This conference poster presents the results of the NORA substudy of the DART trial, which involved 600 patients randomised to initiate antiretroviral therapy (ART) with ZDV+3TC (Combivir, CBV) plus Abacavir (ABC) or Nevirapine (NVP). Primary and secondary endpoints were toxicity at 24 weeks (placebo-blinded), with continued open-label follow-up after 24 weeks for up to 5 years in DART. The study found there was no statistically significant difference in the rate of new WHO 4 events/death or death between participants initiating ART with Combivir plus Neverapine versus Abacavir through 5 years follow up. Including time-dependent factors in multivariable models is the standard method for adjustment in observational anaylses, but provides incomplete adjustment for time-dependent confounders