The Newport News Shipbuilding and Dry Dock Company (“NNS”) appeals from an Order of the United States Department of Labor Benefits Review Board pursuant to Section 21 of the Longshore and Harbor Workers’ Compensation Act, 33 U.S.C.A. § 921 (West 1986) (“the Longshore Act”). Because we find that the Administrative Law Judge’s decision was supported by substantial evidence, we reverse the decision of the Benefits Review Board.
I.
The parties’ dispute arose over payment for medical services which Dr. Loxley rendered to NNS employees. Under the Long-shore Act, workers can select their own doctor; however, the Act limits the Employer’s liability for the ensuing medical charges to the “prevailing rate.”1 Because neither the Act nor its regulations define “prevailing rate,” NNS computed this rate pursuant to the methodology it used in its self-insured health benefit plan. Finding that Loxley’s charges on three particular services exceeded the prevailing rate, NNS refused to reimburse Loxley in full.
The issue before the administrative law judge was whether Loxley’s charges were within the prevailing rate limitation pursuant to section 7 of the Act. At the hearing, NNS introduced evidence explaining that it determined the prevailing rate by using figures from its health benefits plan, a plan which was negotiated with the Shipyard Union and covers some 77,000 workers and dependents. Under this plan, NNS agreed to pay the insured medical charges in full if the fee for a specified service, defined by CPT codes,2 did not exceed the 80th percentile of charges for that particular service.3 NNS incorporated this plan into its determination of the prevailing rate under the Longshore Act by using the 80 percent figure as the prevailing rate. Thus, when Loxley’s charges exceeded its calculations of the prevailing rate for three CPT codes, NNS paid him only the amount represented by the 80th percentile.
At the administrative hearing, Loxley tendered his own testimony and that of Dr. Taylor, his expert. Besides admitting that he did not know what he, or other doctors in the area, charged for the disputed CPT codes, Loxley also presented no data which, challenged use of the 80th percentile standard by NNS. Likewise, Dr. Taylor could not give either his charges or an estimate of the prevailing rate for the services at *514issue. Although he testified that Loxley’s fees were fair, he conceded that he did not know the rates of other doctors and, without such information, he could not disagree with the Employer’s statistical analysis. Moreover, Taylor stated that he had no problem with the Shipyard’s use of the 80th percentile to determine the prevailing rate, although he thought its results were low. Taylor did offer some insight by explaining that the fees of specialists and generalists should not be computed in the same statistical base. NNS does not differentiate by specialty in computing the prevailing rates for the various CPT codes. However, in his testimony, Taylor could not articulate a method by which NNS could reasonably differentiate by specialization.
After hearing all of the evidence, the administrative law judge wrote an extensive opinion concluding that Dr. Loxley's charges exceeded the prevailing rate. He indicated that “the testimony of Drs. Lox-ley and Taylor fell far short of establishing that Dr. Loxley's charges fall within the [prevailing community rate].”
The Benefits Review Board (“the Board”) reversed the administrative law judge’s decision and disregarded his findings of fact. The Board disagreed with the lower court’s determination that Loxley, as the proponent of an order requiring that NNS pay his charges in full, bore the burden of proof on the prevailing rates issue. After holding that NNS carried the burden of proof, the Board further disagreed with the administrative law judge’s statement that, even if the burden fell on NNS, the employer had in fact met its burden. The Board concluded that “the employer’s evidence is wholly insufficient to establish prevailing community charges for the medical services performed by Dr. Loxley.”
II.
According to section 21 of the Longshore Act, the standard of review for an administrative law judge’s decision is whether the record contains sufficient evidence to support the decision. If the evidence meets this standard, the administrative law judge’s findings of fact are “conclusive upon the Board” and “the Board is not free to disregard them or draw other inferences which it thinks may be more reasonable.” Newport News Shipbuilding & Dry Dock Co. v. Director, 681 F.2d 938 (4th Cir.1982).
Reserving for the moment the issue of which party bore the burden of proof, we will first examine whether the Board exceeded its powers of review by disregarding the administrative law judge’s findings of fact. Contrary to the administrative law judge’s determination that its conclusion would have been the same even if NNS carried the burden of proof, the Board found the employer’s evidence lacking. We do not agree with the Board’s interpretation of the evidence presented at the hearing, and we find that the Board erroneously expanded its scope of review by its independent analysis of the facts.
