Browsing by Author "Calmy, Alexandra"

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    Open Access
    Estimating loss to follow-up in HIV-infected patients on antiretroviral therapy: the effect of the competing risk of death in Zambia and Switzerland
    (Public Library of Science, 2011) Schöni-Affolter, Franziska; Keiser, Olivia; Mwango, Albert; Stringer, Jeffrey; Ledergerber, Bruno; Mulenga, Lloyd; Bucher, Heiner C; Westfall, Andrew O; Calmy, Alexandra; Boulle, Andrew; Chintu, Namwinga; Egger, Matthias; Chi, Benjamin H
    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.
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    Open Access
    The first decade of antiretroviral therapy in Africa
    (BioMed Central Ltd, 2011) Ford, Nathan; Calmy, Alexandra; Mills, Edward
    The past decade has seen remarkable progress in increasing access to antiretroviral therapy in resource-limited settings. Early concerns about the cost and complexity of treatment were overcome thanks to the efforts of a global coalition of health providers, activists, academics, and people living with HIV/AIDS, who argued that every effort must be made to ensure access to essential care when millions of lives depended on it. The high cost of treatment was reduced through advocacy to promote access to generic drugs; care provision was simplified through a public health approach to treatment provision; the lack of human resources was overcome through task-shifting to support the provision of care by non-physicians; and access was expanded through the development of models of care that could work at the primary care level. The challenge for the next decade is to further increase access to treatment and support sustained care for those on treatment, while at the same time ensuring that the package of care is continuously improved such that all patients can benefit from the latest improvements in drug development, clinical science, and public health.
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    Mean CD4 cell count changes in patients failing a first-line antiretroviral therapy in resource-limited settings
    (BioMed Central Ltd, 2012) Calmy, Alexandra; Balestre, Eric; Bonnet, Fabrice; Boulle, Andrew; Sprinz, Eduardo; Wood, Robin; Delaporte, Eric; Messou, Eugene; McIntyre, James; El Filali, Kamal; Schechter, Mauro; Kumarasamy, N; Bangsberg, David; McPhail, Patrick; Van Der Borght,
    BACKGROUND: Changes in CD4 cell counts are poorly documented in individuals with low or moderate-level viremia while on antiretroviral treatment (ART) in resource-limited settings. We assessed the impact of on-going HIV-RNA replication on CD4 cell count slopes in patients treated with a first-line combination ART.METHOD:Naive patients on a first-line ART regimen with at least two measures of HIV-RNA available after ART initiation were included in the study. The relationships between mean CD4 cell count change and HIV-RNA at 6 and 12months after ART initiation (M6 and M12) were assessed by linear mixed models adjusted for gender, age, clinical stage and year of starting ART. RESULTS: 3,338 patients were included (14 cohorts, 64% female) and the group had the following characteristics: a median follow-up time of 1.6years, a median age of 34years, and a median CD4 cell count at ART initiation of 107 cells/muL. All patients with suppressed HIV-RNA at M12 had a continuous increase in CD4 cell count up to 18months after treatment initiation. By contrast, any degree of HIV-RNA replication both at M6 and M12 was associated with a flat or a decreasing CD4 cell count slope. Multivariable analysis using HIV-RNA thresholds of 10,000 and 5,000 copies confirmed the significant effect of HIV-RNA on CD4 cell counts both at M6 and M12. CONCLUSION: In routinely monitored patients on an NNRTI-based first-line ART, on-going low-level HIV-RNA replication was associated with a poor immune outcome in patients who had detectable levels of the virus after one year of ART.