                       PUBLISHED


UNITED STATES COURT OF APPEALS
             FOR THE FOURTH CIRCUIT


UNITED STATES OF AMERICA,             
                Plaintiff-Appellee,
               v.                          No. 11-5130
JOHN R. MCLEAN,
            Defendant-Appellant.
                                      
       Appeal from the United States District Court
        for the District of Maryland, at Baltimore.
          William D. Quarles, Jr., District Judge.
                 (1:10-cr-00531-WDQ-1)

                 Argued: February 1, 2013

                  Decided: April 23, 2013

 Before GREGORY and KEENAN, Circuit Judges, and
Robert E. PAYNE, Senior United States District Judge for
 the Eastern District of Virginia, sitting by designation.



Affirmed by published opinion. Judge Gregory wrote the
opinion, in which Judge Keenan and Senior Judge Payne
joined.
2                  UNITED STATES v. MCLEAN
                          COUNSEL

ARGUED: Richard W. Westling, WALLER, LANSDEN,
DORTCH & DAVIS, Nashville, Tennessee, for Appellant.
Sandra Wilkinson, OFFICE OF THE UNITED STATES
ATTORNEY, Baltimore, Maryland, for Appellee. ON
BRIEF: Mark M. Bell, Jessica R. Sievert, WALLER, LANS-
DEN, DORTCH & DAVIS, Nashville, Tennessee; Carol M.
McCarthy, OBER, KALER, GRIMES & SHRIVER, PC, Bal-
timore, Maryland, for Appellant. Rod J. Rosenstein, United
States Attorney, Mark W. Crooks, Assistant United States
Attorney, Thomas F. Corcoran, Assistant United States Attor-
ney, Michelle Purdy, Law Clerk, OFFICE OF THE UNITED
STATES ATTORNEY, Baltimore, Maryland, for Appellee.


                          OPINION

GREGORY, Circuit Judge:

   John McLean, an interventional cardiologist, appeals his
convictions and sentence for health care fraud and making
false statements in connection with the delivery of or payment
for health care services. The convictions arise from a scheme
to defraud insurers by submitting claims for medically unnec-
essary stent procedures. Among other arguments, McLean
contends that there is insufficient evidence to support his con-
victions. Although proof of a physician’s failure to meet med-
ical standards, by itself, could not sustain a conviction for the
federal offense of health care fraud, we find that here the evi-
dence supports the jury’s verdict. Finding no reversible error,
we affirm.

                               I.

  During the relevant time period, McLean was in private
practice in Salisbury, Maryland, and held privileges at Penin-
                    UNITED STATES v. MCLEAN                 3
sula Regional Medical Center ("PRMC"), where he performed
cardiac catheterizations and coronary stent procedures. In the
summer of 2006, PRMC began investigating McLean’s stent-
ing practices after a quality control review revealed he had
placed a stent in a coronary artery with no significant block-
age, or "stenosis." An initial review showed that McLean had
performed inappropriate stent procedures in 13 cases. After an
outside contractor confirmed those findings, the hospital
asked McLean to submit to a concurrent review procedure
pending further investigation. McLean agreed, but subse-
quently violated the procedure in three cases. Near the end of
2006, the outside contractor confirmed that McLean had per-
formed inappropriate stents in approximately half of 25 ran-
domly selected cases. Shortly thereafter, McLean resigned his
hospital privileges after informing PRMC that he had devel-
oped an eye condition causing vision loss in one eye. In the
ensuing months, McLean continued to see patients and review
diagnostic test results in his office.

   In the spring of 2007, the United States subpoenaed 117
patient files from McLean’s practice. After receiving informa-
tion that the files were in peril, the government obtained a
warrant to secure the records. When the FBI agents arrived at
McLean’s office, they found subpoenaed files stacked on
McLean’s desk and a shred bin nearby. McLean admitted that
he was removing documents from the files for shredding.

   Following the conclusion of the government’s investiga-
tion, McLean was indicted on one count of health care fraud
in violation of 18 U.S.C. § 1347 (Count 1), and six counts of
knowingly and willfully making false statements in connec-
tion with the delivery of and payment for health care services
in violation of 18 U.S.C. § 1035(a)(2) (Counts 2-7).1 In the
health care fraud charge, the government alleged that McLean
executed a scheme to defraud Medicare, Medicaid, and pri-
vate insurers by submitting claims for medically unnecessary
  1
   Count 6 was dismissed on the government’s motion.
4                      UNITED STATES v. MCLEAN
procedures and testing. The false statement charges related to
specific records in which McLean was alleged to have will-
fully misrepresented the level of stenosis in patient arteries.

   At trial, the government supported its allegations with testi-
mony from two expert cardiologists, PRMC staff who worked
with McLean, and several of his former employees and
patients. Both experts testified that during the relevant time
period it was generally accepted in the medical community
that coronary stents were not medically necessary absent a
diagnosis of at least 70% stenosis and symptoms of blockage
such as chest pain or a positive stress test. One of the experts,
Dr. Ian Gilchrist, explained that although coronary artery dis-
ease is considered significant when an artery is blocked by
50%, stents are not medically necessary until the 70% thresh-
old because that is the point when the body can no longer
compensate for reduced blood flow to the heart.2 Gilchrist tes-
tified that McLean had grossly overstated the level of block-
age in the patient files he reviewed. A summary of 59 cases
prepared by Gilchrist showed McLean often recorded stenosis
of 80% to 95% for lesions of no more than 10% to 30%. Gil-
christ testified specifically about 15 cases, explaining in detail
how the stenosis shown in the angiograms was overstated in
McLean’s records. Gilchrist further testified that in at least
one case, McLean placed an appropriate stent, showing rea-
sonable technique and "the ability to distinguish what should
be done."