Contrary to the rule that the administrative law judge’s findings of fact are conclusive upon the Board, the appellate panel nonetheless attacked the conclusion that the process by which NNS determined the prevailing rate was adequate. The Board found the evidence submitted by NNS lacking in several respects. First, the Board found that the data offered by NNS did not “represent a true sample of medical fees charged by physicians practicing in the community.” The record shows, however, that NNS made a broad survey of fees which included at least 46,700 charges submitted by approximately 70 percent of the doctors in the Hampton Roads area. That NNS utilized data from its negotiated health benefits plan is of no consequence. Citing the Act’s provision that the employer shall furnish all medical, surgical, and other related treatment, 33 U.S.C.A. § 907(a) (West 1986), the Board concluded that using the 80th percentile to determine the prevailing rate did not satisfy the Act’s requirements. However, the Board’s analysis neglects provisions in the Act and the regulations that an employer’s obligation for medical charges is limited to the prevailing rate. Id. at § 907(g); 20 C.F.R. § 702.413 (1990).
The Board also found that the survey of fees by NNS was “inherently flawed” because it did not distinguish on *515the basis of medical specialization. Focusing on provisions in the Act and regulations which dictate that the prevailing rate should be measured by charges for “the same or similar care,” 33 U.S.C.A. § 907(b), (g) (West 1986); 20 C.F.R. §§ 702.413, 702.-414 (1990), the Board criticized NNS for relying solely on the use of CPT codes to compare fees. The Board noted that without evidence that the services performed by other physicians whose charges made up the data base did in fact constitute the same or similar care as that rendered by Loxley, NNS could not sustain its burden under the Act.
Based on the evidence produced at the hearing,4 the administrative law judge found unpersuasive Loxley’s challenge that NNS should have limited its data to the fees of physicians practicing his specialty, orthopedic surgery. We agree. Although the evidence showed that in two of the three CPT codes involved, the prevailing rate figure was actually higher when NNS used the entire pool of charges than when it measured only the charges of orthopedic surgeons,5 we find that making a distinction between generalists and specialists is not necessary.
A series of factors supports this conclusion. First, the CPT codes were designed by the medical profession as a uniform reference to designate medical, surgical and diagnostic services. The codes do not differentiate by specialist. That each code encompasses “same or similar” services is apparent from their very definitions. Furthermore, the Act and regulations discuss comparable treatment; they do not distinguish between medical providers.6 The Board concluded that NNS should use a separate data base for specialists; however, it did not define specialist and ignored evidence in the record indicating that no such definition is practically available.7 Because we find that use of the CPT codes is sufficient to define “same or similar care” under the Act, we hold that the employer need not differentiate between generalists and specialists in determining the prevailing rate.
We also find improper the Board’s statement that NNS did not submit evidence demonstrating the charges to patients in the relevant geographical area who are covered under any other type of plan. The data used by NNS included over *51646,700 charges made by approximately 1700 doctors; this represents greater than 70% of the physicians in the applicable geographic area. If the Act’s prevailing rate limitation demands that an employer conduct a more-encompassing survey of medical fees, then even employers such as NNS, which has an unusually large amount of resources at its disposal, would face a cumbersome, indeed prohibitive, burden. Although we note the Board’s objection to the use of the previous year’s rates as a basis for the current year’s billings,8 we do not think that this factor alone can undermine the methodology employed by NNS.
Because the Act and regulations give no guidance on how to ascertain the prevailing rate, employers must devise their own means of doing so. Absent more definitive directions for determining the prevailing rate, we believe that an administrative law judge’s conclusion that the employer met its burden of defining such a rate should be given great credence by the Board. The evidence submitted at the hearing sufficiently supported the finding of the administrative law judge that NNS sustained its burden of proving the prevailing rates.
III.
