A prospective study of risk factor profile & incidence of deep venous thrombosis among medically-ill hospitalized patients at a tertiary care hospital in northern India.

Abstract

Hospitalization for medical-illness is associated with an increased risk of deep venous thrombosis (DVT). However, there are no published data from India addressing at this issue. We sought to study the risk factor profile and the incidence of DVT among hospitalized medically-ill patients, a tertiary care hospital in northern India.
All adults admitted to the medical wards and intensive care unit with level 1 or 2 mobility over a period of two years (July 2006 to July 2008) at the All India Institute of Medical Sciences hospital, New Delhi, were prospectively studied. Patients having DVT at admission or an anticipated hospital stay less than 48 h were excluded. The presence of clinical risk factors for DVT was recorded and laboratory evaluation was done for hypercoagulable state. A routine surveillance venous compression Doppler ultrasonography was performed 12 +/- 8 days after hospital admission.
Of the 163 patients, 77 (47%) had more than one risk factor for DVT. Five (3%) patients developed DVT; none of them had symptomatic DVT. None of these patients received anticoagulation prior to the development of DVT. The mean age of those who developed DVT was 40 +/- 13 (25-50) yr; two of five were male. The incidence rate of DVT was 2.7 per 1000 person-days of hospital stay [95% confidence interval (CI): 0.87 to 6.27]. None of the factors was found to be significantly associated with the risk of DVT.
In our setting, although many hospitalized medically-ill patients had risk factors for DVT, the absolute risk of DVT was low compared to the western population but clearly elevated compared to non hospitalized patients. Large studies from India are required to confirm our findings.

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Page 1

?
diseases? that? includes? both? deep? venous? thrombosis?
(DVT)?and?pulmonary?embolism1.?Often,?DVT?is?not?
suspected clinically leading to significant diagnostic
Venous? thrombosis? represents? a? spectrum? of?
A prospective study of risk factor profile & incidence of deep ?
venous?thrombosis?among?medically-ill?hospitalized?patients??
at?a?tertiary?care?hospital?in?northern?India?
Surendra?K.?Sharma,?Varun?Gupta,?Tamilarasu?Kadhiravan,?Amit?Banga,?Ashu?Seith*,?Atin?Kumar*?
Renu?Saxena**, Molly M. Thabah, Vandana Gulati, Indrish Bhatia & Amit A. Kavimandan
Departments of Medicine, *Radio-diagnosis & **Hematology, All India Institute of Medical Sciences
New Delhi, India
Received?February?20,?2009
Background & objectives: Hospitalization for medical-illness is associated with an increased risk of deep
venous thrombosis (DVT). However, there are no published data from India addressing at this issue.
We sought to study the risk factor profile and the incidence of DVT among hospitalized medically-ill
patients, a tertiary care hospital in northern India.
Methods: All adults admitted to the medical wards and intensive care unit with level 1 or 2 mobility over
a period of two years (July 2006 to July 2008) at the All India Institute of Medical Sciences hospital, New
Delhi, were prospectively studied. Patients having DVT at admission or an anticipated hospital stay less
than 48 h were excluded. The presence of clinical risk factors for DVT was recorded and laboratory
evaluation was done for hypercoagulable state. A routine surveillance venous compression Doppler
ultrasonography was performed 12 ± 8 days after hospital admission.
Results: Of the 163 patients, 77 (47%) had more than one risk factor for DVT. Five (3%) patients developed
DVT; none of them had symptomatic DVT. None of these patients received anticoagulation prior to the
development of DVT. The mean age of those who developed DVT was 40 ± 13 (25-50) yr; two of five were
male. The incidence rate of DVT was 2.7 per 1000 person-days of hospital stay [95% confidence interval
(CI): 0.87 to 6.27]. None of the factors was found to be significantly associated with the risk of DVT.
Interpretation & conclusions: In our setting, although many hospitalized medically-ill patients had risk
factors for DVT, the absolute risk of DVT was low compared to the western population but clearly elevated
compared to non hospitalized patients. Large studies from India are required to confirm our findings.
