Citation Nr: 1303805 Decision Date: 02/04/13 Archive Date: 02/08/13 DOCKET NO. 07-09 900A ) DATE ) ) On appeal from the Department of Veterans Affairs Regional Office in St. Paul, Minnesota THE ISSUE Entitlement to service connection for degenerative polyarthritis (claimed as degenerative joint disease), to include as secondary to service-connected hepatitis C. REPRESENTATION Veteran represented by: Disabled American Veterans ATTORNEY FOR THE BOARD Michael Wilson, Associate Counsel INTRODUCTION The Veteran served on active duty from July 1987 to July 1991. This matter comes to the Board of Veterans' Appeals (Board) on appeal from a June 2006 rating decision issued by the Department of Veterans Affairs (VA) Regional Office (RO) in St. Paul, Minnesota, which, in relevant part, denied the benefit sought on appeal. In his April 2007 substantive appeal (VA Form 9), the Veteran checked the box indicating that he would like to be scheduled for a hearing before a Veterans Law Judge (VLJ) of the Board at his local RO. He noted in the column next to the box, however, that he desired to have a hearing before an RO Decision Review Officer (DRO). A letter from the Veteran's representative accompanying his VA Form 9 additionally indicated the Veteran's desire to be scheduled for a DRO hearing. The Veteran was subsequently scheduled to appear for a DRO hearing on November 15, 2007. That same day, however, he provided a statement indicating that he wished to cancel his DRO hearing request. Two subsequent notices in the claims file, both dated in April 2008, indicated that the Veteran had been scheduled to appear for a hearing before a Board VLJ, via videoconference. One notice, provided to the Veteran's representative, indicated that his hearing was scheduled to be held on June 17, 2008. The second notice, addressed directly to the Veteran, indicated that his hearing was scheduled for June 19, 2009. In any event, the Veteran submitted a statement in June 2008 indicating that he wished to cancel his request for a hearing before a Board VLJ. Accordingly, the Board considers the Veteran's requests for hearings on his appeal to be withdrawn. See 38 C.F.R. § 20.704(e) (2012). In May 2010, the Board remanded the Veteran's claim on appeal to the RO via the Appeals Management Center (AMC), in Washington, D.C., for further development. As previously noted by the Board, although the Veteran also expressed his disagreement with the RO's decision to deny his claim for an increased disability rating for service-connected hepatitis C in his January 2007 notice of disagreement, he indicated in his April 2007 substantive appeal that he was only appealing the denial of his service connection claim for degenerative arthritis. Thus, his increased rating claim for hepatitis C is not on appeal before the Board. VHA Opinion In June 2012, the Board referred this case for medical expert opinion with the Veterans Health Administration (VHA). In July 2012, the Board received the VHA opinion. The Veteran was provided a copy of this opinion with an opportunity to present further argument and/or evidence. The Veteran did not submit any additional argument or evidence in support of his claim. Virtual VA Records The Board has also reviewed the Veteran's electronic Virtual VA file. No additional evidence has been added to the Veteran's electronic claims file since the issuance of the May 2011 supplemental statement of the case. FINDING OF FACT The preponderance of the evidence supports a finding that the Veteran's degenerative polyarthritis was incurred in active duty service. CONCLUSION OF LAW Degenerative polyarthritis was incurred in or aggravated by active duty service. 38 U.S.C.A. §§ 1110, 1131, 5107(b) (West 2002); 38 C.F.R. §§ 3.102, 3.303, 3.307, 3.309 (2012). (CONTINUED ON NEXT PAGE) REASONS AND BASES FOR FINDING AND CONCLUSION I. The Veterans Claims Assistance Act of 2000 (VCAA) The Veteran's claim has been granted, as discussed below. As such, the Board finds that any error related to the VCAA on this claim is moot. See 38 U.S.C. §§ 5103, 5103A (West 2002 & Supp. 2012); 38 C.F.R. § 3.159 (2012); Mayfield v. Nicholson, 19 Vet. App. 103, (2005), rev'd on other grounds, Mayfield v. Nicholson, 444 F.3d 1328 (Fed. Cir. 2006). II. The Merits of the Claim The Veteran attributes his current degenerative polyarthritis to his service-connected hepatitis C. In the alternative, he contends that his arthritis disability was incurred during or directly as a result of his active service. Governing Law and Regulations Service connection will be granted for a disability resulting from disease or injury incurred in or aggravated by active service. 