
• The record lacked clinical documentation establishing the baseline severity of the secondary condition before the worsening occurred.
• The examiner concluded that the worsening was entirely due to natural progression without explaining the clinical basis for that conclusion.

More medical evidence may not be needed if:

• The primary disability itself is not service connected.
• There is no verified current diagnosis for the secondary condition.
• The C&P exam was procedurally defective or failed to follow remand instructions, which may represent an administrative or legal issue.

Questions to Ask Your VA-Accredited Representative

• "Did VA evaluate my claim under causation, aggravation, or both theories under 38 CFR § 3.310?"
• "Did the C&P examiner address whether my service-connected condition aggravated my secondary condition beyond natural progression?"
• "Does my claims file contain sufficient evidence to establish a baseline severity for the secondary condition?"
• "Would additional medical evidence addressing aggravation or baseline severity be useful, or is the primary question how VA evaluated the existing record?"