TABLE 2.

Rate of change per month for virologic and immunologic measurements during long-term virologic failure of a stable protease inhibitor-based regimen^a

Variable	Estimate	P
(n = 20)
Plasma HIV RNA level (log copies/ml/mo)	0.008	<0.0001
CD4+ T cells (cells/μl/mo)	1.63	<0.0001
Protease inhibitor susceptibility (fold change/mo, log transformed)	0.02	<0.0001
Zidovudine susceptibility (fold change/mo, log transformed)	0.01	<0.0001
Replicative capacity (% change/mo)	−0.17	0.009

^aRate-of-change estimates were calculated from the earliest date during virologic failure for which a specimen was available until therapy was modified or discontinued (median duration of observation, 26.2 months per individual).