38 U.S.C.A. § 1110, 1131 (West 2002); 38 C.F.R. § 3.303 (2012). Establishing service connection generally requires medical or, in certain circumstances, lay evidence of (1) a current disability; (2) an in-service incurrence or aggravation of a disease or injury; and (3) a nexus between the claimed in-service disease or injury and the present disability. See Davidson v. Shinseki, 581 F.3d 1313 (Fed.Cir.2009); Hickson v. West, 12 Vet. App. 247, 253 (1999); Caluza v. Brown, 7 Vet. App. 498, 506 (1995), aff'd per curiam, 78 F. 3d 604 (Fed. Cir. 1996) (table). The second and third elements may be established by showing continuity of symptomatology. Continuity of symptomatology may be shown by demonstrating "(1) that a condition was 'noted' during service or any applicable presumption period; (2) evidence of post-service continuity of the same symptomatology; and (3) medical or, in certain circumstances, lay evidence of a nexus between the present disability and the post-service symptomatology." Barr v. Nicholson, 21 Vet. App. 303, 307 (2007); see also Davidson, 581 F.3d at 1316; Jandreau v. Nicholson, 492 F.3d 1372, 1377 (Fed. Cir. 2007) (holding that "[w]hether lay evidence is competent and sufficient in a particular case is a factual issue to be addressed by the Board"). "Symptoms, not treatment, are the essence of any evidence of continuity of symptomatology." Savage v. Gober, 10 Vet. App. 488, 496 (1997) (citing Wilson v. Derwinski, 2 Vet. App. 16, 19 (1991)). In making all determinations, the Board must fully consider the lay assertions of record. Davidson, 581 F.3d 1313. A layperson is competent to report on the onset and continuity of his current symptomatology. See Layno v. Brown, 6 Vet. App. 465, 470 (1994) (a Veteran is competent to report on that of which he or she has personal knowledge). Lay evidence can also be competent and sufficient evidence of a diagnosis or to establish etiology if (1) the layperson is competent to identify the medical condition, (2) the layperson is reporting a contemporaneous medical diagnosis, or (3) lay testimony describing symptoms at the time supports a later diagnosis by a medical professional. Davidson, 581 F.3d at 1316; Jandreau, 492 F.3d at 1376-77. When considering whether lay evidence is competent the Board must determine, on a case by case basis, whether the Veteran's particular disability is the type of disability for which lay evidence may be competent. Kahana v. Shinseki, 24 Vet. App. 428 (2011); see also Jandreau, 492 F.3d at 1376-77. The Board is charged with the duty to assess the credibility and weight given to evidence. Madden v. Gober, 125 F.3d 1477, 1481 (Fed. Cir. 1997), cert. denied, 523 U.S. 1046 (1998); Wensch v. Principi, 15 Vet. App. 362, 367 (2001). Indeed, in Jefferson v. Principi, 271 F.3d 1072 (Fed. Cir. 2001), the United States Court of Appeals for the Federal Circuit, citing its decision in Madden, recognized that the Board had inherent fact-finding ability. Id. at 1076; see also 38 U.S.C.A. § 7104(a) (West 2002). The United States Court of Appeals for Veterans Claims (Court) has declared that in adjudicating a claim, the Board has the responsibility to weigh and assess the evidence. Bryan v. West, 13 Vet. App. 482, 488-89 (2000); Wilson v. Derwinski, 2 Vet. App. 614, 618 (1992). As a finder of fact, when considering whether lay evidence is satisfactory, the Board may also properly consider internal inconsistency of the statements, facial plausibility, consistency with other evidence submitted on behalf of the Veteran, and the Veteran's demeanor when testifying at a hearing. See Dalton v. Nicholson, 21 Vet. App. 23, 38 (2007); Caluza v. Brown, 7 Vet. App. 498, 511 (1995), aff'd per curiam, 78 F.3d 604 (Fed. Cir. 1996). In determining the probative value to be assigned to a medical opinion, the Board must consider three factors. See Nieves-Rodriguez v. Peake, 22 Vet. App. 295 (2008). The initial inquiry in determining probative value is to assess whether a medical expert was fully informed of the pertinent factual premises (i.e., medical history) of the case. A review of the claims file is not required, since a medical professional can also become aware of the relevant medical history by having treated a Veteran for a long period of time or through a factually accurate medical history reported by a Veteran. See id. at 303-04. The second inquiry involves consideration of whether the medical expert provided a fully articulated opinion. See Id. A medical opinion that is equivocal in nature or expressed in speculative language does not provide the degree of certainty required for medical nexus evidence. See McLendon v. Nicholson, 20 Vet. App. 79 (2006). The third and final factor in determining the probative value of an opinion involves consideration of whether the opinion is supported by a reasoned analysis. The most probative value of a medical opinion comes from its reasoning. Therefore, a