The administrative law judge found that Dr. Loxley carried the burden of proving that his rates were within the Act’s prevailing rate limitation. The Board reversed, assigning the burden to the Employer. Because we affirm the conclusion of the administrative law judge that Loxley’s charges exceeded the prevailing rate regardless of who carried the burden of proof, we need not decide on whom the burden falls in disposing of this appeal. However, the parties have properly raised the issue and, finding it in the better interests of the parties to resolve the matter, we hold that a physician who seeks an order compelling full payment of his charges carries the burden of proof at the administrative hearing.
The regulations under the Act provide as follows: If an employer refuses fully to compensate a physician for medical care provided under the Act, the physician can request the Director of the Office of Workers’ Compensation Programs (“the Director”) to investigate the unpaid charges. 20 C.F.R. §§ 702.407(b), 702.414(a) (1990). Upon such investigation, the Director makes a finding on “whether the fee exceeded the prevailing community charges or the provider’s customary charges” and advises the parties of his decision. Id. at § 702.414(c). If a party disputes this finding, it has a right to request an administrative hearing pursuant to 5 U.S.C. § 556. Id. at § 702.415. The necessary parties at such a hearing include “the person whose fee or cost charge is in question and the Director, or their representatives. The employer or carrier may also be represented ... in the discretion of the administrative law judge.” Id. at § 702.416.
Neither Section 7 of the Act nor the regulations assign the burden of proof at the administrative hearing. However, for the following reasons we find that the burden is on the physician claiming that his charges are within the prevailing community rates. As the Board properly noted, under section 702.415 a party may request an administrative hearing pursuant to 5 U.S.C. § 556. Therefore, subsection (d) of that provision, which states “Except as otherwise provided by statute, the proponent of a rule or order has the burden of proof”, is applicable. This placing of the burden of proof is consistent with the traditional common law rule, noted by the administrative law judge, that the proponent — the one who seeks to establish the affirmative of an issue — carries the burden of proof. Selma, Rome & C. Railroad v. United States, 139 U.S. 560, 567, 11 S.Ct. 638, 640, 35 L.Ed. 266 (1891); Fleming v. Harrison, 162 F.2d 789, 792 (8th Cir.1947).
Although the Board identified the proper rule regarding the burden of proof, *517it incorrectly applied the rule. Holding that NNS was “the proponent of an order ruling that Dr. Loxley’s medical fees exceed the prevailing community charges,” the Board assigned the burden to NNS. We find the administrative law judge’s analysis more compelling. From a procedural perspective, the fact that NNS requested the hearing does not, ipso facto, make it the proponent of the issue. The request for an administrative hearing by NNS was not, nor do the regulations provide for, an appeal from the finding of the Deputy Commissioner. Rather, the administrative hearing is a de novo proceeding which examines the same issue confrontéd by the Deputy Commissioner. This fact compels us to make two observations: First, it was Loxley, not NNS, who initiated proceedings to clarify whether his rate was within the prevailing rate. Thus, the issue before the administrative law judge was raised by Loxley, not NNS. Second, as the administrative law judge noted, to hold that NNS carried the burden of proof at the hearing would effectively accord “a presumption of correctness to the Deputy Commissioner’s ruling — an approach antithetical to the concept of a de novo hearing” before the administrative law judge.
The regulations which govern the administrative hearing before the administrative law judge also support these conclusions. Section 702.416, a provision which the Board did not address in reaching its conclusion, states that “[a]t formal hearings held pursuant to § 702.415, the necessary parties shall be the person whose fee or cost charge is in question and the Director, or their representatives.” The language of this regulation gives credence to our conclusion that one of the “necessary parties” must bear the burden of proof, and that language identifies a “necessary” party as “the person whose fee or cost charge is in question.” Whether the burden is assigned to “the Director” or to the “person whose fee or cost charge is in question” under the portion of the regulations, it is a reasonable conclusion that such burden is not assigned to one in the position of NNS.
