A drug is effective if better than a harmless control

摘要

Sir- In his Correspondence letter "HIV drug remains unproven without placebo trial" (Nature 434, 137; 2005), Valendar Turner asks on what basis it can be claimed that the single-dose nevirapine regimen is effective in reducing mother-to-infant HIV transmission. He points out that the placebo arm was dropped in the HIVNET 012 trial (of which we were team members) and notes the high variability in reported historical HIV transmission rates. But he ignores the valid comparison made by the HIVNET 012 trial — whose conclusions were recently accepted by a US Institute of Medicine panel — between nevirapine and another drug, zidovudine, which had itself been tested against a placebo in other studies starting at least four weeks before labour.