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Tracing of patients lost to follow-up and HIV transmission: mathematical modeling study based on 2 large ART programs

Janne Estill1, Hannock Tweya, Matthias Egger

  • 1*Institute of Social and Preventive Medicine (ISPM), University of Bern, Bern, Switzerland; †The International Union Against Tuberculosis and Lung Disease, Paris, France; ‡Lighthouse Trust, Lilongwe, Malawi; §Centre for Infectious Disease Epidemiology and Research, University of Cape Town, Cape Town, South Africa; ‖Department of Infectious Diseases, University Hospital Bern, Bern, Switzerland; ¶Department of Infectious Diseases, University of Dakar, Dakar, Senegal; #International Training and Education Center for Health, University of Washington, Seattle, WA.

Journal of Acquired Immune Deficiency Syndromes (1999)
|December 12, 2013
PubMed

Insights

Bringing patients lost to follow-up (LTFU) back into HIV care improves treatment as prevention. However, tracing LTFU patients prevented only a small number of new HIV infections, highlighting the need for improved retention strategies.

Area of Science:

  • Public Health
  • Infectious Disease Epidemiology
  • Mathematical Modeling

Background:

  • Effective HIV treatment as prevention relies on sustained patient engagement in care.
  • Patients lost to follow-up (LTFU) pose a significant challenge to HIV control efforts.
  • Understanding the impact of re-engaging LTFU patients on HIV transmission is crucial.

Purpose of the Study:

  • To investigate the effect of tracing and re-engaging HIV-infected patients lost to follow-up (LTFU) on HIV transmission.
  • To compare the efficiency of immediate versus delayed tracing strategies for LTFU patients.

Main Methods:

  • A stochastic mathematical model simulating cohorts of 1000 HIV-infected patients on antiretroviral therapy was developed.
  • Data from two clinics in Lilongwe, Malawi, informed the model parameters.
  • Scenarios included no LTFU, no tracing, immediate tracing, and delayed tracing (6 months) to estimate new HIV infections based on cohort viral load and transmission probability.

Main Results:

  • Approximately 44% of patients were lost to follow-up over five years.
  • No tracing resulted in an estimated 54 new infections per 1000 patients, compared to 33 with no LTFU.
  • Immediate tracing prevented an estimated 3.6 new infections per 1000 patients, while delayed tracing prevented 2.5, with immediate tracing being more efficient.

Conclusions:

  • Tracing patients lost to follow-up can enhance the preventive impact of antiretroviral therapy.
  • The number of new HIV transmissions prevented by tracing LTFU patients was relatively small.
  • Improved patient retention strategies are essential for maximizing the benefits of HIV treatment as prevention.
Abstract

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