   The other expert, Dr. Joseph Cinderella, Director of the
PRMC Cardiac Catheterization Laboratory, testified that he
had reviewed the stent procedures McLean performed
between 2003 and 2006 and ranked each procedure on a scale
of one to five, where one meant medically appropriate and
five meant inappropriate. Cinderella testified that the fours
    2
    The exception to that rule, Gilchrist testified, is the left main coronary
artery, for which stenosis of 50% could justify a stent. None of the stent
procedures at issue in this case involved the left main coronary artery.
                   UNITED STATES v. MCLEAN                    5
and fives were "pretty black and white"; four meant "most
physicians would not proceed," and five meant "the consensus
for pretty much anyone would be not . . . [to] proceed." Out
of the 707 procedures he reviewed, Cinderella categorized
101 procedures as fives and 108 as fours. Nonetheless, the
evidence showed that McLean certified to insurers that these
procedures were reasonable and medically necessary in order
to obtain reimbursement.

   In addition, the jury heard testimony from PRMC staff who
had seen McLean overstate the stenosis shown in angiograms.
Nurse Paul Kenlon testified that on multiple occasions he dis-
agreed with the percentage McLean recorded and that he
remembered a couple of times when McLean said there were
90% blockages and Kenlon "just simply could not see a lesion
in the vessel." According to Kenlon, hospital staff used to sar-
castically refer to healthy lesions that did not need interven-
tion as "McLean 90 percenter[s]." Another nurse, Charlene
Shellenberger, testified that McLean had placed stents in
patients she had "a very difficult time being able to say . . .
[had] a lesion that needed to be stented." In one case, after
McLean stated that an artery had 99% stenosis, Shellenberger
turned to his assistant and asked, "How can you ethically
write that when you and I both know that is not a 99%
lesion?"

   The jury also heard testimony from patients who had
received medically unnecessary stents from McLean. Patient
F.M. testified that he never experienced the chest discomfort
McLean recorded in his medical records. Another patient,
L.H., testified that McLean gave her a before-and-after pic-
ture of her artery, which purported to show 97% blockage
cleared by the stent. L.H. later learned that she never had any
blockage. Her angiogram, which Gilchrist played for the jury,
showed that the apparent blockage was actually a spasm of
the artery, which subsided after McLean injected nitroglyc-
erin.
6                  UNITED STATES v. MCLEAN
   Witnesses also testified about McLean’s reaction to the
investigation. In an early letter to PRMC, McLean acknowl-
edged that although "[t]here is subjectivity reading the degree
of stenosis, . . . standard practice is a lesion above 70% is felt
to be significant and does receive intervention," but objected
to the hospital’s review, quoting another doctor’s comment
that "you do not second-guess the cardiologist who makes a
decision in the cath lab at the time of the procedure." Accord-
ing to Dr. Thomas Lawrence, Vice President of Medical
Affairs at PRMC, McLean later called the investigation a
"joke" and a "witch hunt." Carol Hales, a former employee of
McLean, testified that McLean had blamed the investigation
on other cardiologists at the hospital who were "[o]ut to get
him." Another former employee, Candace Klopp, testified
that McLean told his employees the hospital "held a gun to
[his] head" to force him to resign his privileges. Patient C.L.
testified that when she confronted McLean and asked him
why he placed a stent in an artery with no blockage, McLean
responded, "[B]ecause it was easy, why not?" And an FBI
agent who executed the warrant at McLean’s office provided
detail about his attempt to shred subpoenaed records.

   In addition, Dr. Jeffrey Weiland, Chief of the Division of
Cardiology at PRMC, testified that prior to resigning from
PRMC, McLean told him that the issues he was having may
have been caused by his vision problems. However, Dr. Neil
Miller, an expert neuro-ophthalmologist, testified that
McLean’s vision loss in one eye was caused by a stroke of the
optic nerve that occurred in October 2006 and would not have
affected his vision prior to that time. Miller also testified that
although McLean had another condition called drusen, which
caused a minimal defect in his field vision, it was highly
unlikely to have significantly impacted his ability to see
because his central vision was normal. At the same time,
numerous witnesses testified that McLean had claimed to
have no trouble seeing. For instance, patient C.L. testified that
McLean told her his eye condition didn’t affect what he did
to her, and he could see "just fine," and Klopp testified that
                      UNITED STATES v. MCLEAN                             7
in spring 2007 McLean said to another employee, "I sit and
watch and look at the cardio scans with you . . . have [I] ever
read a scan wrong?"

   The government also offered peer comparison data, which
showed that although a smaller proportion of McLean’s Medi-
care patients received stents as compared to his peers, the
patients McLean chose to stent received nearly twice as many
stents on average as the patients of his peers.3 The evidence
also showed that the number of stent reimbursement claims
McLean submitted to Medicare increased dramatically in
2004, around the same time he purchased a $1.7 million condo-
minium.4 In addition, the government introduced a document
from McLean’s office showing that patients generally were
scheduled for stress tests every four to six weeks, three
months, six months, and 12-18 months after stent interven-
tions, a pattern confirmed by McLean’s billing data and testi-
mony from his former employees and patients. Dr. Gilchrist
testified that regular diagnostic testing of this kind is not med-
ically necessary after a stent and that stress tests should only
be ordered when a patient has symptoms such as chest pain.

