Table 2.

Hazard ratios for AIDS or death for deferral of combination antiretroviral therapy to a lower CD4 cell count range versus initiation at a higher CD4 cell count range

Higher CD4 cell count range (cells per μL)	Lower CD4 cell count range (cells per μL)	Data for 1989–95*			Data for patients on combination antiretroviral therapy			Hazard ratio (95% CI) for AIDS or death
		Number of patients in higher CD4 cell count range	Estimated median lead time (years)†	Estimated proportion of patients progressing to AIDS/death before reaching upper threshold of lower CD4 cell count range (% [95% CI])	Number of patients	Number of AIDS/death events	Estimated number of unseen events	Naive‡	Adjusted for lead times and unseen events
451–550	351–450	5015	0·67	1·6% (1·1–2·1)	5047	260	53	1·04 (0·81–1·34)	0·99 (0·76–1·29)
426–525	326–425	5792	0·77	2·3% (1·7–2·9)	5898	314	91	1·12 (0·89–1·42)	1·12 (0·87–1·43)
401–500	301–400	6536	0·80	2·7% (2·0–3·4)	6874	366	126	1·04 (0·84–1·29)	1·09 (0·85–1·38)
376–475	276–375	7029	0·84	2·8% (2·2–3·5)	7926	400	151	1·11 (0·91–1·37)	1·19 (0·96–1·47)
351–450	251–350	7433	0·84	3·2% (2·5–3·9)	8989	472	189	1·17 (0·97–1·41)	1·28 (1·04–1·57)
326–425	226–325	7775	0·86	3·3% (2·7–3·8)	10067	530	208	1·08 (0·90–1·28)	1·21 (1·01–1·46)
301–400	201–300	8226	0·89	3·8% (3·1–4·5)	10980	584	258	1·15 (0·98–1·36)	1·34 (1·12–1·61)
276–375	176–275	8519	0·91	5·3% (4·3–6·3)	11 775	640	366	1·23 (1·05–1·44)	1·59 (1·30–1·95)
251–350	151–250	8748	0·92	6·1% (5·2–7·0)	12 104	719	412	1·30 (1·12–1·51)	1·71 (1·43–2·04)
226–325	126–225	8788	0·91	7·0% (6·2–7·8)	12 206	763	452	1·47 (1·27–1·70)	2·01 (1·73–2·35)
201–300	101–200	8878	0·92	8·1% (7·2–9·1)	11 976	822	485	1·59 (1·38–1·82)	2·21 (1·91–2·56)
176–275	76–175	8282	0·90	9·5% (8·6–10·4)	11 534	908	523	1·82 (1·60–2·08)	2·61 (2·27–3·00)
151–250	51–150	7484	0·95	10·8% (9·9–11·7)	10 926	957	549	1·76 (1·55–2·01)	2·59 (2·29–2·92)
126–225	26–125	6742	0·95	13·1% (12·1–14·1)	10 276	1088	642	2·01 (1·78–2·27)	2·88 (2·56–3·25)
101–200	0–100	5871	0·92	17·6% (16·3–18·9)	10 014	1332	969	2·25 (2·01–2·51)	3·35 (2·99–3·75)

CD4 cell count ranges have widths of 100 cells per μL, in increments of 25 cells per μL. Note that results in overlapping ranges are not statistically independent of each other.

^*Data for patients followed up in the era before the introduction of combination antiretroviral therapy.

^†Time from first CD4 cell count measurement in upper range to upper threshold of lower CD4 cell count range, AIDS, or death.

^‡Hazard ratio based on analyses that ignored lead time and unseen AIDS and death events.