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<record><TEI><teiHeader><fileDesc><titleStmt><title xml:lang="en">The relationship between the haemoglobin concentration and the haematocrit in <italic>Plasmodium falciparum </italic>malaria</title><author><name sortKey="Lee, Sue J" sort="Lee, Sue J" uniqKey="Lee S" first="Sue J" last="Lee">Sue J. Lee</name><affiliation><nlm:aff id="I1">Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</nlm:aff></affiliation></author><author><name sortKey="Stepniewska, Kasia" sort="Stepniewska, Kasia" uniqKey="Stepniewska K" first="Kasia" last="Stepniewska">Kasia Stepniewska</name><affiliation><nlm:aff id="I1">Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</nlm:aff></affiliation></author><author><name sortKey="Anstey, Nicholas" sort="Anstey, Nicholas" uniqKey="Anstey N" first="Nicholas" last="Anstey">Nicholas Anstey</name><affiliation><nlm:aff id="I2">Menzies School of Health Research and Royal Darwin Hospital, Darwin, NT, Australia</nlm:aff></affiliation></author><author><name sortKey="Ashley, Elizabeth" sort="Ashley, Elizabeth" uniqKey="Ashley E" first="Elizabeth" last="Ashley">Elizabeth Ashley</name><affiliation><nlm:aff id="I3">Shoklo Malaria Research Unit, Mae Sot, Thailand</nlm:aff></affiliation></author><author><name sortKey="Barnes, Karen" sort="Barnes, Karen" uniqKey="Barnes K" first="Karen" last="Barnes">Karen Barnes</name><affiliation><nlm:aff id="I4">University of Cape Town, South Africa</nlm:aff></affiliation></author><author><name sortKey="Binh, Tran Quang" sort="Binh, Tran Quang" uniqKey="Binh T" first="Tran Quang" last="Binh">Tran Quang Binh</name><affiliation><nlm:aff id="I5">Choray Hospital, Ho Chi Minh City, Vietnam</nlm:aff></affiliation></author><author><name sortKey="D Alessandro, Umberto" sort="D Alessandro, Umberto" uniqKey="D Alessandro U" first="Umberto" last="D'Alessandro">Umberto D'Alessandro</name><affiliation><nlm:aff id="I6">Institute of Tropical Medicine, Antwerp, Belgium</nlm:aff></affiliation></author><author><name sortKey="Day, Nicholas Pj" sort="Day, Nicholas Pj" uniqKey="Day N" first="Nicholas Pj" last="Day">Nicholas Pj Day</name><affiliation><nlm:aff id="I1">Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</nlm:aff></affiliation><affiliation><nlm:aff id="I7">Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK</nlm:aff></affiliation></author><author><name sortKey="De Vries, Peter J" sort="De Vries, Peter J" uniqKey="De Vries P" first="Peter J" last="De Vries">Peter J. De Vries</name><affiliation><nlm:aff id="I8">Division of Infectious Diseases, Tropical Medicine & AIDS, Academic Medical Center, Amsterdam, The Netherlands</nlm:aff></affiliation></author><author><name sortKey="Dorsey, Grant" sort="Dorsey, Grant" uniqKey="Dorsey G" first="Grant" last="Dorsey">Grant Dorsey</name><affiliation><nlm:aff id="I9">University of California, San Francisco, CA, USA</nlm:aff></affiliation><affiliation><nlm:aff id="I10">Institut de Recherche en Sciences de la Sante, Burkino Faso</nlm:aff></affiliation><affiliation><nlm:aff id="I11">Uganda Malaria Surveillance Programme, Uganda</nlm:aff></affiliation></author><author><name sortKey="Guthmann, Jean Paul" sort="Guthmann, Jean Paul" uniqKey="Guthmann J" first="Jean-Paul" last="Guthmann">Jean-Paul Guthmann</name><affiliation><nlm:aff id="I12">Epicentre, France</nlm:aff></affiliation></author><author><name sortKey="Mayxay, Mayfong" sort="Mayxay, Mayfong" uniqKey="Mayxay M" first="Mayfong" last="Mayxay">Mayfong Mayxay</name><affiliation><nlm:aff id="I13">National University of Laos, Laos</nlm:aff></affiliation><affiliation><nlm:aff id="I14">Wellcome Trust- Mahosot Hospital- Oxford University Tropical Medicine Research Collaboration, Laos</nlm:aff></affiliation></author><author><name sortKey="Newton, Paul" sort="Newton, Paul" uniqKey="Newton P" first="Paul" last="Newton">Paul Newton</name><affiliation><nlm:aff id="I14">Wellcome Trust- Mahosot Hospital- Oxford University Tropical Medicine Research Collaboration, Laos</nlm:aff></affiliation></author><author><name sortKey="Nosten, Francois" sort="Nosten, Francois" uniqKey="Nosten F" first="Francois" last="Nosten">Francois Nosten</name><affiliation><nlm:aff id="I3">Shoklo Malaria Research Unit, Mae Sot, Thailand</nlm:aff></affiliation></author><author><name sortKey="Olliaro, Piero" sort="Olliaro, Piero" uniqKey="Olliaro P" first="Piero" last="Olliaro">Piero Olliaro</name><affiliation><nlm:aff id="I7">Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK</nlm:aff></affiliation><affiliation><nlm:aff