   In his defense, McLean argued that the medical standard
for coronary stents alleged by the government was incorrect,
that the process of evaluating angiograms is highly subjective,
  3
     Specifically, between 2004 and 2006, 16 out of every 100 Medicare
patients in McLean’s practice received a stent, a rate 67% below the aver-
age in his peer group (defined as the top 25% of physicians billing for cor-
onary stents in Maryland during that time period). However, while on
average McLean’s peers placed 1.15 stents in each patient, McLean’s
average per patient was 2.03.
   4
     According to the government’s data, McLean submitted Medicare
claims for 92 stents placed in 63 patients in 2000; 85 stents placed in 57
patients in 2003; 304 stents placed in 184 patients in 2004; 351 stents
placed in 171 patients in 2005; and 175 stents placed in 97 patients in
2006. On cross-examination, the government’s witness admitted that she
did no work to determine whether the increase in 2004 was attributable to
an increase in McLean’s patient load after two doctors left his practice.
8                  UNITED STATES v. MCLEAN
that McLean’s alleged error rate was not much higher than the
rate shown in a recent study, and that McLean’s attempt to
shred documents was not inculpatory because the documents
in the shred bin—including records from other physicians, fax
cover sheets, prescription refills, and test results—were not
material to the investigation. The defense’s expert witness,
Dr. Jonathan Marmur, testified that between 2003 and 2006
elective stents were considered medically appropriate if a
patient had at least 50% stenosis and evidence of ischemia or
angina. Marmur testified that 4 out of the 5 cases named in
the indictment met that standard of care. Further, although
Marmur did not agree with the percentage of stenosis McLean
recorded, he testified that some of the angiogram slides in
those cases could support a higher percentage. The defense
also offered testimony from former patients, including several
named in the indictment, that McLean’s treatments relieved
their symptoms, as well as testimony from former employees
that McLean was an attentive doctor who cared about his
patients.

   Following ten days of trial, the jury convicted McLean on
all counts. McLean subsequently moved for a judgment of
acquittal and a new trial, which the district court denied. Dur-
ing sentencing, the district court applied a 16-level enhance-
ment under United States Sentencing Guidelines
§ 2B.1.1(b)(1)(I) after calculating the total losses to be more
than $1 million. The district court sentenced McLean to 97
months imprisonment and three years supervised release, and
entered forfeiture and restitution orders of $579,070.

   On appeal, McLean challenges his convictions on several
grounds, arguing that the health care fraud statute is unconsti-
tutionally vague as applied to him; that the evidence was
insufficient to support his convictions on all counts; and that
his trial was prejudiced by the government’s failure to dis-
close impeachment evidence and certain erroneous evidenti-
ary rulings committed by the district court. He also contends
                   UNITED STATES v. MCLEAN                      9
that the case should be remanded for resentencing because his
sentence is procedurally unreasonable.

                               II.

  McLean first argues that the health care fraud statute, 18
U.S.C. § 1347, is unconstitutionally vague as applied to him
because no clear standard of medical necessity governed the
use of coronary artery stents during the relevant time period.
We review the constitutionality of a statute de novo. United
States v. Williams, 364 F.3d 556, 559 (4th Cir. 2004).

   A statute is unconstitutionally vague if it fails to provide
people of ordinary intelligence a reasonable opportunity to
understand what conduct it prohibits, or if it authorizes or
encourages arbitrary and discriminatory enforcement. Hill v.
Colorado, 530 U.S. 703, 732 (2000). Here, we ask whether an
ordinary person would understand that the health care fraud
statute prohibited McLean’s charged conduct. See United
States v. Passaro, 577 F.3d 207, 218 (4th Cir. 2009) (explain-
ing that vagueness challenges that lie outside of the First
Amendment context must be evaluated based on the facts of
the defendant’s case).

   The health care fraud statute makes it a crime to "know-
ingly and willfully execute[ ] . . . a scheme . . . (1) to defraud
any health care benefit program; or (2) to obtain, by means of
false or fraudulent . . . representations . . . any of the money
. . . [of] any health care benefit program . . . in connection
with the delivery of or payment for health care benefits, items,
or services." 18 U.S.C. § 1347. McLean argues that the statute
is unconstitutionally vague as applied because no government
standard or professional guideline defined the stenosis level
needed to justify a coronary stent during the relevant time
period, and the reading of angiograms is inherently subjective.
As such, he claims he had no way of knowing in advance
whether his conduct was prohibited. We disagree.
10                     UNITED STATES v. MCLEAN
   The health care fraud statute is not a medical malpractice
statute, it is a simple fraud statute. As applied here, it prohib-
ited McLean from knowingly and willfully defrauding insur-
ers by falsely certifying that the stents he placed in arteries
with little to no blockage were reasonable and medically nec-
essary in order to obtain reimbursement. Although the statute
does not enumerate every possible fraud scheme, an average
person would understand that this kind of conduct is prohib-
ited. See United States v. Franklin-El, 554 F.3d 903, 910-11
(10th Cir. 2009) (rejecting an analogous vagueness challenge
to § 1347 premised on complexity in Medicaid regulations
because the statute is simply a fraud statute).5 Further, the
statute’s mens rea requirement mitigates any ambiguity aris-
ing from the lack of clear medical guidance McLean alleges.
See United States v. Jaensch, 665 F.3d 83, 90 (4th Cir. 2011)
(rejecting vagueness challenge to federal statute prohibiting
the production of false government identification documents
based on statute’s scienter requirement). McLean could only
be convicted if the government proved beyond a reasonable
doubt that he acted "knowingly and willfully" to defraud
insurers, which necessarily entails proof that he knew the
stent procedures were unnecessary. This requirement of proof
eliminates the fair notice concerns he raises. As a result, the
health care fraud statute is not unconstitutionally vague as
applied to McLean.6
  5
     Our reasoning is also consistent with an unpublished opinion of this
Court, which we find persuasive. See United States v. Janati, 237 F.
App’x 843, 846-47 (4th Cir. 2007) (unpublished) (rejecting vagueness
challenge to health care fraud statute as applied to prohibit overbilling, and
holding that the statute provides fair notice that overbilling is prohibited
even though the billing manual may lack clarity).
   6
     In urging otherwise, McLean cites an unpublished decision of the Fifth
Circuit, which dealt with a similar vagueness challenge to the health care
fraud statute based on subjectivity in the standard of medical necessity for
coronary artery stents. See United States v. Patel, 485 Fed. App’x 702,
707 (5th Cir. 2012) (unpublished). This case does not provide much sup-
port for McLean. Although the Patel court recognized that the defendant’s
vagueness concerns were not "insubstantial," the court ultimately rejected
his arguments because the evidence showed that the concept of medical
necessity meant something concrete to the defendant. Id. The same can be
said of this case, as McLean’s letter to the hospital indicates he was aware
of the 70% threshold.
                  UNITED STATES v. MCLEAN                   11
                             III.

