ANTHONY GIST, Employee/Respondent, v. ATLAS STAFFING, INC., SELF-INSURED/ MEADOWBROOK CLAIMS SERV., Employer/Appellants, and FRESENIUS MED. CARE, MERCY HOSP., MEDICA HEALTH PLANS, GROUP HEALTH PLAN d/b/a HEALTHPARTNERS, DERMATOLOGY CONSULTANTS, P.A., UNITY HOSP., and MINN. DEP’T OF HUMAN SERVS./BRS, Intervenors.

The employer and its third-party administrator appeal from the compensation judge’s determination, relying on the opinion of the employee’s nephrologist, Dr. George Canas, that exposure to silica sand at work was a substantial contributing cause of the employee’s kidney failure; from the compensation judge’s finding that she did not have jurisdiction to interpret and apply federal Medicaid and Medicare law in determining the medical expense claim of intervenor Fresenius; and from the compensation judge’s rejection of the employer and insurer’s argument that a treatment provider that accepts payments from Medicaid and Medicare is barred from receiving workers’ compensation payment for treatment provided to an injured employee. We affirm as modified.

This proceeding was initiated by the filing of a claim petition on November 14, 2014. The employee alleged work-related kidney failure as a result of exposure to silica sand while working at Waltek, Inc., on temporary assignment through the employer, Atlas Staffing, Inc. The employer and its third-party administrator, Meadowbrook Claims Service (TPA Meadowbrook), denied primary liability.

The employee worked at Waltek from September 13, 2011, through June 28, 2013. The Waltek foundry makes castings of various parts using wax molds. The employee’s job involved taking prepared forms, bolting four to six to a rack, and hanging the rack on a conveyor system. A robot arm took a rack from the conveyor, dipped the forms into a tank filled with liquid, and then into a large vat of fine silica sand. As the forms were immersed in the silica vat, sand shot up on columns of air rising above the lip of the vat. The employee testified he stood right next to the vat and the sand was constantly in his face. There was silica sand on every surface around the vat.^[1]

Pallets of silica sand bags stood to the right of the employee. As the racks were dipped in and out of the sand vat, the sand in the vat got lower. It was the employee’s responsibility to keep the sand vat full. He testified he would pour about eight to ten large bags of silica sand into the vat during the course of his eight hour shift.^[2]

In addition, at least once and sometimes twice per shift, the employee cleaned out a silica sand vat. He climbed into the vat on his knees, sifted the sand with a screen, removed any broken parts, and used a bucket to move the cleaned sand into an empty adjacent vat. The process took approximately two hours. The employee testified his pores were open from the heat and the sand was muddy and stuck to his skin. He testified his clothes, skin, and hair would be covered with silica sand by the end of the process.^[3]

The employee testified he wore safety glasses, gloves, and a paper mask. No other protective equipment was used. The video pictures submitted show workers with bare arms and without masks of any kind.^[4]

On July 23, 2013, the employee was seen by his family practice physician at HealthPartners Anoka, Dr. James Lee, for multiple concerns including cysts on his skin, stress and anxiety, and several months of feeling fatigued and lacking energy. Dr. Lee noted elevated blood pressure and ordered basic metabolic labs.^[5] The lab tests revealed significantly elevated blood urea nitrogen (BUN), serum creatinine, and potassium. The employee was diagnosed with acute kidney failure and admitted to Mercy Hospital that day where he came under the care of Dr. Kyle Onan, a nephrologist with Kidney Specialists of Minnesota.^[6] Serologic and anatomic testing revealed no evidence for autoimmune or infectious disease affecting kidney function. The employee had anatomically normal kidneys on ultrasound imaging. A kidney needle biopsy was performed on July 25, 2013. The kidney pathologist interpreted the tissue as advanced focal segmental glomerulosclerosis (FSGS), not otherwise specified, with severe interstitial fibrosis, global glomerular sclerosis, and severe arteriosclerosis.^[7] There were “foci of moderate acute tubular epithelial injury and foci suspicious for acute tubulointerstitial nephritis with eosinophils suggestive of a hypersensitivity (allergic) reaction.”^[8]

The employee was seen by Dr. Lee on July 30, 2013, after his release from the hospital. The employee believed his kidney failure was due to silica sand exposure, and Dr. Lee advised him to discuss it with the nephrologist at his upcoming appointment. The employee was seen once by Dr. James Rusin, a family practitioner at HealthPartners Anoka, on August 16, 2013. Dr. Rusin did not believe that silica had anything to do with the employee’s kidney problem.^[9]

