Correcting mortality for loss to follow-up: a nomogram applied to antiretroviral treatment programmes in sub-Saharan Africa

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dc.contributor.authorEgger, Matthiasen_ZA
dc.contributor.authorSpycher, Ben Den_ZA
dc.contributor.authorSidle, Johnen_ZA
dc.contributor.authorWeigel, Ralfen_ZA
dc.contributor.authorGeng, Elvin Hen_ZA
dc.contributor.authorFox, Matthew Pen_ZA
dc.contributor.authorMacPhail, Patricken_ZA
dc.contributor.authorvan Cutsem, Gillesen_ZA
dc.contributor.authorMessou, Eugèneen_ZA
dc.contributor.authorWood, Robinen_ZA
dc.date.accessioned2016-01-11T06:50:54Z
dc.date.available2016-01-11T06:50:54Z
dc.date.issued2011en_ZA
dc.description.abstractBackground: The World Health Organization estimates that in sub-Saharan Africa about 4 million HIV-infected patients had started antiretroviral therapy (ART) by the end of 2008. Loss of patients to follow-up and care is an important problem for treatment programmes in this region. As mortality is high in these patients compared to patients remaining in care, ART programmes with high rates of loss to follow-up may substantially underestimate mortality of all patients starting ART. Methods and Findings: We developed a nomogram to correct mortality estimates for loss to follow-up, based on the fact that mortality of all patients starting ART in a treatment programme is a weighted average of mortality among patients lost to follow-up and patients remaining in care. The nomogram gives a correction factor based on the percentage of patients lost to follow-up at a given point in time, and the estimated ratio of mortality between patients lost and not lost to follow-up. The mortality observed among patients retained in care is then multiplied by the correction factor to obtain an estimate of programme-level mortality that takes all deaths into account. A web calculator directly calculates the corrected, programme-level mortality with 95% confidence intervals (CIs). We applied the method to 11 ART programmes in sub-Saharan Africa. Patients retained in care had a mortality at 1 year of 1.4% to 12.0%; loss to follow-up ranged from 2.8% to 28.7%; and the correction factor from 1.2 to 8.0. The absolute difference between uncorrected and corrected mortality at 1 year ranged from 1.6% to 9.8%, and was above 5% in four programmes. The largest difference in mortality was in a programme with 28.7% of patients lost to follow-up at 1 year. Conclusions: The amount of bias in mortality estimates can be large in ART programmes with substantial loss to follow-up. Programmes should routinely report mortality among patients retained in care and the proportion of patients lost. A simple nomogram can then be used to estimate mortality among all patients who started ART, for a range of plausible mortality rates among patients lost to follow-up.en_ZA
dc.identifier.apacitationEgger, M., Spycher, B. D., Sidle, J., Weigel, R., Geng, E. H., Fox, M. P., ... Wood, R. (2011). Correcting mortality for loss to follow-up: a nomogram applied to antiretroviral treatment programmes in sub-Saharan Africa. <i>PLOS Medicince</i>, http://hdl.handle.net/11427/16237en_ZA
dc.identifier.chicagocitationEgger, Matthias, Ben D Spycher, John Sidle, Ralf Weigel, Elvin H Geng, Matthew P Fox, Patrick MacPhail, Gilles van Cutsem, Eugène Messou, and Robin Wood "Correcting mortality for loss to follow-up: a nomogram applied to antiretroviral treatment programmes in sub-Saharan Africa." <i>PLOS Medicince</i> (2011) http://hdl.handle.net/11427/16237en_ZA
dc.identifier.citationEgger, M., Spycher, B. D., Sidle, J., Weigel, R., Geng, E. H., Fox, M. V., ... & Nash, D. (2011). Correcting mortality for loss to follow-up: a nomogram applied to antiretroviral treatment programmes in sub-Saharan Africa. PLoS medicine, 8(1), e1000390. doi:10.1371/journal.pmed.1000390en_ZA