id="I15">WHO TDR, Geneva, Switzerland</nlm:aff></affiliation></author><author><name sortKey="Osario, Lyda" sort="Osario, Lyda" uniqKey="Osario L" first="Lyda" last="Osario">Lyda Osario</name><affiliation><nlm:aff id="I16">Centro Internatcional de Entrenamiento e Investigaciones Medicas, Colombia</nlm:aff></affiliation></author><author><name sortKey="Pinoges, Loretxu" sort="Pinoges, Loretxu" uniqKey="Pinoges L" first="Loretxu" last="Pinoges">Loretxu Pinoges</name><affiliation><nlm:aff id="I12">Epicentre, France</nlm:aff></affiliation></author><author><name sortKey="Price, Ric" sort="Price, Ric" uniqKey="Price R" first="Ric" last="Price">Ric Price</name><affiliation><nlm:aff id="I3">Shoklo Malaria Research Unit, Mae Sot, Thailand</nlm:aff></affiliation></author><author><name sortKey="Rowland, Mark" sort="Rowland, Mark" uniqKey="Rowland M" first="Mark" last="Rowland">Mark Rowland</name><affiliation><nlm:aff id="I17">London School of Hygiene & Tropical Medicine, London, UK</nlm:aff></affiliation></author><author><name sortKey="Smithuis, Frank" sort="Smithuis, Frank" uniqKey="Smithuis F" first="Frank" last="Smithuis">Frank Smithuis</name><affiliation><nlm:aff id="I18">Médecins sans Frontières, The Netherlands</nlm:aff></affiliation></author><author><name sortKey="Taylor, Robert" sort="Taylor, Robert" uniqKey="Taylor R" first="Robert" last="Taylor">Robert Taylor</name><affiliation><nlm:aff id="I15">WHO TDR, Geneva, Switzerland</nlm:aff></affiliation></author><author><name sortKey="White, Nicholas J" sort="White, Nicholas J" uniqKey="White N" first="Nicholas J" last="White">Nicholas J. White</name><affiliation><nlm:aff id="I1">Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</nlm:aff></affiliation><affiliation><nlm:aff id="I7">Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK</nlm:aff></affiliation></author></titleStmt><publicationStmt><idno type="wicri:source">PMC</idno><idno type="pmid">18673575</idno><idno type="pmc">2515851</idno><idno type="url">http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2515851</idno><idno type="RBID">PMC:2515851</idno><idno type="doi">10.1186/1475-2875-7-149</idno><date when="2008">2008</date><idno type="wicri:Area/Pmc/Corpus">001130</idno><idno type="wicri:explorRef" wicri:stream="Pmc" wicri:step="Corpus" wicri:corpus="PMC">001130</idno></publicationStmt><sourceDesc><biblStruct><analytic><title xml:lang="en" level="a" type="main">The relationship between the haemoglobin concentration and the haematocrit in <italic>Plasmodium falciparum </italic>malaria</title><author><name sortKey="Lee, Sue J" sort="Lee, Sue J" uniqKey="Lee S" first="Sue J" last="Lee">Sue J. Lee</name><affiliation><nlm:aff id="I1">Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</nlm:aff></affiliation></author><author><name sortKey="Stepniewska, Kasia" sort="Stepniewska, Kasia" uniqKey="Stepniewska K" first="Kasia" last="Stepniewska">Kasia Stepniewska</name><affiliation><nlm:aff id="I1">Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</nlm:aff></affiliation></author><author><name sortKey="Anstey, Nicholas" sort="Anstey, Nicholas" uniqKey="Anstey N" first="Nicholas" last="Anstey">Nicholas Anstey</name><affiliation><nlm:aff id="I2">Menzies School of Health Research and Royal Darwin Hospital, Darwin, NT, Australia</nlm:aff></affiliation></author><author><name sortKey="Ashley, Elizabeth" sort="Ashley, Elizabeth" uniqKey="Ashley E" first="Elizabeth" last="Ashley">Elizabeth Ashley</name><affiliation><nlm:aff id="I3">Shoklo Malaria Research Unit, Mae Sot, Thailand</nlm:aff></affiliation></author><author><name sortKey="Barnes, Karen" sort="Barnes, Karen" uniqKey="Barnes K" first="Karen" last="Barnes">Karen Barnes</name><affiliation><nlm:aff id="I4">University of Cape Town, South Africa</nlm:aff></affiliation></author><author><name sortKey="Binh, Tran Quang" sort="Binh, Tran Quang" uniqKey="Binh T" first="Tran Quang" last="Binh">Tran Quang Binh</name><affiliation><nlm:aff id="I5">Choray Hospital, Ho Chi Minh City, Vietnam</nlm:aff></affiliation></author><author><name sortKey="D Alessandro, Umberto" sort="D Alessandro, Umberto" uniqKey="D Alessandro U" first="Umberto" last="D'Alessandro">Umberto D'Alessandro</name><affiliation><nlm:aff id="I6">Institute of Tropical Medicine, Antwerp, Belgium</nlm:aff></affiliation></author><author><name sortKey="Day, Nicholas Pj" sort="Day, Nicholas Pj" uniqKey="Day N" first="Nicholas Pj" last="Day">Nicholas Pj Day</name><affiliation><nlm:aff