Citation Nr: A21020047 Decision Date: 12/15/21 Archive Date: 12/15/21 DOCKET NO. 200521-86621 DATE: December 15, 2021 REMANDED Service connection for obstructive sleep apnea (OSA) (claimed as secondary to service-connected PTSD) is remanded. REASONS FOR REMAND The Veteran served on active duty from January 1984 to December 1986 and from August 1989 to August 1994. This matter is before the Board of Veterans' Appeals (Board) on appeal from an April 2020 rating decision. The Veteran initiated this appeal via a May 2020 VA Form 10182 (Notice of Disagreement) electing the Direct Review appeal lane. Here, the Board finds that the April 2020 VA medical opinion was inadequate. It is well established that medical opinions addressing a secondary service connection theory of entitlement must address the issue of causation and aggravation. See El-Amin v. Shinseki, 26 Vet. App. 136 (2012). Although the examiner provided an opinion as to proximate causation, he did not address aggravation of OSA by service-connected PTSD. This is a pre-decisional duty to assist error that requires correction on remand. The matters are REMANDED for the following action: Obtain an opinion from a qualified clinician as to the following: Whether it is at least as likely as not that the Veteran's OSA is aggravated by his service-connected PTSD? *Note that aggravation means any incremental increase in disability in non-service-connected disabilities (i.e., any additional impairment of earning capacity) resulting from service-connected conditions). The examiner is asked to provide the underlying reasons for all opinions expressed, and is reminded that the term "as likely as not" does not mean "within the realm of medical possibility," but rather that the evidence of record is so evenly divided that, in the examiner's expert opinion, it is as medically sound to find in favor of the proposition as against it. Jennifer White Veterans Law Judge Board of Veterans' Appeals Attorney for the Board Kyle McKone The Board's decision in this case is binding only with respect to the instant matter decided. This decision is not precedential and does not establish VA policies or interpretations of general applicability. 38 C.F.R. § 20.1303.