medical opinion containing only data and conclusions is not entitled to any weight. In fact, a review of the claims file does not substitute for a lack of a reasoned analysis. See Nieves-Rodriguez, 22 Vet. App. at 304; see also Stefl v. Nicholson, 21 Vet. App. 120, 124 (2007) ("[A] medical opinion ... must support its conclusion with an analysis that the Board can consider and weigh against contrary opinions."). Service connection may be granted for certain chronic diseases, including arthritis, when such disability is manifested to a degree of 10 percent or more within one year of discharge from service. See 38 U.S.C.A. §§ 1101, 1112(a) (West 2002); 38 C.F.R. §§ 3.307, 3.309 (2012). Service connection may also be granted for a disease first diagnosed after discharge when all of the evidence, including that pertinent to service, establishes that the disease was incurred in service. See 38 C.F.R. § 3.303(d) (2012). Service connection may be granted on a secondary basis for a disability that is proximately due to or the result of an established service-connected disorder. See 38 C.F.R. § 3.310(a) (2012). A claim for secondary service connection generally requires competent evidence of a causal relationship between the service-connected disability and the nonservice-connected disease or injury. See Jones (Wayne L.) v. Brown, 7 Vet. App. 134 (1994). There must be competent evidence of a current disability; evidence of a service-connected disability; and medical evidence of a nexus between the service-connected disability and the current disability. See Wallin v. West, 11 Vet. App. 509, 512 (1998); Reiber v. Brown, 7 Vet. App. 513, 516-7 (1995). Similarly, any increase in severity of a nonservice-connected disease or injury that is proximately due to or the result of a service-connected disease or injury, and not due to the natural progress of the nonservice-connected disease, will be service connected. See 38 C.F.R. § 3.310(b) (2012); Allen v. Brown, 7 Vet. App. 439 (1995). In the latter instance, the nonservice-connected disease or injury is said to have been aggravated by the service-connected disease or injury. See 38 C.F.R. § 3.310(b) (2012). In cases of aggravation of a Veteran's nonservice-connected disability by a service-connected disability, the Veteran shall be compensated for the degree of disability over and above the degree of disability existing prior to the aggravation. See 38 C.F.R. § 3.322 (2012). When there is an approximate balance of positive and negative evidence regarding any issue material to the determination of a matter, the Secretary shall give the benefit of the doubt to the claimant. See 38 U.S.C.A. § 5107 (West 2002); see also Gilbert v. Derwinski, 1 Vet. App. 49, 53 (1990). Analysis Considering first whether the Veteran meets the current disability requirement in order to establish service connection, abundant VA treatment records reveal that the Veteran has received continuing treatment over the last several years for nonspecific seronegative spondyloarthropathy. Moreover, during his most recent July 2011 VA examination, the VA examiner diagnosed the Veteran with reactive arthritis, undifferentiated spondyloarthropathy, and noted that he had been diagnosed with this disability since June 2006. The examiner further noted that X-ray examination revealed degenerative changes in his cervical spine at C4-7, multilevel degenerative changes in his lumbosacral spine, minimal degenerative changes in his left hip, and distractive joint changes in the first metatarsophalangeal joint of each of his feet. Based on these diagnoses, the Veteran has clearly satisfied the first required element to establish service connection for degenerative polyarthritis, current diagnosis. See Davidson, supra. With respect to the second required element for service connection, in-service incurrence of a disability or injury, a review of the Veteran's service treatment records reveals no indication that he complained of or was treated for painful joints or any arthritic condition during his service. His May 1991 separation examination similarly did not contain any clinical findings related to an arthritic condition. Rather, the earliest medical evidence of record noting that the Veteran may have suffered from a joint condition is noted in an October 2006 letter from S. E. L., M.D., wherein he indicated that he treated the Veteran from May 1993 to September 1993 with a diagnosis of chronic metatarsalgia and plantar fasciitis in both feet. The first confirmed evidence of a painful joint condition is found in a March 1999 private physical examination report from L. D., M.D., indicating that the Veteran suffered from painful knees and feet. Dr. D. indicated that the metacarpophalangeal joints (MCPs) of the bilateral