SLEEP APNEA SYNDROMES (OBSTRUCTIVE CENTRAL MIXED)

Summary

The veteran, who served from June 1970 to March 1972, appeals the denial of service connection for obstructive sleep apnea and hypertension, both claimed as secondary to his service-connected bilateral knee disability with obesity as an intermediate step. The veteran also appeals the denial of Total Disability based on Individual Unemployability (TDIU). The Board reviewed multiple VA medical opinions, finding the August 2025 and December 2025 opinions more probative. These favorable opinions concluded that the veteran's bilateral knee disability aggravated his obesity, which in turn contributed to his sleep apnea and hypertension. The Board found these opinions more responsive to the specific causal chain than the negative opinions, which focused on direct causation or general medical principles. The Board resolved reasonable doubt in the veteran's favor, granting service connection for sleep apnea and hypertension as secondary to the knee condition. For the TDIU claim, the Board considered the veteran's occupational history as a teacher and housing specialist, along with medical evidence detailing significant limitations from his knee condition and severe daytime somnolence from sleep apnea. The Board found these combined disabilities precluded him from substantially gainful employment, granting TDIU and resolving doubt in his favor.

Rationale

Favorable opinions found knee disability aggravated obesity, which caused sleep apnea.; Negative opinions did not adequately address obesity as an intermediate step.; Evidence found in equipoise, with doubt resolved in veteran's favor.

Full Decision Text

Citation Nr: A26038834
Decision Date: 04/27/26	Archive Date: 04/27/26

DOCKET NO. 260324-640798
DATE: April 27, 2026

ORDER

Service connection for obstructive sleep apnea as secondary to the service-connected bilateral knee disability, with obesity as an intermediate step, is granted.

Service connection for hypertension as secondary to the service-connected bilateral knee disability, with obesity as an intermediate step, is granted.

Entitlement to a total disability rating based on individual unemployability (TDIU) is granted.

FINDINGS OF FACT

1. The most probative medical evidence demonstrates that the Veteran's currently diagnosed sleep apnea was caused or aggravated by his service-connected bilateral knee disability.

2. The most probative medical evidence demonstrates that the Veteran's currently diagnosed hypertension was caused or aggravated by his service-connected bilateral knee disability.

3. The Veteran's service-connected disabilities precluded him from securing or following substantially gainful employment.

CONCLUSIONS OF LAW

1. The criteria for service connection for sleep apnea as secondary to the service-connected bilateral knee disability are met.  38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.310; VAOPGCPREC 1-2017.

2. The criteria for service connection for hypertension as secondary to the service-connected bilateral knee disability are met.  38 U.S.C. §§ 1110, 5107; 38 C.F.R. §§ 3.102, 3.310; VAOPGCPREC 1-2017.

3. The criteria for a TDIU are met.  38 U.S.C. §§ 1155, 5107, 5110; 38 C.F.R. §§ 3.2500, 3.400, 4.16.

REASONS AND BASES FOR FINDINGS AND CONCLUSIONS

The Veteran served on active duty from June 1970 to March 1972.

These matters come to the Board of Veterans' Appeals (Board) on appeal from a September 2025 and March 2026 rating decisions issued by the Department of Veterans Affairs (VA) Regional Office (RO).

The Board acknowledges the recent United States Court of Appeals for Veterans Claims (Court) decision in Williams v. McDonough, 37 Vet. App. 305 (2024) which found that under 38 C.F.R. § 20.202(c)(2), the Board generally may not decide an appeal before the deadline for requesting an AMA docket switch has elapsed.  38 C.F.R. § 20.202(c) allows appellants to switch AMA dockets by completing and submitting a new VA Form 10182 within 60 days from when the Board receives the original VA Form 10182, or one year from the date the AOJ mails notice of the decision on appeal, whichever is later, unless (1) an appellant has already submitted evidence or testimony as described in 38 C.F.R. §§ 20.302 and 20.303, or (2) the appellant or representative has requested a waiver of the ability to request to switch dockets during this timeframe.  See also Williams, 37 Vet. App. 305.  