Key words?Deep?venous?thrombosis?-?intensive?care?unit?-?medical?illness?-?pulmonary?embolism?-?venous?compression?ultrasonography
delays.?Venous?thrombosis?results?in?considerable,?but?
potentially?preventable,?morbidity?and?mortality?among?
hospitalized?patients.?Most?of?the?hospitalized?patients?
have?a?high?risk?of?DVT,?and?hospitalization?for?acute?
726
Indian?J?Med?Res?130,?December?2009,?pp?726-730

Page 2

medical-illness?is?known?to?be?associated?with?about?
eight-fold?increased?risk?of?DVT2.?
?
incidence?of?DVT?is?unknown.?There?is?a?lack?of?adequate?
studies?on?the?incidence?of?DVT.?Only?a?few?studies?exist?
published?literature?most?of?which?were?done?on?surgical?
patients.?There?are?little?published?data?available?on?the?
risk?of?DVT?among?hospitalized?medically-ill?patients.?
Hence, we sought to study the profile of risk factors and
the?incidence?of?DVT?among?medically-ill?patients?treated?
at?a?tertiary?care?hospital?in?northern?India.
Because?of?the?high?rate?of?missed?diagnosis,?the?true?
Material & Methods
?
to?the?medical?wards?and?intensive?care?unit?with?level?
1?or?2?mobility?over?a?period?of?two?years?from?July?
2006?to?July?2008?at?the?All?India?Institute?of?Medical?
Sciences? hospital,? New? Delhi,? were? prospectively?
included.?Patients?who?had?DVT?at?admission?or?an?
anticipated?hospital?stay?less?than?48?h,?were?excluded.?
The level of immobilization was defined as follows -
level?1:?total?bed?rest?or?sedentary?patient;?level?2:?level?
1?with?bathroom?privileges;?and?level?3:?level?2?with?
activity?as?tolerated?by?the?patient.?A?written?informed?
consent?was?obtained?from?all?patients?participating?
in? the? study.? The? study? protocol? was? reviewed? and?
approved?by?the?Institute?Ethics?Committee?at?the?All?
India?Institute?of?Medical?Sciences,?New?Delhi
Consecutive?adults?aged?18?yr?or?more?admitted?
?
primary diagnosis, and specific risk factors for DVT
using? a? pre-designed? data? collection? instrument.?At?
enrollment,?a?general?physical?examination?including?
a?detailed?examination?of?the?lower?limbs?for?signs?
of?DVT?was?performed?on?all?patients.?In?addition?to?
evaluation?of?clinically?suspected?DVT?or?pulmonary?
thromboembolism? as? decided? by? the? treating?
physician,? a? routine? surveillance? Doppler? venous?
ultrasonography?was? performed? on? all?patients.?The?
venous?ultrasonography?was?performed?by?one?of?the?
two?consultant?radiologists?(AS?and?AK)?using?Philips?
HDI?5000®?or?Philips?Envisor?HD®?sonographic?units?
(Philips?International?B.V.,?Amsterdam,?Netherlands).?
Examination?was?performed?using?a?7.5-10?MHz?linear?
transducer?with?compression?of?deep?veins?of?the?thigh?
and?calf?in?a?sequential?manner?in?1?to?2?cm?increments?
from the common femoral, superficial femoral, and
popliteal?veins.?The?lack?of?venous?compressibility?with?
the?transducer?held?transverse?to?the?artery?and?vein?
was interpreted as a positive study and was confirmed
with color flow and pulsed wave Doppler analysis3-5.?
The?data?were?collected?on?demographic?details,?
?
within?24?h?of?admission?and?repeat?it?weekly?for?low-
risk? patients? and? twice-weekly? for? high-risk? patients?
during?the?hospital?stay.?However,?due?to?the?large?patient?
load?on?the?radiology?unit,?the?venous?ultrasounds?were?
performed?once?after?12?±?8?days?of?hospitalization.?
