 |
|
|
| |
Treatment Breaks With >400 Copies Raise Risk of Later Rebound
|
| |
| |
8th International Congress on Drug Therapy in HIV Infection
November 12-16, 2006
Glasgow, Scotland
Mark Mascolini
Interrupting antiretroviral therapy when the viral load exceeds 400 copies boosts the risk of viral rebound if the interrupter resumes therapy and reaches a load under 50 copies [1]. Three or more treatment breaks make later rebound risk more likely than one or two breaks--even after statistical adjustment for confounding factors.
Those conclusions emerged from a study of 12,997 people in the UK CHIC cohort who pushed their viral load below 50 copies with antiretroviral therapy. From that group, 2246 (17.3%) had taken at least one treatment break, including 2047 who took one or two breaks and 199 who took three or more.
With London colleagues Loveleen Bansi from the Royal Free and University College Medical School undertook the study because earlier research showed that many people who suspend antiretroviral therapy can control HIV when they resume treatment. But no one had analyzed whether such people risk rebound after suppression.
Defining viral rebound as two consecutive loads above 400 copies or one load above 400 copies followed by a regimen change, Bansi counted 2202 rebounds in 31,060 person-years of follow-up among people who never took a drug holiday for a rate of 7.1 rebounds per 100 person years. Among people who took one or two holidays, she tallied 704 rebounds in 5799 person-years for a rebound rate of 12.1 per 100 person-years. And among people who took three or more holidays, she chalked up 106 rebounds in 472 person-years for a rate of 22.5 per 100 person-years.
Statistical analysis adjusted for whether viral load was detectable at treatment interruption determined that people with an undetectable load at interruption did not have a higher risk of later rebound than people who never suspended therapy. But people who took one or two breaks with a detectable load had a 34% higher risk of rebound than noninterrupters, and people who took three or more breaks had an 89% higher risk. In addition, every additional failed regimen on a person's chart also independently raised the risk of rebound. These analyses also factored in viral load when antiretroviral therapy began, time since beginning antiretroviral therapy, and the interaction between time with an undetectable load and the number of regimens that failed.
With senior investigator Andrew Phillips, Bansi proposed that rebound rates may increase with a higher number of treatment breaks because resistant virus may emerge during drug holidays with a detectable viral load. Unmeasurable variables, such as worse adherence in people who tend to suspend treatment, may also contribute to the inflated rebound risk.
The researchers caution that "patients should be made aware that there is a potential risk associated with treatment interruption even if viral suppression is achieved" after the drug break.
Reference
1. Bansi L, Benzie A, Sabin CA, Phillips AN. Are treatment interruptions associated with higher viral rebound rates in patients with viral suppression? 8th International Congress on Drug Therapy in HIV Infection, November 12-16, 2006, Glasgow. Abstract PL8.3.
|
| |
|
|
|
|
|