The Board acknowledges that the Appellant's case has been advanced on the docket pursuant to 38 C.F.R. § 20.902(c).  The Board finds such constitutes an implicit waiver of the Appellant's ability to request a docket switch, which would otherwise require the Board to hold the appeal open until one year following the rating decisions in this case.  In addition, given the Board's decision herein granting the benefits sought on appeal, there is no prejudice to the Veteran.

Service Connection - Laws and Regulations

Establishing service connection on a secondary basis requires evidence sufficient to show (1) that a current disability exists, and (2) that the current disability was either (a) caused by or (b) aggravated by a service-connected disability.  Allen v. Brown, 7 Vet. App. 439, 448 (1995) (en banc); see also Spicer v. McDonough, No. 2022-1239 (Fed. Cir. March 8, 2023) (invalidating the requirement of "proximate cause" and instead holding that "but for" causation or aggravation is enough to show entitlement to secondary service connection).  In other words, the but-for causation standard is not limited to a single cause and effect, but rather contemplates multi-causal links, including action and inaction.  The "but-for causation standard is broader than the proximate cause evidentiary standard.

VA's General Counsel has held that
 Allen v. Brown, 7 Vet. App. 439, 448 (1995) (en banc); see also Spicer v. McDonough, No. 2022-1239 (Fed. Cir. March 8, 2023) (invalidating the requirement of "proximate cause" and instead holding that "but for" causation or aggravation is enough to show entitlement to secondary service connection).  In other words, the but-for causation standard is not limited to a single cause and effect, but rather contemplates multi-causal links, including action and inaction.  The "but-for causation standard is broader than the proximate cause evidentiary standard.

VA's General Counsel has held that obesity may act as an intermediate step between a service-connected disability and a current disability that may be service-connected on a secondary basis under 38 C.F.R. § 3.310 (a).  VAOPGCPREC 1-2017 (Jan. 6, 2017).  However, obesity itself is not a disease for purposes of 38 U.S.C. §§ 1110 and 1131 and therefore "may not be service connected on a direct basis." Id.   In Walsh v. Wilkie, 32 Vet. App. 300 (2020), the Court extended the rationale from the General Counsel's opinion and concluded that obesity as an "intermediate step" in a causal chain for service connection can be established on either a causal or aggravation basis. 

The Board must analyze the credibility and probative value of the evidence, account for the evidence that it finds persuasive or unpersuasive and provide the reasons for its rejection of any material evidence favorable to the claimant.? Kahana v. Shinseki, 24?Vet. App.?428, 433 (2011).? This includes weighing the credibility and probative value of lay evidence against the remaining evidence of record.? See King v. Shinseki, 700 F.3d 1339 (Fed. Cir. 2012); Kahana, 24?Vet. App.?at 433-34.? 

A veteran bears the evidentiary burden to establish all elements of a service connection claim, including the nexus requirement.? Fagan v. Shinseki, 573 F.3d 1282, 1287 (Fed. Cir. 2009).? 

VA is responsible for determining whether the evidence supports the claim or is in relative equipoise, with a claimant prevailing in either event.? 38?U.S.C. §?5107(b); 38?C.F.R. §?3.102.? The claimant is entitled to the benefit of the doubt when there is an "approximate" (meaning nearly equal) balance of positive and negative evidence regarding any material determination.? See?Lynch v. McDonough, 999 F.3d 1391 (2021); Ortiz?v.?Principi, 274 F.3d 1361 (Fed. Cir. 2001).

Sleep Apnea - Evidence and Analysis

The Veteran asserts that service connection for sleep apnea is warranted as secondary to his service-connected bilateral knee disability, with obesity as an intermediate step.

The first element of the claim is met as there is evidence of a current disability.  Specifically, the record reflects a diagnosis of obstructive sleep apnea.  See e.g., June 2025 VA examination report.