On August 27, 2013, the employee was examined by Stephanie Gordon, a nurse practitioner (NP) at Kidney Specialists of Minnesota. NP Gordon stated the employee had no known history of hypertension and recalled normal blood pressures when giving blood at plasma clinics. She additionally indicated family history was positive for hypertension involving his father, that the employee smoked a ½ pack of cigarettes per day, and that he used marijuana. Ms. Gordon did not believe the employee’s kidney biopsy results were consistent with some type of exposure. The employee was seen again by NP Gordon on October 22, 2013. He had begun transplant workup through Abbott Northwestern Hospital and preparations for dialysis. Ms. Gordon agreed to set up the employee’s next Kidney Specialists appointment with a doctor to address the possibility of silica exposure causing his kidney failure.^[10]

In a November 12, 2013, chart note, Janet Anderson, RN, kidney transplant coordinator at Abbott Northwestern, indicated she had spoken with Dr. Onan who stated that the kidney biopsy indicated FSGS, but it was “hard to say if the silica sand caused his renal failure.”^[11] In a November 26, 2013, follow-up with the employee, Dr. Lee noted that “[o]f the information I have at my disposal, silicosis can be a cause of chronic renal failure. I read several articles in this regard which confirmed this.”^[12]

By the end of February 2014, the employee’s condition had worsened. The employee’s treatment was assumed by Dr. George Canas, medical director at Kidney Specialists of Minnesota, Coon Rapids, on March 3, 2014, and dialysis was initiated at the Fresenius Medical Care facility.^[13]

On April 10, 2014, the employee was seen by Drs. Karega Paisley and David Parker in occupational and environmental medicine at HealthPartners. In a chart note of May 1, 2014, Dr. Parker indicated the employee’s case had been reviewed with Dr. Ken Rosenman at Michigan State University. It was felt that given the time delay since exposure and the lack of pulmonary silicosis findings it was unlikely the employee’s renal disease was related to silica exposure.^[14] On July 10, 2014, Dr. Lee diagnosed “[s]uspected silicosis-induced renal failure.”^[15]

On October 21, 2014, Dr. Canas issued a narrative report regarding his treatment and evaluation of the employee’s kidney disease. Dr. Canas reviewed the employee’s medical records dating back to 2005 and performed medical research on the implications of exposure to silica in the development of end-stage kidney failure. Dr. Canas opined the most likely, and most reasonable, cause of the employee’s kidney failure was through his exposure to silica as a result of his work through both a respiratory route and direct contact.^[16]

On February 18, 2015, the employee was evaluated by Dr. Merlin Brown, an internal medicine specialist, on behalf of the employer and TPA Meadowbrook. Dr. Brown opined that silica exposure was not a substantial contributing factor in the employee’s renal failure. He observed there is an association between smoking and chronic kidney disease, and opined there were other traditional risk factors in the employee’s history and medical records that placed the employee at an increased risk for developing kidney disease.^[17]

The employee continued to treat with Dr. Canas and receive dialysis at Fresenius Medical Care through June 2015. At about that time the employee moved to Michigan where he had family. The employee continued dialysis with Fresenius Medical Care in Kalamazoo and South Haven, Michigan.^[18]

The case was heard by a compensation judge at the Office of Administrative Hearings on August 5, 2016. In Findings and Order issued on October 24, 2016, the compensation judge accepted the opinion of the employee’s treating nephrologist and found the employee’s exposure to silica at work was a substantial contributing factor to the employee’s end-stage renal disease. The compensation judge further found she did not have jurisdiction to interpret federal Medicaid and Medicare law for the purpose of determining whether Fresenius’s Spaeth claim^[19] was barred by acceptance of payments from these entities. The compensation judge ordered the employer and TPA Meadowbrook to pay medical expenses, related to the employee’s kidney treatment, to the intervening medical providers, including Fresenius, and required that payments be made “in accordance with all other state and federal laws.” We affirm as modified.

