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PAPER SPOTLIGHT
Study Finds No Increased Risk of
Transmission of CLL Through Blood
Transfusions
An analysis of from
Denmark and Sweden
has shown that chronic
lymphocytic leukemia
(CLL) and monoclonal
B-cell lymphocytosis
(MBL) does not appear to
be transmitted in blood
products transfused from
affected donors.
Previous studies have
speculated whether
the transmission of
MBL, the presence of
small monoclonal B-cell
subpopulations in the
peripheral blood, through
blood transfusions may
increase the risk of CLL
or small lymphocytic lymphoma (SLL) in the donor
recipient. “Some investigations have added to
the concerns [about MBL
transmission] by suggesting an increased risk
of CLL and/or SLL among
transfused patients,”
Henrik Hjalgrim, MD,
first author of the analysis published in Blood,
and co-authors explained.
“Meanwhile, other studies observe no or even
an inverse association
between transfusion and
CLL/SLL risk, emphasizing that comparisons of
transfused patients and
non-transfused controls
are challenging due to
fundamental differences
between the two groups.”
Dr. Hjalgrim, from
the Department of
Epidemiology Research
at Statens Serum Institut
in Copenhagen, Denmark,
and colleagues conducted
a study using the binational Scandinavian Do-
ASHClinicalNews.org
nations and Transfusions
(SCANDAT2) database,
which includes long-term
health information on 1.5
million blood donors and
2.1 million recipients, to
evaluate whether potential MBL transmission
impacted recipients’ risk
of developing CLL. Specifically, they investigated
whether a diagnosis of
CLL among recipients
clustered to individual donors by assessing if these
recipients developed CLL
after the donation.
SCANDAT2 includes
all Danish and Swedish
blood banks between
1968 and 2010, though
the researchers used
data from 1980 to 2012
for reasons related to
coding homogeneity. The
researchers assessed the
possibility of MBL/CLL
transmission with whole
blood, red blood cell, or
platelet products, in two
analyses:
1. They identified all
donors diagnosed with
CLL subsequent to
their earliest registered
donation, and for each
index donor, identified
up to 10 donors without
CLL at the time of
diagnosis of the index
donor (matched for
age, sex, county,
number of donations,
and blood group).
2. They identified all
recipients of blood
products from the
two groups of donors
and followed them
There was little indication of CLL clustering
among recipients of blood
from individual donors,
and an analysis of the
entire database did not
determine evidence of
CLL clustering among
recipients of blood from
individual donors (TABLE 1).
from transfusion until
date of CLL diagnosis,
death, emigration,
disappearance, or end
of the study period.
In the “look-back analysis,” Dr. Hjalgrim and
authors identified 7,413
recipients of blood from
Stockholm, Sweden, told
ASH Clinical News. “First,
it means that there was
no evidence that one
should track down past
transfusion recipients
of newly diagnosed CLL
patients who have re-
Number of CLL Cases Among Recipients of Blood
from Individual Donors
TABLE 1.
Cases of CLL
Observed
Frequency
Expected
Frequency
0
1,416,610
1,416,593.42
1.00 (1.00-1.00)
1
8,535
8,567.82
1.00 (0.98-1.02)
2
87
71.09
1.22 (0.98-1.50)
3+
1
0.66
1.51 (0.09-6.66)
796 donors who were
subsequently diagnosed
with CLL (exposed
recipients), and 80,431
recipients of blood from
7,477 donors free of CLL
at index donor diagnosis
(unexposed recipients).
During follow-up, 12
patients in the exposed
group and 107 patients
in the unexposed group
developed CLL, for an incidence ratio (IR) of 0.94
(95% CI 0.52-1.71). When
the exposure was redefined as blood donated
less than 10 years prior to
donor CLL diagnosis, the
IR was reduced to 0.46
(95% CI 0.12-1.85). Ultimately, the researchers
concluded, “the analyses
provided little evidence
that showed that donor
MBL/CLL transmission in
blood products influences
recipients’ CLL risk.”
The authors noted
some limitations of the
study, the most notable
being the absence of
actual donor MBL status.
Also, because both MBL
prevalence and CLL
incidence increase with
age, it was not possible
to determine whether
blood products from older
donors conferred greater
recipient CLL risk. Transfusion circumstances and
recipient immune status
also may have affected
CLL susceptibility.
“The fact that we
found no evidence that
patients with CLL or other
clonal B-cell lymphocytosis are transfusiontransmissible have two
implications for clinicians,” Gustaf Edgren,
MD, PhD, a co-author of
the study from Karolinska
University Hospital in
Mutual Ratios
(95% CI)
cently been blood donors.
Second, it also means
that patients with CLL
who have previously been
transfused do not need to
worry that they ‘received’
their CLL through their
past transfusions.”
“However, since we can
safely assume that many
of the blood donors with
CLL in our study probably
had some clonal B-cell
lymphocytosis already
when they were blood
donors and that many of
their recipients received
some of these cells,” Dr.
Edgren added, “it does
not seem to lead to any
detectable negative effects for the transfused
patients.” ●
REFERENCE
Hjalgrim H, Rostgaard K, Vasan SK, et al. No
evidence of transmission of chronic lymphocytic
leukemia through blood transfusion. Blood. 2015
August 24. [Epub ahead of print]
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