   McLean next argues that his convictions on all counts are
unsupported by sufficient evidence. We review the suffi-
ciency of the evidence de novo. United States v. Ryan-
Webster, 353 F.3d 353, 359 (4th Cir. 2003). "A defendant
bringing a sufficiency challenge must overcome a heavy bur-
den, and reversal for insufficiency must be confined to cases
where the prosecution’s failure is clear." United States v.
Engle, 676 F.3d 405, 419 (4th Cir. 2012) (internal quotation
marks and citations omitted). Our review is limited to deter-
mining whether, viewing the evidence in the light most favor-
able to the government, the jury’s verdict is supported by
"substantial evidence," that is, "evidence that a reasonable
finder of fact could accept as adequate and sufficient to sup-
port a conclusion of a defendant’s guilt beyond a reasonable
doubt." United States v. Burgos, 94 F.3d 849, 862 (4th Cir.
1996) (en banc). We are mindful that "the jury, not the
reviewing court, weighs the credibility of the evidence and
resolves any conflicts in the evidence presented, and if the
evidence supports different, reasonable interpretations, the
jury decides which interpretation to believe." Id. (internal
quotation marks, alterations, and citation omitted).

                              A.

   McLean first challenges the sufficiency of the evidence as
to the health care fraud charge (Count 1). To sustain a convic-
tion under 18 U.S.C. § 1347, the government was required to
prove beyond a reasonable doubt that McLean knowingly and
willfully executed a scheme to defraud insurers by billing for
medically unnecessary procedures. "[T]he specific intent to
defraud may be inferred from the totality of the circumstances
and need not be proven by direct evidence." United States v.
Harvey, 532 F.3d 326, 334 (4th Cir. 2008) (internal quotation
marks, alteration, and citation omitted). After carefully
reviewing the record, we conclude that substantial evidence
supports McLean’s conviction.
12                    UNITED STATES v. MCLEAN
   To begin, McLean’s pattern of overstating blockage by a
wide margin and placing unnecessary stents in a large number
of cases was direct evidence of a fraudulent scheme. Accord-
ing to Dr. Cinderella, over 100 of McLean’s cases involved
blockage of 25% or less. And Dr. Gilchrist testified that
McLean grossly overstated blockage in the 59 procedures he
reviewed. For example, patient AW had 0% blockage, and
McLean recorded it as 80% to 90%. Similarly, patient DD had
10% blockage, and McLean recorded it as 80%. McLean sub-
sequently sought reimbursement from insurers, certifying that
the procedures were reasonable and medically necessary
based on the falsely recorded stenosis levels. The stark dispar-
ity between what McLean recorded and what the angiogram
showed strongly suggests he intentionally committed fraud.

   There was also sufficient evidence to rule out non-criminal
explanations for McLean’s overstatements. Gilchrist testified
that the skill McLean displayed in an appropriate stent proce-
dure demonstrated reasonable technique and the ability to dis-
cern appropriate treatment, undermining the possibility that
McLean was simply a negligent physician. Dr. Miller, the
expert neuro-ophthalmologist, testified that the optic stroke
McLean suffered in his left eye in October 2006 would not
have affected his vision in years prior and that his preexisting
drusen was highly unlikely to have significantly affected his
ability to see because it caused only a minor field defect and
did not affect his central vision.7 Based on his testimony, a
rational juror could exclude McLean’s eye conditions as an
explanation for his blockage overstatements. Finally, although
Gilchrist admitted that angiogram reading is subjective, he
testified that physicians should be in the same ballpark and
inter-reviewer variability should not exceed 10% to 20%.
Both Gilchrist and Cinderella testified that the cases at issue
were not borderline cases where inter-reviewer variability
  7
    Although Miller could not test the effect of the drusen on McLean’s
left eye due to the optic stroke, his opinion was based on the effect of the
drusen on his right eye because the drusen was symmetrical in both eyes.
                  UNITED STATES v. MCLEAN                   13
would come into play. And the jury viewed many of the
angiograms themselves, providing them an opportunity to
determine whether they were within the borderline area where
subjectivity could account for McLean’s overstatements.
Based on this evidence, the jury could reasonably exclude the
phenomenon of inter-reviewer variability as an explanation
for McLean’s conduct.