A? ProC®? Global? assay? (Dade? Behring,? Marburg,?
GmbH)? was? performed? on? all? patients? to? screen? for?
abnormalities?of?the?protein?C/S?pathway.?Patients?with?
a?normalized?ratio?<?0.7?underwent?further?estimation?of?
protein?C?and?S?and?antithrombin?levels?in?the?plasma.?
Antithrombin? was? estimated? by? nephelometry? using?
Turbox®?antithrombin? kit? (Orion? Diagnostica,? Espoo,?
Finland);?the?lower?limit?of?normal?was?200?mg/l?for?
this?assay.?Protein?C?and?S?levels?were?estimated?by?
enzyme-linked?immunosorbent?assay?(ELISA)?using?the?
REAADS®?kit?(Corgenix?Inc.,?Colorado,?USA).?Lower?
limit?of?normal?for?protein?C?was?70?per?cent?and?that?for?
protein?S?was?60?per?cent.?In?addition,?estimation?of?IgM?
and?IgG?antiphospholipid?antibodies?by?ELISA?using?
the?AESKULISA®Phospholipid-Screen-GM?kit?(Aesku?
Diagnostics?GmbH)?was?done?in?all?the?patients.
It? was? planned? to? perform? a? venous? ultrasound?
?
a?Poisson?distribution?using?a?statistical?software?package?
(Intercooled?stata?8.0?for?windows,?Stata?Corp.,?College?
Station,?Texas,?USA).?We?compared?the?categorical?data?
between?groups?by?the?Fisher’s?exact?test?and?continuous?
variables?by?the?independent?samples?t-test.?
The?incidence?rate?of?DVT?was?calculated?assuming?
Results
?
days?of?observation?were?studied.?None?of?the?patients?
had?a?prior?history?of?DVT.?Table?I?summarizes?the?
primary? medical-illness? necessitating? hospitalization?
of?these?patients.?All?patients?had?immobilization?as?
a? risk? factor? for? DVT.? Other? risk? factors? that? were?
recorded?included?age,?sex,?duration?of?hospital?stay,?
smoking,? alcoholism,? known? hypercoagulable? state,?
malignancy,?haematological?disorder,?surgery,?trauma,?
immobilization,? intake? of? oral? contraceptive? pills,?
past?history?of?DVT,?varicose?veins,?central?venous?
catheterization?and?use?of?mechanical?ventilation.?Of?
the? 163? patients,? 77? (47%)? had? more? than? one? risk?
factor?for?DVT.?Thirty?four?(21%)?patients?had?two?
risk?factors?whereas?three?risk?factors?were?present?in?
27? (17%)? patients.?Thirteen? (8%)? patients? had? four,?
two had five and one patient had seven risk factors
for?DVT.?Regarding?critical?care?risk?factors,?in?total?
45? (28%)? received? mechanical? ventilation;? of? them?
two? developed? DVT.? Mean? duration? of? mechanical?
ventilation? in? patients? who? developed? DVT? was? ?
A?total?of?163?patients?contributing?to?1860?person-
?SHARMA?et al: DVT?AMONG?MEDICALLy-ILL?HOSPITALIzED?PATIENTS? 727

Page 3

10.5?days?as?compared?to?6?days?in?patients?who?did?not?
develop?DVT.?On?surveillance,?5?(3%)?of?163?patients?
were?detected?to?have?DVT?(all?proximal);?none?of?
them?had?symptomatic?DVT.?None?of?these?patients?
received? anticoagulation? prior? to? the? development?
of DVT. The demographic profile and risk factors in
patients?with?and?without?DVT?are?presented?in?Table?
II.?The?mean?age?of?those?who?developed?DVT?was?40?
±?13?(25-50)?yr,?and?two?were?male.?The?incidence?rate?
of?DVT,?calculated?assuming?a?Poisson?distribution,?
was?2.7?per?1000?person-days?of?hospital?stay?[95%?
confidence interval (CI): 0.87 to 6.27]. The results of
laboratory? evaluation? for? hypercoagulable? state? are?
presented?in?Table?III.?Hypercoagulability?parameters?
were?found?to?be?positive?in?a?comparatively?higher?
percentage?of?patients?with?DVT.?However,?no?factor?
was significantly associated with the risk of DVT.
