Q: I've been on combination therapy for two years. When I started, my CD4 count was at a low of 12, but for the past year it has danced between 250 and 350. I've faithfully kept taking Bactrim to prevent PCP (Pneumocystis carinii pneumonia), but I'm tired of juggling so many pills and managing the side effects. Is it safe for me to drop it?

--J.C., Topeka, Kansas

Malte Schultz, MD
Associate Director of HIV Services, Illinois Masonic Medical Center, and Assistant Professor of Medicine, Rush Medical College, Chicago

Until recently, standard guidelines called for every PWA who's ever had fewer than 200 CD4 cells to stay on PCP-preventative meds for life. But now opinion has shifted and the federal guidelines have been revised. With your numbers, if you've never had PCP, it should be safe to stop Bactrim. Three studies published this year found that when CD4 counts rebounded to more than 200 for at least three to six months, patients did not develop PCP for up to a year after stopping primary prophylaxis (medication to prevent a first-time infection). Long-term data are not yet available. But if you had PCP in the past and are taking Bactrim to prevent a recurring infection (known as secondary prophylaxis), I would be very cautious about stopping it, as there is little data about the safety of that. Either way, if your viral load isn't fully suppressed--that is, undetectable--I would hesitate to withdraw Bactrim, because your CD4 count might drop back down below 200 in the future.

Charles Carpenter, MD
Physician-Chief, Miriam Hospital, and Professor of Medicine, Brown University, Providence

While I agree that existing data support stopping PCP primary prophylaxis whenever the CD4 count has remained above 200 on two tests over a three month period, I would put the upper limit of viral load at 10,000. Although one recent study suggested that it might be safe to discontinue Bactrim with a viral load of up to 30,000, I prefer the lower number because of that test's imprecision. When a test result shows 10,000, I feel confident that the true value lies between 3,000 and 30,000. If this guideline is followed, PCP is exceedingly rare.

This column contains general medical information only. Consult your physician before making decisions.