In reviewing cases on appeal, the Workers’ Compensation Court of Appeals must determine whether “the findings of fact and order [are] clearly erroneous and unsupported by substantial evidence in view of the entire record as submitted.” Substantial evidence supports the findings if, in the context of the entire record, “they are supported by evidence that a reasonable mind might accept as adequate.” Where evidence conflicts or more than one inference may reasonably be drawn from the evidence, the findings are to be affirmed.^[20] Similarly, “[f]actfindings are clearly erroneous only if the reviewing court on the entire evidence is left with a definite and firm conviction that a mistake has been committed.” Findings of fact should not be disturbed, even though the reviewing court might disagree with them, “unless they are clearly erroneous in the sense that they are manifestly contrary to the weight of the evidence or not reasonably supported by the evidence as a whole.”^[21] A decision which rests upon the application of a statute or rule to essentially undisputed facts generally involves a question of law which the Workers’ Compensation Court of Appeals may consider de novo.^[22]

There is no dispute the employee was exposed to silica sand and dust while working at Waltek. The issue in this case was whether a causal relationship exists between the employee’s silica exposure and his kidney failure. The employer and TPA Meadowbrook contend the record as a whole supports the conclusion that the employee’s exposure to silica sand while working for the employer was not a substantial contributing cause of his end-stage renal failure.

The appellants assert the record is replete with opinions from the employee’s treating providers stating that silica exposure did not cause his kidney failure. Assessments from physicians at HealthPartners clinics — who were not kidney specialists — are mixed. While Dr. Rusin, a general practitioner who saw the employee one time, did not believe that silica had anything to do with the employee’s kidney problem, Dr. Lee, the employee’s family practice physician, stated that based on information at his disposal, silicosis could be a cause of renal failure and diagnosed suspected silicosis-induced renal failure. Drs. Karega Paisley and David Parker, occupational and environmental medicine specialists, found research conducted at Michigan State University in 1999 that showed an autoimmune direct nephrotoxic effect associated with silica exposure. The employee’s case was reviewed with Dr. Ken Rosenman at Michigan State University, and it was concluded that given the time delay since exposure and the lack of pulmonary silicosis findings, it was unlikely the employee’s renal disease was related to silica exposure. On the other hand, Dr. Onan, a nephrologist with Kidney Specialists of Minnesota, stated it was hard to say if the silica sand caused the employee’s renal failure.

Ultimately, the question of causation in this case rests on medical expert opinion. The compensation judge found Dr. Canas’s opinion more persuasive, and concluded that although the employee had certain risk factors that may have put him at increased risk for developing kidney disease, the employee’s silica sand exposure while working at Waltek was a substantial contributing cause of the employee’s end-stage renal disease.^[23]

The facts upon which an expert relies for an opinion must be supported by the evidence.^[24] An expert medical opinion is not competent if it is based on assumptions that lack a factual basis or if it materially relies on facts contrary to those found by the compensation judge.^[25] An expert need not be provided with every possible fact, but must have enough facts to form a reasonable opinion that is not based on speculation or conjecture.^[26]

The employer and TPA Meadowbrook argue that Dr. Canas’s causation opinion is inadequate because the facts he assumed in rendering his opinions are not supported by the evidence. The employer and TPA Meadowbrook assert that Dr. Canas did not review all of the employee’s pre-exposure medical records. However, Dr. Canas’s narrative report states he reviewed the employee’s medical records back to 2005. There is no evidence in the record to indicate that Dr. Canas failed to review the employee’s complete medical history.

The appellants contend Dr. Canas relied on the employee’s subjective and inaccurate history and failed to consider pre-existing, traditional risk factors for kidney disease. They maintain the employee had numerous risk factors for developing kidney failure that were unrelated to his employment with the employer, including smoking, marijuana use, possible diabetes, and hypertension. The employer and TPA Meadowbrook argue Dr. Canas’s reasoning demonstrates that his reliance on this incorrect information played a large role in his differential diagnosis of silica as a contributing cause of the employee’s kidney failure.

In his October 21, 2014, report Dr. Canas specifically addressed risk factors, stating the employee displayed dramatic onset kidney failure in the absence of traditional risk factors necessary for the evolution of kidney failure in a young man,^[27] including pre-existing uncontrolled hypertension, diabetes mellitus, and exposure to illicit drugs (cocaine, heroin, methamphetamine). We can find nothing in the trial record, via expert medical opinion or otherwise, that defines uncontrolled high blood pressure or describes its role in end-stage renal disease, nor is it evident that the employee had chronic high blood pressure. The employer and TPA Meadowbrook’s assertion that high blood pressure/hypertension is the second most common cause of end stage renal disease is supported by a link to a web site accessed after the hearing below and not by anything in the record. There is only one medical visit in which the possibility of diabetes was raised.^[28] There is no confirmed diagnosis of diabetes in the record. Nor did the employer’s expert, Dr. Brown, opine that the employee’s kidney failure was caused by hypertension, diabetes, or marijuana use.