Discussion
?
factors?for?DVT,?only?a?small?proportion?of?patients?
hospitalized?for?a?medical-illness?developed?DVT.?In?
earlier?studies?from?western?countries,?the?cumulative?
incidence? of? DVT? among? medical? in-patients? was?
found?to?be?10-20?per?cent,?and?it?was?10-80?per?cent?
among? critical? care? patients6.? In? a? recent? survey? of?
hospitals?from?32?countries?worldwide,?about?42?per?
cent? of? hospitalized?medical?patients? were? found? to?
be?at?risk?for?venous?thrombosis7.?In?the?same?study,?
a?comparable?proportion?(45%)?of?medical?in-patients?
in?India?was?found?to?be?at?risk7.?However,?we?did?
not find a statistically significant association between
any?of?the?clinical?or?laboratory?risk?factors?and?the?
development?of?DVT.?This?is?most?probably?due?to?a?
lack?of?adequate?statistical?power?in?view?of?the?very?
low?number?of?patients?who?developed?DVT.?
It?was?found?that?despite?the?high?proportion?of?risk?
?
of?the?published?studies?from?India8-17?have?reported?
a?low?incidence?of?DVT?among?hospitalized?patients?
(Table?IV).?However,?all?these?studies?were?carried?
out?on?surgical?or?orthopedic?patients,?and?ours?is?the?
first attempt from India to find out the incidence of
DVT?in?hospitalized?medically-ill?patients.?The?risk?
of?DVT?was?clearly?elevated?in?hospitalized?patients?
As?far?as?the?incidence?of?DVT?is?concerned,?most?
Table I. Primary?medical-illness?necessitating?hospitalization?in?
the?study?population
Underlying?disease*Patients?without?
DVT
(n?=?158)
97?(61)
53?(33)
12?(8)
4?(2)
8?(5)
20?(13)
9?(6)
27?(17)
5?(3)
21?(13)
4?(2)
3?(2)
2?(1)
5?(3)
6?(4)
2?(1)
Patients?with?
DVT
(n?=?5)
3?(60)
2?(40)
1?(20)
Infectious?diseases
Pulmonary infection
GI and liver infection
Genitourinary infection
CNS infection
Systemic infection
Malignancy
Chronic?pulmonary?disease
Cardiac?disease
Rheumatic?disease?
Endocrine?disease
Acute?poisoning
Hematological?disease
Hepatic?disease
Neurological?disease
Others
Psychiatric?illness
Data?presented?as?n?(%);?*,?not?mutually?exclusive,?some?patients?
had?multiple?underlying?diseases;?DVT,?deep?venous?thrombosis;?
GI,?gastrointestinal;?CNS,?central?nervous?system
-
-
-
-
-
-
-
-
1?(20)
-
-
-
-
- 1?(20)
Table II. Demographic profile and risk factors in patients with and
without?DVT
Risk?factor Patients?without?
DVT
(n?=?158)
44?±?18?(18-85) 40?±?13?(25-50)
86??(54)
21.3?±?12.2?
(1-62)
54?(34)
29?(18)
0
11?(7)
4?(2)?
5?(3)
9?(6)
158?(100)
1
0
1
10?(6)
43?(27)
Patients?with?
DVT?
(n?=?5)
Age, yr [mean ± SD (range)]
Male?sex
Duration?of?hospital?stay,?days?
[mean ± SD(range)]
Smoking??
Alcoholism
Known?hypercoagulable??state?
Malignancy
Hematological?disorder
Surgery
Trauma
Immobilization
Intake?of?OCPs?
Past?history?of?DVT
Varicose?veins?
Central?venous?catheterization
Mechanical?ventilation?