   McLean nonetheless argues that the government’s pattern
evidence is not probative of fraud because a 2009 – 2010
study published in the Journal of the American Medical Asso-
ciation found that 12% of stents performed nationwide were
medically unnecessary. He argues that his own error rate was
not much higher, as the Cinderella fives constituted only 15%
of the total stent procedures he performed between 2003 and
2006. We are not persuaded that this study undermines the
government’s pattern evidence. First, if the Cinderella fours
are included, McLean’s error rate was approximately 30%,
not 15%. But more importantly, the import of the pattern evi-
dence is not simply that McLean repeatedly performed medi-
cally unnecessary stents, but rather that he repeatedly
overstated blockage by a wide margin. Indeed, we do not
believe that pattern evidence showing that a physician placed
more unnecessary stents than the national average necessarily
would be probative of fraud, for such a pattern might only
suggest negligence. The distinction here is that McLean
repeatedly overstated blockage by a margin well beyond the
normal variation between observers. McLean cites nothing
from the study showing that his pattern of misrepresentation
was comparable to the conduct of other physicians nation-
wide. As a result, the study does not undermine the weight of
the pattern evidence described above.

  Moreover, even assuming the study McLean cites calls into
question the strength of the government’s pattern evidence,
separate evidence of fraud provided a substantial basis for the
conviction. Tellingly, McLean told patient C.L. that he placed
a stent in an artery with no blockage "because it was easy,"
14                 UNITED STATES v. MCLEAN
not because he saw blockage. That statement implies he knew
the stent was unnecessary and the blockage he recorded was
false. Additionally, the evidence indicates McLean made
other misrepresentations to create the illusion of medical
necessity. He gave patients misleading pictures purporting to
show cleared blockage when the angiogram, viewed in full,
showed no significant blockage. In L.H.’s case, the apparent
blockage was actually a spasm of the artery, which McLean
knew occurred because he treated it. McLean also recorded
symptoms patients did not experience. For instance, patient
F.M. testified that he never experienced the chest discomfort
McLean recorded. And in two of the cases named in the
indictment, medical records showed that patients had previ-
ously denied symptoms, such as chest pain, which McLean
nevertheless recorded after the stent procedures were com-
pleted. McLean also gave inconsistent explanations for his
conduct, suggesting on at least one occasion to Dr. Weiland
that his eye condition had caused the inappropriate stents, but
insisting on many other occasions to patients and employees
that his vision was fine. These inconsistencies reasonably sug-
gest that McLean falsely blamed his conduct on his eye condi-
tion to cover up his true fraudulent intent. See United States
v. Hughes, 716 F.2d 234, 240-41 (4th Cir. 1983) (noting that
a defendant’s inconsistent alibi statements can be probative of
illicit intent). Finally, McLean attempted to shred patient files
subpoenaed by the United States. McLean argues that this
incident was not probative of fraud because he was honest
about what he was doing, and the documents found in the
shred bin were not material to the investigation. However,
viewing the evidence in the light most favorable to the gov-
ernment, as we must, a reasonable juror could conclude
McLean had something to hide, even if his motives for select-
ing particular documents are unclear.

   There was also sufficient evidence to prove McLean had a
financial motive for the fraudulent scheme. McLean received
reimbursement for each stent procedure he performed, as well
as for a series of regularly scheduled diagnostic tests after the
                     UNITED STATES v. MCLEAN                          15
procedure, which were administered to patients at his office
pursuant to standing orders.8 This evidence showed that stent-
ing provided a significant source of reimbursement for
McLean’s private practice, and thus, that he had a financial
motive for executing the fraudulent scheme.

   Based on the direct evidence that McLean overstated block-
age in numerous cases, his pattern of misleading patients and
making other misrepresentations in patient files, his admission
to C.L. that he placed an unnecessary stent "because it was
easy," his inconsistent explanations for his conduct, his
attempt to shred patient files, and the circumstantial evidence
of a financial motive, we hold that McLean’s health care
fraud conviction is supported by substantial evidence.

   McLean’s two remaining challenges to the evidence do not
persuade us otherwise. First, McLean argues that the govern-
ment’s peer comparison evidence was actually exculpatory.
The government used the evidence to show that McLean
placed twice as many stents on average in each patient he
chose to stent as his peers. As McLean notes, however, the
evidence also showed that McLean only stented 16 out of 100
patients in his practice, a rate 67% lower than the average of
his peers. We are not persuaded that this evidence is exculpa-
tory. The peer comparison evidence simply compared the
number of stent procedures McLean performed to the average
of his peers; it said nothing about the necessity of those proce-
dures. As such, its probative value was marginal at best. Even
construing the evidence as McLean urges, proof that he
stented less patients on average than his peers does not under-
mine the other evidence of fraud outlined above.

  Second, McLean argues that the evidence of his condomin-
  8
   McLean argues that the government failed to prove beyond a reason-
able doubt that standing orders existed. However, billing data and testi-
mony from patients and staff provided a sufficient basis for the jury to
make this finding.
16                 UNITED STATES v. MCLEAN
ium purchase was not adequate to prove a financial motive
because the funds he received from stent procedures consti-
tuted a small fraction of the purchase price. We agree with
McLean that this evidence is not particularly probative. A
condominium purchase is hardly evidence of a financial
motive to commit fraud; it is a personal financial decision that
falls well within the bounds of law-abiding conduct. How-
ever, as explained above, there was separate evidence show-
ing that McLean benefitted financially from the unnecessary
stent procedures and follow-up diagnostic tests he performed.
Thus, even setting aside the condominium purchase, there was
sufficient evidence to show McLean had a financial motive to
commit fraud.