Dr. Canas provided two reports, explaining in detail his conclusions and how he arrived at them. Dr. Canas, a kidney treatment specialist with extensive research experience related to hypertension, diabetes, and kidney disease, also independently researched the effects of silica exposure on the kidneys. Dr. Canas opined the rapid onset of the employee’s kidney failure associated with exposure at work, and biopsy findings suggesting a hypersensitivity (allergic) reaction, supported the conclusion that the most likely cause of the employee’s kidney failure was his exposure to silica at work.^[29]

In his independent medical examination (IME) report, Dr. Brown noted an association between smoking and chronic kidney disease. He indicated that from his review of the medical literature provided to him, it was clear there is an association between silica exposure and kidney disease, but he did not find enough evidence to conclude the employee’s exposure was a substantial contributing factor in light of the absence of silica in the employee’s skin or lungs.^[30]

Dr. Canas responded that a rapid course of kidney failure in a young man and the time of exposure, the absence of underlying glomerulonephritis/interstitial nephritis and family/genetic disease, and normal serologic evaluation begs for additional explanation aside from merely tobacco exposure. Although associated with progressive kidney disease, Dr. Canas stated that clinical evidence showed that “pure” blood vessel-derived disease in the kidneys due to heavy tobacco use is not manifested in an individual until their 6th or 7th decade of life. Dr. Canas further stated, based on additional research he conducted, that toxicity from silica is not necessarily found in other organs (e.g., the skin or lungs) in an exposed individual, that short exposure times to silica may be associated with kidney disease, and that indirect toxicity can bring forth renal disease.^[31]

Dr. Brown subsequently indicated that certain of the employee’s kidney biopsy results were consistent with silica exposure. While he stated he could not say “with certainty” that silica caused the kidney failure, Dr. Brown did acknowledge that Dr. Canas’s view was “reasonable.”^[32]

The Minnesota Supreme Court has recognized that disability from diseases of uncertain cause may be compensable. It is not necessary to express absolute certainty in the matter which is the subject of the opinion. It is sufficient if, in the view of the medical expert, it is probably true.^[33]

The adequacy of foundation for an expert opinion is a decision within the discretion of the compensation judge.^[34] Once expert medical opinion has been admitted into evidence without objection the evidentiary issue becomes one of weight rather than one of competence.^[35] The employer and TPA Meadowbrook raised no objection to the introduction of Dr. Canas’s report. This court has long given substantial deference to a compensation judge’s decision to accept and rely on the opinion of one medical expert over that of another.^[36] Substantial evidence, including medical expert opinion, supports the compensation judge’s finding that the employee’s exposure to silica sand at Waltek, while working for the employer, was a substantial contributing factor to the employee’s kidney failure. We, accordingly, affirm.

As a consequence of the employee’s end-stage renal disease, he has needed regular and frequent dialysis treatment. The employee began treating at Fresenius Medical Care in Minnesota in March 2014. The employee subsequently moved to Michigan and his dialysis was transferred to Fresenius Medical Care clinics in that state. Fresenius received Medicaid payments in Minnesota (Medical Assistance) and Michigan and, eventually, Medicare, for the employee’s kidney treatment. Fresenius intervened seeking payment of workers’ compensation medical expenses representing the clinics’ charges for the employee’s treatment. The employer and insurer argue that because Fresenius accepted payment from Medicaid and Medicare, the claims are deemed to have been paid in full and Fresenius can make no claim for additional payments.

The threshold question is whether the compensation judge, and this court, have jurisdiction to interpret and apply federal Medicaid and Medicare law for the purpose of determining whether Fresenius’s Spaeth claim^[37] is barred by acceptance of payments from these entities. The compensation judge held she did not have jurisdiction to do so.

Subject matter jurisdiction is the court’s authority to hear the type of dispute at issue and to grant the type of relief sought.^[38] The jurisdiction of workers’ compensation courts is limited to “questions of law and fact arising under the workers’ compensation laws of th[is] state.” The jurisdiction of workers’ compensation courts does not extend to interpreting or applying laws designed specifically for the handling of claims outside the workers’ compensation system.^[39]

The appellants ask this court to interpret and apply portions of federal statutes and rules that require a state Medicaid plan to limit participation in the Medicaid program to providers who accept the amounts paid by the agency on behalf of recipients as payment in full. Similarly, they assert, to accept payment from Medicare, Fresenius had to have entered into an agreement with Medicare to not charge more than the deductible for these services. These provisions, the employer and insurer argue, bar Fresenius from seeking additional payment from a workers’ compensation insurer.

