Table 1. Stratification of cohort into HIV-1 disease progression groupings.

No of Individuals	Range of CD4 counts utilised per person	Median annual CD4 count change (Interquartile range)		Cut-off CD4 T-cells per µl/year	Stratification group
		Undjusted1	Adjusted2
7	8–18	−113 (−116 to −102)	−118 (−119 to −109)	<−101	1
8	10–17	−81 (−89 to −75)	−88 (−95 to −86)	−91 to +10	2
78	10–27	−24 (−47 to −13)	−38 (−58 to −29)		3
3	20–21	+10 (10 to 10)	−0 (−10 to −0)		4
14	14–24	+24 (20 to 46)	+9 (5 to 19)	>16	5

¹CD4+ T cell decline without adjusting for first CD4 count and age of the participant.

²CD4+ T cell decline after adjusting for first CD4 count and age of the participant.

Table 1 illustrates the stratification of 110 chronically HIV-1 adults into distinct progression groups. Six-monthly retrospective CD4 counts were used in a multilevel regression model to derive individual participant CD4 slopes. The slopes were calculated over a median observation time of 610 months (minimum-maximum 18–97 months). Annual CD4+ T-cell changes are expressed as medians with interquartile ranges. Positive (+) symbols indicate increasing CD4+ counts while (−) indicates decreasing CD4+ counts over time. Individuals in the extreme stratification group 1 were selected as rapid progressors (RP, n = 7) while those in group 5 were selected as slow progressors (SP, n = 14). Groups 2, 4and 4 were categorised as normal progressors (NP, n = 89). Normal progressors were those with CD4 slopes between −91/year to +10/year; RPs had CD4 slopes <−91/year while SPs had CD4 slopes >+10/year.