  For these reasons, we hold that McLean’s health care fraud
conviction is supported by substantial evidence.

                               B.

   McLean next challenges the sufficiency of the evidence as
to the false statement charges (Counts 2-5, 7). To sustain a
conviction under 18 U.S.C. § 1035, the government was
required to prove beyond a reasonable doubt that McLean
"knowingly and willfully . . . ma[de] . . . materially false . . .
or fraudulent statements . . . in connection with the delivery
of or payment for health care benefits, items, or services." 18
U.S.C. § 1035. The specific intent to defraud may be inferred
from the totality of the circumstances, and need not be proven
by direct evidence. Harvey, 532 F.3d at 334.

   Dr. Gilchrist testified about the cases cited in the indict-
ment and explained to the jury how McLean overstated the
level of stenosis in each case. Even McLean’s own expert, Dr.
Marmur, disagreed with the stenosis diagnoses McLean
recorded, although he testified that some slides could support
a higher reading. Given the sheer disparity between the steno-
sis McLean recorded and what the angiograms showed, and
the other evidence of fraud outlined above, there was suffi-
                   UNITED STATES v. MCLEAN                    17
cient evidence for the jury to conclude that McLean intention-
ally overstated stenosis levels in the patient files named in the
indictment. Further, the evidence showed that these misrepre-
sentations were material insofar as they were necessary for
McLean to justify the stents and obtain reimbursement from
insurers.

   McLean’s challenge to the sufficiency of the evidence on
these counts is based on the same arguments he raises with
respect to the health care fraud charge. He argues that the
government failed to prove that his misrepresentations were
intentional and that he was not simply a negligent physician,
and that the phenomenon of inter-reviewer variability and his
vision problems could explain his overstatements. As dis-
cussed above, however, there was sufficient evidence from
which the jury could rule out these non-criminal explanations
for his conduct.

   For these reasons, we hold that there is substantial evidence
to support the false statement convictions.

                               C.

   Lastly, McLean argues that the evidence was insufficient as
to all counts because the government failed to prove beyond
a reasonable doubt that an objective standard of medical
necessity existed. There was ample evidence, however, that a
standard existed. Both government experts testified that stents
are not justified unless there is 70% or more stenosis in an
artery and the patient suffers from symptoms of blockage.
McLean was aware of this standard because he referenced it
in a letter to the hospital. Although Dr. Marmur disagreed
with the minimum threshold of stenosis required to justify a
stent, he agreed with the government’s experts that stents are
contraindicated in cases of less than 50% stenosis. At a mini-
18                     UNITED STATES v. MCLEAN
mum, the evidence clearly showed that stents are objectively
unnecessary in cases of less than 50% stenosis.9

                                    IV.

   McLean next argues that his trial was prejudiced by the
government’s failure to disclose impeachment evidence and
by certain evidentiary and discovery rulings committed by the
district court. We do not believe a new trial is warranted
based on these assertions of error for the reasons stated below.

                                     A.

   Shortly after McLean’s trial, the government issued a press
release stating that it had reached an agreement with PRMC
to settle a civil fraud investigation of the hospital for being
aware of and failing to take action to prevent McLean’s medi-
cally unnecessary procedures. Subsequent disclosures
revealed that the parties had reached a handshake settlement
months before. McLean argues that the government’s failure
to disclose this information to him before trial violated his due
process rights because he could have used the information to
impeach the PRMC witnesses. In particular, he argues that the
evidence would have allowed him to explore Dr. Cinderella’s
motivations for testifying and to probe bias, thereby under-
mining the credibility of a key witness.

   The due process clause of the Fifth Amendment requires
the government to disclose favorable impeachment evidence
to the defendant. See Brady v. Maryland, 373 U.S. 83, 87
(1963) (holding that due process requires the disclosure of
  9
    McLean points out that Dr. Gilchrist sometimes referred to 50% steno-
sis when explaining why a particular stent was inappropriate, arguing that
his reference to something other than the 70% threshold highlights the
inadequacy of proof on this issue. Dr. Gilchrist, however, testified that
stents are contraindicated at stenosis less than 50%, and we do not find his
reference to that threshold in individual cases inconsistent with his opinion
that stents are generally necessary only after stenosis reaches 70%.
                   UNITED STATES v. MCLEAN                    19
evidence favorable to the accused and material to guilt or pun-
ishment); Giglio v. United States, 405 U.S. 150, 154-55
(1972) (including impeachment evidence within the scope of
materials that Brady requires prosecutors to disclose). A due
process violation occurs when (1) the evidence is favorable to
the accused because it is exculpatory or impeaching; (2) the
evidence was suppressed by the government, either willfully
or inadvertently; and (3) the evidence is material. United
States v. Moussaoui, 591 F.3d 263, 285 (4th Cir. 2010). To be
material, there must be a reasonable probability that disclo-
sure of the evidence would have produced a different out-
come. Kyles v. Whitley, 514 U.S. 419, 434 (1995).

   We find no due process violation here because the settle-
ment information had little impeachment value, and there was
no reasonable probability it would have affected the jury’s
verdict. Neither Cinderella nor any other PRMC witness was
a party to the settlement, and they did not agree to testify in
exchange for the release of the government’s claims against
the hospital—the impeachment value of the information was
therefore minimal. If anything, disclosure of the settlement to
the jury likely would have bolstered the government’s case,
for the hospital’s liability was based entirely on its failure to
prevent McLean’s misconduct. Finally, even assuming the
settlement had some impeachment value, the jury’s verdict
could have rested on the testimony from Dr. Gilchrist and the
many other former employees and patients who testified at
trial. We cannot say there is a reasonable probability that dis-
closure of the settlement would have altered the jury’s verdict.