Data presented as n (%), unless specified; DVT, deep venous
thrombosis;?OCPs,?oral?contraceptive?pills
2??(40)
33.5?±?33.2?
(10-30)
2?(40)
1?(20)
0
0
1?(20)
0
0
5?(100)
0
0
0
1?(20)
2?(40)
Table III. Laboratory?evaluation?for?hypercoagulability?in?patients?
with?and?without?DVT
Laboratory?abnormality Patients?without?
DVT?
(n?=?158)
53?(33)
4?(2)
Patients?with?
DVT?
(n?=?5)
1?(20)
1?(20)
Pro?C®?Global?<?0.7?
IgM?antiphospholipid?antibody-
positive?(>15?IU)
IgG?antiphospholipid?antibody-
positive??
Antithrombin?<?200?mg/l
Protein?C?<?70%?
Protein?S?<?60%
Data?presented?as?n?(%);?DVT,?deep?venous?thrombosis
10
4?(2)
0
26?(16)
36?(23)
2?(40)
2?(40)
728? INDIAN?J?MED?RES,?DECEMBER?2009

Page 4

in?our?study?compared?to?non?hospitalized?patients,?
where?risks?were?around?1.5?per?1000?person-years18.?
Our? study? results? are? in? contrast? to? earlier? studies?
from? western? countries? and? reinforce? the? repeated?
finding of a low incidence of DVT among surgical
patients? in? India.? However,? a? large? autopsy-based?
study?from?India?had?found?a?high?prevalence?(16%)?
of?pulmonary?embolism?at?autopsy?in?patients?dying?
of?a?medical-illness17. The significance of this isolated
autopsy-based?study?in?the?face?of?mounting?evidence?
to?the?contrary?is?unclear.
?
clinically,?and?there?is?a?possibility?of?underdiagnosis.?
Therefore,?venous?compression?ultrasonography?was?
performed?for?all?patients?irrespective?of?the?clinical?
suspicion.?Doppler?analysis?has?emerged?as?a?sensitive?
and accurate non-invasive test for confirming the
presence?of?acute?DVT19. Its sensitivity and specificity
for?the?diagnosis?of?symptomatic?proximal?DVT?are?
97?and?94?per?cent,?respectively.?Therefore,?although?
ascending?contrast?venography?is?considered?the?gold?
standard?for?the?diagnosis?of?DVT,?the?method?employed?
to?diagnose?DVT?in?the?present?study?is?an?acceptable?
alternative,?and?this?is?unlikely?to?be?the?reason?for?the?
low?incidence?of?DVT?in?the?present?study.?
The? diagnosis? of? DVT? is? often? not? suspected?
?
study,? and? we? included? consecutive? adults?
Our?study?has?its?merit?in?being?a?prospective?
hospitalized?for?a?medical-illness?both?to?the?medical?
wards? and? the? ICU.? Thus,? our? study? population?
faithfully reflects the clinical spectrum of illness
encountered?by?a?physician?in?a?typical?tertiary?care?
set-up.?Patients?in?a?tertiary?care?set-up?are?likely?to?
be?sicker?and?possibly?are?at?a?comparatively?higher?
risk?of?DVT?than?patients?treated?at?the?secondary?
care?level.? Notwithstanding?
we? found? a? low? incidence? of? DVT? in? our? study?
population.? The? limitation? of? our? study? was? that?
venous?ultrasonography?could?not?be?performed?as?
planned?due?to?operational?constraints.
this?possibility,?
?
a?small?number?of?our?patients?developed?DVT?as?
compared?to?the?western?population?despite?apparently?
being?at?comparable?risk.?Our?study?was?not?addressed?
at?this?question,?and?this?deserves?further?research.?
Inclusion? of? symptomatic? cases? in? some? of? these?
studies?could?explain?the?difference?from?our?study.?
Another?possible?explanation?is?the?difference?in?the?
genetic?make?up?of?the?population.?Irrespective?of?the?
reason?for?this?difference,?the?results?of?our?study?and?
most?other?Indian?studies?on?surgical?patients?question?
the?advisability?of?routine?use?of?thromboprophylaxis?
in? hospitalized? medically-ill? patients? which? is? now?
considered?the?standard-of-care?in?western?countries.?
