TABLE 6.

Comparison of between-laboratory precision in absolute T-cell counts for predicate method versus Flow-Count method^a

T cells	CD4 stratum (cells/μl)	Median %CV (P vs predicate method)
		Predicate method	Flow-Count method
CD4	All	18.2	10.8 (0.000)
	<200	19.5	12.0 (0.000)
	200–500	16.7	9.4 (0.007)
	>500	18.8	12.1 (0.055)
CD8	All	16.9	10.1 (0.000)
	<200	18.1	10.8 (0.000)
	200–500	15.5	7.9 (0.002)
	>500	17.2	10.8 (0.098)

^a%CVs were calculated from the same specimens analyzed by both methods in all five laboratories. %CV by the predicate method was compared with %CV by the test method as described in Materials and Methods. A P value of <0.025 was considered significant.