Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland

 

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dc.contributor.author Schöni-Affolter, Franziska en_ZA
dc.contributor.author Keiser, Olivia en_ZA
dc.contributor.author Mwango, Albert en_ZA
dc.contributor.author Stringer, Jeffrey en_ZA
dc.contributor.author Ledergerber, Bruno en_ZA
dc.contributor.author Mulenga, Lloyd en_ZA
dc.contributor.author Bucher, Heiner C en_ZA
dc.contributor.author Westfall, Andrew O en_ZA
dc.contributor.author Calmy, Alexandra en_ZA
dc.contributor.author Boulle, Andrew en_ZA
dc.contributor.author Chintu, Namwinga en_ZA
dc.contributor.author Egger, Matthias en_ZA
dc.contributor.author Chi, Benjamin H en_ZA
dc.date.accessioned 2016-01-11T06:57:29Z
dc.date.available 2016-01-11T06:57:29Z
dc.date.issued 2011 en_ZA
dc.identifier.citation Schöni-Affolter, F., Keiser, O., Mwango, A., Stringer, J., Ledergerber, B., Mulenga, L., ... & Chintu, N. (2011). Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland. PLoS One, 6(12), e27919. doi:10.1371/journal.pone.0027919 en_ZA
dc.identifier.uri http://hdl.handle.net/11427/16319
dc.identifier.uri http://dx.doi.org/10.1371/journal.pone.0027919
dc.description.abstract BACKGROUND: Loss to follow-up (LTFU) is common in antiretroviral therapy (ART) programmes. Mortality is a competing risk (CR) for LTFU; however, it is often overlooked in cohort analyses. We examined how the CR of death affected LTFU estimates in Zambia and Switzerland. Methods and FINDINGS: HIV-infected patients aged ≥18 years who started ART 2004-2008 in observational cohorts in Zambia and Switzerland were included. We compared standard Kaplan-Meier curves with CR cumulative incidence. We calculated hazard ratios for LTFU across CD4 cell count strata using cause-specific Cox models, or Fine and Gray subdistribution models, adjusting for age, gender, body mass index and clinical stage. 89,339 patients from Zambia and 1,860 patients from Switzerland were included. 12,237 patients (13.7%) in Zambia and 129 patients (6.9%) in Switzerland were LTFU and 8,498 (9.5%) and 29 patients (1.6%), respectively, died. In Zambia, the probability of LTFU was overestimated in Kaplan-Meier curves: estimates at 3.5 years were 29.3% for patients starting ART with CD4 cells <100 cells/µl and 15.4% among patients starting with ≥350 cells/µL. The estimates from CR cumulative incidence were 22.9% and 13.6%, respectively. Little difference was found between naïve and CR analyses in Switzerland since only few patients died. The results from Cox and Fine and Gray models were similar: in Zambia the risk of loss to follow-up and death increased with decreasing CD4 counts at the start of ART, whereas in Switzerland there was a trend in the opposite direction, with patients with higher CD4 cell counts more likely to be lost to follow-up. CONCLUSIONS: In ART programmes in low-income settings the competing risk of death can substantially bias standard analyses of LTFU. The CD4 cell count and other prognostic factors may be differentially associated with LTFU in low-income and high-income settings. en_ZA
dc.language.iso eng en_ZA
dc.publisher Public Library of Science en_ZA
dc.rights This 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.uri http://creativecommons.org/licenses/by/4.0 en_ZA
dc.source PLoS One en_ZA
dc.source.uri http://journals.plos.org/plosone en_ZA
dc.subject.other Antiretroviral therapy en_ZA
dc.subject.other Zambia en_ZA
dc.subject.other HIV en_ZA
dc.subject.other Cohort studies en_ZA
dc.subject.other Switzerland en_ZA
dc.subject.other Body mass index en_ZA
dc.subject.other Death rates en_ZA
dc.subject.other Antiretrovirals en_ZA
dc.title Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland en_ZA
dc.type Journal Article en_ZA
dc.rights.holder © 2011 Schöni-Affolter et al en_ZA
uct.type.publication Research en_ZA
uct.type.resource Article en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Health Sciences en_ZA
dc.publisher.department Department of Public Health and Family Medicine en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Schöni-Affolter, F., Keiser, O., Mwango, A., Stringer, J., Ledergerber, B., Mulenga, L., ... Chi, B. H. (2011). Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland. <i>PLoS One</i>, http://hdl.handle.net/11427/16319 en_ZA
dc.identifier.chicagocitation Schöni-Affolter, Franziska, Olivia Keiser, Albert Mwango, Jeffrey Stringer, Bruno Ledergerber, Lloyd Mulenga, Heiner C Bucher, et al "Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland." <i>PLoS One</i> (2011) http://hdl.handle.net/11427/16319 en_ZA
dc.identifier.vancouvercitation Schöni-Affolter F, Keiser O, Mwango A, Stringer J, Ledergerber B, Mulenga L, et al. Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland. PLoS One. 2011; http://hdl.handle.net/11427/16319. en_ZA
dc.identifier.ris TY - Journal Article AU - Schöni-Affolter, Franziska AU - Keiser, Olivia AU - Mwango, Albert AU - Stringer, Jeffrey AU - Ledergerber, Bruno AU - Mulenga, Lloyd AU - Bucher, Heiner C AU - Westfall, Andrew O AU - Calmy, Alexandra AU - Boulle, Andrew AU - Chintu, Namwinga AU - Egger, Matthias AU - Chi, Benjamin H AB - BACKGROUND: Loss to follow-up (LTFU) is common in antiretroviral therapy (ART) programmes. Mortality is a competing risk (CR) for LTFU; however, it is often overlooked in cohort analyses. We examined how the CR of death affected LTFU estimates in Zambia and Switzerland. Methods and FINDINGS: HIV-infected patients aged ≥18 years who started ART 2004-2008 in observational cohorts in Zambia and Switzerland were included. We compared standard Kaplan-Meier curves with CR cumulative incidence. We calculated hazard ratios for LTFU across CD4 cell count strata using cause-specific Cox models, or Fine and Gray subdistribution models, adjusting for age, gender, body mass index and clinical stage. 89,339 patients from Zambia and 1,860 patients from Switzerland were included. 12,237 patients (13.7%) in Zambia and 129 patients (6.9%) in Switzerland were LTFU and 8,498 (9.5%) and 29 patients (1.6%), respectively, died. In Zambia, the probability of LTFU was overestimated in Kaplan-Meier curves: estimates at 3.5 years were 29.3% for patients starting ART with CD4 cells <100 cells/µl and 15.4% among patients starting with ≥350 cells/µL. The estimates from CR cumulative incidence were 22.9% and 13.6%, respectively. Little difference was found between naïve and CR analyses in Switzerland since only few patients died. The results from Cox and Fine and Gray models were similar: in Zambia the risk of loss to follow-up and death increased with decreasing CD4 counts at the start of ART, whereas in Switzerland there was a trend in the opposite direction, with patients with higher CD4 cell counts more likely to be lost to follow-up. CONCLUSIONS: In ART programmes in low-income settings the competing risk of death can substantially bias standard analyses of LTFU. The CD4 cell count and other prognostic factors may be differentially associated with LTFU in low-income and high-income settings. DA - 2011 DB - OpenUCT DO - 10.1371/journal.pone.0027919 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2011 T1 - Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland TI - Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland UR - http://hdl.handle.net/11427/16319 ER - en_ZA


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This 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. Except where otherwise noted, this item's license is described as This 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.