Further large studies from India are needed to confirm
the findings of the present study.
The?obvious?question?that?arises?now?is?why?only?
Acknowledgment
?
from Pfizer India Ltd. to SKS. The?sponsor?played?no?role?in?the?
study?design,?data?collection,?analysis,?or?the?decision?to?submit?for?
publication.
This?study?was?supported?by?an?unrestricted?educational?grant?
Conflicts of interest:?SKS?participated?as?an?investigator?
in?the?EXCLAIM?and?LIFENOX?clinical?trials?sponsored?
by Sanofi Aventis. TK was a co-investigator in the
LIFENOX clinical trial sponsored by Sanofi Aventis.
References
1.? Kroegel?C,?Reissig?A.?Principle?mechanisms?underlying?venous?
thromboembolism:?epidemiology,?risk?factors,?pathophysiology?
and?pathogenesis.?Respiration?2003;?70?:?7-30.
Bonthier? J.? The? venous? thrombotic? risk? in? non-surgical?
patients.?Drugs?1996;?52?(Suppl):?16-29.
Cronan?JJ,?Dorfman?GS,?Scola?FH,?Schepps?B,?Alexander?
J.? Deep? venous? thrombosis:? US? assessment? using? vein?
compression.?Radiology?1987;?162?:?191–4.
Poppiti?R,?Papanicolaou?G,?Perese?S,?Weaver?FA.?Limited?
B-mode venous imaging versus complete color-flow duplex
venous? scanning? for? detection? of? proximal? deep? venous?
thrombosis. J Vasc Surg?1995;?22?:?553-7.
2.?
3.?
4.?
Table IV. Studies?from?India?on?incidence?of?DVT?among?hospitalized?
patients
Study? Study?design Study?
population
No.?of?
patients?
studied
50
112
104
72
30
Incidence?
of?DVT?
(%)
28
19.6
60
2.7
23.3
Shead?et al8
Sharma?et al9
Agarwala?et al10
Jain?et al11
Bhan?et al12
Prospective
Prospective
Prospective
Prospective
Prospective,?
multicentric
Surgical?
Orthopedic?
Orthopedic
Orthopedic
Orthopedic
Leizorovicz?et al13Prospective,?
international,?
multicentric
Retrospective? Orthopedic
Prospective
Orthopedic2420*
2.3
Maini?et al14
Saraf?et al15
Mavalankar?et al16Prospective
Kakkar?et al17
271
70
125
1000?
autopsies
163
9.9
10
7.2
15.9†
Orthopedic
Orthopedic
Medical?in-
patients
Medical?
indoor?
patients
Autopsy-?
based
ProspectivePresent?study3
DVT,? deep? venous? thrombosis;?*,? conducted? in? 39? centers? in? 11?
Asian? countries? including? 403? patients? from? nine? centers? in? India;? ?
†,?pulmonary?embolism?diagnosed?at?autopsy,?not?DVT
?SHARMA?et al: DVT?AMONG?MEDICALLy-ILL?HOSPITALIzED?PATIENTS? 729

Page 5

5.?Mitchell?DC,?Grasty?MS,?Stebbings?WS,?Nockler?IB,?Lewars?
MD,?Levison?RA,?et al.?Comparison?of?duplex?ultrasonography?
and?venography?in?the?diagnosis?of?deep?venous?thrombosis.?
Br J Surg?1991;?78?:?611-3.
Geerts?WH,?Bergqvist?D,?Pineo?GF,?Heit?JA,?Samama?CM,?
Lassen?MR,?et al.?Prevention?of?venous?thromboembolism:?
American? College? of? Chest? Physicians? Evidence-Based?
Clinical? Practice? Guidelines,? (8th? Ed).? Chest? 2008;? 133? ?
(6?Suppl)?:381S-453.?
