The Spectrum projection package: improvements in estimating incidence by age and sex, mother-to-child transmission, HIV progression in children and double orphans

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Abstract

Background

The Spectrum program is used to estimate key HIV indicators from the trends in incidence and prevalence estimated by the Estimation and Projection Package or the Workbook. These indicators include the number of people living with HIV, new infections, AIDS deaths, AIDS orphans, the number of adults and children needing treatment, the need for prevention of mother-to-child transmission and the impact of antiretroviral treatment on survival. The UNAIDS Reference Group on Estimates, Models and Projections regularly reviews new data and information needs, and recommends updates to the methodology and assumptions used in Spectrum.

Methods

The latest update to Spectrum was used in the 2009 round of global estimates. This update contains new procedures for estimating: the age and sex distribution of adult incidence, new child infections occurring around delivery or through breastfeeding, the survival of children by timing of infection and the number of double orphans.

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Most cited references 15

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Early exclusive breastfeeding reduces the risk of postnatal HIV-1 transmission and increases HIV-free survival.

K. Nathoo, Jeffrey J. Iliff, Lawrence Moulton … (2005)

The promotion of exclusive breastfeeding (EBF) to reduce the postnatal transmission (PNT) of HIV is based on limited data. In the context of a trial of postpartum vitamin A supplementation, we provided education and counseling about infant feeding and HIV, prospectively collected information on infant feeding practices, and measured associated infant infections and deaths. A total of 14 110 mother-newborn pairs were enrolled, randomly assigned to vitamin A treatment group after delivery, and followed for 2 years. At baseline, 6 weeks and 3 months, mothers were asked whether they were still breastfeeding, and whether any of 22 liquids or foods had been given to the infant. Breastfed infants were classified as exclusive, predominant, or mixed breastfed. A total of 4495 mothers tested HIV positive at baseline; 2060 of their babies were alive, polymerase chain reaction negative at 6 weeks, and provided complete feeding information. All infants initiated breastfeeding. Overall PNT (defined by a positive HIV test after the 6-week negative test) was 12.1%, 68.2% of which occurred after 6 months. Compared with EBF, early mixed breastfeeding was associated with a 4.03 (95% CI 0.98, 16.61), 3.79 (95% CI 1.40-10.29), and 2.60 (95% CI 1.21-5.55) greater risk of PNT at 6, 12, and 18 months, respectively. Predominant breastfeeding was associated with a 2.63 (95% CI 0.59-11.67), 2.69 (95% CI 0.95-7.63) and 1.61 (95% CI 0.72-3.64) trend towards greater PNT risk at 6, 12, and 18 months, compared with EBF. EBF may substantially reduce breastfeeding-associated HIV transmission.

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Late postnatal transmission of HIV-1 in breast-fed children: an individual patient data meta-analysis.

Philip D. Harris, Ruth Nsuati, Gertrud L. G. Haverkamp … (2004)

We analyzed individual patient data to determine the contribution of late postnatal transmission to the overall risk of mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) and the timing and determinants of late postnatal transmission. Eligible trials were conducted where breast-feeding was common; included >/=2 HIV-1 tests by 3 months, and, if follow-up continued, >/=2 tests at 3-12 months; and regularly assessed infant-feeding modality. Data on children born before January 2000 were analyzed. Of 4085 children from 9 trials (breast-fed singletons for whom HIV-1 testing was performed), 993 (24%) were definitively infected (placebo arms, 25.9%; treatment arms, 23.4%; P=.08). Of 539 children with known timing of infection, 225 (42%) had late postnatal transmission. Late postnatal transmission occurred throughout breast-feeding. The estimated hazard function for time to late postnatal transmission was roughly constant. The cumulative probability of late postnatal transmission at 18 months was 9.3%. The overall risk of late postnatal transmission was 8.9 transmissions/100 child-years of breast-feeding and was significantly higher with lower maternal CD4(+) cell counts and male sex. Late postnatal transmission contributes substantially to overall mother-to-child transmission of HIV-1. The risk of late postnatal transmission is generally constant throughout breast-feeding, and late postnatal transmission is associated with a lower maternal CD4(+) cell count and male sex. Biological and cultural mechanisms underlying the association between sex and late postnatal transmission should be further investigated. Interventions to decrease transmission of HIV-1 through breast-feeding are urgently needed.

