314   START Observational Study: Longitudinal Follow-Up of Virologic and Immunologic Responses in START I and START II Patients.

R. Murphy*¹, J. Santana², K. Squires³, B. Yangco⁴, D. Peterson⁵, J. Adams⁶, J. Mauney⁶, M. Perry⁶, R. Grosso⁷, J. Tudor⁷, M. Stevens⁷, and the Start Observation Team.
¹Northwestern Univ., Chicago, IL,²San Juan AIDS Program, Santruce, PR;³Univ. of Southern California, Los Angeles;⁴Infectious Disease Res. Inst., Tampa, FL;⁵Univ. of Texas Southwestern Med. Ctr., Dallas;⁶PharmaResearch Corp., Morrisville, NC; and⁷Bristol-Myers Squibb, Princeton, NJ.

Background:The START trials were prospective, randomized, open label, multicenter studies that compared d4T + 3TC + IDV ("A"; n = 101; START I) and d4T + ddI (chewable tablets) + IDV ("B"; n = 102; START II) to ZDV + 3TC + IDV ("C"; n = 206; START I and II) in treatment (tx)-naive patients (pts) for a minimum of 48 weeks. Data from available pts who re-consented for continued follow-up through October 2000 are included.

Methods:Plasma HIV-1 RNA levels and CD4 counts were obtained every 6—12 weeks following START I or II participation. Comparisons of the proportions of pts with plasma HIV-1 RNA <500 copies/mL were made using Fisher's exact test. CD4 count changes from baseline (pre-tx) were compared among regimens using the Wilcoxon rank-sum test.

Results:Overall median (range) baseline HIV-1 RNA and CD4 counts were 4.53 (3.10—5.96) log₁₀copies/mL and 407 (136—1176) cells/mm³

respectively; values were similar in all tx groups. At week 72, the proportions of available pts remaining on initial therapy with HIV-1 RNA <500 copies/mL were 39/44 (89%), 27/35 (77%), and 55/67 (82%) in those assigned to the A, B, and C groups, respectively (p > 0.20 for all pairwise comparisons). At week 144, these proportions were 7/13 (54%) in group A, 2/7 (29%) in group B, and 7/15 (47%) in group C (p = 0.35). Median (range) changes from baseline in CD4 counts at week 72 were 246 (20 to 798), 269 (-91 to 617), and 232 (-354 to 741) cells/mm³in pts continuing to receive originally assigned tx in groups A (n = 41), B (n = 31), and C (n = 61), respectively (p > 0.35). At week 144 these changes (cells/mm³) were 446 (287 to 571) in group A (n = 8), 414 (305 to 523) in group B (n = 2), and 561 (164 to 1074) in group C (n = 7) (p > 0.55).

Conclusions:There were no statistically significant differences among d4T + 3TC + IDV, d4T + ddI + IDV, and ZDV + 3TC + IDV pts experiencing durable virologic and immunologic responses at weeks 72 and 144.