June 2012 - American Association for Clinical Chemistry

higher hba1c levels linked
To better outcomes in
advanced heart failure
study of patients with advanced heart
a
failure found higher levels of HbA1c
to be associated with improved outcomes
in patients who also had diabetes
(Am J Cardiol 2012; doi:10.1016/j.amj
card.2012.02.022). The authors called for
further investigations to understand the
mechanisms underlying this finding.
Despite the evidence linking diabetes, insulin
resistance, and hyperglycemia to worse
outcomes in patients with heart failure, there
is insufficient data and guidance on optimal
strategies to manage diabetes in patients with
chronic heart failure. This prompted the researchers
to reevaluate the relationship between
HbA1c levels and outcomes in a large
cohort of advanced heart failure patients.
The study involved 845 patients followed
by physicians at the University of California
Los Angeles’ David Geffen School of Medicine.
The patients had baseline HbA1c and
other diagnostic testing at the time of referral
and were followed for 2 years. Nearly
three-quarters were men, more than threequarters
had New York Heart Association
class III or IV heart failure, and 42% had
diabetes. In those with diabetes, the mean
HbA1c level was 7.6% compared with 6.0%
in those without. The researchers stratified
patients both with and without diabetes by
HbA1c quartiles. The primary endpoints
of the study were death or need for urgent
heart transplant, or all-cause mortality.
When the authors analyzed HbA1c as a
continuous variable in multivariate analysis,
they found that for each unit increase
diagNostiC
and CPOCT Division Present
Promoting a Culture of
Quality and Consistency in
Critical and Point-of-Care Testing
26 CliniCal laboratory news June 2012
p r o f i L e s
p r o f i L e s
in HbA1c, there was an 8% decreased risk
for death or need for urgent heart transplantation.
In the cohort with diabetes,
survival free from death or urgent heart
transplantation was significantly higher in
the highest HbA1c quartile. In this group,
analyzing HbA1c as a continuous variable,
the authors found that for each unit increase
in HbA1c there was a 15% decrease
in risk of death, urgent heart transplantation,
and all-cause mortality. In the cohort
without diabetes, there was no difference in
outcomes by HbA1c quartile.
in-hospital lipid Testing falls short
of guideline recommendations
canadian researchers found over the
course of a decade a significant temporal
increase in in-hospital statin therapy
in patients with acute coronary syndrome
(ACS), but only a modest increase
in in-hospital lipid testing (Am J Cardiol
2012;109:1418–24). However, at the same
time they also found a strong association
between lipid testing and in-hospital
statin therapy. Patients who had lipid testing
performed and had higher low-density
lipoprotein cholesterol (LCL-C) levels were
more likely to be treated with a statin during
hospitalization. The authors concluded that
a substantial portion of patients with ACS
are not receiving guideline-recommended
lipid testing, and that strategies to boost
adherence to these guidelines would likely
improve patient outcomes.
The authors examined temporal trends
in lipid testing and statin therapy in hospitalized
patients using prospective registry data
that had been collected in a standardized
format for adult patients with a presumptive
diagnosis of ACS and diagnostic findings
consistent with ACS. The researchers
accessed data from 57 hospitals representing
13,947 patients and stratified the study population
into three groups based on the years
in which the participants were registered.
Overall, 70.8% of patients had lipid testing,
and 79.4% received in-hospital statin
therapy. However, during the 9-year study
period, while there was a significant increase
in in-hospital statin therapy—rising from
70% in the 1999–2004 cohort to 84.5% in
the 2007-2008 group—there was only a
minor increase in in-hospital lipid testing,
from 69.4% in the 1999–2004 group to
72.4% in the 2007–2008 cohort. Lipid testing
was independently associated with inhospital
statin use, and patients with LDL-C
levels >130 mg/L were more than twice as
likely as those with levels 99th percentile
in 13–40% of CAD patients with an adjudicated
diagnosis of AMI. The high incidence
of elevated cTn levels in this patient population
challenges application of the 99th percentile
as the decision limit for diagnosing
AMI. The authors also determined that cutoffs
for CAD patients tended to be higher
than in patients without a history of CAD,
and that the performance of the sensitive
cTn assays was most pronounced in CAD
patients with recent onset of chest pain.
However, the accuracy of these assays in diagnosing
acute coronary syndrome was significantly
lower in patients with pre-existing
CAD than in those who did not have preexisting
CAD.
esr, crP, and Wbc markers
of Pre-arthroplasty infection,
not just inflammation
sedimentation rate (ESR),
e rythrocyte
C-reactive protein (CRP) level, and
synovial fluid white blood cell (WBC)
count with differential are useful for diagnosing
periprosthetic joint infection
in patients with inflammatory or non-
inflammatory arthritis (J Bone Joint Surg
Am 2012;94:594–600). The findings dispel
the common belief that these markers do
not accurately identify periprosthetic joint
infection in patients with underlying inflammatory
conditions.
The study involved 871 consecutive patients
who underwent hip or knee arthroplasty
and who were evaluated for periprosthetic
joint infection. All had serum ESR
and CRP levels tested at the time of initial
evaluation, and joint aspiration for synovial
fluid WBC count with differential culture.
The researchers found the rate of periprosthetic
joint infection to be significantly
higher in patients with inflammatory arthritis
versus those without (31% versus
18%). Optimal ESR cutoffs for patients
with noninflammatory and inflammatory
arthritis were 32 and 30 mm/hr, respectively;
for CRP, 15 and 17 mg/L, respectively;
and for WBC, 3450/µL and 3444/µL,
respectively. Areas under the curves, sensitivities,
specificities, negative- and positivepredictive
values for all tests were comparable
in both sets of patients.
Based on these findings, the authors
concluded that physicians evaluating patients
with failed or painful total hip or knee
arthroplasty should not assume that elevated
ESR, CRP levels, and WBC with differential
are secondary to inflammatory arthritis.
Instead, these biomarkers may indicate
periprosthetic joint infection and should
prompt further evaluation for infection.