great toes were most consistently involved. The Veteran's military occupational specialty (MOS) was as a field medical service technician, or as a corpsman, during his active service. Moreover, he was noted to have had a needle puncture in February 1988, while working as a Navy corpsman, and he reported having at least one additional needle stick during his service. His hepatitis C infection was found to be likely secondary to needle sticks and service connection for hepatitis C was granted on this basis. Accordingly, the Board is left to consider whether all of the evidence, including that pertinent to service, establishes that his claimed arthritis, as shown by the evidence to have been diagnosed after his separation from service, was incurred during or as a result of his active service, to include as secondary to his service-connected hepatitis C. See 38 C.F.R. §§ 3.303(d), 3.310(a) (2012). Here, the Board notes that the abundant medical evidence of record, including multiple medical opinions, is conflicting with respect to whether the Veteran incurred his claimed arthritis disability during his service or a secondary to his service-connected hepatitis C. During a December 2005 VA rheumatology clinic consultation, the Veteran was noted to have a 10 year history of diffuse joint pain and swelling. The Veteran indicated that the pain began in his left knee, with progression to his right knee, ankles, metatarsophalangeal joints (MTPs), MCPs, and shoulders. X-rays taken in December 2005 revealed mild degenerative changes of the lumbar spine and mildly ill-defined sacroiliac joints. Further X-rays showed erosions consistent with spondyloarthritis, most likely reactive arthritis. The report noted that while this typically presented with a history of dysentery or a genitourinary (GU) tract infection, that it was possible that such an infection was non-clinical. Similar findings are frequently reported in the Veteran's VA treatment records dated through July 2011. In connection with his service connection claim, the Veteran was first afforded a VA joints examination in February 2006. After examining the Veteran, the VA examiner diagnosed the following disabilities: mild degenerative disc disease of the cervical spine at C4-5,with mild functional impairment of the cervical spine consistent with pain and fatigue; mild degenerative changes of the lumbosacral spine; bilateral knee strain; right and left ankle calcaneal spur erosions consistent with seronegative spondyloarthitis; erosive changes of the first interphalangeal joint with destruction of the joint of the left foot; and symmetric destructive erosive changes of the right foot consistent with seronegative spondyloarthropathy, such as Reiter's arthritis, psoriatic arthritis, and ankylosing spondylitis. The examiner then provided the opinion that the Veteran's current polyarthritis is not the consequence of his history of hepatitis C. Notably, however, the examiner did not provide a rationale for this opinion, or otherwise provide an opinion as to whether the Veteran's current polyarthritis disability was incurred during or as a result of his active service, or was aggravated by his service-connected hepatitis C. See Nieves-Rodriguez v. Peake, 22 Vet. App. 295, 301 (2008) (stating that a medical examination report must contain not only clear conclusions with supporting data, but also a reasoned medical explanation connecting the two). Such an opinion therefore, is inadequate for evaluating the Veteran's claim. In support of his claim, the Veteran has submitted statements from a VA Staff Rheumatologist dated in December 2006 and December 2009. In the December 2006 statement, the VA physician described the Veteran's reactive arthritis diagnosis and explained that reactive arthritis is generally considered to be a reactive disease in response to a gastrointestinal (GI) or GU infectious process, although many patients did not recall symptomatic infection prior to the onset of joint symptoms, and that the onset of arthritis symptoms is frequently insidious and a definite date of onset cannot be identified. He further noted that the Veteran had significant symptoms of reactive arthritis prior to May 1993, where treatment records from S. L., D.P.M., showed that he had chronic metarsalgia and plantar fasciitis of both feet at that time. The VA physician indicated that these were classical findings in an individual with reactive arthritis. He also noted that the Veteran had had difficulty with therapy for reactive arthritis because such therapy was causing worsening of elevated liver function tests. Thus, the physician explained, treatment for his reactive arthritis could potentially become very difficult. Based on these fact, the VA physician concluded that it was more likely