The folks in the lab coats have an on-again, off-again relationship with what’s called CD4-guided intermittent therapy—taking HIV meds only when your CD4 count falls and ditching them when it rebounds. Two studies with cute acronyms—SMART and STACCATO—reached drastically different conclusions this year. The bigger trial (SMART: 5,472 enrollees) suggests we can’t safely go on and off meds; STACCATO (430) says maybe we can. Which should we trust?

Each study divided subjects into a group taking meds continuously and another starting and stopping based on CD4s. The SMART on-off group restarted meds at 250 CD4s, STACCATO at 350. After 14 months, SMART was halted because the intermittent group had 120 AIDS complications or deaths compared with 47 in the continuous group. In STACCATO, the on-off group didn’t experience more illnesses or deaths—or drug resistance—over 21 months.  

More study is needed, says Bernard Hirschel, MD, STACCATO leader. Meanwhile, SMART investigator Cal Cohen, MD, warns, “Even above 350 CD4s, SMART patients off meds with [detectable HIV] had higher risk compared to those on continuous treatment.” If nothing else, the studies pinpoint the trade-off: higher risk of illness vs. perpetual daily doses. Some choice! Whichever way you turn, ask Doc first.