Subsequent to the Board's April 2025 remand, VA obtained medical opinions in June 205, August 2025, December 2025, January 2026, and February 2026.

On review, the Board resolves any reasonable doubt in the Veteran's favor and finds that the diagnosed obstructive sleep apnea is etiologically related to his service-connected bilateral knee disability, with obesity as an intermediate step.

Evidence against the claim includes the June 2025, January 2026, and February 2026 medical opinions. 

In June 2025, a VA examiner opined that the sleep apnea was less likely than not proximately due to or the result of the service-connected right and left knee disabilities and less likely than not aggravated beyond its natural progression by those disabilities.  However, the rationale largely addressed whether arthritis directly caused sleep apnea and included reasoning that did not respond to the Board's remand question regarding obesity as an intermediate step.

In January 2026, a VA examiner opined that sleep apnea was less likely than not aggravated beyond its natural progression by the service-connected bilateral knee disabilities and that obesity was not a substantial factor in causing sleep apnea.  The examiner relied primarily on general medical propositions, including that obesity is a multifactorial and that some individuals with obstructive sleep apnea are not obese.  Similarly, in February 
 not proximately due to or the result of the service-connected right and left knee disabilities and less likely than not aggravated beyond its natural progression by those disabilities.  However, the rationale largely addressed whether arthritis directly caused sleep apnea and included reasoning that did not respond to the Board's remand question regarding obesity as an intermediate step.

In January 2026, a VA examiner opined that sleep apnea was less likely than not aggravated beyond its natural progression by the service-connected bilateral knee disabilities and that obesity was not a substantial factor in causing sleep apnea.  The examiner relied primarily on general medical propositions, including that obesity is a multifactorial and that some individuals with obstructive sleep apnea are not obese.  Similarly, in February 2026, a VA examiner opined that the Veteran's obesity was less likely than not caused or aggravated by his bilateral knee disabilities and that a nexus had not been established between the knee disabilities, obesity, and obstructive sleep apnea.

In support of the claim, the record contains favorable August 2025 and December 2025 opinions.

In August 2025, a VA examiner opined that the Veteran's obesity was at least as likely as not aggravated beyond its natural progression by his service-connected bilateral knee disability, including the effects of medications taken for treatment thereof.  The examiner explained that chronic bilateral knee osteoarthritis causes pain, stiffness, decreased range of motion, and reduced physical activity and functional mobility, which promote positive energy balance and gradual weight gain, thereby contributing to worsening obesity over time.

In December 2025, a VA examiner likewise opined that the Veteran's obesity was at least as likely as not aggravated beyond its natural progression by his service-connected bilateral knee disability.  The examiner explained that the Veteran's bilateral knee disability caused persistent pain, reduced range of motion, stiffness, and functional limitations, thereby limiting his ability to engage in regular physical activity and weight-bearing exercise.  The examiner further noted a relationship between worsening bilateral knee symptoms and progressive weight gain.  Significantly, the same examiner then opined that the Veteran's sleep apnea was at least as likely as not proximately due to obesity, explaining that obesity was the primary driving factor in the development of his sleep apnea. 

On review, the Board finds that the evidence is at least in equipoise.  The August 2025 and December 2025 opinions are more responsive to the dispositive question in this case because they directly address whether the service-connected bilateral knee disabilities aggravated obesity and whether that obesity in turn led to sleep apnea.  These opinions reflect consideration of the Veteran's particular medical history, functional limitations, and the chronology of worsening knee symptoms and weight gain, and they provided reasoned explanations for the conclusions reached.  See Nieves-Rodriguez v. Peake, 22 Vet. App. 295 (2008). 

By contrast, the negative opinions primarily analyzed whether knee arthritis directly cause sleep apnea, rather than the raised theory of obesity as an intermediate step.  Others relied largely on general medical principles without persuasively explaining why those general principles outweighed the specific facts of this Veteran's case.