than not that the Veteran acquired reactive arthritis during his military career. Specifically, the presence of chronic inflammatory foot arthritis in May 1993 suggested the onset was some time before that and was likely due to an infection acquired during his active duty. While he further indicated that the Veteran's arthritis would become more severe and potentially disabling in the future due the negative impact of potential therapies for this disease caused by his coexisting chronic hepatitis C, such an opinion regarding the aggravation of his arthritis is speculative, where such worsening was not currently noted by the physician to have occurred but presumed to occur in the future. In the December 2009 opinion, the VA physician noted that on examination, the Veteran was found to have significant arthritis of the knees, ankles, shoulders, wrists and toes, and evidence of erosive disease of the small joint of the feet on X-ray. Radiographic evidence also showed erosive sacroiliitis and inflammatory disease at the insertion of the plantar fascia consistent with previous complaints. Thus, the diagnosis of undifferentiated spondyloarthropathy made at that time mostly consisted of reactive arthritis. The VA physician reiterated that the onset of the Veteran's symptoms was shortly after discharge from service and his previous military work as a medic [which caused his exposure to hepatitis C] suggested that he acquired his reactive arthritis while on active duty. Exposure to infectious diseases was noted to be a prerequisite to the onset of reactive arthritis. The VA physician further noted that the Veteran's lack of GI or GU symptoms prior to the development of arthritis made it more difficult to pinpoint the time of onset, but did not rule out such a diagnosis. Additionally, however, while citing to medical research, the VA physician indicated that hepatitis C was also associated with arthritis. The physician further explained that because this arthritis was not clearly infectious, it was sometime termed a reactive arthritis, which did not put it into the same category as the spondyloarthropathy, which was also called reactive arthritis, because the latter was much more severe and destructive. The physician explained that nonetheless, the possibility remained that in a susceptible person, hepatitis C could initiate the disease process that produced the Veteran's form of reactive arthritis. The physician further explained that it was also possible that the Veteran was exposed to more infectious diseases than hepatitis C while working as a Navy medic and that another such disease initiated his spondyloarthropathy. Therefore, the physician concluded, based on the timing of the Veteran's initial symptoms, his previous experience as a Navy medic, and the presence of an additional infectious disease while on active duty, it was at least as likely as not that the Veteran acquired a subclinical infection while on active duty that led to the development of reactive arthritis (spondyloarthropathy). Due to the speculative nature of the December 2006 and December 2009 VA medical opinions and the noted inadequacies of the February 2006 VA examiner's opinion, the Board remanded the Veteran's claim in May 2010 in order to afford the Veteran a new and contemporaneous VA examination and to obtain an adequate medical opinion regarding the nature and etiology of the Veteran's arthritis disability. See McLendon v. Nicholson, 20 Vet. App. 79 (2006) (a medical opinion that is equivocal in nature or expressed in speculative language does not provide the degree of certainty required for medical nexus evidence). The Veteran was afforded a new VA joints examination in July 2011. The VA examiner again described the Veteran's multi-symptomatic arthritis disability and, as noted previously, diagnosed reactive arthritis, undifferentiated spondyloarthropathy and noted the presence of arthritic symptoms in various joints. The examiner then noted that he was unable to confirm that the Veteran's current degenerative polyarthritis was related to his military service. He explained that there was not sufficient data in the relevant medical literature to establish a direct relationship between polyarthritis and chronic hepatitis C. With respect to whether it was at least as likely as not that the Veteran's current degenerative polyarthritis was caused by or aggravated beyond its natural progression by service-connected hepatitis C, he indicated that based on available medical literature, he was unable to confirm a direct connection between the Veteran's service-connected hepatitis C and his progressive degenerative polyarthritis. He then noted that the current medical examination was not sufficient to confirm that the Veteran's degenerative polyarthritis was