BJA
Correspondence
K. G. Fields*
J. YaDeau
New York, USA
*
E-mail: [email protected]
1 Desmet M, Braems H, Reynvoet M, et al. I.V. and perineural dexamethasone are equivalent in increasing the analgesic duration of a
single-shot interscalene block with ropivacaine for shoulder
surgery: a prospective, randomized, placebo-controlled study. Br J
Anaesth 2013; 111: 445–52
2 Herman A, Botser IB, Tenenbaum S, Chechick A. Intention-to-treat
analysis and accounting for missing data in orthopaedic randomized
clinical trials. J Bone Joint Surg Am 2009; 91: 2137– 43
3 Ye C, Giangregorio L, Holbrook A, Pullenayegum E, Goldsmith C,
Thabane L. Data withdrawal in randomized controlled trials: defining
the problem and proposing solutions. Contemp Clin Trials 2011; 32:
318–22
4 Moher D, Hopewell S, Schulz KF, et al. for the CONSORT Group.
CONSORT 2010 explanation and elaboration: updated guidelines
for reporting parallel group randomised trials. J Clin Epidemiol
2010; 63: e1 –37
doi:10.1093/bja/aet455
Ethnicity and acute kidney injury: the correct
definition of acute kidney injury?
Editor—We read with great interest the article by Chew and
colleagues1 on the association of ethnicity and acute
kidney injury (AKI) after cardiac surgery in a South East
Asian population. The role of genetics in health and pathology is a fascinating area of study which requires much
more exploration. There are, however, some questions we
would like to pose.
The study’s main outcome was postoperative AKI defined as
‘a 25% or greater increase in preoperative to a maximum postoperative serum creatinine level within three days after
surgery’. We feel that the relatively low fractional change in
serum creatinine used by the authors to define AKI has led to
a larger number of patients being categorized as having AKI.
We would be interested to know if these differences in rates
of AKI between the ethnic groups persist when the evidencebased international consensus definitions of AKI such as the
RIFLE criteria2 and Acute Kidney Injury Network (AKIN)3
staging system are used.
The RIFLE criteria for acute renal dysfunction were developed by the consensus conference of the Acute Dialysis
Quality Initiative in 2003. This system uses GFR criteria or
urine output criteria to classify patients into three severity
categories—risk, injury, and failure—and two outcome
categories—loss and end-stage renal failure. The RIFLE criteria
define ‘Risk’ as an increase in serum creatinine of 1.5 times the
baseline and ‘Injury’ as an increase in serum creatinine two
times the baseline. Both the ‘risk’ and ‘injury’ classifications
are highly sensitive in determining potential AKI. AKIN, an
international group of nephrologists and critical care experts,
agreed by consensus a staging system for the spectrum of
AKI, where mild AKI is defined as a percentage increase in
serum creatinine of more than or equal to 50% (1.5-fold)
from baseline. If the authors had used these widely accepted
classification systems, we suspect that the statistics would
be quite different.
On a final point of interest, we would be fascinated to know if
there was any difference in the distribution of the ethnic groups
between the two hospitals or between individual surgeons?
Could patients’ self-selection in terms of presentation to a
particular hospital or to a particular surgeon be having an
impact on their outcome?
Declaration of interest
None declared.
G. Atwal*
S. Stacey
P. Yate
London, UK
*
E-mail: [email protected]
1 Chew STH, Mar WMT, Ti LK. Association of ethnicity and acute kidney
injury after cardiac surgery in a South East Asian population. Br J
Anaesth 2013; 110: 397–401
2 Bellomo R, Ronco C, Kellum JA, Mehta RL, Palevsky P. Acute renal
failure—definition, outcome measures, animal models, fluid
therapy and information technology needs: the Second International Consensus Conference of the Acute Dialysis Quality Initiative
(ADQI) Group. Crit Care 2004; 8: R204– 12
3 Mehta RL, Kellum JA, Shah SV, et al. Acute Kidney Injury Network:
report of an initiative to improve outcomes in acute kidney injury.
Crit Care 2007; 11: R31
doi:10.1093/bja/aet452
Organ failure related to ethnicity
Editor—We read with great interest the article by Chew and
colleagues1 dealing with acute kidney failure (AKI) after
cardiac surgery comparing three groups of people: Indians,
Malays, and Chinese, all from South Asia. This prospective
study determined that the ethnic populations of India and
the Malays were at a higher risk for developing renal failure
than Chinese. It is not surprising that this may occur since
the life styles of these people are so different from Chinese.
The genetics are different and also food intake, cultural background, and environment. All must be taken into consideration
to determine health status which in many South Asian countries is below standard. The people of these populations are
known not to live long lives because of various illnesses and
conditions. By and large, Chinese people are healthier than
other South Asian countries.
The authors of the article1 point out themselves that genetics plays a major role in developing renal failure post-cardiac
surgery and their results show the gene –environment interaction.
