TABLE II.

Diagnostic accuracy of the CD4/CD8 ratio in the P²C² HIV cohort at the 9-month age interval (151–365 days; n = 78 HIV-positive and n = 372 HIV-negative patients)

			Diagnostic accuracy measures
CD4/CD8 ratio	HIV-positive group No.*	HIV-negative group No.*	SE	SP	PPV	NPV	DLR+ (95% CI)	DLR− (95% CI)	Posttest probability (% [95% CI])
1.00	50	10	0.64	0.97	0.83	0.93	23.8 (12.7–44.9)	0.4 (0.3–0.5)	83 (80–86)
1.20	55	22	0.71	0.94	0.71	0.94	11.9 (7.8–18.3)	0.3 (0.2–0.4)	71 (66–75)
1.40	56	37	0.72	0.90	0.60	0.94	7.2 (5.2–10.1)	0.3 (0.2–0.5)	60 (54–64)
1.60	58	56	0.74	0.85	0.51	0.94	4.9 (3.8–6.5)	0.3 (0.2–0.4)	50 (45–55)
1.80	65	88	0.83	0.76	0.42	0.96	3.5 (2.9–4.3)	0.2 (0.1–0.4)	42 (36–47)
2.00	68	115	0.87	0.69	0.37	0.96	2.8 (2.4–3.4)	0.2 (0.1–0.3)	37 (31–41)
2.20	71	145	0.91	0.61	0.33	0.97	2.3 (2.0–2.7)	0.2 (0.1–0.3)	32 (28–37)
2.40	74	175	0.95	0.53	0.30	0.98	2.0 (1.8–2.3)	0.1 (0.0–0.3)	29 (25–34)
2.60	77	207	0.99	0.44	0.27	0.99	1.8 (1.6–2.0)	0.03 (0.0–0.2)	27 (22–31)
Total†	78	372

The pretest probability is 17% (95% CI, 14% to 20%).

SE, Sensitivity; SP, specificity; PPV, positive predictive value; NPV, negative predictive value; DLR⁺, diagnostic positive likelihood ratio; DLR⁻, diagnostic negative likelihood ratio.

^*Number of infants having a CD4/CD8 ratio of less than the cutoff point within each HIV group.

^†Total, Number of infants in this age interval within each HIV group.