Accordingly, the Board finds that the evidence is at least in approximate balance as to whether the Veteran's service-connected bilateral knee disability aggravated his obesity, and whether that obesity was an intermediate step leading to sleep apnea.  Resolving reasonable doubt in the Veteran's favor, service connection for sleep apnea is warranted.

Hypertension - Evidence and Analysis

The Veteran asserts that service connection for hypertension is warranted as secondary to his service-connected bilateral knee disability, with obesity as an intermediate step.

The first element of the claim is met as there is evidence of a current disability.  Specifically, the record reflects a diagnosis of hypertension.  See e.g., June 2025 VA examination report.

Subsequent to the Board's April 2025 remand, VA obtained June 2025, August 2025, December 2025, January 2026, and February 2026 medical opinions.

On review, the Board resolves any reasonable doubt in the Veteran's favor and finds that the diagnosed hypertension is etiologically related to his service-connected bilateral knee disability, with obesity as an intermediate step.

Evidence against the claim includes the June 2025, January 2026, and February 2026 VA medical opinions.

In June 2025, a VA examiner opined that hypertension was less likely than not proximately due to or the result of the service-connected right and left knee disabilities and less likely than not aggravated beyond its natural progression by those disabilities.  However, the rationale primarily addressed whether arthritis directly caused hypertension and did not adequately address the theory of obesity as an intermediate step.

In January 2026 and February 2026, Va examiners again provided negative opinions.  These examiners emphasized that obesity is multifactorial, that the Veteran had other
 to his service-connected bilateral knee disability, with obesity as an intermediate step.

Evidence against the claim includes the June 2025, January 2026, and February 2026 VA medical opinions.

In June 2025, a VA examiner opined that hypertension was less likely than not proximately due to or the result of the service-connected right and left knee disabilities and less likely than not aggravated beyond its natural progression by those disabilities.  However, the rationale primarily addressed whether arthritis directly caused hypertension and did not adequately address the theory of obesity as an intermediate step.

In January 2026 and February 2026, Va examiners again provided negative opinions.  These examiners emphasized that obesity is multifactorial, that the Veteran had other possible risk factors for hypertension, and that the record did not establish that the bilateral knee disabilities caused or aggravated obesity in a legally significant manner.  However, those opinions again relied heavily on generalized medical principles and did not persuasively explain why the Veteran's documented bilateral knee pain, mobility limitations, and progressive weight gain did not materially contribute to hypertension.  

In support of the claim, the record contains favorable August 2025 and December 2025 opinions.  

In August 2025, a VA examiner opined that the Veteran's obesity was at least as likely as not aggravated beyond its natural progression by his service-connected bilateral knee disability, including treatment effects.  The examiner explained that chronic bilateral knee osteoarthritis caused pain, stiffness, decreased range of motion, and reduced physical activity and functional mobility, thereby contributing to worsening obesity over time.  

In December 2025, a VA examiner likewise opined that the Veteran's obesity was at least as likely as not aggravated beyond its natural progression by the service-connected bilateral knee disability.  The examiner explained that the bilateral knee disability limited standing, walking, weight-bearing, and exercise tolerance, thereby reducing caloric expenditure and contributing to progressive weight gain beyond what would be expected from normal aging alone.  The examiner then opined that the Veteran's hypertension was at least as likely as not proximately due to obesity, explaining that obesity is one of the strongest and most consistently supported contributors to hypertension through increased sympathetic nervous system activity, activation of the renin angiotensin-aldosterone system, insulin resistance, endothelial dysfunction, vascular stiffness, and increased intravascular volume.  The examiner further stated that the Veteran's obesity, which was aggravated by the service-connected bilateral knee disability, materially and significantly contributed to the development of hypertension.

The Board acknowledges that the December 2025 opinion also included a statement that it was less likely than not that hypertension would not have occurred but for the obesity aggravated by the service-connected bilateral knee disabilities.  However, the examiner expressly found that obesity aggravated by the service-connected knee disabilities materially and significantly contributed to the development of hypertension.  The presence of multiple risk factors does not preclude entitlement where the evidence otherwise shows a but for causal chain involving service-connected disability, aggravated obesity, and the claimed condition.  See Spicer, supra.