aggravated by hepatitis C beyond its natural progression. Again, unfortunately, the opinion provided by the July 2011 VA examiner was not adequate to determine the etiology of the Veteran's claimed polyarthritis disability. Notably, the VA examiner indicated that the examination was not sufficient to confirm whether the Veteran's degenerative polyarthritis was aggravated by his service-connected hepatitis C. Concerning this question specifically, he did not indicate whether further testing was required or whether it was not possible to determine such a relationship in the Veteran's case due to any other reason. See Jones v. Shinseki, 23 Vet. App. 382, 390 (2010) (an examiner's remarks should clearly indicate whether a conclusion cannot be reached from current medical knowledge that a specific in-service injury or disease can possibly cause the claimed disability, or whether the actual cause is due to multiple potential causes). Accordingly, the Board sought further medical comment by referring the Veteran's case for a VHA medical opinion in June 2012. See 38 C.F.R. § 20.901(a) (2012) (the Board may obtain a medical opinion from an appropriate health care professional in the VHA of VA on medical questions involved in the consideration of an appeal when, in its judgment, such medical expertise is needed for equitable disposition of an appeal). A VHA staff rheumatologist provided the requested opinion in July 2012. With respect to whether or not the Veteran's degenerative polyarthritis was at least as likely as not the result of his military service, the VHA specialist noted that degenerative polyarthritis is a complex process, incurred secondary to genetic and environmental factors. He noted that environmental factors such as chronic joint damage because of repetitive joint load, impact, or damage are well documented. The specialist further stated that the Veteran served in the United States Navy from 1987 to 1991, and while there are no descriptions of his routine activities while in service, in most cases military service involves strenuous physical activity. He concluded that if this were so for the Veteran, then his opinion was that it was at least as likely as not that his degenerative polyarthritis was in part the result of his military service. With respect to whether the Veteran may have incurred polyarthritis as a result of a needle stick injury, the VHA specialist indicated that such a relation was extremely unlikely (much less than 50 percent probability). He explained that needle stick injuries per se do not cause degenerative polyarthritis, and that infections such as HIV, hepatitis B, hepatitis C, malaria, and babesia, do not cause degenerative polyarthritis. He further opined that it was very unlikely (less than five percent probability) that hepatitis C caused the Veteran's degenerative polyarthritis, and that while hepatitis C can cause arthritides of different kinds, including arthritis with inflammation and arthritis similar to rheumatoid arthritis, it does not cause degenerative arthritis. Similarly, the VHA specialist concluded that it was very unlikely (less than five percent probability) that the Veteran's hepatitis C aggravated his degenerative polyarthritis, where hepatitis C has not been described to have an influence in the course of degenerative polyarthritis. Finally, with respect to whether there were any other possible intercurrent causes for the Veteran's degenerative arthritis, such as a steroid injection given in a podiatry clinic or subclinical infectious diarrhea, the VHA specialist concluded, first, that steroid injections were very unlikely (less than 10 percent probability) to be a cause of degenerative polyarthritis. He specifically noted that the injection given to the Veteran was a "plantar fascia injection," and that such an injection should not get into any joint. The specialist did note that to answer the question with absolute certainty, the records from the injection would need to be reviewed, but that he considered the association very unlikely. Next, the VHA specialist noted that diarrheal diseases are not associated with degenerative polyarthritis. He further noted that the "subclinical infectious diarrhea" described in the Veteran's treatment records consisted of a hypothesis to explain his spondyloarthritis, and the association between the two was well documented in the literature, but was not a cause for degenerative polyarthritis. He thus concluded that it was very unlikely (one percent or less probability) that any diarrheal episode was a cause of degenerative polyarthritis. The VHA specialist finally concluded that the only other possible intercurrent cause for degenerative polyarthritis that he could find in the Veteran's record was his occupation. He noted that