id="I1">Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</nlm:aff></affiliation><affiliation><nlm:aff id="I7">Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK</nlm:aff></affiliation></author><author><name sortKey="De Vries, Peter J" sort="De Vries, Peter J" uniqKey="De Vries P" first="Peter J" last="De Vries">Peter J. De Vries</name><affiliation><nlm:aff id="I8">Division of Infectious Diseases, Tropical Medicine & AIDS, Academic Medical Center, Amsterdam, The Netherlands</nlm:aff></affiliation></author><author><name sortKey="Dorsey, Grant" sort="Dorsey, Grant" uniqKey="Dorsey G" first="Grant" last="Dorsey">Grant Dorsey</name><affiliation><nlm:aff id="I9">University of California, San Francisco, CA, USA</nlm:aff></affiliation><affiliation><nlm:aff id="I10">Institut de Recherche en Sciences de la Sante, Burkino Faso</nlm:aff></affiliation><affiliation><nlm:aff id="I11">Uganda Malaria Surveillance Programme, Uganda</nlm:aff></affiliation></author><author><name sortKey="Guthmann, Jean Paul" sort="Guthmann, Jean Paul" uniqKey="Guthmann J" first="Jean-Paul" last="Guthmann">Jean-Paul Guthmann</name><affiliation><nlm:aff id="I12">Epicentre, France</nlm:aff></affiliation></author><author><name sortKey="Mayxay, Mayfong" sort="Mayxay, Mayfong" uniqKey="Mayxay M" first="Mayfong" last="Mayxay">Mayfong Mayxay</name><affiliation><nlm:aff id="I13">National University of Laos, Laos</nlm:aff></affiliation><affiliation><nlm:aff id="I14">Wellcome Trust- Mahosot Hospital- Oxford University Tropical Medicine Research Collaboration, Laos</nlm:aff></affiliation></author><author><name sortKey="Newton, Paul" sort="Newton, Paul" uniqKey="Newton P" first="Paul" last="Newton">Paul Newton</name><affiliation><nlm:aff id="I14">Wellcome Trust- Mahosot Hospital- Oxford University Tropical Medicine Research Collaboration, Laos</nlm:aff></affiliation></author><author><name sortKey="Nosten, Francois" sort="Nosten, Francois" uniqKey="Nosten F" first="Francois" last="Nosten">Francois Nosten</name><affiliation><nlm:aff id="I3">Shoklo Malaria Research Unit, Mae Sot, Thailand</nlm:aff></affiliation></author><author><name sortKey="Olliaro, Piero" sort="Olliaro, Piero" uniqKey="Olliaro P" first="Piero" last="Olliaro">Piero Olliaro</name><affiliation><nlm:aff id="I7">Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK</nlm:aff></affiliation><affiliation><nlm:aff id="I15">WHO TDR, Geneva, Switzerland</nlm:aff></affiliation></author><author><name sortKey="Osario, Lyda" sort="Osario, Lyda" uniqKey="Osario L" first="Lyda" last="Osario">Lyda Osario</name><affiliation><nlm:aff id="I16">Centro Internatcional de Entrenamiento e Investigaciones Medicas, Colombia</nlm:aff></affiliation></author><author><name sortKey="Pinoges, Loretxu" sort="Pinoges, Loretxu" uniqKey="Pinoges L" first="Loretxu" last="Pinoges">Loretxu Pinoges</name><affiliation><nlm:aff id="I12">Epicentre, France</nlm:aff></affiliation></author><author><name sortKey="Price, Ric" sort="Price, Ric" uniqKey="Price R" first="Ric" last="Price">Ric Price</name><affiliation><nlm:aff id="I3">Shoklo Malaria Research Unit, Mae Sot, Thailand</nlm:aff></affiliation></author><author><name sortKey="Rowland, Mark" sort="Rowland, Mark" uniqKey="Rowland M" first="Mark" last="Rowland">Mark Rowland</name><affiliation><nlm:aff id="I17">London School of Hygiene & Tropical Medicine, London, UK</nlm:aff></affiliation></author><author><name sortKey="Smithuis, Frank" sort="Smithuis, Frank" uniqKey="Smithuis F" first="Frank" last="Smithuis">Frank Smithuis</name><affiliation><nlm:aff id="I18">Médecins sans Frontières, The Netherlands</nlm:aff></affiliation></author><author><name sortKey="Taylor, Robert" sort="Taylor, Robert" uniqKey="Taylor R" first="Robert" last="Taylor">Robert Taylor</name><affiliation><nlm:aff id="I15">WHO TDR, Geneva, Switzerland</nlm:aff></affiliation></author><author><name sortKey="White, Nicholas J" sort="White, Nicholas J" uniqKey="White N" first="Nicholas J" last="White">Nicholas J. White</name><affiliation><nlm:aff id="I1">Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</nlm:aff></affiliation><affiliation><nlm:aff id="I7">Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK</nlm:aff></affiliation></author></analytic><series><title level="j">Malaria Journal</title><idno type="eISSN">1475-2875</idno><imprint><date when="2008">2008</date></imprint></series></biblStruct></sourceDesc></fileDesc><profileDesc><textClass></textClass></profileDesc></teiHeader><front><div type="abstract" xml:lang="en"><sec><title>Background</title><p>Malaria is a very important cause of anaemia in tropical countries. Anaemia is assessed either by measurement of the haematocrit or the haemoglobin concentration. For comparisons across studies, it is often necessary to derive one measure from the other.