On review, the Board assigns higher probative weight to the August 2025 and December 2025 opinions.  These opinions are more responsive to the theory expressly raised by the record and specifically addressed whether the service-connected bilateral knee disability aggravated the Veteran's obesity in turn contributed to hypertension.  These opinions reflect consideration of the Veteran's particular medical history, functional limitations, and the chronology of worsening knee symptoms and weight gain, and they provided reasoned explanations for the conclusions reached.  See Nieves-Rodriguez v. Peake, 22 Vet. App. 295 (2008). 

Accordingly, the Board finds that the evidence is at least in approximate balance as to whether the Veteran's service-connected bilateral knee disability aggravated his obesity, and whether that obesity was an intermediate step leading to hypertension.  Resolving reasonable doubt in the Veteran's favor, service connection for hypertension is warranted.

TDIU

Total disability ratings for compensation may be assigned, where the schedular rating is less than total, when a veteran is unable to secure or follow a substantially gainful occupation as a result of service-connected disabilities. 38 C.F.R. § 4.16(a).

The phrase "unable to secure and follow a substantially gainful occupation" contains both economic and noneconomic components. See Ray v. Wilkie, 31 Vet. App. 58, 73 (2019). The economic component is met when the Veteran is unemployed or marginally employed. Marginal employment generally shall be deemed to exist when the Veteran's earned annual income does not exceed the amount established by the U.S. Department of Commerce, Bureau of the Census, as the poverty threshold for one person. 38 C.F.R. § 4.16(a). Marginal employment includes employment in a protected environment, such as a family business or sheltered workshop, which involves a lower-income position that,
 4.16(a).

The phrase "unable to secure and follow a substantially gainful occupation" contains both economic and noneconomic components. See Ray v. Wilkie, 31 Vet. App. 58, 73 (2019). The economic component is met when the Veteran is unemployed or marginally employed. Marginal employment generally shall be deemed to exist when the Veteran's earned annual income does not exceed the amount established by the U.S. Department of Commerce, Bureau of the Census, as the poverty threshold for one person. 38 C.F.R. § 4.16(a). Marginal employment includes employment in a protected environment, such as a family business or sheltered workshop, which involves a lower-income position that, due to the Veteran's service-connected disabilities, is shielded in some respect from competition in the employment market. LaBruzza v. McDonough, 37 Vet. App. 111, 123-24 (2024). Consideration shall be given in all claims to the nature of the employment and the reason for termination. 38 C.F.R. § 4.16(a). 

The non-economic component of the phrase "unable to secure and follow a substantially gainful occupation" includes consideration of the Veteran's history, education, skill, and training; whether the Veteran has the physical ability (both exertional and non-exertional) to perform the type of activities required by the occupation at issue (e.g., lifting, bending, sitting, standing, walking, climbing, as well as auditory and visual limitations); and whether the Veteran has the mental ability to perform the activities required by the occupation at issue (e.g., memory, concentration, ability to adapt to change, handle work place stress, get along with coworkers, and demonstrate reliability and productivity). Ray, 31 Vet. App. at 73. 

The ultimate question of whether a veteran is capable of substantial gainful employment is not a medical one but rather a determination for the adjudicator.  See Geib v. Shinseki, 733 F.3d 1350, 1354 (Fed. Cir. 2013).

Neither nonservice-connected disabilities nor advancing age may be considered in the determination.  38 C.F.R. §§ 3.341, 4.19; Van Hoose v. Brown, 4 Vet. App. 361, 363 (1993).

Evidence and Analysis

According to a March 2022 knee examination report, the examiner indicated that the Veteran's bilateral knee disability impacted his ability to work.  The examiner noted that the Veteran had retired from teaching and later worked for the federal government in a desk job but had to rest frequently due to knee pain.