                               B.

   The day before McLean’s expert was scheduled to testify,
the district court allowed the government to conduct voir dire
on him to remedy McLean’s failure to provide adequate dis-
closures under Federal Rule of Criminal Procedure 16.
McLean argues that the court’s ruling was erroneous and that
it deprived him of a fair trial.
20                 UNITED STATES v. MCLEAN
   We review the district court’s decision as to the appropriate
remedy for a violation of Rule 16 for abuse of discretion.
United States v. Barile, 286 F.3d 749, 759 (4th Cir. 2002). A
court abuses its discretion if its decision is "guided by errone-
ous legal principles" or "rests upon a clearly erroneous factual
finding." United States v. Johnson, 617 F.3d 286, 292 (4th
Cir. 2010) (internal quotation marks and citation omitted).

   Rule 16 imposes mutual obligations on the prosecution and
the defendant to disclose, at the other party’s request, a writ-
ten summary of any expert testimony that will be used at trial.
The summary must describe the expert’s opinions and "the
bases and reasons for those opinions." Fed. R. Crim. P.
16(b)(1)(C); id. 16(a)(1)(G). If a party fails to comply with
this rule, the court may "prohibit that party from introducing
the undisclosed evidence" or "enter any other order that is just
under the circumstances." Id. 16(d)(2)(C).

   On June 24, 2011, three weeks before trial, McLean
informed the government that Dr. Marmur would be testifying
at trial and provided a Rule 16 disclosure describing his testi-
mony. The disclosure stated that Marmur would testify that in
five cases he had reviewed, McLean’s stent treatment met the
"interventional cardiology standard of care." Four days later,
the government asked McLean to clarify the definition of the
"interventional cardiology standard of care" and the bases and
reasons for Marmur’s opinions. McLean did not respond. As
a result, on July 17, 2011, the government moved the court to
exclude Marmur’s testimony regarding the five cases. On July
20, 2011, the day the defense case began, the court considered
the government’s motion. Rather than excluding Marmur’s
testimony, the court gave the government the option to con-
duct voir dire of Marmur the next morning.

  We see no abuse of discretion in this ruling. Because
McLean’s Rule 16 disclosure did not describe Marmur’s opin-
ions "beyond stating the conclusion he had reached and did
not give the reasons for those opinions as required under Rule
                   UNITED STATES v. MCLEAN                    21
16(b)(1)(C)," the disclosure did not satisfy the rule. Barile,
286 F.3d at 758. It was not an abuse of discretion to allow the
government voir dire, especially given the fact that Marmur
was scheduled to testify the following day. See id. ("Upon
finding a violation of Rule 16, the district court has discretion
under the Federal Rules of Criminal Procedure to determine
the proper remedy.") (citing Fed. R. Crim. P. 16(d)(2); United
States v. Muse, 83 F.3d 672, 675 (4th Cir. 1996)). By that
point, the government’s need to discover the bases and rea-
sons for his opinions was pressing, and there was no excuse
for McLean’s delay.

                               C.

   McLean also argues that the district court erroneously sus-
tained the government’s objection to several aspects of Dr.
Marmur’s testimony. Specifically, McLean argues that the
district court erred in excluding Marmur’s testimony on: (1)
the medical necessity of follow-up tests post-stent interven-
tion; (2) the treatment McLean gave other patients beyond
those named in the Rule 16 disclosure; (3) the Journal of
American Medicine Association article showing a national
error rate of 12% in stent procedures; and (4) that four of the
five cases named in the indictment met the interventional car-
diology standard of care, in part, because Marmur had seen
other doctors perform similar stents. We review the district
court’s evidentiary rulings for abuse of discretion. United
States v. Basham, 561 F.3d 302, 325 (4th Cir. 2009). Eviden-
tiary rulings are subject to harmless error review under Fed-
eral Rule of Criminal Procedure 52. United States v. Heater,
63 F.3d 311, 325 (4th Cir. 1995). To find a district court’s
error harmless, we need only say "with fair assurance, after
pondering all that happened without stripping the erroneous
action from the whole, that the judgment was not substantially
swayed by the error." Id. (internal quotation marks and cita-
tion omitted).

   With respect to the first two topics, we find no abuse of dis-
cretion because McLean did not provide notice that Marmur
22                 UNITED STATES v. MCLEAN
planned to testify on these subjects as required by Rule 16.
See Fed. R. Crim. P. 16(d)(2)(C) (allowing courts to exclude
undisclosed evidence to remedy a Rule 16 violation); Barile,
286 F.3d at 758-59 (finding no abuse of discretion in district
court’s decision to exclude part of expert’s testimony based
on defendant’s failure to provide adequate notice of the testi-
mony under Rule 16).

   As for the journal article, assuming without deciding that
the court abused its discretion, any error was harmless.
McLean introduced the study during his cross-examination of
Dr. Gilchrist, and defense counsel relied on it during closing
argument, emphasizing that the error rate discovered was
12%. Because the pertinent evidence from the study was
introduced through other means, we can say with fair assur-
ance that the jury’s verdict was not swayed by the district
court’s ruling.

