Six RCTs were included (n=1,663 at 24 weeks: 679 AZT-treated and 984 d4T-treated patients; n=1,595 at 48 weeks: 649 AZT-treated and 946 d4T-treated patients).
The mean Hb levels decreased with AZT by 0.4 g/dL (SE=0.05) at 24 weeks and by 0.2 g/dL (SE=0.06) at 48 weeks. However, the mean Hb levels increased with d4T by 0.45 g/dL (SE=0.03) and 0.58 g/dL (SE=0.04), respectively.
AZT-based regimens were associated with significantly reduced Hb levels at 24 and 48 weeks in comparison with d4T-based regimens (SMDs 0.87 and 0.79, respectively).
All studies found that AZT increased anaemia and grade 1 to 4 neutropenic events in comparison with d4T (the results for the individual studies were tabulated), although no statistical analysis was reported.
There were no statistically significant differences between the treatments in terms of CD4 counts at 24 or 48 weeks (respective changes in cells/mm3: +147 with AZT versus +158 with d4T; +193 with AZT versus +199 with d4T), or in viral load at 24 or 48 weeks (respective changes in log copies/mL: -2.33 with AZT versus -2.44 with d4T; -2.35 with AZT versus -2.44 with d4T).
There was no significant difference in haematological events between regimens containing 3TC and those containing ddI as the second agent (no data were reported).