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Time from HIV seroconversion to death: a collaborative analysis of eight studies in six low and middle-income countries before highly active antiretroviral therapy.

Etienne Karita, Ram Rangsin, T. Nelson … (2007)

To estimate survival patterns after HIV infection in adults in low and middle-income countries. An analysis of pooled data from eight different studies in six countries. HIV seroconverters were included from eight studies (three population-based, two occupational, and three clinic cohorts) if they were at least 15 years of age, and had no more than 4 years between the last HIV-negative and subsequent HIV-positive test. Four strata were defined: East African cohorts; South African miners cohort; Thai cohorts; Haitian clinic cohort. Kaplan-Meier functions were used to estimate survival patterns, and Weibull distributions were used to model and extend survival estimates. Analyses examined the effect of site, age, and sex on survival. From 3823 eligible seroconverters, 1079 deaths were observed in 19 671 person-years of follow-up. Survival times varied by age and by study site. Adjusting to age 25-29 years at seroconversion, the median survival was longer in South African miners: 11.6 years [95% confidence interval (CI) 9.8-13.7] and East African cohorts: 11.1 years (95% CI 8.7-14.2) than in Haiti: 8.3 years (95% CI 3.2-21.4) and Thailand: 7.5 years (95% CI 5.4-10.4). Survival was similar for men and women, after adjustment for age at seroconversion and site. Without antiretroviral therapy, overall survival after HIV infection in African cohorts was similar to survival in high-income countries, with a similar pattern of faster progression at older ages at seroconversion. Survival appears to be significantly worse in Thailand where other, unmeasured factors may affect progression.

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Author and article information

Journal

Journal ID (nlm-ta): Sex Transm Infect

Journal ID (publisher-id): sti

Journal ID (hwp): sextrans

Title: Sexually Transmitted Infections

Publisher: BMJ Group (BMA House, Tavistock Square, London, WC1H 9JR )

ISSN (Print): 1368-4973

ISSN (Electronic): 1472-3263

Publication date (Print): December 2010

Publication date PMC-release: December 2010

Volume: 86

Issue: Suppl_2 , The 2009 HIV and AIDS estimates and projections: methods, tools and analyses

Pages: ii16-ii21

Affiliations

[1 ]Futures Institute, Glastonbury, Connecticut, USA

[2 ]US Census Bureau, Washington, DC, USA

[3 ]Department of Disease Epidemiology, Imperial College London, London, UK

[4 ]Department of Population Studies, London School of Hygiene and Tropical Medicine, London, UK

[5 ]INSERM, unité 897, Centre de recherche ‘Epidémiologie et Biostatistique,’ Bordeaux, France

[6 ]Institut de Santé Publique Epidémiologie Développement (ISPED), Université Victor Segalen Bordeaux 2, Bordeaux, France

[7 ]Department of Population Studies, London School of Hygiene and Tropical Medicine, London, UK

Author notes

Correspondence to Mr John Stover, Futures Institute, 41A New London Turnpike, Glastonbury, CT 06033, USA; jstover@ 123456futuresinstitute.org

Article

Publisher ID: sextrans44222

DOI: 10.1136/sti.2010.044222

PMC ID: 3173821

PubMed ID: 21106510

SO-VID: 6f371f97-ab23-4b53-927e-966fe446c568

Copyright © © 2010, Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

License:

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited, the use is non commercial and is otherwise in compliance with the license. See: http://creativecommons.org/licenses/by-nc/2.0/ and http://creativecommons.org/licenses/by-nc/2.0/legalcode.

The Spectrum projection package: improvements in estimating incidence by age and sex, mother-to-child transmission, HIV progression in children and double orphans

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Abstract

Background

Methods

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Annual Reviews HIV/AIDS: Public Health and Society

Most cited references 15

Early exclusive breastfeeding reduces the risk of postnatal HIV-1 transmission and increases HIV-free survival.

Late postnatal transmission of HIV-1 in breast-fed children: an individual patient data meta-analysis.

Time from HIV seroconversion to death: a collaborative analysis of eight studies in six low and middle-income countries before highly active antiretroviral therapy.

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