</p></sec><sec sec-type="methods"><title>Methods</title><p>Data on patients with slide-confirmed uncomplicated falciparum malaria were pooled from 85 antimalarial drug trials conducted in 25 different countries, to assess the haemoglobin/haematocrit relationship at different time points in malaria. Using a linear random effects model, a conversion equation for haematocrit was derived based on 3,254 measurements from various time points (ranging from day 0 to day 63) from 1,810 patients with simultaneous measurements of both parameters. Haemoglobin was also estimated from haematocrit with the commonly used threefold conversion.</p></sec><sec><title>Results</title><p>A good fit was obtained using Haematocrit = 5.62 + 2.60 * Haemoglobin. On average, haematocrit/3 levels were slightly higher than haemoglobin measurements with a mean difference (± SD) of -0.69 (± 1.3) for children under the age of 5 (n = 1,440 measurements from 449 patients).</p></sec><sec><title>Conclusion</title><p>Based on this large data set, an accurate and robust conversion factor both in acute malaria and in convalescence was obtained. The commonly used threefold conversion is also valid.</p></sec></div></front><back><div1 type="bibliography"><listBibl><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct><biblStruct></biblStruct></listBibl></div1></back></TEI><pmc article-type="research-article"><pmc-dir>properties open_access</pmc-dir>
<front><journal-meta><journal-id journal-id-type="nlm-ta">Malar J</journal-id><journal-title>Malaria Journal</journal-title><issn pub-type="epub">1475-2875</issn><publisher><publisher-name>BioMed Central</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="pmid">18673575</article-id><article-id pub-id-type="pmc">2515851</article-id><article-id pub-id-type="publisher-id">1475-2875-7-149</article-id><article-id pub-id-type="doi">10.1186/1475-2875-7-149</article-id><article-categories><subj-group subj-group-type="heading"><subject>Methodology</subject></subj-group></article-categories><title-group><article-title>The relationship between the haemoglobin concentration and the haematocrit in <italic>Plasmodium falciparum </italic>malaria</article-title></title-group><contrib-group><contrib id="A1" contrib-type="author"><name><surname>Lee</surname><given-names>Sue J</given-names></name><xref ref-type="aff" rid="I1">1</xref><email>sue@tropmedres.ac</email></contrib><contrib id="A2" contrib-type="author"><name><surname>Stepniewska</surname><given-names>Kasia</given-names></name><xref ref-type="aff" rid="I1">1</xref><email>kasia@tropmedres.ac</email></contrib><contrib id="A3" contrib-type="author"><name><surname>Anstey</surname><given-names>Nicholas</given-names></name><xref ref-type="aff" rid="I2">2</xref><email>nick.anstey@menzies.edu.au</email></contrib><contrib id="A4" contrib-type="author"><name><surname>Ashley</surname><given-names>Elizabeth</given-names></name><xref ref-type="aff" rid="I3">3</xref><email>Elizabeth.ASHLEY@epicentre.msf.org</email></contrib><contrib id="A5" contrib-type="author"><name><surname>Barnes</surname><given-names>Karen</given-names></name><xref ref-type="aff" rid="I4">4</xref><email>kbarnes@uctgsh1.uct.ac.za</email></contrib><contrib id="A6" contrib-type="author"><name><surname>Binh</surname><given-names>Tran Quang</given-names></name><xref ref-type="aff" rid="I5">5</xref><email>binhtq@hcm.vnn.vn</email></contrib><contrib id="A7" contrib-type="author"><name><surname>D'Alessandro</surname><given-names>Umberto</given-names></name><xref ref-type="aff" rid="I6">6</xref><email>UDAlessandro@itg.be</email></contrib><contrib id="A8" contrib-type="author"><name><surname>Day</surname><given-names>Nicholas PJ</given-names></name><xref ref-type="aff" rid="I1">1</xref><xref ref-type="aff" rid="I7">7</xref><email>nickd@tropmedres.ac</email></contrib><contrib id="A9" contrib-type="author"><name><surname>de Vries</surname><given-names>Peter J</given-names></name><xref ref-type="aff" rid="I8">8</xref><email>p.j.devries@xs4all.nl</email></contrib><contrib id="A10" contrib-type="author"><name><surname>Dorsey</surname><given-names>Grant</given-names></name><xref ref-type="aff" rid="I9">9</xref><xref ref-type="aff" rid="I10">10</xref><xref ref-type="aff" rid="I11">11</xref><email>gdorsey@medsfgh.ucsf.edu</email></contrib><contrib