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Session 81 Poster Abstracts
Antiretroviral Treatment Strategies
Monday, 1:30 - 3:30 pm
Poster Hall


568    
Biphasic Decline of CD4 Cell Count during Scheduled Treatment Interruptions
C Fagard1, J Ananworanich1, M Le Braz1, S Saenawat2, S Wicharuk2, T Perneger1, L Perrin1, D Cooper3, M Cavassini4, C Ebnöther5, D Genné6, P Vernazza7, E Bernasconi8, R Nuesch9, and B Hirschel*1
1Univ. Hosp. Geneva, Switzerland; 2HIVNAT, Bangkok, Thailand; 3Natl. Ctr. in HIV Epidemiology and Clin. Res., Univ. of New South Wales, Sydney, Australia; 4CHUV, Lausanne, Switzerland; 5Univ. Hosp. Zurich, Switzerland; 6Hosp. de La Chaux de Fonds, Switzerland; 7Kantonsspital St. Gallen, Switzerland; 8Hosp. Civico, Lugano, Switzerland; and 9Univ. Hosp., Basel, Switzerland

Background:  Scheduled treatment interruptions aim to diminish costs and side effects of HAART. CD4 cell counts tend to decline during scheduled treatment interruptions, but the speed and the size of the decline vary among patients. We investigated kinetics of the decline, and predictive factors.

Methods:  We analyzed CD4 cell counts from 195 patients with at least 4 weeks’ treatment interruption who participated in three prospective trials of scheduled treatment interruption (SSITT-1, SITT-2, and Staccato). In 94 of these, scheduled treatment interruptions lasted at least 24 weeks. CD4 cell counts were measured after 4, 8, 12, and 24 weeks of treatment interruption.

Results:  Pre-HAART viral load (relative risk of starting treatment before week 24 = 2.3 per log decrease) , and pre-HAART CD4 count (RR of 1.8 per 100 increase) predicted long (³24 weeks), as compared to short (<24 weeks) scheduled treatment interruptions. Of the 195 patients, 130 completed 12 weeks of treatment interruption, and 94 completed 24 weeks. The mean CD4 count before HAART was 350 (11 to 1892), with a mean viral load of 82,370, and CD4 counts during the first 24 weeks are scheduled treatment interruptions is shown in the table below:

 

 

week 0

 

week 4

 

week 8

 

week 12

 

week 24

n

130

 

130

 

130

 

130

 

94

CD4 count (mean)

784

 

645

 

642

 

611

 

595

Mean fall/week

 

35

 

0.75

 

7.8

 

4.1

Fall in % per week

 

3.8

 

0.10

 

0.89

 

0.52

 

p between declines/week

 

 

<0.001

 

NS

 

NS

 

 

 

The higher the CD4 count at week 0, and the higher the viral load rebound at week 4, the steeper the decline in CD4 cells from weeks 0 to 4 (p <0.01 in multivariate analysis). This correlation held true when percentage decline was substituted for absolute decline. There was no significant correlation between viral load or CD4 count pre-HAART, and CD4 decline during scheduled treatment interruptions.

Conclusions:  In patients with long (³ 12 weeks) scheduled treatment interruptions, CD4 counts decline by approximately 35 cells per week during the first 4 weeks of scheduled treatment interruption, and by approximately 4 cells per week during the next 20 weeks.

 

Keywords: Scheduled Treatment Interruptions; STI; CD4 counts