Should treatment breaks be guided by CD4? Study suggests yes

Michael Carter
Estimated reading time 2 minutes
This article is more than 21 years old.

According to research presented as a poster to the Seventh ICAAC in Chicago on September 15th, individuals may be able to interrupt HAART if they have a high nadir CD4 cell count, lost CD4 cells slowly before starting anti-HIV therapy, and have maintained an undetectable viral load for at least a year whilst taking HAART. Data presented this week at the 43rd Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC) suggested that patients whose nadir CD4 cell count was above 350 cells/mm3 and had achieved an undetectable viral load for at least a year whilst sustaining a CD4 cell count of over 800 cells/mm3, could safely interrupt HAART for a prolonged period.

Investigators conducted a multi-centre, observational, retrospective study involving 140 patients from several treatment centres in Italy, Sweden and the UK. To be included in the analysis, a patient must have taken HAART for at least twelve months, have a nadir CD4 cell count above 250 cells/mm3, a pre-treatment interruption CD4 cell count of at least 500 cells/mm3, and to have taken a break from HIV therapy for at least four weeks.

HAART was restarted if a patient’s CD4 cell count fell below 350 cells/mm3 or if they expressed a wish to recommence treatment.

Glossary

nadir

Lowest of a series of measurements. For example, an individual’s CD4 nadir is their lowest ever measured CD4 count.

treatment interruption

Taking a planned break from HIV treatment, sometimes known as a ‘drugs holiday’. As this has been shown to lead to worse outcomes, treatment interruptions are not recommended. 

retrospective study

A type of longitudinal study in which information is collected on what has previously happened to people - for example, by reviewing their medical notes or by interviewing them about past events. 

observational study

A study design in which patients receive routine clinical care and researchers record the outcome. Observational studies can provide useful information but are considered less reliable than experimental studies such as randomised controlled trials. Some examples of observational studies are cohort studies and case-control studies.

chemotherapy

The use of drugs to treat an illness, especially cancer.

Median CD4 cell count when the study patients initially started HAART was 410 cells/mm3, and median viral load was 26,000 copies/mL. The study participants had been infected with HIV for an average of three and a half years.

At the point of treatment interruption, median CD4 cell count was 804 cells/mm3 and median viral load was 50 copies/mL.

As of April 1st 2003, 53% of patients were still off-therapy, 24.3% had experienced a drop in their CD4 cell count to below 350 cells/mm3 and 22% had restarted HAART. The median duration of the treatment interruption at this point was 104 weeks.

Investigators established that independent predictors of having to restart therapy were lowest ever CD4 cell count, duration of an undetectable HIV viral load whilst on HAART, the rate with which CD4 cell count declined before HAART was initially started, and HIV viral load immediately before the treatment break was commenced.

An individual can interrupt HAART for a long-time, the investigators conclude, if their CD4 cell count never dropped below 350 cells/mm3 prior to first commencing anti-HIV therapy, HAART achieved a viral load below 50 copies/mL for at least twelve months, their CD4 cell count fell slowly before HAART was initiated, and during the treatment break HIV viral load only rebounds to low levels.

References

Mussini C et al. CD4-guided treatment interruptions: a new therapeutic strategy. 43rd ICAAC, abstract H-856, Chicago 14 -17th September, 2003.

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