id="A11" contrib-type="author"><name><surname>Guthmann</surname><given-names>Jean-Paul</given-names></name><xref ref-type="aff" rid="I12">12</xref><email>jp.guthmann@invs.sante.fr</email></contrib><contrib id="A12" contrib-type="author"><name><surname>Mayxay</surname><given-names>Mayfong</given-names></name><xref ref-type="aff" rid="I13">13</xref><xref ref-type="aff" rid="I14">14</xref><email>mmayxay@yahoo.com</email></contrib><contrib id="A13" contrib-type="author"><name><surname>Newton</surname><given-names>Paul</given-names></name><xref ref-type="aff" rid="I14">14</xref><email>paul@tropmedres.ac</email></contrib><contrib id="A14" contrib-type="author"><name><surname>Nosten</surname><given-names>Francois</given-names></name><xref ref-type="aff" rid="I3">3</xref><email>francois@tropmedres.ac</email></contrib><contrib id="A15" contrib-type="author"><name><surname>Olliaro</surname><given-names>Piero</given-names></name><xref ref-type="aff" rid="I7">7</xref><xref ref-type="aff" rid="I15">15</xref><email>olliarop@who.int</email></contrib><contrib id="A16" contrib-type="author"><name><surname>Osario</surname><given-names>Lyda</given-names></name><xref ref-type="aff" rid="I16">16</xref><email>lydaosorio@cideim.org.co</email></contrib><contrib id="A17" contrib-type="author"><name><surname>Pinoges</surname><given-names>Loretxu</given-names></name><xref ref-type="aff" rid="I12">12</xref><email>Loretxu.PINOGES@epicentre.msf.org</email></contrib><contrib id="A18" contrib-type="author"><name><surname>Price</surname><given-names>Ric</given-names></name><xref ref-type="aff" rid="I3">3</xref><email>ricprice@doctors.org.uk</email></contrib><contrib id="A19" contrib-type="author"><name><surname>Rowland</surname><given-names>Mark</given-names></name><xref ref-type="aff" rid="I17">17</xref><email>mark.rowland@lshtm.ac.uk</email></contrib><contrib id="A20" contrib-type="author"><name><surname>Smithuis</surname><given-names>Frank</given-names></name><xref ref-type="aff" rid="I18">18</xref><email>frank_smithuis@yahoo.com</email></contrib><contrib id="A21" contrib-type="author"><name><surname>Taylor</surname><given-names>Robert</given-names></name><xref ref-type="aff" rid="I15">15</xref><email>btaylor@oucru.org</email></contrib><contrib id="A22" corresp="yes" contrib-type="author"><name><surname>White</surname><given-names>Nicholas J</given-names></name><xref ref-type="aff" rid="I1">1</xref><xref ref-type="aff" rid="I7">7</xref><email>nickw@tropmedres.ac</email></contrib></contrib-group><aff id="I1"><label>1</label>Mahidol-Oxford Tropical Medicine Research Unit (MORU), Mahidol University, Faculty of Tropical Medicine, 3rd Floor, 60th Anniversary Chalermprakiat Building, 420/6 Ratchawithi Rd., Ratchathewi District, Bangkok 10400, Thailand</aff><aff id="I2"><label>2</label>Menzies School of Health Research and Royal Darwin Hospital, Darwin, NT, Australia</aff><aff id="I3"><label>3</label>Shoklo Malaria Research Unit, Mae Sot, Thailand</aff><aff id="I4"><label>4</label>University of Cape Town, South Africa</aff><aff id="I5"><label>5</label>Choray Hospital, Ho Chi Minh City, Vietnam</aff><aff id="I6"><label>6</label>Institute of Tropical Medicine, Antwerp, Belgium</aff><aff id="I7"><label>7</label>Centre for Clinical Vaccinology and Tropical Medicine, Oxford, UK</aff><aff id="I8"><label>8</label>Division of Infectious Diseases, Tropical Medicine & AIDS, Academic Medical Center, Amsterdam, The Netherlands</aff><aff id="I9"><label>9</label>University of California, San Francisco, CA, USA</aff><aff id="I10"><label>10</label>Institut de Recherche en Sciences de la Sante, Burkino Faso</aff><aff id="I11"><label>11</label>Uganda Malaria Surveillance Programme, Uganda</aff><aff id="I12"><label>12</label>Epicentre, France</aff><aff id="I13"><label>13</label>National University of Laos, Laos</aff><aff id="I14"><label>14</label>Wellcome Trust- Mahosot Hospital- Oxford University Tropical Medicine Research Collaboration, Laos</aff><aff id="I15"><label>15</label>WHO TDR, Geneva, Switzerland</aff><aff id="I16"><label>16</label>Centro Internatcional de Entrenamiento e Investigaciones Medicas, Colombia</aff><aff id="I17"><label>17</label>London School of Hygiene & Tropical Medicine, London, UK</aff><aff id="I18"><label>18</label>Médecins sans Frontières, The Netherlands</aff><pub-date pub-type="collection"><year>2008</year></pub-date><pub-date pub-type="epub"><day>2</day><month>8</month><year>2008</year></pub-date><volume>7</volume><fpage>149</fpage><lpage>149</lpage><ext-link ext-link-type="uri" xlink:href="http://www.malariajournal.com/content/7/1/149"></ext-link><history><date date-type="received"><day>8</day><month>4</month><year>2008</year></date><date date-type="accepted"><day>2</day><month>8</month><year>2008</year></date></history><permissions><copyright-statement>Copyright © 2008 Lee et al; licensee BioMed Central Ltd.