Cohen?AT,?Tapson?VF,?Bergmann?JF,?Goldhaber?Sz,?Kakkar?
AK,?Deslandes?B,?et al.?Venous?thromboembolism?risk?and?
prophylaxis? in? the? acute? hospital? care? setting? (ENDORSE?
study):? a? multinational? cross-sectional? study.? Lancet? 2008;?
371?:?387-94.
Shead?GV,?Narayanan?R.?Incidence?of?postoperative?venous?
thromboembolism?in?south?India.?Br J Surg 1980;?67?:?813-4.?
Sharma?H,?Maini?L,?Agrawal?N,?Upadhyay?A,?Vishwanath?
J,?Dhaon?BK.?Incidence?of?deep?vein?thrombosis?in?patients?
with?fractures?around?hip?joint:?a?prospective?study.?Indian J
Orthop?2002;?36?:?5.
10.? Agarwala?S,?Wadhwani?R,?Modhe?JM,?Bhagwat?AS.?Screening?
for? deep? venous? thrombosis? in? postoperative? orthopaedic?
patients:?comparison?of?color?Doppler?sonography?and?contrast?
venography.?Indian J Orthop 2002;?36?:?4.
11.? Jain?V,?Dhaon?BK,?Jaiswal?A,?Nigam?V,?Singla?J.?Deep?vein?
thrombosis? after? total? hip? and? knee? arthroplasty? in? Indian?
patients.?Postgrad Med J?2004;?80?:?729-31.
6.?
7.?
8.?
9.?
12.? Bhan? S,? Dhaon? BK,? Gulati? y,?Aggarwal? S.? Deep? venous?
thrombosis?prophylaxis?-?a?multicentric?study.?Indian J Orthop
2004;?38?:?178-82.
13.? Leizorovicz?A,?Turpie?AG,? Cohen?AT,?Wong? L,?yoo? MC,?
Dans? A;? SMART? Study? Group.? Epidemiology? of? venous?
thromboembolism? in? Asian? patients? undergoing? major?
orthopedic?surgery?without?thromboprophylaxis.?The?SMART?
Study.?J Thromb Haemost 2005;?3?:?28-34.
14.? Maini?PS,?Talwar?N,?Nijhawan?VK,?Dhawan?M.?Results?of?
cemented?bipolar?hemiarthroplasty?for?fracture?of?the?femoral?
neck-10?year?study.?Indian J Orthop 2006;?40?:?154-6.
15.? Saraf?SK,?Rana?RJ,?Sharma?OP.?Venous?thromboembolism?in?
acute?spinal?cord?injury?patients.?Indian J Orthop?2007;?41?:?
194-7.
16.? Mavalankar? AP,?Majmundar?D,?Rani?S.?Routine?chemoprophylaxis?
for deep venous thrombosis in Indian patients: is it really justified?
Indian J Orthop 2007;?41?:?188-93.
17.? Kakkar? N,? Vasishta? RK.? Pulmonary? embolism? in? medical?
patients:?an?autopsy-based?study.?Clin Appl Thromb Hemost?
2008;?14?:?159-67.
18.? Naess?IA,?Christiansen?SC,?Romundstad?P,?Cannegieter?SC,?
Rosendaal?FR,?Hammerstrom?J.?Incidence?and?mortality?of?
venous? thrombosis:? a? population-based? study.? J Thromb
Haemost?2007;?5?:?692-9.?
19.? Fraser? JD,?Anderson? DR.? Deep? venous? thrombosis:? recent?
advances?and?optimal?investigation?with?US.?Radiology?1999;?
211?:?9-24.
Reprint requests: Prof. S.K. Sharma, Chief, Division of Pulmonary, Critical Care & Sleep Medicine, Head,?Department?of?Medicine?
? All?India?Institute?of?Medical?Sciences,?Ansari?Nagar,?New?Delhi?110?029,?India
e-mail:?sksharma@aiims.ac.in;?surensk@gmail.com
730?INDIAN?J?MED?RES,?DECEMBER?2009