Recommendations concerning the use of NNRTIs in the recently
updated BHIVA guidelines have been questioned in two recent letters to The
Lancet.
Dr Philip Hay of St George’s Hospital, London, and Dr Julio Montaner, INCAS
Principal Investigator, have both questioned the suggestion that the use of
non-nucleosides nevirapine and delavirdine should be confined to people with
baseline viral load below 50,000.
Dr Hay cites two studies: a poster presented in Geneva by Dr Julio Montaner
and colleagues on the INCAS study, and a retrospective audit of people in the UK
who received nevirapine through the expanded access programme.
"The meta analysis cited does not provide evidence to support the threshold
for an NNRTI and two nucleoside combination…there is evidence to indicate that
NNRTIs are effective in patients with pretreatment viral loads in excess [of
50,000 copies].", writes Dr Hay (The Lancet 352, October 10 1998, p1226)
Although Montaner’s group demonstrated a trend towards poorer viral
suppression as baseline viral load increased, the only significant threshold for
poorer viral load suppression was above 250,000 copies. People with baseline
viral load above 250,000 copies were 2.33 times more likely than those with
viral load below 50,000 copies to experience a rebound in viral load above 5,000
copies by week 48 of the study.
The audit of participants in the UK nevirapine expanded access programme by
Dr Martin Fisher and colleagues showed no relation between reaching undetectable
viral load and baseline viral load for treatment naïve patients.
Montaner and colleagues point out that although they found a significant
relationship between baseline viral load and subsequent viral suppression,
"there was no clear cut off point beyond which nevirapine was no longer
effective to reduce or maintain pVL at a low level…these results do not allow us
to propose an upper limit of baseline pVL for the effective initiation of
nevirapine or PI containing regimens".
Montaner also notes that there are no comparative data on the relative merits
of the currently available NNRTIs, and that it may be premature to suggest that
efavirenz is more potent than other NNRTIs on the basis of Staszewski’s open
label comparison of efavirenz with indinavir in DMP-266-006.
The full text of the British HIV Association 1998 guidelines can be href="../October/story7.htm">read here