</copyright-statement><copyright-year>2008</copyright-year><copyright-holder>Lee et al; licensee BioMed Central Ltd.</copyright-holder><license license-type="open-access" xlink:href="http://creativecommons.org/licenses/by/2.0"><p>This is an Open Access article distributed under the terms of the Creative Commons Attribution License (<ext-link ext-link-type="uri" xlink:href="http://creativecommons.org/licenses/by/2.0"></ext-link>), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.</p><pmc-comment>
Lee
J
Sue
sue@tropmedres.ac
The relationship between the haemoglobin concentration and the haematocrit in Plasmodium falciparum malaria
2008 Malaria Journal 7(1): 149-. (2008) 1475-2875(2008)7:1<149> urn:ISSN:1475-2875
</license></permissions><abstract><sec><title>Background</title><p>Malaria is a very important cause of anaemia in tropical countries. Anaemia is assessed either by measurement of the haematocrit or the haemoglobin concentration. For comparisons across studies, it is often necessary to derive one measure from the other.</p></sec><sec sec-type="methods"><title>Methods</title><p>Data on patients with slide-confirmed uncomplicated falciparum malaria were pooled from 85 antimalarial drug trials conducted in 25 different countries, to assess the haemoglobin/haematocrit relationship at different time points in malaria. Using a linear random effects model, a conversion equation for haematocrit was derived based on 3,254 measurements from various time points (ranging from day 0 to day 63) from 1,810 patients with simultaneous measurements of both parameters. Haemoglobin was also estimated from haematocrit with the commonly used threefold conversion.</p></sec><sec><title>Results</title><p>A good fit was obtained using Haematocrit = 5.62 + 2.60 * Haemoglobin. On average, haematocrit/3 levels were slightly higher than haemoglobin measurements with a mean difference (± SD) of -0.69 (± 1.3) for children under the age of 5 (n = 1,440 measurements from 449 patients).</p></sec><sec><title>Conclusion</title><p>Based on this large data set, an accurate and robust conversion factor both in acute malaria and in convalescence was obtained. The commonly used threefold conversion is also valid.</p></sec></abstract></article-meta></front><body><sec><title>Background</title><p>Malaria is a major cause of anaemia in tropical countries. It results from the obligatory destruction of parasitized erythrocytes, the accelerated destruction of normal erythrocytes, and variable dyserythropoiesis. Anaemia is assessed either by measurement of the haematocrit or the haemoglobin concentration. Clinical and epidemiological studies of malaria use either measure, so for comparisons across studies, it is often necessary to derive one measure from the other. Malaria is associated with increased acute phase protein concentrations and severe malaria increases erythrocyte rigidity, which may affect the relationship between haemoglobin and haematocrit. Recently, it has been suggested that the threefold conversion that is commonly used to equate the two measures (haemoglobin = haematocrit/3), consistently overestimates the haemoglobin concentration resulting in an underestimate of the prevalence of anaemia [<xref ref-type="bibr" rid="B1">1</xref>,<xref ref-type="bibr" rid="B2">2</xref>].</p><p>This is important as anaemia is an important measure both of the efficacy of antimalarial treatment and the effectiveness of malaria control programmes. Data from patients with slide-confirmed, uncomplicated falciparum malaria were pooled from 85 antimalarial drug trials conducted in 25 different countries, to assess the haemoglobin/haematocrit relationship at different time points in malaria.</p></sec><sec sec-type="methods"><title>Methods</title><p>There were 78,239 haematocrit (Ht) measurements from 17,739 patients compared with 26,863 haemoglobin (Hb) measurements from 13,092 patients. The conversion equation for haematocrit was based on 3,254 measurements from various timepoints from 1,810 patients with simultaneous measurements of both parameters (mean Hb 10.5 g/dl, standard deviation (SD) 2.5 g/dl; mean Ht 33.0%, SD 7.1%). Post-treatment follow-up ranged from 14 to 63 days. Haematocrit was measured by centrifugation for 673 patients and by conductivity for 1,137 patients.