The position taken by the employer and TPA Meadowbrook requires the interpretation and application of federal law implementing the Medicaid and Medicare programs. We conclude the compensation judge properly determined she lacked jurisdiction to interpret and apply Medicaid and Medicare statutes and rules in determining liability for workers’ compensation benefits, and affirm.

Fresenius asserts its acceptance of Medicare or Medicaid payments does not relieve the employer and TPA Meadowbrook of their obligation to pay the medical expenses of an injured employee under the Minnesota Workers’ Compensation Act. The intervenor argues that Medicaid and Medicare laws do not occupy and do not preempt the field of workers’ compensation payments to medical providers. Rather, the programs only step in when a workers’ compensation insurer has denied or failed to provide coverage for an injured workers’ medical treatment. Medicare and Medicaid are payers of last resort and if the primary workers’ compensation carrier is found liable, Medicare and Medicaid step out of the process. Thus, Medicaid and Medicare law do not conflict with Minnesota workers’ compensation law that requires an employer to pay reasonable and necessary medical costs for an injured employee.

This question was addressed by the North Carolina Supreme Court in Pearson v. C.P Buckner Steel Erection Company.^[40] In Pearson, the employer refused to pay the difference between amounts the medical providers had received from Medicaid and amounts due under the state workers’ compensation medical fee schedule. The North Carolina court noted that Medicaid is intended as a safety net for those unable to otherwise obtain adequate medical care, thus state plans must take steps to ensure that Medicaid is the payer of last resort.^[41] The court observed the intervenor providers were not seeking to obtain additional payment from the employee (the Medicaid beneficiary), but were seeking only to recover amounts due under the workers’ compensation system, directly from the workers’ compensation insurer. The court concluded the workers’ compensation act was not contrary to or inconsistent with Congressional objectives in enacting Medicaid and was not preempted by federal Medicaid statutes or regulations.

This state’s Medicaid program similarly requires that third-party liability be ascertained when medical services are paid by Medicaid. “Third-party payer” refers to any entity that has a probable obligation to pay all or part of the costs of a beneficiary’s health services including a workers’ compensation plan. ^[42] Similarly, Medicare is not payable when payment can reasonably be expected to be made by certain third-party payers including workers’ compensation plans.^[43]

Other cases cited by the employer and TPA Meadowbrook involve settlements with tortfeasors which are governed by regulations that prohibit “balance billing” against a beneficiary or against a beneficiary’s personal property for Medicaid- or Medicare-covered services. None of the cases address third party liability or secondary payer provisions. The California Supreme Court noted the difference in Olszewski v. Scripps Health,^[44] emphasizing that the federal statutes and regulations do not bar a provider from recovering from liable third parties.

A compensation judge possesses such authority as is necessary to administer the workers’ compensation act. The authority to approve payment of medical expenses incurred for services furnished to an injured employee is provided by statute. Minn. Stat. §§ 176.135, 176.136. Under these provisions, the judge has jurisdiction to determine what medical expenses must be paid and in what amount. The claim in this case involves an application by the intervenor for workers’ compensation medical expenses, to be paid by the employer and insurer.^[45]

Intervenor Fresenius asserts that, according to the supreme court decision in Spaeth, accepting a third-party payment from a secondary payer — no matter who that entity is — does not deprive a medical provider of its right under the workers’ compensation act to receive payment of medical expenses from the employer and insurer. In Spaeth, a medical provider made a claim for medical expenses over and above amounts paid by the employee’s Blue Cross Blue Shield insurance. The supreme court adopted the WCCA dissenting opinion and ruled that a provider making a claim for medical expenses under the Minnesota workers’ compensation act is not limited to the amounts accepted from a third-party payer but is entitled to payment of medical charges for services provided to the employee for a work-related injury, up to the maximum allowed under the Minnesota workers’ compensation medical fee schedule.

We conclude the compensation judge properly rejected the employer and TPA Meadowbrook’s argument that a medical provider that accepts payments from Medicaid and Medicare is barred from receiving workers’ compensation payment for treatment provided to an injured employee, and properly awarded payment of the outstanding medical intervention interests associated with treatment of the employee’s end-stage renal disease pursuant to the Minnesota workers’ compensation medical fee schedule and in accordance with the workers’ compensation law/fee schedule of the state of Michigan for services rendered in that state.

To the extent the compensation judge directed that payment be made “in accordance with all other state and federal laws,” the Findings and Order is modified. The judge’s order is contrary to the determination, affirmed by this court, that she lacked jurisdiction to apply federal law. Further, in the absence of any reference to the state or federal law(s) which should be applied, the order is too vague to be enforceable. We, accordingly, vacate that portion of orders 3 and 4.