dc.identifier.ris TY - Journal Article AU - Egger, Matthias AU - Spycher, Ben D AU - Sidle, John AU - Weigel, Ralf AU - Geng, Elvin H AU - Fox, Matthew P AU - MacPhail, Patrick AU - van Cutsem, Gilles AU - Messou, Eugène AU - Wood, Robin AB - Background: The World Health Organization estimates that in sub-Saharan Africa about 4 million HIV-infected patients had started antiretroviral therapy (ART) by the end of 2008. Loss of patients to follow-up and care is an important problem for treatment programmes in this region. As mortality is high in these patients compared to patients remaining in care, ART programmes with high rates of loss to follow-up may substantially underestimate mortality of all patients starting ART. Methods and Findings: We developed a nomogram to correct mortality estimates for loss to follow-up, based on the fact that mortality of all patients starting ART in a treatment programme is a weighted average of mortality among patients lost to follow-up and patients remaining in care. The nomogram gives a correction factor based on the percentage of patients lost to follow-up at a given point in time, and the estimated ratio of mortality between patients lost and not lost to follow-up. The mortality observed among patients retained in care is then multiplied by the correction factor to obtain an estimate of programme-level mortality that takes all deaths into account. A web calculator directly calculates the corrected, programme-level mortality with 95% confidence intervals (CIs). We applied the method to 11 ART programmes in sub-Saharan Africa. Patients retained in care had a mortality at 1 year of 1.4% to 12.0%; loss to follow-up ranged from 2.8% to 28.7%; and the correction factor from 1.2 to 8.0. The absolute difference between uncorrected and corrected mortality at 1 year ranged from 1.6% to 9.8%, and was above 5% in four programmes. The largest difference in mortality was in a programme with 28.7% of patients lost to follow-up at 1 year. Conclusions: The amount of bias in mortality estimates can be large in ART programmes with substantial loss to follow-up. Programmes should routinely report mortality among patients retained in care and the proportion of patients lost. A simple nomogram can then be used to estimate mortality among all patients who started ART, for a range of plausible mortality rates among patients lost to follow-up. DA - 2011 DB - OpenUCT DO - 10.1371/journal.pmed.1000390 DP - University of Cape Town J1 - PLOS Medicince LK - https://open.uct.ac.za PB - University of Cape Town PY - 2011 T1 - Correcting mortality for loss to follow-up: a nomogram applied to antiretroviral treatment programmes in sub-Saharan Africa TI - Correcting mortality for loss to follow-up: a nomogram applied to antiretroviral treatment programmes in sub-Saharan Africa UR - http://hdl.handle.net/11427/16237 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/16237
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pmed.1000390
dc.identifier.vancouvercitationEgger M, Spycher BD, Sidle J, Weigel R, Geng EH, Fox MP, et al. Correcting mortality for loss to follow-up: a nomogram applied to antiretroviral treatment programmes in sub-Saharan Africa. PLOS Medicince. 2011; http://hdl.handle.net/11427/16237.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentDesmond Tutu HIV Centreen_ZA
dc.publisher.facultyFaculty of Health Sciencesen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_ZA
dc.rights.holder© 2011 Egger et alen_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/4.0en_ZA
dc.sourcePLOS Medicinceen_ZA
dc.source.urihttp://journals.plos.org/plosmedicineen_ZA
dc.subject.otherDeath ratesen_ZA
dc.subject.otherAntiretroviral therapyen_ZA
dc.subject.otherAIDSen_ZA
dc.subject.otherAfricaen_ZA
dc.subject.otherHIV epidemiologyen_ZA
dc.subject.otherKenyaen_ZA
dc.subject.otherAntiretroviralsen_ZA
dc.subject.otherMonte Carlo methoden_ZA
dc.titleCorrecting mortality for loss to follow-up: a nomogram applied to antiretroviral treatment programmes in sub-Saharan Africaen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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