Zidovudine-induced neutropenia: are we too cautious?

30 patients with recurrent zidovudine-induced neutropenia were followed up for a total of 493 months of treatment to evaluate their risk of bacterial infection. Zidovudine was temporarily discontinued only when the polymorphonuclear (PMN) cell count fell to less than 500/microliters. The incidence of bacterial infection during periods of severe neutropenia (PMN less than 500/microliters) was 230% higher than when the PMN count was 500-1000/microliters, and 600% higher than when the count was greater than 1000/microliters. The difference between periods when the PMU count was 500-1000/microliters and non-neutropenic periods was not significant. The findings suggest that zidovudine therapy can be continued despite neutropenia without a major increase in the incidence of bacterial infection provided the PMN count does not fall to less than 500/microliters.