</p><p>Because haematocrit or haemoglobin concentrations change during recovery from malaria, adjustment for time was included. The potential effect of age and sex on the haematocrit/haemoglobin relationship was also explored.</p></sec><sec><title>Results and discussion</title><p>As there was significant random variation within each individual as well as between individuals (Breusch and Pagan Lagrange multiplier test for random effects, p < 0.0001) [<xref ref-type="bibr" rid="B3">3</xref>] a linear random effects model was constructed using the equation:</p><p><disp-formula id="bmcM1"><label>(1)</label>Ht<sub>it </sub>= α + Hb<sub>it </sub>* β<sub>hb </sub>+ time * β<sub>time </sub>+ v<sub>i </sub>+ e<sub>it</sub></disp-formula></p><p>(where Ht is haematocrit (%), Hb is haemoglobin (g/dL), v<sub>i </sub>is the random effect for each individual, i, β is the coefficient for each parameter that the model estimated, e<sub>it </sub>is the deviation for each individual, i, at time, t, and α is the intercept) and obtained: Ht = 5.66 + 2.58 * Hb + 0.01 * time which explained approximately 80% of the variance in the model (r<sup>2 </sup>(within) = 0.63, r<sup>2 </sup>(between) = 0.82, r<sup>2 </sup>(overall) = 0.83). Age and sex did not significantly improve the model fit (p = 0.22 and p = 0.17, respectively).</p><p>Although time contributed significantly to the model fit (95% CI 0.005, 0.023), its effect was very small. For example, a haematocrit value of 35.5% at day 0 would change to 35.78% (35.5 + 0.28) on day 28 if time were taken into account.</p><p>A simpified conversion without the time covariate using a random effects model gave:</p><p><disp-formula id="bmcM2"><label>(2)</label>Ht = 5.62 + 2.60 * Hb</disp-formula></p><p>The model fit was still good (r<sup>2 </sup>(within) = 0.63, r<sup>2 </sup>(between) = 0.82, r<sup>2 </sup>(overall) = 0.82; Figure <xref ref-type="fig" rid="F1">1a</xref>).</p><fig position="float" id="F1"><label>Figure 1</label><caption><p>a) Plot of observed versus predicted haematocrit measurements with a line to depict the relationship with the actual haematocrit values, b) Bland-Altman plot of agreement between actual haematocrit measurements and haematocrit values estimated from haemoglobin measurements.</p></caption><graphic xlink:href="1475-2875-7-149-1"></graphic></fig><p>Using a Bland -Altman plot [<xref ref-type="bibr" rid="B4">4</xref>] to compare the values obtained using the conversion equation with the original observed values, the mean difference was -0.019 (95% CI -0.12 to 0.09) percentage points indicating that, overall, the predictions from the conversion equation tended to give slightly lower haematocrit estimates by up to 0.12 percentage points (Figure <xref ref-type="fig" rid="F1">1b</xref>). However, the conversion equation also overestimated haematocrit by up to 0.23 percentage points. Limits of agreement were calculated as the mean difference ± 1.96 SD and 94.3% of the values fell within these limits.</p><p>Comparing these results with those reported by Carneiro <italic>et al</italic>, haemoglobin was also estimated from haematocrit with the commonly used threefold conversion using data from children under the age of five only (n = 1,440 measurements from 449 patients). The Bland-Altman plot showed good agreement when comparing haemoglobin in the field and values estimated using the threefold conversion. On average, haematocrit/3 levels were slightly higher than haemoglobin measurements with a mean difference (± SD; 95% CI) of -0.69 (± 1.3; -0.75 to -0.62). 74.2% of haematocrit/3 levels were higher than haemoglobin measurements. In contrast to Carneiro <italic>et al</italic>, but similar to Rodriguez-Morales <italic>et al</italic>, larger negative differences were not observed with decreasing haemoglobin levels (Figure <xref ref-type="fig" rid="F2">2a</xref>). Agreement was also good when applying the threefold conversion to measurements from patients between five and 14 years of age (n = 501 measurements from 216 patients, Figure <xref ref-type="fig" rid="F2">2b</xref>), but was best when used in adults (15 years and older, n = 1,306 measurements from 376 patients, Figure <xref ref-type="fig" rid="F2">2c</xref>).