Table 1.

Characteristics of the Cohort (Men and Women Infected With HIV Type 1) and the 20% Subcohort at Baseline and During Follow-up, Multicenter AIDS Cohort Study and Women’s Interagency HIV Study, 1996–2007

Characteristic	Cohort (n = 950)			Subcohorta (n = 190)
	%	Mean (SD)	No.	%	Mean (SD)	No.
At baseline in 1996
Mean age, years		39 (8)			38 (8)
Female sex	61		578	57		108
African-American race	59		560	54		102
Mean CD4 cell count, no. of cells/mm3		498 (279)			489 (283)
Mean log10 HIV-1 RNA level, no. of copies/mL		4.5 (0.7)b			4.5 (0.7)c
Over follow-up between 1996 and 2007
No. of person-years			4,456			861
No. of exposed person-years			2,974			590
No. with incident AIDS or death			211			41

Abbreviations: AIDS, acquired immunodeficiency syndrome; HIV, human immunodeficiency virus; SD, standard deviation.

^aThe subcohort comprised 20% of 950 cohort participants chosen at random.

^bAmong 705 detectable measurements.

^cAmong 145 detectable measurements.