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Treatment Interruption in a Primary Care Antiretroviral Therapy Program in South Africa: Cohort Analysis of Trends and Risk Factors

Kranzer, Katharina MBBS, MRCP, MSc, MSc*†; Lewis, James J BA, MSc, PhD‡§; Ford, Nathan MPH, PhD; Zeinecker, Jennifer MBChB, MPH*; Orrell, Catherine MBChB, MMed, MSc*; Lawn, Stephen D BMedSci, MBBS, MRCP, MD*†; Bekker, Linda-Gail MBChB, FCP, PhD*; Wood, Robin BSc, BM, MMed, FCP*

JAIDS Journal of Acquired Immune Deficiency Syndromes: November 1st, 2010 - Volume 55 - Issue 3 - p e17-e23
doi: 10.1097/QAI.0b013e3181f275fd
Implementation and Operational Research: Epidemiology and Prevention

Objective: To investigate antiretroviral treatment (ART) interruption in a long-term treatment cohort in South Africa.

Methods: All adults accessing ART between 2004 and 2009 were included in this analysis. Defaulting was defined as having stopped all ART drugs for more than 30 days. Treatment interrupters were patients who defaulted and returned to care during the study, whereas loss to follow-up was defined as defaulting and not returning to care. Kaplan-Meier estimates and Poisson regression models were used to analyze rates and determinants of defaulting therapy and of treatment resumption.

Results: Overall rate of defaulting treatment was 12.8 per 100 person-years (95% confidence interval: 11.4 to 14.4). Risk factors for defaulting were male gender, high baseline CD4 count, recency of ART initiation, and time on ART. The probability of resuming therapy within 3 years of defaulting therapy was 42% (event rate = 21.4 per 100 person-years). Factors associated with restarting treatment were female gender, older age, and time since defaulting.

Conclusions: Defaulting treatment need not be an irreversible event. Interventions to increase retention in care should target men, less immunocompromised patients, and patients during the first 6 months of treatment. Resumption of treatment is most likely within the first year of interrupting therapy.

From the *The Desmond TUTU HIV Centre, Institute for Infectious Disease and Molecular Medicine, Faculty of Health Science, University of Cape Town, South Africa; †Department of Infectious and Tropical Diseases, Clinical Research Unit, London School of Hygiene and Tropical Medicine, London, United Kingdom; ‡Aurum Institute for Health Research, Johannesburg, South Africa; §Department of Epidemiology and Population Health, Infectious Disease Epidemiology Unit, London School of Hygiene and Tropical Medicine, London, United Kingdom; and ∥Centre for Infectious Disease Epidemiology and Research, University of Cape Town, South Africa.

Received for publication May 3, 2010; accepted July 16, 2010.

The authors K.K. and S.D.L. are funded by the Wellcome Trust, London, United Kingdom. J.L. is funded by the Consortium to Respond Effectively to the AIDS TB Epidemic, who received funding from the Bill and Melinda Gates foundation. R.W. is funded in part by the National Institutes of Health through a CIPRA grant 1U19AI53217-01 and RO1 grant (A1058736-01A1).

No conflicts of interest to declare.

The authors K.K. designed the study, collected the data, and wrote the article with input from N.F., J.L., J.Z., C.O., S.D.L. and R.W.; K.K. designed and did the statistical analyses with input from J.L. and N.F; J.Z. and C.O. oversaw the field site; and R.W. was responsible for research infrastructure. All authors contributed to and approved the final version of the article.

Correspondence to: Katharina Kranzer, Desmond Tutu HIV Centre, Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory 7925Cape Town, South Africa (e-mail:

© 2010 Lippincott Williams & Wilkins, Inc.