In the August 2022 VA Form 21-8940, Veterans Application for Increased Compensation based on Unemployability, the Veteran reported that he last worked full-time in 2013 as a housing specialist for the U.S. Department of Housing and Urban Development.  He reported four years of college education and no additional education or training.  

During the November 2022 knee examination, the examiner again found that the Veteran's bilateral knee disability impacted his ability to work.  The examiner explained that prolonged sitting caused the Veteran to need assistance getting up due to fatigue and difficulty bending and flexing both knees.  The examiner further noted that the Veteran used a cane for stability, was limited in his ability to walk and stand for more than a few minutes and had been prescribed a scooter to assist with mobility.  

November 2022 and June 2025 hypertension examination and May 2023 sleep apnea examination noted no impact on the Veteran's ability to work.  

During a December 2025 sleep apnea examination, the examiner found that the Veteran's sleep apnea did impact his ability to work.  The examiner explained that the Veteran experienced severe daytime somnolence, which would significantly reduce his ability to perform mental tasks and would make it dangerous to perform activities requiring the functioning of equipment and heavy machinery. 

On review, the Board finds that entitlement to a TDIU is warranted. 

Considering the Veteran's occupational and educational background together with the above-mentioned evidence, the Board finds that the Veteran's service connected disabilities preclude him from maintaining substantially gainful employment consistent with his education and work history.  The Veteran's prior employment was as a teacher and later he worked in a federal desk job.  Thus, the relevant question is whether he retains the mental and physical capacity to perform work of that nature.  Here, the record shows that he does not.

Regarding the economic component described in Ray, the Veteran reported that he last worked full-time in 2013.  There is no indication that he has maintained substantially gainful employment since that time.

Regarding the non-economic component, the Board finds that the combined effects of the service-connected disabilities would prevent the Veteran from securing
 with the above-mentioned evidence, the Board finds that the Veteran's service connected disabilities preclude him from maintaining substantially gainful employment consistent with his education and work history.  The Veteran's prior employment was as a teacher and later he worked in a federal desk job.  Thus, the relevant question is whether he retains the mental and physical capacity to perform work of that nature.  Here, the record shows that he does not.

Regarding the economic component described in Ray, the Veteran reported that he last worked full-time in 2013.  There is no indication that he has maintained substantially gainful employment since that time.

Regarding the non-economic component, the Board finds that the combined effects of the service-connected disabilities would prevent the Veteran from securing and following substantially gainful employment consistent with his background.  The evidence shows that his bilateral knee disability limits prolonged sitting, standing, walking, bending, flexing, and even the ability to rise after sitting without assistance.  These limitations would significantly impair even desk-based sedentary employment, which ordinarily requires the ability to sit for extended periods, change positions independently, and ambulate safely in an office environment.  In addition, the December 2025 sleep apnea examiner found that severe daytime somnolence would significantly reduce the Veteran's ability to perform mental tasks.  The Board finds that such impairment would directly affect the type of work for which this Veteran is qualified, including teaching and federal office work, both of which require sustained concentration, alertness, and reliability throughout the workday. 

The Board finds that the March 2022 and November 2022 knee examinations, the December 2025 sleep apnea examination, and the Veteran's August 2022 VA Form 21-8940 are highly probative.  This evidence directly address the Veteran's actual occupational limitations and, when considered together, show that the Veteran's service-connected disabilities impair both the physical and mental acts required for employment consistent with his education and work history.  Although other examiners noted no occupational impact from sleep apnea or hypertension, the Board finds that this evidence does not outweigh the more specific findings describing the Veteran's inability to sit for prolonged periods, difficulty rising, need for assistive devices, very limited walking and standing tolerance, and severe daytime somnolence affecting mental functioning.  At the very least, the evidence is in approximate balance.

For these reasons, the Board resolves reasonable doubt in the Veteran's favor and finds that that entitlement to a TDIU is warranted. 

 

 

S. B. MAYS

Veterans Law Judge

Board of Veterans' Appeals

Attorney for the Board	A. Yaffe, Counsel 

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.