In making this conclusion as to the burden of proof, we do not purport to determine how a physician should or could sustain this burden at an administrative hearing. In the context of the record before us, however, we find that Loxley did not offer sufficient evidence to prove that his charges fell within the prevailing rate. As previously discussed, Loxley offered little if any useful information as to what constitutes the prevailing rate. At the hearing, he did not offer any evidence attacking the methodology used by NNS. Although Taylor testified that he thought the resulting prevailing rates were low, when asked whether he “had a particular problem” with the use of the 80th percentile, he responded, “I don’t, personally, and I don’t think the peer review group has any problem with that.” Taylor commented that NNS should inform physicians in the area of its practice in determining the prevailing rate, but he testified that he could not dispute the documentation underlying NNS’s statistical analysis. At the hearing, counsel for Loxley was willing to stipulate that “Dr. Loxley has not made an exhaustive statistical analysis, and I further stipulate that it would be illegal for him to do so.” The only testimony Loxley and Taylor submitted against the NNS determinations of the prevailing rate was their respective comments, unsupported by any evidence, that Loxley’s fees were fair.
Upon hearing the testimony and examining the evidence, the administrative law judge was not persuaded by Loxley’s attempt to show that his rates were within those that prevailed in the community. We find that the record contained sufficient evidence to support the findings of fact of the. administrative law judge which thus became “conclusive upon the Board.” The Board erred in disregarding these findings of fact.
For the reasons indicated, the judgment of the Board is
REVERSED.
. The Act limits fees payable "to such charges as prevail in the community for such treatment.” 33 U.S.C.A. § 907(g) (West 1986). Under the governing regulation, such charges "shall not exceed the customary charges of the medical care provider for the same or similar services.” 20 C.F.R. § 702.413 (1990).
. The services at issue are coded according to the Current Procedural Terminology (CPT), a uniform coding used in "identifying, describing, and coding medical, surgical, and diagnostic services performed by practicing physicians.” A.M.A. Physicians' Current Procedural Terminology at iii (4th ed. 1986). The coding system is "the most widely accepted nomenclature for the reporting of physician procedures and services under government and private health insurance programs.” Id.
.Using charges for specific CPT codes which were submitted under its health benefits plan during the previous year, NNS calculated the amount below which 80 percent of the charges fell. NNS reimbursed in full only those fees at or below the 80th percentile.
. The evidence on this point included Taylor’s testimony that orthopedic surgeons’ charges differ from those of other specialists or primary care physicians for the services that fall within the same CPT codes, and documents submitted by NNS showing that other carriers, such as Blue Cross Blue Shield, do not differentiate by specialists.
. For the purposes of the hearing, NNS conducted a survey of fees submitted only by “specialists” to its health care plan. NNS defined "specialists” by selecting names listed under "orthopedic surgeons” in the yellow pages. The results of this survey indicated that the rate at the 80th percentile for the specialists charges was below the same rate calculated with respect to all fees submitted in two of the three CPT codes at issue.
We do not base our conclusion that differentiation by specialty is not mandated by the Act on the results of this second survey by NNS. The Board disregarded the survey, stating that it was insufficient because it was limited to those charges submitted to the NNS health benefit plan. We simply find that the results of the survey are immaterial as the nature of the services performed, not’ the status of the medical care provider, are relevant in determining the prevailing rate under the Act.
. See 33 U.S.C.A. § 907(g) (West 1986) (“All fees ... shall be limited to such charges as prevail in the community for such treatment....”); 20 C.F.R. § 702.413 (1990) (“All fees ... shall be limited to such charges for the same or similar care (including supplies) as prevail in the community ... and shall not exceed the customary charges of the medical care provider for the same or similar services.”); and 20 C.F.R. § 702.414 (1990) (discussing "similar treatment”).
. At the hearing, Taylor indicated the difficulty in defining "specialist.” Although he indicated that one determining factor would be whether a physician was "Board-certified” or "Boardeligi-ble," he stated that if he had to determine who in the area was "Board-eligible,” he would "Simply go around and talk to people.” The burdensome task of defining "specialist" is, moreover, unnecessary, given the fact that the CPT code system allows for the use of modifiers which help to distinguish a type of medical care. By using a modifier, a physician can indicate that a particular service was altered in some respect even though its code number was not changed. See A.M.A. Physicians’ Current Procedural Terminology at xi-xiii (4th ed.1986).
. Use of the prior year’s rates does not account for the effects of inflation or other factors which might increase fees. However, as the administrative law judge noted, Blue Cross Blue Shield also uses rates from the previous year, in what is the most practicable way to establish such rates. Trying to do so on a monthly, or other short-term, basis could well not produce enough billing to constitute a valid sample.