</p><fig position="float" id="F2"><label>Figure 2</label><caption><p>Bland-Altman plots of agreement between actual haemoglobin measurements and haemoglobin values estimated from haematocrit measurements, by age group (Note: age was missing for seven patients).</p></caption><graphic xlink:href="1475-2875-7-149-2"></graphic></fig></sec><sec><title>Conclusion</title><p>In summary, based on this large data set, the conversion factor to equate haemoglobin and haematocrit (Ht = 5.62 + 2.60 * Hb) is accurate and robust both in acute uncomplicated malaria and in convalescence. The two measures can be readily interconverted. The commonly used threefold conversion is also valid.</p></sec><sec><title>Competing interests</title><p>The authors declare that they have no competing interests.</p></sec><sec><title>Authors' contributions</title><p>NJW, KS and SJL conceived the idea for paper. The data were collected from research that was designed and conducted by all the other authors. KS and SJL conducted the analysis and wrote the paper, with input from NJW and all other authors.</p></sec></body><back><ack><sec><title>Acknowledgements</title><p>This study was funded by the UNICEF/UNDP/World Bank/WHO Special Programme on Research & Training in Tropical Diseases (TDR) [Grant A50977] and was part of the Wellcome Trust-Mahidol University-Oxford Tropical Medicine Research Programme.</p><p>The opinions expressed in this paper are those of the authors and may not reflect those of their employing organizations. PO is a staff member of the WHO and WRJT was a member at the time of the conduct of the study; the authors alone are responsible for the views expressed in this publication and they do not necessarily represent the decisions, policy or views of the WHO.</p></sec></ack><ref-list><ref id="B1"><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Carneiro</surname><given-names>IA</given-names></name><name><surname>Drakeley</surname><given-names>CJ</given-names></name><name><surname>Owusu-Agyei</surname><given-names>S</given-names></name><name><surname>Mmbando</surname><given-names>B</given-names></name><name><surname>Chandramohan</surname><given-names>D</given-names></name></person-group><article-title>Haemoglobin and haematocrit: is the threefold conversion valid for assessing anaemia in malaria-endemic settings?</article-title><source>Malar J</source><year>2007</year><volume>6</volume><fpage>67</fpage><pub-id pub-id-type="pmid">17519019</pub-id><pub-id pub-id-type="doi">10.1186/1475-2875-6-67</pub-id></citation></ref><ref id="B2"><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Rodriguez-Morales</surname><given-names>AJ</given-names></name><name><surname>Sanchez</surname><given-names>E</given-names></name><name><surname>Arria</surname><given-names>M</given-names></name><name><surname>Vargas</surname><given-names>M</given-names></name><name><surname>Piccolo</surname><given-names>C</given-names></name><name><surname>Colina</surname><given-names>R</given-names></name><name><surname>Franco-Paredes</surname><given-names>C</given-names></name></person-group><article-title>Haemoglobin and haematocrit: the threefold conversion is also non valid for assessing anaemia in <italic>Plasmodium vivax</italic> malaria-endemic settings</article-title><source>Malar J</source><year>2007</year><volume>6</volume><fpage>166</fpage><pub-id pub-id-type="pmid">18086306</pub-id><pub-id pub-id-type="doi">10.1186/1475-2875-6-166</pub-id></citation></ref><ref id="B3"><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Breusch</surname><given-names>TS</given-names></name><name><surname>Pagan</surname><given-names>AR</given-names></name></person-group><article-title>The Lagrange Multiplier Test and its Applications to Model Specification in Econometrics</article-title><source>The Review of Economic Studies</source><year>1980</year><volume>47</volume><fpage>239</fpage><lpage>253</lpage><pub-id pub-id-type="doi">10.2307/2297111</pub-id></citation></ref><ref id="B4"><citation citation-type="journal"><person-group person-group-type="author"><name><surname>Bland</surname><given-names>JM</given-names></name><name><surname>Altman</surname><given-names>DG</given-names></name></person-group><article-title>Statistical methods for assessing agreement between two methods of clinical measurement</article-title><source>Lancet</source><year>1986</year><volume>1</volume><fpage>307</fpage><lpage>310</lpage><pub-id pub-id-type="pmid">2868172</pub-id></citation></ref></ref-list></back></pmc></record>Pour manipuler ce document sous Unix (Dilib)
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