   As for the last topic, the government’s voir dire revealed
that there were two bases for Marmur’s opinion that the stan-
dard of care was met in four of the five cases he reviewed: (1)
that the patients had at least 50% stenosis and symptoms or
evidence of ischemia; and (2) that he had seen other doctors
perform similar stents. The district court sustained the govern-
ment’s objection to the latter basis for Marmur’s opinion, rea-
soning that Marmur’s personal observations were not
sufficiently reliable to be admissible under Federal Rule of
Evidence 702. See Fed. R. Ev. 702 (providing that admissible
expert testimony must be "the product of reliable principles
and methods"); Daubert v. Merrell Dow Pharmaceuticals,
Inc., 509 U.S. 579, 592-93 (1993) (holding that district courts
must make a preliminary assessment of whether the reasoning
or methodology underlying an expert’s testimony is scientifi-
cally valid and can be applied to the facts in issue).

  McLean argues that this ruling was an abuse of discretion
because medical standards of care are defined, in part, by the
behavior of physicians in the relevant medical community.
                   UNITED STATES v. MCLEAN                    23
We need not decide whether the court’s ruling was an abuse
of discretion because even assuming it was erroneous, any
error was harmless. The court allowed Marmur to testify that
the standard of care was met in the four cases because the
objective criteria he referenced (50% stenosis plus symptoms
or evidence of ischemia) were satisfied. That an additional
explanation for his opinion was excluded did not detract from
the ultimate point of his testimony, which was that in his
opinion, the stents were within the standard of care. We see
no prejudice resulting from the district court’s decision.

                               V.

   Finally, McLean argues that his sentence is procedurally
unreasonable because the district court erred in calculating the
loss amount. We review the sentence imposed by the district
court under "a deferential abuse-of-discretion standard," Gall
v. United States, 552 U.S. 38, 41 (2007), applying clear error
review to the district court’s finding of fraud loss, United
States v. Pierce, 409 F.3d 228, 234 (4th Cir. 2005).

   In calculating the appropriate sentence, the Sentencing
Guidelines allow the district court to consider as relevant con-
duct the acts of the defendant, as well as the acts "willfully
caused by the defendant" and "all harm that resulted from the
acts and omissions." U.S.S.G. § 1B1.3. In deciding whether to
apply an enhancement under Guidelines § 2B.1.1, the district
court "need only make a reasonable estimate of the loss,"
U.S.S.G. § 2B1.1, cmt. n.3(C), based on a preponderance of
the evidence, see United States v. Mehta, 594 F.3d 277, 282
(4th Cir. 2010). Because the traditional rules of evidence are
not applicable to sentencing proceedings, Fed. R. Evid.
1101(d)(3), the sentencing court may consider any "relevant
information . . . [that] has sufficient indicia of reliability to
support its probable accuracy," U.S.S.G. § 6A1.3(a).

  To establish the amount of loss, the government submitted
evidence showing that from 2003 to 2006, McLean received
24                    UNITED STATES v. MCLEAN
$579,070 in reimbursement from Medicare and private insur-
ers for the unnecessary stent procedures and related follow-up
tests. Mary Hammond, an auditor from the U.S. Attorney’s
Office, testified that the number of unnecessary stent proce-
dures was calculated as the sum of procedures Dr. Cinderella
categorized as fours and fives. Hammond also testified the
hospital repaid $1.3 million to federal programs in connection
with the settlement, which corresponded to reimbursement it
received for hospital facilities used in McLean’s unnecessary
stent procedures. For purposes of the settlement, Hammond
testified that the unnecessary stents were defined as the Cin-
derella fives, fours, and a few threes. Based on these figures,
the district court found that "with the 579,000 clear stent-
related loss and the hospital’s reimbursement . . . there cer-
tainly is a loss in excess of a million dollars, and the 16-level
enhancement should apply."10

   McLean argues that loss was not established by the prepon-
derance of the evidence because Cinderella’s analysis was
unreliable, the government failed to prove that any specific
follow-up test was inappropriate, and the hospital’s losses
were not caused by "relevant conduct." We are not persuaded.
Neither the follow-up tests nor the hospital’s losses would
have occurred but for the medically unnecessary stents
McLean performed; as such, they were properly included as
losses from relevant conduct. See U.S.S.G. § 1B1.3(a)(3)
(permitting sentencing courts to consider "all harm that
resulted from the acts and omissions" of the defendant).
Moreover, the district court did not clearly err in relying on
Cinderella’s analysis. McLean contends that Cinderella was
biased and his opinions were not grounded in objective
criteria. However, the district court had the opportunity to
  10
     McLean argues that the case should be remanded for resentencing
because the district court did not specify the amount of loss. We disagree.
Although the district court did not do the math in open court, the court
clearly found that the total loss equaled the sum of $579,000 and the hos-
pital’s $1.3 million settlement figure, as the above statements demonstrate.
                      UNITED STATES v. MCLEAN                           25
evaluate Cinderella’s credibility and the strength of his opin-
ions at trial, and we cannot say it was unreasonable to credit
his testimony. In sum, we find no clear error in the district
court’s loss calculations.11

                                   VI.

   For the reasons explained above, the convictions and sen-
tence are affirmed.

                                                            AFFIRMED




  11
    McLean also argues that the hospital’s repayments for Cinderella
threes should have been excluded because the government never
attempted to prove that these cases were fraudulent. We disagree.
Although Cinderella classified these cases as "judgment call[s]," the judg-
ment that they were inappropriate was made when the hospital agreed to
repayment. Based on that judgment, it was not clear error to find that the
procedures were more likely than not part of McLean’s fraudulent scheme.