being a nurse and having to stand or be physically active with repetitive activity for several hours per day could accelerate the process of degenerative polyarthritis. After a thorough review of the evidence of record, the Board finds that the evidence is at least in equipoise. In such cases, the benefit of the doubt must go to the Veteran. See 38 U.S.C.A. § 5107 (West 2002); see also Gilbert v. Derwinski, 1 Vet. App. 49, 53 (1990). Therefore, his service connection claim must prevail. In reaching this determination, the Board again notes that it is charged with the duty to assess the credibility and weight given to evidence when adjudicating a claim. Madden, 125 F.3d at 1481; Wensch, 15 Vet. App. at 367. Indeed, the Board has the responsibility to do so. See Bryan, 13 Vet. App. at 488-89; Wilson, 2 Vet. App. at 618. In this regard, the Board is free to favor one medical opinion over another, provided it offers an adequate basis for doing so. See Evans v. West, 12 Vet. App. 22, 30 (1998); Owens v. Brown, 7 Vet. App. 429, 433 (1995). While the Board is not free to ignore the opinion of a treating physician, it is free to discount the credibility of that physician's statement. See Guerrieri v. Brown, 4 Vet. App. 467, 471-73 (1993); Sanden v. Derwinski, 2 Vet. App. 97, 101 (1992). In weighing the medical evidence of record including all medical opinions, the Board notes that there appears to be some disagreement in the record with respect to the Veteran's exact arthritis diagnosis. On numerous occasions, the Veteran has been diagnosed with seronegative spondyloarthritis, with reactive arthritis, and with degenerative polyarthritis. Nonetheless, considering that the VHA specialist had the opportunity to review all evidence of record and to comment on the more likely etiology of the Veteran's arthritis disability, the Board will consider the noted diagnosis of degenerative polyarthritis to be the more accurate diagnosis of the Veteran's disability. Thus, in considering the VHA specialist's medical opinion, while the specialist indicated that the Veteran's polyarthritis was very likely not incurred as a result of his hepatitis C or as a result of any in-service needle stick injury, theories that have been supported in the record based on spondyloarthritis or reactive arthritis diagnoses, he did indicate that with respect to the incurrence of degenerative polyarthritis, if the Veteran's service involved strenuous physical activity, then it was at least as likely as not that degenerative polyarthritis was at least in part incurred as a result of his military service. Although this opinion hinges upon a requisite physicality of the Veteran's duties during service, the Board finds that the opinion does, to a sufficient degree, link the Veteran's claimed arthritis disability to his active service, and that it is at least as persuasive as either of the two VA examination reports which did not provide adequate opinions with respect to whether the etiology of the Veteran's arthritis disability. Moreover, considering the Veteran's MOS as a corpsman or field medical service technician, the Board notes the very strong likelihood that he was put through strenuous physical activity. Notably, not only would the Veteran have been put through the basic physical training exercises consistent with military service, but also, such an MOS would very likely consist of performing duties much like his post-service occupation as a nurse. Further, as noted by the VA examiner, such an occupation requires long hours of standing and repetitive physically activity. Thus, in weighing the evidence, the Board will afford greater probative value to the June 2012 VHA specialist's opinion, and based on this opinion, the Board will conclude that the required elements to establish service connection have been met. See Davidson, supra; 38 C.F.R. § 3.303(d) (2012). In rendering this conclusion, the Board is reminded that an "absolutely accurate" determination of etiology is not a condition precedent to granting service connection, nor is "definite" or "obvious" etiology. See Alemany v. Brown, 9 Vet. App. 518, 519 (1996). Rather, this need only be an as likely as not proposition (minimum 50 percent probability) for all reasonable doubt to be resolved in the Veteran's favor and his claim resultantly granted. Accordingly, applying the benefit of the doubt doctrine, all doubt is resolved in favor of the Veteran. See 38 C.F.R. § 3.102 (2012). Therefore, the Veteran's claim for service connection for degenerative polyarthritis must be granted. ORDER Entitlement to service connection for degenerative polyarthritis is granted. ____________________________________________ K. A. KENNERLY Acting Veterans Law Judge, Board of Veterans' Appeals Department of Veterans Affairs