We would like to suggest a different retrospective or prospective scientific investigation concerning this problem of
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BJA
Correspondence
AKI. Instead of incorporating other South Asian populations,
just investigate the Chinese populations of Northern China vs
Central vs Southern China and compare the results with
Chinese people living in Taiwan or other countries.
All these people are relatively homogenous and their socioeconomic factors may be very similar or different. This study
would tell us how this single ethnic population reacts to
cardiac surgery and postoperative organ dysfunction. The
Chinese life style is known to be much higher and better than
other South Asian countries. Patient care would be improved
substantially.
A similar investigation occurred years ago, around 1966– 7
which dealt with two ethnic Caucasian populations in two different countries investigating a neuromuscular blocking agent
to see the difference in response.2 This study pointed out that
even in similar ethnic groups, there are different reactions.
Comparing Chinese groups for AKI would be very interesting
and noteworthy to all physicians, anaesthesiologists, and surgeons alike.
Declaration of interest
None declared.
C. Kakazu*
M. Lippmann
Torrance, CA, USA
*
E-mail: [email protected]
1 Chew STH, Mar WMT, Ti LK. Association of ethnicity and acute kidney
injury after cardiac surgery in a South East Asian population. Br J
Anaesth 2013; 110: 397–401
2 Katz RL, Norman J, Seed RF, Conrad L. A comparison of the effects of
suxamethoium and tubocurarine in patients in London and
New York. Br J Anaesth 1969; 41: 1041–7
doi:10.1093/bja/aet456
did not reach statistical significance (OR 1.399, CI 0.95– 2.0,
P¼0.08). We shall be repeating the analyses with a bigger
sample of patients.
Our study population is unique as the city state is relatively
homogenous with a high standard of healthcare and access
to healthcare from patients is unimpeded. The two heart
centres are public institutions doing more than 80% of all
heart surgeries in the country and the distribution of patients
between the centres is fairly even, often with porosity
between the two. The referral base to these hospitals comes
from the various public primary care clinics with little surgeon
bias.
Declaration of interest
None declared.
S. T. Chew*
L. K. Ti
Singapore, Singapore
*
E-mail: [email protected]
1 Chew STH, Mar WMT, Ti LK. Association of ethnicity and acute kidney
injury after cardiac surgery in a South East Asian population. Br J
Anaesth 2013; 110: 397–401
2 Chew STH, Newman MF, White WD, et al. Preliminary report on the
association of apolipoprotein E polymorphisms, with postoperative
peak serum creatinine concentrations in cardiac surgical patients.
Anesthsiology 2000; 93: 325– 31
3 Loef BG, Epema AH, Stegeman CA, et al. Immediate postoperative
renal function deterioration in cardiac surgical patients predicts
in-hospital mortality and long-term survival. J Am Soc Nephrol
2005; 16: 195–200
4 Ryckwaert F, Boccara G, Colson PH, et al. Incidence, risk factors, and
prognosis of a moderate increase in plasma creatinine early after
cardiac surgery. Crit Care Med 2002; 30: 1495–8
doi:10.1093/bja/aet453
Ethnicity and acute kidney injury: the correct
definition of acute kidney injury?
Reply from the authors
Pharmacological perioperative brain
neuroprotection: nimodipine?
Editor—We are grateful for this opportunity to reply to Dr Atwal
and his colleagues’ comments on our article.1
We used the relatively low fractional change in serum creatinine as it has been previously described in one of our
papers.2 Loef and colleagues3 in using the same criteria have
shown that the immediate and small decline in renal function
is associated not only with early mortality but also mortality in
the longer term. A fractional change in serum creatinine of at
least 25% represents a decrease in GFR of at least 20% which
may be significant in the long term.4 This will identify patients
who require specific preventive measures during the follow-up
period. We have also analysed the data based on the AKIN criteria and there is a racial difference in that the Malays have a
higher risk compared with the Chinese [odds ratio (OR) 1.457,
confidence interval (CI) 1.04 –2.0, P¼0.02], but the Indians
Editor—I read with great interest the article ‘Pharmacological
perioperative brain neuroprotection: a qualitative review of
randomized clinical trials’ by Bilotta and colleagues.1 The
authors reviewed 25 randomized clinical trials addressing perioperative pharmacological neuroprotection. They concluded
that only atorvastatin and magnesium sulphate were associated with a lower incidence of new postoperative neurological deficits. I would like to draw your attention to a missing
prospectively performed, randomized clinical trial with 30
patients published in Neurosurgery revealing the neuroprotective efficacy of perioperative nimodipine medication for the
preservation of facial and cochlear nerve functions in vestibular
schwannoma surgery.2 The results were significant for a better
outcome for both hearing (P¼0.041) and facial nerve (P¼0.045)
preservation in the group of patients who received a
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