Low and decreasing rate of viral rebound with prolonged viral suppression on HAART: insights into the long-termimpact of resistance

With all the headlines in the press screaming about the likelihood of patients losing their viral load suppression many patients get discouraged. This study suggests that if you keep your viral load undetectable for two years and remain adherent long-term viral suppression may occur.

Andrew Phillips, with the Royal Free and University College Medical School in London, reported on this study of 406 drug-na´ve patients starting a HAART regimen including protease inhibitor or NNRTI therapy with 2 NRTIs. The median baseline viral load was 250,000 copies/ml (range 830-5 million). The median CD4 was 259. Using a sensitive viral load assay the median VL decline was 4.8 logs by week 48. This method permitted characterizing the full VL decline, which is normally cut off by detection limits of the assays usually used. Ninety-one percent reached VL <500 copies/ml by 24 weeks. Of those who achieved a VL <500 (n=342), 69 had a viral rebound (2 consecutive values >500 copies/ml) in 344 person years of follow-up. There was a fairly low overall rate of rebound. By week 48 21% experienced a VL rebound after initial suppression below 500 copies/ml. However, the rate of VL rebound decreased as only 26% experienced rebound at the 96 week time-point.

Ninety-seven percent of patients who reduced their VL <500 copies/ml had at least 1 HIV-RNA value <50 copies/ml. Statistical analysis (Cox regression analysis) indicated that there was a significant decrease in the rate of viral rebound with increasing length of viral suppression. That is,  the longer you stay undetectable the longer you are more likely to remain undetectable, if adherent. There was a rate of only 0.8 rebounds per 10 years (8 rebounds in 99 person-years; i.e. average of 1 rebound per 12.4 years) in people who had experienced VL <500 copies/ml for over 1 year.

In conclusion.  Phillips said that although we have not followed patients for more than a maximum of about 3 years this low and decreasing rate of viral rebound in patients with at least 1 year viral suppression implies that, if prolonged complete drug adherence were possible, long-term viral suppression for 10 years and more seems within the capacity of presently available regimens.